Acoustics in the Worship Space IX

Acoustic excellence is derived from wise design planning and decision-making regarding elements that are already “givens” within a project and budget

Acoustics in the Worship Space I, II, III, IV, V, VI, VII, VIII, and IX have appeared in The Diapason, May 1983, May 1984, January 1986, May 1987, April 1988, April 1990, July 1991, May 1992, and April 2009 issues respectively.

In today’s world and economy, costs and budgets loom large in almost all activities and endeavors. During discussions of new church building or renovation projects, it might not be uncommon to hear the following ideas expressed: “Good acoustics aren’t really worth it for the average worshipper who won’t notice or appreciate it—that’s just for the elite ‘Carnegie Hall crowd;’” or, “It will cost too much to have good acoustics, and we cannot afford it.” When these notions surface they can sometimes be the cause for a church being doomed to a less than excellent acoustic environment.

Scientifically and experientially, it can be proven that good acoustic settings are indeed noticeable and appreciated by many, and not only by the “Carnegie Hall crowd”! In fact, acoustic qualities such as speech intelligibility, musical balance, and rhythmic and tuning accuracy can be scientifically tested and documented as being perceived and valued by a cross section of the population. The notion that “regular folks” won’t notice good acoustics is just scientifically false!

Economic issues are often the most difficult to resolve in many projects. Reduced availability of funds, lack of confidence in the economy, and the fear of future economic conditions are often governing factors. Indeed, when constructing a new worship facility or remodeling an existing one, many important matters tug at the purse strings, and budgeting can often be a stressor to a project. That said, it would still be eminently beneficial to consider acoustic issues seriously, and not simply dismiss acoustic excellence as being unaffordable or unattainable. Acoustic excellence does not necessarily mean purchasing “extra” or expensive features. Often, acoustic excellence can be realized from wise decisions and design choices regarding elements that are already a given part of a project.  

The primary architectural factors that affect the acoustic environment include the geometric form of a room (does the structure’s cubic air volume and shape enhance or detract from good sound?), the interior materials of a room (to what extent do selected interior finishes reflect, absorb, or transmit sound energy in a structure?), and the location of key elements (do the relative proximities of things such as microphones, speakers, singers, organ pipes, instruments, and even potentially noise-generating equipment help or hinder sound perception?). Wise or poor design choices regarding any of these factors can result in acoustic excellence or disaster.  

Geometric form of a room

Geometric room forms can distribute and project sound evenly through a space, or can generate unwanted tonal focusing, echoes, and standing waves. Successful worship space geometries typically have generous cubic air volumes, longer and shorter axes, and unobstructed “line of sight” sound projection paths. Sound-diffusing wall and ceiling surface profiles and features will also contribute to even distribution and dispersing of sound energy. Alternatively, low ceilings, flat and parallel surfaces, concave forms, deep transepts, etc., typically limit acoustical potential and create echoes, “hot spots,” “dead spots,” flutters, trapping, and other unwanted and disturbing acoustical anomalies.

Interior materials of a room

Appropriate ratios of sound-reflective to sound-absorbing materials in a room can result in a vibrant and reverberative space that enlivens music and liturgical participation, and produces 

authoritative speech. Alternatively, excessive amounts of carpeting, draperies, and other sound-absorbing features can deliver a dull, dead effect that suffocates worship participation and leaves music and speech uninspiring. Having a carefully selected ratio of sound-reflecting to sound-absorbing materials, which results in an appropriate reverberation period, is essential to a worthwhile acoustic setting.  

Location of key elements

Then there is location! The relative placement of organ pipes and choir singers together will allow choristers to hear accompaniments and each other clearly and facilitate accurate rhythm and tuning. For example, positioning singers in an ensemble format, forward and below organ cases or chambers, can maximize musical potential. If singers are placed far from organ pipes, within restrictive alcoves, behind obstructions, or strung out in long lines, the entire musical ensemble will suffer from being disengaged. Similarly, the correct location of loudspeakers relative to both microphones and the listening congregation can assure speech intelligibility for all, while inappropriate placement of sound system components can result in frustration and lost clarity for all; if loudspeakers are placed with direct “line of sight” access to all listeners, they can deliver sound with clarity. Ultimately, it is not enough to have all of the sound sources and listeners “somewhere” in the room.  Relational locations and proximities are critical to success.

Finally, even if all of the beneficial acoustic design features for room geometry, material selections, and functional proximities are adopted, all can still be ruined if unwanted and interrupting noises invade the worship space. Techniques such as placing noise-generating equipment and functions away from the worship space, and using resilient mountings and discontinuous structures can mitigate “noise to listener” pathways.  

Acoustic excellence

In all of these examples, acoustic success is not derived from expensive treatments or extra apparatus. Acoustic excellence is instead derived from wise design planning and decision-making regarding elements that are already “givens” within a project and budget. It may cost no more or less to place organ pipes in good or poor proximity to choir singers! It may cost no more or less to place noise-generating air-conditioning compressors near or far from the worship space! It may cost no more or less to angle a wall profile to avoid or create an echo! In many instances, the good acoustic choice can indeed be the least costly choice. For example, a hard surface floor that reinforces sound energy will last a lifetime, while a carpeted floor that removes sound energy from an environment will wear over time and eventually require replacement.  

While significant acoustic success can be realized from informed design and decision-making, it should not be inferred, however, that all acoustic matters are free and easy! There are some acoustic benefits worth paying for. Hard, dense walls that reinforce and balance low frequency tone near organ pipes and choir singers are indeed more expensive than thin gypsum board, but the price of the thin walls can be perpetually brittle and “tinny” music. It may cost more to hoist heavy loudspeakers to a high ceiling location than to wall-mount smaller units, but the price of poor speaker placement is a missed opportunity to proclaim the word with clarity and intelligibility. It may cost more to line air-conditioning ducts to prevent noise transmission, but constant HVAC noise interrupting speech and music during worship ruins the experience for all. While these and similarly important acoustic details do have an initial price tag, the cost of remedying these details later is even greater. As a wise observer once said, “If you don’t have the funds to do it right the first time, where are you going to find the additional funds to do it over again?” So, the functional value of design decisions must also be considered along with cost.

Substantial and significant acoustic benefits can result from making wise choices about already-fixed costs. A building will have floors, walls, and ceiling; these can be designed to work in favor of a good acoustic environment through careful detailing, and not necessarily through additional expense. A good acoustical environment can be defeated through uninformed and unwise design, and not necessarily because of lack of spending! Great acoustical worship environments are indeed achievable, even on a budget. Careful overall planning that maximizes the acoustic potential of a design, combined with reasonable spending on priority features, can result in architectural, functional, and inspirational value for generations.

Photo credit: Scott R. Riedel & Associates.

An heretical view of acoustics

In the world of music at large the organ is often considered an outcast, a curiosity, or at best an antique. One reason is that much of the organ world is thought to be more concerned with sound for its own sake than with music. This characterization may be unfair, but it is partly our own fault. Organ builders and organists are notorious for demanding acoustics with exceptionally long reverberation times. True, much choral and organ music (often that written for the church) sounds best in a resonant environment, but this fact has often clouded our thinking . . . and the music! A great deal of music played on the organ is not served well by overly long reverberation because clarity is lost. Too much reverberation can blur form, harmonic structure, rhythm, articulation, and dynamic contrasts. Although it is hard for organ devotees to admit it, a resonant acoustic that is excellent for orchestral and other music can also serve the organ well.

There are two reasons for the dogmatic insistence on long reverberation times. First, it is a natural reaction to the discouraging trend toward studio-like acoustics in modern church architecture. In order to gain any reverberation at all, we have become used to asking for the moon. Ask for five seconds and be happy with one and a half is the usual formula. Unfortunately, however, this strategy often backfires, leaving organ advocates with little credibility among architects, acousticians and those who pay for buildings.

The second reason is that organs in highly reverberant rooms make a spectacular sonic effect. It is said that any kind of noise sounds well in a stone cathedral. But what does this mean? Does it mean that the overall result is musical? Or does it mean only that the sound itself is exciting, dramatic, rich with color? All too often the latter is the answer. Likewise, amateur singing sounds fine in the shower as does student trumpeting in an empty gymnasium. But these, of course, are illusions. What is being perceived as music is often nothing more than exaggerated sound. More is required of an acoustical environment to make satisfying music.

What is a good acoustic for the pipe organ?

It is commonly believed that all organs are enhanced by a very long reverberation time. We must differentiate among general types of organs (and the music played on them) and their acoustical environments. First, consider the cathedral organ. Although no music is successful when all clarity is lost through excessive reverberation, certain branches of the organ and choral repertoire--particularly that written for grand churches--require a reverberation time that is greater than that required for other forms of music.

At the other extreme is the high pressure theater organ. This type of instrument is far more successful in a studio or heavily draped theater. Otherwise the detail is lost. Their unique ability to create accent and to carry complex rhythmic patterns is partially defeated if reverberation is too great. Special purpose venues for these two extremes of the spectrum are not our concern here. This article deals instead with acoustical requirements for organs in the middle ground that are required to perform an eclectic repertoire in typical American churches and in multi-purpose concert halls.

Amount of reverberation

Too much is just as bad as too little. The lower limit of reverberation is easy to determine. It is the point at which music sounds dry, dull, and lifeless. This lower limit is higher for organ than for other instruments primarily because organ pipes are simply on or off. There is little that can be done to shape their tone. Some organ builders strive to improve the flexibility and responsiveness of the pipe organ; however, it seems unlikely that this can be achieved to the degree it is found in other instruments or in the human voice. Therefore a reasonably resonant acoustic is necessary for the church or concert pipe organ.

It is more difficult to determine the upper limit of reverberation. When does reverberation stop adding warmth and grandeur and start adding confusion? There are five determinants:

* When there is so much overlap of sequential sounds that musical line and structure lose definition despite the most careful articulation by the player; in other words, when the player's ideas get lost in the process of transmission to the audience. At that point the performance becomes an impression of sounds rather than a projection of musical ideas. (Those satisfied only with impressions of sounds are much like the early Hi-Fi enthusiasts who favored recordings of locomotives!)

* When the player loses control of rhythm.

* When it becomes impossible to create accent, which on the organ is accomplished more through durations of silence and sound than it is by increase of loudness.

* When sudden changes of dynamic level are obscured.

* When sharp contrast in tone color is clouded.

All of these musical situations, and others, caused by excessive reverberation are not tolerated by most musicians. Unfortunately, however, they are sadly disregarded by many in the organ profession, much to the detriment of their credibility in musical circles. We are sometimes willing to sacrifice ten minutes of music to get five seconds of sound at the end of the last chord!

Quality of reverberation

Frequently, the total amount of reverberation time is the only consideration in specifying ideal organ acoustics. But we should be far more interested in the quality of reverberation than in its duration. There are three qualitative elements that seem most important to me as an organ designer:

* The intensity (power curve) must be as high as possible. I was first made aware of this in visiting some of the great churches of France. There was a quality of reverberation there quite different from even the best reverberant rooms in this country. Why this is so must be the subject of another enquiry; however, the nature of this quality is vitally important. What I found was that the intensity of sound stayed quite high throughout the reverberation period and then trailed off rather quickly. This produced a most satisfying, rich, warm sound. In other buildings with an equal duration of reverberation, but with quickly decreasing intensity, the result is a disturbing confusion. I attribute this to the changing nature of the sound during the reverberation period. My conclusion, based upon much observation, is that it is far better to have a short, intense reverberation period than to have a long, weak one. The charts below show this concept.

      A measurement which may be more valuable than reverberation time (RT) in expressing this quality of intensity is early decay time (EDT). This is the time it takes a sound to decay by 15 decibels, whereas RT measures the sound until it decays by 60 decibels. Obviously EDT is measuring the first and most intense part of the reverberation. A high sound level during the first seconds and a total reverberation period extending very little longer than the EDT describes my ideal reverberation characteristic in a more precise way. Exact numbers, of course, vary with each situation; however, the idea of a           ratio of EDT to RT is true in all cases.

* The decay of sound should be smooth. A series of fast echos (much like clapping one's hands at the top of a deep well) are called flutter echos. These often occur in buildings with parallel walls located close together or with domes and barrel vaults which have a focal point at a sound source. These are extremely deleterious to musical effect. They can be so serious as to confuse performers while irritating the listeners. Sometimes they can be sensed throughout the room, but often they are localized. This characteristic of reverberation, a yodeler's delight, is ruinous to music, or for that matter, clarity of speech. The quality of reverberation that we seek is a sound dying away, not a sound being reiterated.

* The room should sound the way it looks. The eye leads the ear to expect a certain amount of reverberation. When it is either more or less, even the amateur listener detects that something is wrong.

Frequency response

Reverberation time is such an issue that other related characteristics are sometimes overlooked in specifying acoustical design. Frequency response is one of the most important of these. I find it far easier to work in a building with a smooth frequency response than one where there are peaks and valleys along the spectrum. The amount of reverberation should progress evenly through each frequency range. The bass should have slightly more reverberation than the mid range and the treble should have slightly less. One of the great faults of most buildings is the inability to support the deep bass of the organ. The unfortunate tendency of many buildings to also exaggerate treble makes bass seem even weaker. Bass is, after all, one of the characteristics that makes the organ the king of instruments. However, if low frequency reverberation is overemphasized, the heavy, often slightly slow speaking bass of the pipe organ becomes ill-defined. Similarly, if there is an overbalance on the high end, it is difficult to avoid shrillness.

Dispersion

The sound producing area of a pipe organ is large. Sounds of different color and intensity emanate from various places within the organ case or chamber. If a room is shaped in such a way that sounds coming from different points are focused to particular listening areas, it is impossible to achieve good ensemble. The ideal acoustic disperses sound evenly throughout a room. Acousticians and architects can achieve this through the application of various shaped dispersion elements.

Distribution

Sound should be distributed evenly throughout the listening area. Organ builders encounter many rooms which have hot spots and dead spots. Some of these may involve loudness, others may emphasize certain frequencies. The first concern in good distribution is correct placement of the organ. Whether free-standing or in a chamber, an organ must have adequate communication with the listeners. Once that is achieved, the architect and acoustician can eliminate sound traps and provide proper reflective surfaces.

Presence

Reverberation that appears to be happening at a distance is not very satisfying. The listener should be immersed in the reverberant field, otherwise the effect is similar to listening to music coming from the next room. It is most often desirable for the organ to sound as though it is located in the same room as the listener, even if it is in a chamber. Many points of organ design are involved in this issue but acoustical factors are important as well. The chamber opening to the listening room should be as large as possible. The chamber should not be overly deep nor wider or taller at the back than it is at the front. Finally, the organ should occupy enough space so that the chamber does not possess its own reverberant field. If the sound being projected into the listening room comes with a built-in echo or hollowness, the result is more confusion. It must be noted that in some liturgical settings the opposite of presence, a sense of mystery, is valued. It is much easier to produce this quality in a chamber than in a free-standing case. Thus, a chamber can, in some circumstances, be advantageous. 

Background Noise

Because the organ is a "sostenuto" instrument lacking the percussive attack possibility of most other instruments, control of background noise is especially important since most background noise is also of a sustained nature. I refer especially to air handling equipment. Many types of organs have as one of their great virtues an extremely wide dynamic range. If background noise is not under control, the softer end of the organ's range is lost.

Loudness

Obviously, all of the qualities listed above which contribute to a warm, resonant sound require adequate loudness. This is a question of organ design. If an organ does not have the sonic energy to excite the reverberant field of the room, all of the efforts of acousticians and architects will be to no avail. The organ builder must design the instrument to fit the acoustical size of the listening room without being overbearing. All too often acoustical size is confused with the number of stops. Sound output has a great deal more to do with stop selection, layout, scaling, wind pressure, voicing, and finishing. In most cases, it is best to keep the organ as small as possible to achieve the musical and acoustical results desired.

Placement of the Organ

Placement of organ pipes is a critical element in acoustical design. If sound is not projected properly from its source, even the finest acoustic will not save the instrument. Proper placement and the tonal design of organs to fit various placement situations should be the subjects of a lengthy article, however a few summary comments are in order here. Although high, side organ chambers are often very successful in churches where the organ's role is primarily accompanimental, it is generally true that the best placement for an organ is directly behind and above the other performing forces. The organ should speak down the central, long axis of the room. This often poses a problem especially when inserting a pipe organ into an existing space. Usually, the difficulty is finding height for the organ. The lowest point of the sound opening should start one to two feet above the heads of the farthest "upstage" row of choristers when standing. This is often as much as 15¢ above floor level. The top of the tone opening should be a minimum of 18¢ above that. For some types of organs it should be more. If adequate height is not available, there arises the challenge of how to present the organ visually. Traditionally, organs are narrow and tall. Short, squat ones tend to look ridiculous. Since the organ is known as the king of instruments and produces a fittingly noble sound, a "Punch & Judy" pipe display is inappropriate. There are no easy solutions. If a compromise must be made, the musical result must always be favored over the visual one. Sometimes it is best not to show pipes at all and let the instrument speak through grilles.  A smaller instrument is often the best solution. It will open far more options for good placement than a larger one. A well placed organ is an acoustically efficient organ.

Summary

Over the years I have found it most comfortable to work in buildings with a moderate acoustic. It is depressing to face a totally dry environment where the organ's tone is given no help at all; however, it is equally frustrating to deal with an overly live building where all of one's efforts in careful tone regulation are lost in a musical muddle. Approximately two and one-half to three seconds of intense, smooth reverberation (when the room is occupied) combined with even frequency response, good dispersion, distribution, and presence, as well as limited background noise yields the ideal atmosphere. A few examples from my experience that come quickly to mind are Old South Church in Boston, First-Plymouth Congregational Church in Lincoln, Nebraska, the University of Arizona (Holsclaw Hall) in Tucson, Severance Hall in Cleveland, the Boston Symphony Hall, and many of the famous 19th-century town halls throughout England. In other words, this writer's ideal for organ sound is the same as that for a first class symphony hall of the more reverberant type. Such an environment provides warmth for organ tone combined with clarity of musical line.

Jack Bethards is president and tonal director of Schoenstein & Co., Organ Builders of San Francisco. This article is based on a paper he presented in a forum with acoustical engineer Paul Scarbrough at the 136th meeting of the Acoustical Society of America, Norfolk, Virginia, in October, 1998.

Graphs by Paul Scarbrough, Acoustical Engineer, Norwalk, CT

Jim Toevs has a doctorate in nuclear astrophysics. While a professor at Hope College, he taught and consulted in acoustics. A musician, for 20 years he was the principal trumpet in the Los Alamos (NM) Symphony Orchestra and has sung in and directed church choirs.

Introduction1
With the installation and voicing of the wonderful new Fisk Opus 133 tracker organ in the First Presbyterian Church of Santa Fe, New Mexico, a number of interesting effects and impacts of Santa Fe’s thin air became apparent. This article will note the major observations and describe the physical acoustics related to organ pipe function at high altitude.
Santa Fe is located at the foot of the southern Sangre de Cristo mountains at an altitude of about 7,000 feet above sea level. In fact, the altitude at the church is 2,127 meters or 6,978 feet. At this altitude, both the atmospheric pressure and density of air are reduced to about 77% of their values at sea level. This difference in pressure corresponds to about 92 inches of water. Considering that most organs operate with a wind pressure of 2 to 4 inches (water column), this difference is quite significant. It is not surprising that organ operation is impacted by this difference; perhaps what is surprising is that the impact is not greater. The fine people of C. B. Fisk dealt with these differences with little difficulty.
Parameters in which high altitude might impact pipe organ performance include:
• Pipe intonation—essentially no effect;
• Windchest blower requirements—observed significant effect;
• Tone production: pre-voicing and voicing—observed significant effect;
• Sensitivity to windchest pressure—observed significant effect;
• Sanctuary acoustics—small but real effect.

Pipe intonation
The impact of altitude on the basic intonation of the organ pipes themselves is minimal. The frequency at which a pipe sounds (fundamental) is based on the length of the pipe and the speed of sound. The length, of course, does not depend on altitude, and fortunately neither does the speed of sound because the ratio of the pressure to density remains the same so long as the temperature is fixed. Basic intonation is therefore not affected by altitude.

Windchest blower requirements
The relationship between blower output (cubic feet per minute, or CFM) and desired windchest pressure (usually measured in equivalent inches of water column supported above the ambient pressure) is given by Bernoulli’s equation. This is perhaps the most fundamental law of fluid flow and basically is just a statement of the conservation of energy. Because density also decreases with altitude, a higher blower capacity will be required in high altitude installations than at sea level in order to obtain the same windchest pressure used at sea level. Using a higher output blower has become standard practice for high altitude installations.

Tone production: pre-voicing and voicing
As Mitchell and Broome have pointed out,2 windchest pressure must compensate for altitude differences when pre-voicing will be performed in a shop that is at a different altitude than the location at which the organ will be installed and receive final voicing. In both flue and reed pipes, the velocity has a direct impact on tuning and sound quality, and it is clearly desirable to produce the same pipe velocities during both pre-voicing and voicing. Once again from Bernoulli’s equation, since the density of air is greater at sea level than at high altitude, a higher windchest pressure must be used at sea level to produce the same velocities in the shop as in the installation. The desired shop windchest pressure is found by multiplying the desired windchest pressure at altitude by the inverse ratio of the atmospheric pressures at the two locations. This is the formula described by Mitchell and Broome.
Pressures of 3 inches and 4 inches were required for Opus 133, and the inverse pressure ratio between Santa Fe and sea level is 1/0.77 = 1.3. Therefore, pre-voicing in the Fisk Gloucester shop used pressures of 3.9 inches and 5.2 inches (water column).

Sensitivity to windchest pressure
During the final stages of voicing in Santa Fe, Fisk Opus 133 was performing very well, but suddenly developed significant intonation and sound quality problems when the HVAC (heat, ventilation, and air conditioning) system for the sanctuary switched between its two modes of operation. The change resulted in an increase of windchest pressure from 3 inches to 3¼ inches (water column). At sea level a change of ¼ inch could be accommodated without greatly impacting organ tuning and voicing, but in Santa Fe such was not the case. This sensitivity was not anticipated, but can be understood through an examination of tone production in organ pipes. In both flue and reed pipes steady energy is supplied through air streams produced by the windchest pressure, and a complex mechanism converts this energy into oscillating energy (sound).

Flue Pipes
In both a tin whistle and in flue pipes, production of oscillation, that is, tone, is through “edge tone generation.” The edge tone frequency depends strongly on air velocity through the windway, and must resonate with one of the natural modes (frequencies) of the pipe; the fundamental mode is always chosen. However, a small change in frequency of the edge tone can pull the edge-tone-pipe system away from the desired intonation. A small change in windchest pressure at altitude will result in a larger change in velocity (and therefore in pitch) than at sea level, due to the reduced density of air at altitude.

Reed pipes
In a reed pipe, air is supplied to the boot from the windchest at a pressure greater than the pressure in the resonator. This causes air to flow under the reed (tongue) into the resonator. Oscillation and therefore tone generation occur when very specific relationships are met among the variables and the stiffness of the reed. Both the stiffness and the oscillating length of the reed are set by the tuning wire.
The effect of a small change in windchest pressure on the frequency of a reed pipe is also greater than it is at sea level. Furthermore, the operating point of the reed, that is, the zero point of its oscillation, moves closer to the shallot as windchest pressure is increased. This may sharpen the onset of each cycle of the oscillation, increasing high frequency content, and, if close enough to the shallot, cause the flow under the reed to become turbulent. Both effects can alter the sound quality of the reed pipe.
To summarize this discussion, for both reed and flue pipes the sensitivity to small changes in windchest pressure is greater at altitude than at sea level, as the Fisk personnel discovered. The solution to this problem for Opus 133 was to gain a better understanding of the Santa Fe FPC sanctuary HVAC system and take appropriate steps to minimize the windchest pressure difference between the two operating modes. Figure 1 is a schematic of the system. The two modes of operation are as follows:
• Recycle mode: Air flows from the blower room to the sanctuary and is returned through the bellows room to the blower room. Valve R is open and Valve FA is closed down to 15%.
• Outside air mode: Outside air is brought in to the blower room and distributed to the sanctuary, and exits through the roof when the sanctuary pressure rises above that of the outside. The recycle valve is closed and the fresh air valve is 70% open.
Cost and environment are the two reasons for two modes of HVAC operation. During winter when outside air is well below the desired ambient temperature in the sanctuary, the air exchange is limited to the 15% required by code for healthy fresh air in the sanctuary (corresponding to the 15% setting of the fresh air valve). A larger percentage of fresh air would require more preheating, increasing gas costs. During summer when outside air is warmer than that desired for the sanctuary, a larger fresh air fraction would increase electric costs for cooling. On the other hand, during spring and fall, when some cooling is needed and outside air is marginally cooler than the desired sanctuary temperature, an increased recycle fraction saves cooling costs. Of course, environmental concerns track with increased gas and electric costs.
Organ pressure is supplied by the small blower in the bellows room and regulated by the bellows. It was found with a simple manometer (U-shaped tube with water) that the organ pressure during the recycle mode was 3 inches of water (that is, water in the manometer rose 3 inches), and in the outside air mode, the organ pressure was 3¼ inches (water column). The ¼-inch change significantly impacted tuning and sound quality. The reason for the ¼-inch change was that the recycle mode involved a great amount of air flow in the return ducts through the bellows room to the blower room, creating a pressure drop of ¼ inch in the return ducts. In this mode, then, the bellows regulating system had to supply 3¼ inches of pressure in order to yield the desired 3 inches of windchest pressure.
When the recycle valve closed to change to the fresh air mode of operation, the only flow in the return duct from the sanctuary to the bellows room was the much smaller flow used by the organ itself. Therefore, there was no loss in that section of duct, and the bellows room was essentially at the same pressure as the sanctuary. With the bellows regulation system still set at 3¼ inches, the windchest pressure became 3¼ inches.
During this time, the main HVAC blower was operating at 100% capacity (60 Hz) even though the blower system included a variable speed control. The following experiment was performed: the variable speed control was set to reduce the blower speed to 2/3 of full capacity (40 Hz), and the pressure differential between the sanctuary and the blower room was measured for both modes of operation—recycle with 15% air exchange and fresh air with 70% air exchange. The only change from the original HVAC settings is that the blower now operates at a lower speed. It was found that the pressure differential at 15% air exchange was 1⁄8 inch, and at 70% air exchange (recycle valve closed) was 1⁄16 inch. As expected, with the organ operating with the bellows regulating system set at 3¼ inches, the organ pressure was 33⁄8 inches at 15% air exchange (recycle mode) and 35⁄16 inches at 70% air exchange.
The bellows regulating system is now set at 31⁄16 inches, yielding an organ-to-sanctuary pressure of 3 or 31⁄16 inches in the two modes of operation—a difference of 1⁄16 inch, small enough that tuning is now not adversely affected. In addition, HVAC noise has been greatly reduced, and the air circulation in the sanctuary, while quite adequate, is less drafty for those sitting in the ends of pews near the walls, where the supply air vents are located.

Sanctuary acoustics
FPC Santa Fe underwent major renovation before Fisk Opus 133 was installed. This included considerable acoustic work in the sanctuary to prepare it for this fine instrument; much of the focus was on steps to increase the reverberation time. The chancel has diamond plaster side walls, which diverge slightly to help sound radiate into the sanctuary. The sanctuary has hardwood floors with minimal carpeting, hard plaster walls, and hardwood pews with reasonably reflective pew cushions. The ceiling was rebuilt with heavy plywood above latillas, and fine sand one foot deep was poured onto the plywood to help contain low frequencies from the organ. Although the reverberation time has not been measured, it is estimated to be about 1.5–2.2 seconds.
In addition to sound energy absorption each time a sound wave encounters a surface, sound energy can be lost through absorption in air. Absorption in air is a rather complex phenomenon involving molecular dynamics, and it varies with air density and relative humidity in a manner that is counterintuitive: thin, dry air attenuates sound more than thick, wet air. Furthermore, the attenuation varies with frequency. Table 1 provides values for attenuation at different frequencies for sea level and the Santa Fe altitude and for 10% and 50% relative humidity. Notice that absorption is greater at low humidity, high altitude, and higher frequency. At high altitude air is thinner and can hold less moisture; relative humidity of 12%–15% is not unusual on summer days in Santa Fe. To mitigate against the drying effects on organ components, a humidifying system is used to maintain relative humidity at around 40%; this also helps to reduce air absorption at higher frequencies.
In Table 1, the sound absorption is given in decibels per kilometer, which is just a little farther than sound travels during a reverberation time of 2.2 seconds. Figure 2 provides a plot of these attenuation data at sea level and in Santa Fe at 50% relative humidity.
Clearly, the attenuation is greater at high altitude and high frequency. However, to understand whether or not this will impact the sound of the organ in the sanctuary, the attenuation must be compared with reverberation decay, the decay in sound energy due to reflection off surfaces. This comparison showed that at 4 kHz, the air attenuation at sea level would be barely noticeable if at all, and would be completely negligible at lower frequencies. In Santa Fe a very astute listener might notice the lack of high frequency components after initial transients on a very dry day, but otherwise the sanctuary acoustics should be little affected by the high altitude.

Conclusion
The differences in organ acoustics and operation between sea level locations and Santa Fe are real and observable, but not severe. Judicious choices of windchest pressure for pre-voicing and voicing and better understanding of the HVAC system both have contributed to a very successful installation: Fisk Opus 133 is now performing regularly and brilliantly. It is hoped that these observations will serve others who choose to install a fine organ at similar altitudes.

Martin Ott Pipe Organ Company, Inc., St. Louis, Missouri
Trinity Evangelical Lutheran Church, Spring, Texas
Opus 68, b. 1991

From the builder
Trinity Lutheran is a large Missouri Synod Lutheran Church located in Spring, Texas, north of Houston. The area was settled by Germans who brought with them their Lutheran faith and customs. The church, founded in 1874, is still located on its original property. As the church has grown, sanctuaries have been removed and new ones have been built. In 1991, our Opus 68 began as the hope of Melvin Schiwart, the music director at the time. Mr. Schiwart had been to Germany. He wanted a good quality German organ for Trinity Church, and his search led him to our firm. A mechanical action organ with a detached console was designed. Although the organ has German influences, it is an eclectic instrument in style and adapts well to its American environment. In 1994, the 49-rank, 39-stop organ was installed in the previous sanctuary’s balcony.
The church membership grew through the 1990s, and the organ continued to be an important part of worship. As plans were made for a new sanctuary, the congregation decided to relocate the organ into the new church. Moving the instrument to the new space enabled the church to keep ties with their past. The organ and the church bell were the only items moved from the old church to the new one. The cost for moving the organ was a small fraction of what a new instrument would cost.
From the very beginning, our firm was invited to participate in the design of the new worship space, specifically the layout of the balcony. We worked with architect John Gabriel, of Gabriel Architects, Inc., and acoustician Scott Riedel, of Scott R. Riedel & Associates, Ltd. The new sanctuary has 44,000 square feet and seats 1,325 parishioners in the nave. Of special concern was how the existing organ could be best incorporated in the new building both visually and acoustically. The music is performed from the “west balcony” opposite the chancel with the altar, pulpit, baptismal font and lectern. Mr. Gabriel designed the large new balcony to accommodate the organ, the choirs, and the orchestral musicians. He was enthusiastic about the organ project and understood the physical and logistic needs. The overall design of the organ remained unchanged. Crown molding was added to give the instrument a stronger visual presence in the new room. We also have added a 32′ Bombarde, a 32′ Untersatz, and a Zimbelstern with a rotating star. As the instrument was reassembled, we thoroughly cleaned every part. The reed pipes were disassembled and completely cleaned before reassembly.
Trinity Lutheran was very enthusiastic about the project. During the weeks we spent reconstructing the organ and voicing, many parishioners would visit to see the progress. Among these visitors was singer-songwriter Lyle Lovett, born near Trinity Church, who asked us many questions about organ building. Mr. Lovett attended Texas A&M University where he studied journalism and German. He also spent time in Germany for his studies. Through his conversations with me, Mr. Lovett learned that the Ravinia Festival in Chicago owned an Ott portative organ; and at the July 12, 2008 concert at this festival, Mr. Lovett used the organ for several pieces in front of a full capacity audience.
The revoiced and visually altered instrument at Trinity Lutheran Church certainly brings vigor in sight and sound to this new sanctuary. We have many people to thank for their assistance in the project: Senior Pastor Richard Noack, Dr. William Brusick, Mr. Melvin Schiwart, and all of the Trinity Lutheran parishioners who were supportive and helpful. I would like to thank all who worked on Opus 68.
1994: John Albright, Albert Brass, James Fantasia, Jeffery Fantasia, Richard Murphy, Earl Naylor, Martin Ott, Thorsten Ott, Mary Welborn. On-site help: new choir risers designed by Jack Rimes, built by Gerhardt Pipho and Melvin Schiwart; riser banisters by Rick Davis; pipe shades in organ towers painted by Duane Schiwart.
2008: James Cullen, Bill Dunaway, Marya Fancey, Larry Leed, Aleksandr Leshchenko, Eileen McGuinn, Earl Naylor, Martin Ott, Inna Sholka. On-site help: Paul Jernigan, Shawn Sanders.
—Martin Ott
Martin Ott Pipe Organ Company

From the acoustical consultant
Trinity Lutheran approached Riedel for consultation in architectural acoustics and sound system design services in August 2001. Our goal for acoustic design was to develop a space that supports and enhances the Lutheran liturgy. Important considerations include reverberation period, HVAC noise control, noise control between spaces and from the outdoors, sound projection from the music area, support for musical ensemble and congregation hymn singing, and speech intelligibility.
The completed Trinity Lutheran sanctuary has a reverberation time, during unoccupied conditions, of 3.5 seconds. This generous reverberance provides excellent sound distribution and enhancement of organ and traditional choral tone. It also benefits Lutheran liturgical practices, encourages congregational sung and spoken participation, and gives a strong sense of listener envelopment.
Excellent speech intelligibility is achieved through innovative sound system technologies and careful design practices. Digitally steerable line array speakers provide very clear sound in this reverberant environment with minimal visual intrusion. A digital signal processor automates the system and replaces older multiple component technologies.
While the organ and traditional choir are an integral part of the congregation’s worship life, the growing use of contemporary instruments in Trinity Lutheran’s music ministry will necessitate a lower reverberation period at times. Treatment options have been presented to facilitate a more contemporary music service, and may be implemented by the client. These treatments include adding modest sound absorbing wall surfaces in select areas of the room.
A flutter echo reflection pattern is audible in the center aisle, resulting from the smooth, curved “barrel vault” ceiling profile favored by the architect. This curve focuses sound energy toward the center aisle of the room, such that the flutter effects are much less noticeable in the congregation seating areas. The overall room shape is cruciform, with organ and choir located at the end of the long axis of the space, in a rear gallery; this facilitates a full and even distribution of musical sound throughout the environment.
We are honored to be part of the Trinity Lutheran Church design team, and we are proud to have assisted in creating an environment that enhances the Ott organ, all in the service of the church.
—Scott Riedel
Scott R. Riedel & Associates, Ltd.

From the minister of music
In May 2007, I was blessed to receive a call from Trinity Lutheran Church in Spring, Texas. One month later, after serving as minister of music for fifteen years at Grace Lutheran in St. Petersburg, Florida, I accepted the call to Trinity. Like Grace, Trinity is a benchmark church in the community that puts a high value on the role of music in quality worship. Throughout the northwest Houston area, Trinity is known for its particular strength in traditional, liturgical worship. To this end, an instrument was sought that would be capable of leading and enhancing this style of worship. All roads inevitably led to Martin Ott.
I am blessed to be the recipient of the hopes, the dreams and the fortitude of a congregation and former minister of music who put such high value on quality music and the instrument that will lead it for generations. Although I had studied on a Holtkamp tracker organ, I had never had the privilege of playing a Martin Ott instrument until my pre-call interview in March 2007. The organ, located in the former sanctuary, looked and sounded spectacular; and yet, it was unfinished. The missing extensions of the two 32′ stops and the absence of any crown molding on the casework were testament to the inevitable expansion that still lay ahead. For myself, one who has been trained in and enjoys improvising on hymns and hymn tunes, the variety of colors and the wide dynamic range made this organ a especially thrilling instrument to play. As a composer, it is also fair to say that having an organ like this is like having a world-class orchestra at your disposal.
While the organ’s weekly mainstay is the leading of over a thousand worshippers in great works of hymnody, our music ministry also calls upon the organ to gently accompany a soloist, add equal support to a majestic brass choir, and blend into and uphold the mighty forces of a full orchestra and chorus. All of these our organ does effortlessly. In this way, I am confident that the Ott Opus 68 pipe organ can provide the style of high quality music that Trinity has come to expect and appreciate over its many years of great musical leadership.
But the blessings don’t end here. While it is a rare opportunity for an organist to meet the creators of their instrument, it is indeed even rarer to have the opportunity to work close at hand with them. Because of the relocation of the organ, I have had the distinct privilege of establishing a close-knit relationship with Martin Ott and his highly skilled team. Over the four months of planning and physically moving the organ, I began to see the care and craftsmanship and the sheer love that Martin has for his instruments and for the churches that will be led by them. During even the most stressful moments of the project, his focus and faith in the outcome never wavered. This instilled great comfort in all of us, knowing that the end result would be beyond everyone’s imagination.
As minister of music at Trinity Lutheran Church, I can speak for all when I say that we are indeed fortunate to have Martin Ott’s Opus 68, which has the potential to bring the highest level of both sacred and secular music to its listeners—leading worship, lifting song, inspiring creativity, enhancing the Word, and energizing the soul.
—William R. Brusick, D.Mus.
Minister of Music
Trinity Evangelical Lutheran Church, Spring, Texas

From the pastor
The dream for a fine pipe organ at Trinity Lutheran Church began in the mid 1980s with our former (now retired) minister of music, Melvin Schiwart. His vision was that we would have a mechanical key action instrument ideally suited to lead robust congregational singing. In response to Mr. Schiwart’s leadership and vision, the congregation decided to establish a special organ fund to bring the project into reality.
Mr. Schiwart interviewed a number of leading organ builders in the United States and in Europe. In the early 1990s the congregation selected Martin Ott of St. Louis, Missouri, to design and build Trinity’s pipe organ.
Martin Ott’s Opus 68 was installed in our former sanctuary in 1994. In June 2008 it was moved into Trinity’s new 1425-seat sanctuary. The organ was expanded with additional stops and enhanced with beautiful casework.
The sanctuary has a classic basilica design and is constructed with internal surfaces that provide a rich reverberation. These features optimize the blessing that is the organ. Martin Luther commented that music often inspired him to preach. I must say that a rousing presentation by a capable organist of Ein feste Burg, At the Lamb’s High Feast We Sing or Crown Him with Many Crowns has definitely inspired my preaching on more than one occasion!
The wonderful marriage of our organ and our new building has yielded many blessings. Our current minister of music, Dr. William (Bill) Brusick, and our pastors enjoy our worship planning sessions. It is fun and energizing to find creative ways to maximize the impact of this superb instrument.
Leading worship in the Name of the Trinity is a high and holy calling. Our magnificent organ is integral to our worship and enhances our worship immensely. It is a great treasure and we are keenly aware that we must exercise faithful stewardship of it to the glory of Jesus Christ.
—Rev. Dr. Richard C. Noack
Senior Pastor
Trinity Evangelical Lutheran Church, Spring, Texas

Trinity Evangelical Lutheran Church, Spring, Texas
39 stops, 49 ranks, 4 extensions

HAUPTWERK (Manual II)
16′ Bordun 56 pipes oak
8′ Prinzipal 56 pipes 75% tin
8′ Rohrflöte (1–12 Bdn) 44 pipes 40% tin
4′ Oktave 56 pipes 75% tin
4′ Nachthorn 56 pipes 40% tin
22⁄3′ Quinte 56 pipes 50% tin
2′ Oktave 56 pipes 75% tin
Mixtur IV–V 255 pipes 75% tin
8′ Trompete 56 pipes 50% tin
8′ Horizontale Trompete 56 pipes 80% tin
4′ Schalmei 56 pipes 75% tin
Zimbelstern  5 Schulmerich bells

SCHWELLWERK (Manual III)
8′ Viola 56 pipes 50% tin
8′ Viola Celeste tc 44 pipes 50% tin
8′ Holzgedackt 56 pipes oak
4′ Prinzipal 56 pipes 50% tin
4′ Gemsflöte 56 pipes 40% tin
Sesquialter II mc 64 pipes 40% tin
2′ Oktave 56 pipes 50% tin
Scharf III–IV 214 pipes 75% tin
16′ Dulzian 56 pipes spruce
8′ Trompete 56 pipes 75% tin
Tremulant

POSITIV (Manual I)
8′ Holzprinzipal 56 pipes oak
8′ Bleigedackt 56 pipes 25% tin
4′ Rohrflöte 56 pipes 40% tin
22⁄3′ Nasat 56 pipes 50% tin
2′ Nachthorn 56 pipes 40% tin
13⁄5′ Terz 56 pipes 75% tin
11⁄3′ Quinte 56 pipes 75% tin
Zimbel III–IV 180 pipes 75% tin
8′ Krummhorn 56 pipes 50% tin
8′ Horizontale Trompete (from HW)
Tremulant

PEDAL
32′ Untersatz (ext Subbass) 12 pipes spruce
16′ Prinzipal 30 pipes 75% tin
16′ Subbass 30 pipes oak
8′ Oktavbass (ext Prinz 16′) 18 pipes 75% tin
8′ Pommer (ext Subbass) 12 pipes oak
4′ Choralbass 30 pipes 50% tin
Mixtur IV 120 pipes 75% tin
32′ Bombarde (ext16′) 12 pipes spruce
16′ Posaune 30 pipes spruce
8′ Trompete (from Hauptwerk)
4′ Schalmei (from Hauptwerk)

Couplers
Schwellwerk/Hauptwerk
Positiv/Hauptwerk
Schwellwerk/Pedal
Hauptwerk/Pedal
Positiv/Pedal

A skill of great value to most organists is the ability to make recordings of music on the organ. As students we have teachers and colleagues to give feedback on our playing, but when formal study ceases do we stop learning new works? Most organists are continually learning new music and reworking old pieces for performance in concert and/or church. We rely primarily on our own musical taste and experience, of course, but who is listening to us--objectively and with complete attention--when we grapple with the often difficult and complicated process of working up a piece on the organ? A tape recorder will give us an excellent idea of how we're doing--if we use one. Robert Noehren reports that he records about half of his practicing, enabling him to listen to and analyze his playing.1 Why don't more organists use tape recording as a learning tool? Many say they would like to, but either they "don't know how to do it" or think "it's too much of a production" to be practical.

The purpose of this article is threefold:

1) to give organists a set of basic tools and techniques with which they can, easily and quickly, make diagnostic tape recordings of their own playing;

2) expand on the above with more advanced techniques to achieve recordings suitable for mastering on cassette or CD;

3) give professional techniques, some unique to recording the organ, which can help organists who are working with sound engineers achieve the highest quality recordings.

The information in this article comes from the author's personal experience, research on the subject, experimentation based on the research, and in-depth interviews with some of the leading professional sound engineers who specialize in recording the organ and who have generously shared their knowledge and techniques:

Michael Barone, Pipedreams

John Eargle, Delos International

Frederick Hohman, Pro Organo

Michael Nemo, Towerhill

Jack Renner, Telarc International

David Wilson, Wilson Audiophile.

The footnotes give either background information to supplement the text, or specific information on sources of items mentioned in the text.

Selecting Microphones

The function of the microphone is to convert sound energy into electrical energy which can be recorded. There are two basic types: dynamic and condenser. Dynamic microphones are generally lower in quality and price, and they are not recommended for the rigorous challenges of organ recording.2 Condenser or electret condenser microphones do require a power source (usually an internal battery) and can give very high quality recordings at a quite reasonable price. Some of the experts recommended less-expensive condenser mikes marketed by: Audio-Technica, Beyer, EV, Nakamichi, Shure and Sony.

Frequency Response

Since the frequency of low CC of a 16' pipe is 32 cycles per second (or Hz), the minimum microphone frequency response you need for organ recording is 30-15,000 Hz. For quality microphones, the frequency response specification is given like this: 30-15,000 ±3.5 dB, or 20-18,000 ±3.0 dB. The first spec means that from 30Hz (just below 16'CC) all the way up to 15,000Hz (which approaches the upper limit of hearing), sounds recorded by the microphone will be within a range no greater or no less than 3.5 decibels from the mean, which is pretty good. The second spec indicates a higher quality microphone, which at a low limit of 20Hz "hears" well down into the 32' range (low CCC of a 32' pipe is 16Hz), up through the range of human hearing and which, at ±3.0 dB has a slightly flatter (better) frequency response curve than the other microphone. Some pro mikes respond down to 5 Hz, which is lower than CCCC of a 64' stop!

Polar Response Pattern

Another key microphone characteristic is the polar response pattern, which simply refers to the direction in which the microphone "listens." An "omnidirectional" microphone picks up sounds equally in all directions--top, bottom, left, right, front and rear.3 On the other hand, a "cardioid" (sometimes referred to as "unidirectional") microphone is directional--it responds to sound from a broad angle in front of the microphone and rejects sound from the rear. While there are other response patterns (hemispherical, supercardioid, figure of eight, etc.), these are subsets of the two main types. Both omnidirectional and cardioid microphones can make excellent organ recordings, and in certain situations one may be preferred over the other.

It should be noted that you don't necessarily have to choose between the two types when purchasing a microphone, however, if you get a microphone with interchangeable "capsules." The Nakamichi CM-100 condenser microphone, an excellent microphone which the author uses, has a list price of $150 with a cardioid capsule, and an interchangeable omnidirectional capsule is available for $30.4 Since you may need both omnidirectional and cardioid pickup patterns, depending on where you are recording, microphones with interchangeable capsules are most attractive (see Fig. 1).

Stereo vs. Mono Mikes

Of course you want to make stereo recordings, but should you use one stereo microphone or two monophonic microphones to do it? In general, you have a great deal more flexibility with two monophonic mikes. A "stereo" microphone is simply two mono microphones in one housing. There are two categories: the big, high-quality and very expensive professional version and the small, inexpensive and generally inferior amateur version. The former type is too expensive for amateur recording, and the latter usually doesn't have sufficient frequency response for organ recording.5 However, a mid-priced "stereo" microphone can be a convenient solution for personal recordings made with recorders which have a single stereo miniplug microphone input (more details on this follow).

PZM Microphones

One of the best microphone values, and an excellent choice for personal recordings of the organ, is the "pressure zone microphone" or PZM from Radio Shack (catalog no. 33-1090B) which sells for $60 each.6 The Radio Shack PZM is a low impedance condenser microphone with a 1/4" phone plug. The advantage of the PZM mike is that it allows great freedom in placement (you can tape them to walls, or lay them on the floor or on top of the console--no microphone stands required), they have excellent clarity and frequency response. The pickup pattern is "hemispherical," which means that they are omnidirectional above the plane upon which they are lying (see Fig. 2).

Plugging the Mikes In

On one end of the cable is the microphone and on the other end is a plug. Making sure the microphone plug is electronically and physically compatible with the recorder input is a challenge which requires forethought and planning. Professional equipment--microphones, mixers and recorders--use a low impedance (150 to 600 ohm) system that usually announces itself by the presence of a "balanced" 3-wire XLR plug. This allows long cable runs without hum via XLR extension cables.

Semi-pro microphones (such as the Nakamichi CM-100 mentioned earlier) also use the balanced low impedance system. The microphone itself has an XLR plug (see Fig. 3) and the supplied microphone cable has an XLR on one end and a 1/4" phone plug on the other. This cable is, in effect, an adapter which converts the balanced XLR to an unbalanced 1/4" phone plug. Phone plugs used to be the standard for microphone inputs on home audio gear7 and continue to be the standard on semi-pro equipment. If you need to extend the cable for proper microphone placement, use XLR 3-wire extension cables (the kind with a male plug on one end and a female plug on the other).8 This will prevent hum, whereas the less-expensive shielded extension cables with 1/4" phone plugs on either end will quite possibly cause hum.

The Stereo Miniplug Input

If your recorder9 has a single, stereo miniplug mike input, you have a potential problem. In order to use two mono mikes with 1/4" phone plugs, you need a "Y" adapter with two 1/4" female mono connectors on one end and a stereo male mini (3.5mm) plug on the other (see Fig. 4). This is not an easy item to find, but trying to "create" one from the various plugs and adapters commonly found in electronics stores is a recipe for disaster--it is virtually guaranteed to cause hum (see Fig. 5). The Hosa Company markets the correct part (model YMP-137)10 through independent audio/electronic supply stores.

Another solution, if your recorder has a single stereo miniplug input, is to purchase the best semi-pro stereo mike which terminates in this kind of plug. The Audio-Technica AT822 is a high-quality mike of this type with a frequency response of 30-20,000 Hz. It sells for a pricey $350,11 but it does plug right in and works well. The "under $100" stereo mikes don't have sufficient bass response for organ recording.

As an alternative to using the stereo miniplug microphone input, you can use a mixer and go directly into the "line" inputs.12 The "mixer" solution--which we will discuss shortly--is required if the recorder has no microphone inputs at all.

Cassette vs. DAT

There are basically two choices for a recording medium: cassette tape and digital audio tape (DAT). We will ignore a myriad of other systems such as the digital cassette, the digital minidisc, the recordable CD, 1/4" reel to reel, and recording on "hi-fi" videotape as they are either marginal, impractical or inferior.

Everybody is familiar with cassette tapes. They are great for making personal "analysis" recordings because the tape itself is inexpensive, you can listen to the results in the car, etc. While the original recorded cassette can sound great on playback, the inherent noise level of the medium makes it a less good choice if your goal is to make master tapes for release on cassette or CD.13

Because of its superior quality, digital audio tape (DAT) is an excellent medium for personal analysis recordings and more ambitious projects as well.14A home DAT or portable DAT recorder will cost a minimum of $550, and professional portable models cost from $1500 to $4000. DAT 120-minute tapes are about $10 each.

Cassette "Deck" Challenges

There are some challenges to using home cassette decks--the A.C. "plug into the wall" models which are a component of a home stereo system--for location recording. As virtually none of the newer models have microphone inputs, a "mixer" is required between the mikes and the "line" inputs on the recorder (this is also true of home A.C. DAT decks). Further, few newer cassette decks allow you to plug in headphones and listen to playback, and of those which do very few have a volume control for the headphones. This is mandatory for playback in the field, but a mixer solves this problem too, as we shall discuss. Also, many low-to-midpriced cassette recorders suffer from excessive wow and flutter distortion, which is particularly annoying on the sustained tones of the organ. The bottom line: it is not a good idea to purchase an A.C. home cassette deck for location recording. If you own an older model with microphone inputs and a headphone output with volume control, you are all set (see Fig. 6). However, if you own a newer model cassette deck without these features, we'll show you how to make the best use of it.

Portable Location Recorders

Battery-operated portable recorders designed for high quality music recording--with mike inputs and full headphone capabilities--are not a common item.15 The Sony Walkman Pro series has two cassette recorders: the WM-D3 at $250 and the WM-D6C at $350.16 These are quality cassette recorders. The rugged WM-D6C especially is a fine recorder and a good value. They will do well for personal analysis recordings. Their performance must be compared with the Sony TCD-D7 DAT portable, however, which at a "street" price of $550 makes substantially superior recordings. All three of these Sony recorders have a single stereo miniplug input for the microphone, stereo miniplugs for the line inputs and outputs, plus a headphone jack and volume control.

Using an Audio Mixer

Suppose that you have a perfectly good home cassette deck or home DAT deck without mike inputs. You want to do some analysis recording with it, and you don't mind unhooking it and taking to the church. In addition to the microphones, you will need a mixer to convert the microphone's output into a "line" input the recorder can use. I will confess to "mixer paralysis"--I didn't understand the button-laden beasts and steered well clear of them. This was a mistake I finally rectified, as Rudy Trubitt points out in his excellent book written for the beginner titled Compact Mixers:

Beneath its dizzying array of controls, a mixer actually has some important similarities to a home stereo receiver. A stereo receiver has controls that let you switch between different components of your hi-fi system, and also enables you to set overall volume, the balance between left and right speakers, and tone controls to shape the overall sound. A mixer does many of these things as well, and in addition allows you to control and combine or mix sounds from many different sources [such as two or more microphones] at once.17

For stereo recording, mixers need controls called pan pots. Inexpensive "mixers" designed for the party DJ market. including those sold by Radio Shack, lack this essential feature. Michael Barone and other audio professionals recommend the Mackie MS1202 compact mixer, which is specifically featured in Mr. Trubitt's book. It is priced at $299, which is very inexpensive for a fully professional mixer.18 I have found mine to be small, light weight, easy to use and of excellent quality (see Fig 7).

A mixer will also enable you to listen to playback in the field from recorders which have no headphone volume control or no headphone output at all. Simply run a patch cord from the line output of the recorder to the line input of the mixer. This is very simple to do and gives new utility to recorders with neither headphone volume control nor headphone output (see Fig. 8).

Setting the Record Level

To achieve the cleanest recorded sound, you want to record the loudest sections of the music at the loudest level possible on the tape without causing distortion.19 To set the recorder properly, simply play the loudest section of the music to be recorded at a given session20 and adjust the record level so you get the appropriate reading on the VU meter.21  The "appropriate reading" on the VU meter is different for different mediums.

With DAT, you never want the level to exceed 0dB on the DAT recorder's VU meter, so--while the loudest chord is being held--advance the record level control so that the meter reads 0dB.22 Once the level is set, you don't need to touch it again for the duration of your recording session.

There are three different kinds of cassette tape: Standard (Type I), Chromium Dioxide or CrO2 (Type II), and Metal (Type IV).  Type II tape can accept a louder signal than Type I without distortion, and Type IV can accept a louder signal than Type II. The record level should be adjusted with Type I tape so that the peak level is 0dB on the VU meter. With Type II the peak level should be +1dB and with Type IV it is +3dB. Note that these last two settings will have the peaks in the red of the VU meter, and that's fine as long as no audible distortion results.

When choosing cassette tape, skip the somewhat noisy "standard" tape and try the CrO2 (Type II) tape recorded with Dolby B sound reduction. This is a good compromise on price and compatibility,23 and it gives excellent quality on playback. There will be a switch on the recorder which you need to set at "CrO2" or "Type II" or "High Bias," which are three ways to refer to this one kind of tape. Depending on your situation, you may also want to experiment with "metal" tape (Type IV) and Dolby C, which, all other things being equal, gives the highest quality on cassette.

Listening to Playback

One of the requirements for location recording is a good set of headphones. The best designs have circular padded cushions which completely surround each ear and provide some degree of acoustic isolation. You are shielded from noise in the room, and people in the room are less likely to be annoyed by playback from your earphones. Quality headphones provide a lot of sound for a reasonable price. The Sony MDR-V600 dynamic stereo headphones the author uses have clean, lifelike sound with a frequency response which extends well down into the 32' range.24 Priced around $100, they come with a clever screw-on adapter which converts the integral stereo miniplug to a 1/4" stereo phone plug (see Fig. 9). This is very handy as small portable recorders have a miniplug headphone output, and mixers and other audio gear have a 1/4" phone jack.

Stands and Safety

Anyone who can imagine a tall microphone stand crashing down amidst a sea of pews appreciates that basic safety rules must be followed at all times to protect life and property. Use only a stable microphone stand and if necessary, weigh down the base with sandbags.25 Attach the mike cable(s) to the top of the stand with cable ties,26 allowing a bit of slack between the cable tie and the mike, so the weight of the cable doesn't pull on the mike. Run the microphone cable down the stand and either tie it around the base of the stand or preferably attach it securely with a cable tie. Then if the cable gets an unexpected jerk, the force will act on the relatively stable base of the stand and not on the very unstable top.

Microphone stands for organ recording should ideally allow you to position the microphones 20' or more in the air, which precludes many less-expensive audio stands. Audio engineers often use heavy-duty motion picture lighting stands adapted to accept the 5/8" thread which is the audio industry standard.27 Michael Barone recommends, in levels of increasing capability and cost: 1) Shure microphone stands, 2) Bogen light stands, 3) the Ultimate Support system.

If the public is in the room, the microphone cables must be taped down to the floor lengthwise with 2" masking tape so no one trips. These precautions are necessary because no recording is important enough to risk injuring someone, and we live in a very litigious society.

In Part II we will look at one of the most critical aspects of the art of recording--microphone placement.

Notes

1.              Correspondence of September, 1995.

2.              Dynamic mikes don't require a battery. If the microphone you are considering requires a battery, it is not a dynamic mike.

3.              Omnidirectional microphones tend to become more directional--and less omnidirectional--above 3000 Hz, so it is important to point them toward the sound source. Because the response from the sides and back of the mike begins to fall off above 3000 Hz (pitches at and above 3000 Hz are an important component of the harmonics of most 8' voices), you get enough directionality to maintain a clear sense of left and right.

4.              For a list of dealers, contact: Nakamichi America Corporation, 955 Francisco St., Torrance, CA 90502, (310)538-8150.

5.              A frequency response no lower than 50 Hz, which is typical for inexpensive stereo mikes, won't pickup the bottom octave of a 16' Bourdon.

6.              Crown International of Elkhart, Indiana, manufactures a full range of PZM mikes for the professional.

7.              Home audio recorders no longer have microphone inputs, and portable amateur recorders often have a single stereo miniplug input for the microphones.

8.              XLR extension cables cost about $16 per 25' or $47 per 100'.

9.              Such as the Sony Walkman Pro or the Sony DAT portable (TCD-D7).

10.           For availability contact: Hosa Technology, Inc., 6910 E. 8th St., Buena Park, CA 90620.

11.           For availability contact: Audio-Technica, 1221 Commerce Drive, Stow, OH 44224.

12.           In most cases there will be two RCA jacks for the left and right channel inputs, and you will use a standard RCA male-male patch cord to connect the mixer to the recorder. But on some portable recorders you may find a stereo miniplug line input, in which case you need a patch cord with two RCA male connectors on one end (for the mixer) and a male stereo miniplug on the other end (for the recorder).

13.           There is no escaping the fact that the cassette started life as a lowly medium for dictation. The ultra-slow 17/8" per second tape speed and the narrow tape width cause a certain amount of hiss despite the best efforts of tape recorder designers and Dolby® noise reduction systems.

14.           Because DAT is digital and cassettes are analog, comparing them is like comparing apples and oranges. All cassette recorders have measurable wow and flutter distortion from tape speed fluctuations, whereas DAT machines generally have no measurable wow and flutter. The frequency response, signal to noise ratio, dynamic range and overall distortion specifications of the best cassette machines are not as good as even the less-expensive, amateur DAT recorders.

15.           There are some less expensive (approx. $100) portable cassette recorders by Aiwa with a stereo mike input and a headphone output. They have neither Dolby noise reduction for the record function nor a record level control (AGC only), very important features for reasonable quality with cassettes.

16.           These are "street" prices--the lowest purchase price I could find--not list prices.

17.           Rudy Trubitt, Compact Mixers, published in 1995 by Hal Leonard Corporation, 7777 W. Bluemound Rd., P.O. Box 13819, Milwaukee, WI, 53213, page 3.

18.           Available from the "Pro Audio" department of Guitar Center stores nationally. Inquire at 7425 Sunset Blvd., Hollywood, CA, 90046, (213) 874-1060 for a list of locations.

19.           This technique maximizes the "signal to noise ratio." The "signal" is the music and the "noise" is the tape hiss and amplifier hum. Since the noise is at a more-or-less constant low level, the louder the music level the more it stands out from the noise. While softer than the loud sections, the quiet portions of the music will also sound as clean as possible.

20.           If the session extends over several days, use one level setting based on the loudest piece. The only exception would be a program with one or two loud pieces and many softer ones. I would consider using one level setting for the loud work(s) and a louder recording setting for the softer pieces, as this will maximize clarity among the latter group.

21.           The recorder's "VU" meter allows you to set non-distorting recording levels consistently. It has numbers in decibels (dB), with a range of positive numbers (+1, +2, +3, etc.) "in the red" above zero dB and a range of numbers "in the black" below (-1, -5, -20). The range of numbers below zero dB is where most recording takes place. The meter can take two forms: an older style needle which swings on a pivot throughout the meter's range, and the newer style LEDs which illuminate (no moving parts to break).

22.           This is generally true, but also consult the recorder's instruction manual.

23.           Not every tape player, especially in cars, has a setting for Metal (Type IV) tape or Dolby C noise reduction. Playing metal tapes and/or Dolby C tapes in a machine set up for Type II tape and Dolby B will result in a significant loss of fidelity.

24.           They are also excellent for listening to organ CDs on a portable CD player--you can pick up many nuances that you might miss when listening via speakers. The claimed frequency response is 5 to 30,000 Hz.

25.           Fully sealed 15# sandbags in a "saddlebag" configuration for this purpose are available from motion picture equipment supply houses and some professional audio supply houses.

26.           The Lowel-Light Company, 140 58th St., Brooklyn, NY 11220, phone (800) 334-3426, makes secure and inexpensive reusable plastic cable ties which are available in larger photo stores. Velcro cable ties are also available.

27.           The author uses the Lowel KS stand ($135) which will extend to 8' (see footnote 26). The Lowel KP extension pole ($58) allows 5' of extension, and you can use several of those (sandbags are essential if you use extension poles). On the very top you need the Lowel Tota-Tilter T1-36 ($25), a 1/4-20 to 3/8 screw thread adapter (available in most photo stores) and a special 3/8 to 5/8 screw thread adapter thread available from Alan Gordon Enterprises, 1430 Cahuenga Blvd., LA, CA 90028, (213) 466-3561. The microphone holder screws into the 5/8" thread.

Other articles in this series, and by Joseph Horning, etc.:

Recording the organ part 2: Microphone placement

Chorale Preludes of Johannes Brahms

Recording the sound of a pipe organ in church

Microphone arrangement for recording a pipe organ

Part I appeared in the February issue, pp. 16-18.

The "art" of sound recording consists of selecting the proper microphones for a given situation and placing them in the most advantageous position. We will look at three basic techniques--coincident, near coincident and spaced omnidirectional--and then discuss which might be more beneficial given the specifics of organ layout and room acoustics.

Coincident Microphone Placement

We've probably all been to a concert where a professional recording engineer has set up one very large and impressive microphone on an equally large and impressive stand with which to make a stereo recording. Within that large microphone were actually two directional microphones which the engineer, with an amazing amount of flexibility, can select, position and modify by remote control. Coincident means "to occupy the same area in space," and that's what a stereo microphone has: two mono mikes occupying the same space within the microphone housing. One of the characteristics of all coincident techniques is that the sound arrives at the left and right microphones completely "in phase."28

Figure 10 shows how you can position two cardioid (unidirectional) microphones in a coincident position. The strength of this technique is that it gives a fairly realistic stereo image when played back through speakers (i.e., the first violins seem to be on the left, and the double basses seem to be on the right). The weakness is that the stereo image seems to lack a "sense of space."29 Since cardioid microphones are directional, they accept sound from the source in front of them and reject sound, such as reverberation, coming from the room behind the microphones. This may be a plus in an extremely reverberant room.

Professionals may also choose to use two "figure of eight" directional microphones30 set in an "X" pattern at 90° to one another, each of which picks up not only sound from in front but some from behind as well. This coincident technique, invented by British scientist Alan Blumlein in the 1930s, can give very natural sound in some circumstances.

Another coincident technique favored by some professionals is the "M-S" system31, which requires a special processing network to resolve the recorded sound into left and right stereo signals. An advantage here is that it gives the mixing engineer greater control of the stereo image from the mixing desk than is available with any other technique.32

Near-Coincident Techniques

In a successful attempt to improve the stereo illusion, sound engineers began to separate the coincident microphones ever so slightly so the sound arrives at the microphones just slightly out of phase, thus contributing additional information which enhances the stereo image.33

We'll discuss two similar setups, the ORTF system from the French National Broadcasting Organization and the NOS system from Dutch Broadcasting. Both of these use cardioid (unidirectional) microphones. The ORTF system splays the microphones out at a 110° angle and separates the recording capsules by 17 cm (63/4"), whereas the NOS has the mikes at a 90° angle with a 30 cm (113/4") separation.34 These near-coincident techniques are superior to two strictly coincident cardioid microphones. Professional audio stores sell inexpensive adjustable rigs to hold two cardioid microphones on one mike stand in a near-coincident configuration similar to NOS (see Fig. 11). A near-coincident variation of the Blumlein technique places two figure of eight mikes at 90° to each other in an "X" configuration, but separated by about 7".

Spaced Omnidirectional Mikes

In many of the coincident or near-coincident configurations we just discussed, you are recording primarily the sound of the organ alone. With a spaced pair of omnidirectional microphones, however, you are recording not only the direct sound from the source, but also the room's response to the sound--reverberation--which is a big plus in organ recording. Under the best circumstances, the sound of spaced omnis can be very open and sensual indeed.35

How far apart should the microphones be spaced? The minimum is about 4'--that is, 2' on each side of the centerline drawn between the sound source and the microphones. Omni mikes are typically spaced 1/3 of the way in from the edges of the sound source. For example, if the organ is 18' wide the microphones could be placed 6' apart--3' on either side of the centerline (see Fig. 12).

If the sound source is very wide, however, two omnidirectional microphones may be spread so far apart that an aural "hole in the middle" becomes apparent. This is alleviated by placing a third omnidirectional microphone directly in the center, and then with a mixer adding just a bit of its sound to the left and right channels.26 If the volume of the center mike isn't kept quite soft compared to the left and right mikes, however, you will kill the stereo effect. A variation of this "center channel" technique provides a third mike to accent a soloist.

Spaced Pair of PZMs

Spaced PZM microphones behave very much like a spaced pair of omnidirectional mikes. The bass response of PZM mikes is enhanced when they are resting on a surface at least 4x4'--thus the floor is an excellent place for them. However, you don't want to bury them in the shadow of a pew or other obstructions, as this will modify their hemispherical pickup pattern. The author's favorite PZM setup uses two 4x4' pieces of masonite37 which are stored at the church and placed on top of the pews as needed. For flattest frequency response, place the PZM 1/3 of the way off center--8" off center on a 4x4' panel38 (see Fig. 13). For personal analysis recordings, you may be able to position the mikes on the console (see Fig. 14).

Which Is Better?

There is a spirited debate in the audio world between the proponents of coincident or near-coincident techniques versus the advocates of a spaced pair of omnidirectional mikes. The coincident techniques--which ensure that the left and right channels are in phase--used to solve problems that no longer exist today: the difficulties of cutting the master from which LP recordings (remember LPs?) were stamped, the difficulties of phono cartridges (remember them?) tracking low frequency sounds on LPs, and the problem of sound cancellation on mono radio stations (a rare breed) as out-of-phase stereo signals were summed to mono.

Further, as Edward Tatnall Canby observed in Audio, the bureaucracy at National Public Radio mandates coincident recording techniques (especially M-S) and gives them a hard sell in spite of the fact that many listeners find something important missing in the resulting recordings.39 Agreeing with Mr. Canby, Christopher Czeh, Technical Director of WNYC Public Radio in New York wrote:

The phase differences between spaced omnidirectional microphones help the listener in mentally recreating the spatial acoustics of the original performance. I have used spaced omnis for classical recordings for six years and have obtained excellent results. The major reason I prefer spaced omnis over coincident mikes is that they sound better in most circumstances.40

David Wilson of Wilson Audiophile Recordings, agrees and notes the crucial difference between the ears and microphones:

Microphones "hear" very differently than ears do. The microphone is very literal in what it picks up. There is no neurological ear-brain system that compensates for ambiance and perspective. For most recording, I prefer omnidirectional microphones because they are more natural sounding. That is, they more naturally integrate the sound of the instrument with room acoustics, and that's very important with pipe organs. In almost every organ recording I've made, however, I've experimented with a coincident pair of directional microphones, almost out of a sense of technical duty. After listening to the test results, I've almost always gone back to a spaced pair of omnis.

Frederick Hohman of Pro Organo has a different view:

My personal preference is for good directional microphones--not omnidirectional. A pair of these can be placed in any conventional pattern and configuration one desires. A single stereo mike could be the easiest way to do a quick setup, since this eliminates the factor of microphone spacing.

Jack Renner of Telarc, who has recorded Michael Murray in many diverse situations, looks at the broad picture:

The thing about coincident or near-coincident microphone techniques such as the ORTF configuration with directional mikes, or the crossed figure of eights, or the M-S systems, is that while they may not be everyone's cup of tea in terms of finished sound--I myself like the sound of a pair of spaced omnis--the coincident techniques will give you a perfectly acceptable recording and are a very safe way to approach a recording of anything.

How Far from the Organ?

How far the microphone(s) are placed from the sound-producing elements of the organ is one of the critical decisions in any recording setup, and it won't be the same for all circumstances. If an organist is making personal "analysis" recordings, a relatively close microphone position will give increased clarity, especially in a reverberant room. If the goal of the recording is to show the organ/room combination to its best advantage, a more distant position will increase the proportion of room (reflected) sound. Pipedreams' Michael Barone, who has probably listened to more organ recordings than anyone and who has made quite a few organ recordings as well, has some definite opinions:

A lot of people think that to get a sense of space they need to record from the back of the hall, and so many organ recordings are made miserable by this "gray tunnel" effect. But you don't want to put the microphones within two or three feet of the chamber either. You want to place the microphones where there is an obvious focus of the sound, but where the sound has begun to excite the room and participate in the acoustics of the space.

John Eargle of Delos agrees that most people tend to place the microphones too far from the organ, and describes how he decides where to place the microphones:

First I walk around the room while listening to the instrument. The best place for the mikes is within a zone where the direct sound of the organ and the reverberant sound coalesce. What you have at this magic point is a very natural blend of room sound, plus good articulation from the instrument.

David Wilson is a firm believer in recording some "tests" to determine the best place for the microphones:

Generally I will start testing with a very close placement, say perhaps 10 or 12', which is closer than I believe is ideal. We will record 30 seconds or so of music and move the microphones back--generally I move them back in 3' increments--and record another test. We repeat this procedure five times. I also vary the height, starting with a height which is less than ideal--I believe 8' or so is the minimum satisfactory height--and go up from there to perhaps 20' or higher. I also vary the spacing between microphones. I start with the microphones closer together than I think they should be, say 4', and separate them further. By listening to the playback of these tests, we discover the best distance from the organ, height and between-mike spacing.

Jack Renner also stresses listening:

In placing the microphones, a lot of it is experience and a lot is listening. I have the organist play with various combinations of stops and I walk around the room listening until I find a place that sounds focused and blended--a place where all the registers seem to come together and where the bass pipes especially sound good and solid. You will find a point where there is good balance between the direct sound from the pipes themselves and the reverberant sound of the room, where you have a pleasing mix and where you don't hear various voices "popping" in and out, which is one of the biggest pitfalls in organ recording.

Aesthetics and Mike Distance

Crucial factors in deciding how far the microphones should be placed from the organ may well be the type of organ, the type of room and the type of music to be recorded. You might expect one type of presence, articulation, clarity and room sound for an all-Bach program on a tracker organ in a moderate-sized church, and have completely different expectations for a program of Romantic music on a large Romantic organ in a reverberant cathedral. Personally, I think a good number of recordings of the latter type have been ruined because the engineer was striving for too much clarity. These misguided attempts often have harsh, close-up organ tone and inadequate reverberation from mike positions that were too close. In this context it is very educational to listen to the same organ played by various artists and recorded by different engineers.41 Despite what the "experts" say, only you can decide if you like cathedral music to wash over you in a sea of reverberation.42

More than two Mikes?

When the sound source is very wide, for example a symphony orchestra or an organ that is quite spread out from left to right, you may have to spread a pair of omnis so far apart that you begin to lose sound from the middle--giving rise to the expression "the hole in the middle." Some recording engineers solve this problem by placing a third omni mike directly on the center axis of the sound source and mixing it on site into the left and right channels at a much softer level. This is Telarc's standard three-mike setup for symphony orchestras, although for concertos they will use additional mikes if necessary to highlight the soloist. Telarc's standard organ setup is two spaced omnis. However, they used a three-mike setup to record the wide organ at Methuen Music Hall, with the mikes about 35-40' back from the organ. When John Eargle recorded Robert Noehren on the large Rieger which sits front and center in the chancel of the Pacific Union College Church in Angwin, California:

We used three spaced omni mikes, 15-18' from the organ case. This case, like most trackers, is fairly shallow--eight feet deep at most. If there is a magic zone for mike placement that seems to work with this type of instrument, it is in the 17-20' range.

Other recording engineers, David Wilson included, do not use this technique because they feel that mixing a centrally-positioned monophonic mike into the left and right channels dilutes the stereo effect.

Recording the Reverberation

In order to capture the way an organ really sounds in a room, it is sometimes necessary to add additional microphones to record the reverberation. Few American churches have an excess of reverberation, but many have more than would be captured by the setups we have described thus far--two or three microphones placed relatively close to the organ. So a pair of microphones at some distance from the organ, with a small amount of the output of the left "reverb" mike mixed into the left channel and vice versa, does the trick. One might think that a single mike placed at a distance with the output shared between the channels--a variation on the "hole in the middle" technique--would suffice, but this is not usually done:

Reverberation from a single [distant] source divided between the left and right channels is unsatisfactory because the resulting sound, which, to give a natural effect, should be distributed across the space between the two loudspeakers, appears in this case to emanate from a single point.43

When John Eargle recorded Robert Noehren playing the organ he had built in 1967 for The First Unitarian Church in San Francisco:

I wanted to accurately portray the physical layout of the organ--which is arranged left to right in the rear gallery--so the primary mikes were a pair of directional cardioids splayed in a near-coincident configuration. The room is not reverberant, but there is enough room sound to give a nice glow and enhance the music. So we used an additional coincident pair of directional mikes, aimed more or less at the side walls, to capture this glow.

When Michael Barone recorded the Fisk organ at House of Hope in St. Paul, Minnesota, he encountered a similar situation:

The organ, which has a Rückpositiv, is located in the rear gallery. It generates a lot of bass energy, but that is not apparent in all areas of the room and generally not along the center aisle as the bass energy tends to hug the walls. So we placed a single stereo mike in the center aisle on a stand tall enough to get it well above the Rückpositiv. We also placed a pair of omni mikes a little further back from the organ closer to the side aisles, and then mixed the four inputs together until it sounded good--it's a little like cooking!

John Eargle describes his technique recording the large encased Rosales tracker organ at Trinity Episcopal Cathedral in Portland, Oregon:

The organ is located at the back of a rather deep chancel. Two omnidirectional microphones were used for direct pickup of the instrument in the chancel area, while a coincident pair of directional mikes was placed out in the church for reverberant pickup.

Improving the Room

There are basically two things you can physically do to the room before recording: decrease the noise and increase the reverberation. Potential noise sources that you may be able to do something about include: ventilation and heating systems, buzzing fluorescent lights, open doors or windows, etc. You may have to work around other noise sources like vehicular and air traffic, school children, and even expansion sounds from the roof as the sun heats it up mid-morning and it cools down in the evening.

It will increase the reverberation in an empty church significantly if the pew cushions can be removed. This is John Eargle's standard practice and he gets a lot of benefit for a reasonable effort. If the church is large and storage of the cushions is a problem, try stacking the cushions from two pews on top of the third, etc., etc. This will expose two-thirds of the hard pew surfaces (see Fig. 15). Or if the church has theater-type chairs with plush cushions, flip all the bottoms upright to minimize the absorptive surfaces.

Some Typical Solutions

The following are some microphone selection and placement solutions for various types of rooms:

Excessive reverberation--Use a pair of cardioid (unidirectional) microphones in a near-coincident configuration such as ORTF or NOS.

Minimal or average reverberation in a large room--Start with a pair of spaced omnis or PZM mikes and then, if you have mixer capabilities,44 try an additional coincident pair of directional microphones further back in the room mixed very subtly into the main pair (left into left and right into right).

Very wide sound source--Use a pair of spaced omnis or PZMs 1/3 in from the edges of the sound source. If necessary, a third omni in the center can be very subtly mixed in if there is an audible "hole in the middle." Alternatively, experiment with a splayed pair of directional cardioid mikes in the ORTF or NOS configuration.

Divided organ on the left and right sides of chancel or gallery--Try a pair of spaced omnis or PZMs. At Grace Cathedral in San Francisco, David Wilson recorded the huge Aeolian-Skinner which is divided in left and right chambers in the chancel plus a Bombarde Division at the rear center of the chancel. He used just two omnis spaced 8' apart, on stands about 20' high placed in the nave about 15' from the organ.

Rear gallery placement or organ high in the chancel--Unless the rear gallery is very deep (potentially allowing microphone placement within the gallery), you will need stands that allow you to get the microphones well up in the air.

Gallery placement with a Rückpositiv--The mike stands must enable placing the mikes well above the Rückpositiv if the correct balance between divisions is to be recorded (review the section on mike stand safety).

Organ is in a chamber on one side of a large chancel--The "standard" placement of a pair of spaced omnis on either side of the center aisle or a pair of coincident mikes in the center aisle pointed toward the rear of the chancel will pick up too much sound in one channel and not enough in the other. If the chancel is big enough, you might try a pair of spaced omnis within the chancel, each of which is the same distance from the organ.45 Alternatively, you might try a pair of cardioid directional mikes in the ORTF or NOS configuration within the chancel placed opposite the organ chamber and pointing at it. A third possibility is a pair of PZM mikes taped to the chancel wall opposite the organ.  With these solutions, the reverberation component will likely be nil, calling for reverberation mikes further back in the nave.

Organ is in a chamber on one side of a small chancel--If the chancel is not that large, try to adapt either of the above alternatives through placement within the nave. For example, if the pipes are on the left of the chancel, place a near coincident pair of cardioids on the right side of the nave pointing towards the organ. Or if using a spaced pair of omnis, keep the left and right microphones approximately equidistant from the pipes. Always avoid placing an omni mike too close to a wall to prevent hard reflections.

Modifying Registrations

If the purpose of the recording is to hear the effect of a piece you're learning or to document a recital performance, then the registrations are chosen for the live performance and the recording is secondary. But if the primary purpose is to create a recording which shows the music, artist, organ and room off to best advantage, the question of modifying registrations to serve that end is legitimate. English recording engineer Michael Smythe offers this advice:

One must keep a keen ear open for stops that do not record well. What may sound fine in the church may come through the loudspeaker as an opaque noise, for example, the booming sound which 16' pipes quite often produce on certain notes. Therefore the organist has to rethink his registration for recording, which may be totally different from a recital. Sometimes one can do nothing about it, however, there being no suitable alternate stops.46

The late Michael Nemo of Towerhill, who made numerous recordings of John Rose on the huge Austin at St. Joseph Cathedral in Hartford, concurred:

From a technical point of view, there are some problem stops. For example, 32' flues like a Bourdon or Open Wood can be quite pleasing in person. As most stereo systems won't reproduce anything at all from the bottom range of a 32' stop, however, it doesn't mean much on a recording. And by virtue of strong, low-frequency fundamental, these stops often create enormous standing wave problems in the room. No two 32' stops are alike in the way they record, however--some can be quite delicious and others only cause problems.

Excessive Dynamic Range

In addition to eliminating problem stops, there is the question of the dynamic range of large, Romantic organs. Consider Dupré's Cortège et Litanie, which begins very quietly on a solitary Choir Dulciana (sans pedal) and ends fff with a page of crashing chords over an octave pedal point. While this enormous dynamic range can sound glorious in person, if the recording level is set as it should be for the fff climax, the pp sections on tape will recede into inaudibility. If you turn up the playback volume so you can actually hear some detail in the pp sections--which you certainly can in a live performance--when the piece gets to the ff and fff sections you will be blasted into the next county unless you turn the volume back down again.

In the analog days when recording was done on magnetic tape, you would have a good bit of tape hiss competing with the Dulciana and thus there was motivation to avoid excessively soft sounds. But now that professional recording is done on hiss-free DAT,47 many engineers--reveling in the huge dynamic range of DAT recordings released on CD--are creating recordings of large, Romantic organs that virtually force listeners to keep their fingers on the volume control, especially when using headphones.

There are two ways around this. One is for the organist to compress the dynamic range of the organ by, in the Cortège et Litanie, for example, leaving the sub and super couplers off48 for the climax and substituting the Geigen Diapason for the Dulciana at the beginning--at that volume level the Geigen will sound like a Dulciana and the climax will be good and loud nonetheless. Another option is for a recording engineer who reads music and can follow the score to increase the volume level of the very quiet parts at the mastering stage.49 The final recording should not simply enshrine the technical capabilities of the DAT/CD medium but should be a reasonable facsimile of the way the performer's artistry actually sounds in the room.

Conclusion

Making recordings can be a useful tool for self study, a means of communicating with potential employers and professional competitions, a satisfying hobby, a part-time career, or the means to artistic fulfillment. We have endeavored to explain the bare minimum required for an understanding of the process. We have given some "quick and easy" prescriptions for personal recording. And finally, we have explored professional recording techniques used by some of the top pros in the field, whom we sincerely thank for their time and generosity.