Sample Photo

Making Cameron Carpenter's -Revolutionary- A Telarc recording using a Marshall and Ogletree virtual pipe organ with Eminent Technology TRW-17 Rotary Woofers. An outside view of the church bell tower which faces Wall Street. The historic Trinity Wall street Sanctuary was used for this recording

Sanctuary View

A view from the balcony at the rear of the sanctuary, one of two Marshall and Ogletree organ consoles is installed here. The stage is set for a Haydn Concert which took place March 10th and 11th, 2008 conducted by Jane Glover. The rotary woofers were installed during the daytime practice sessions.

Robert adjusting the mix

A temporary recording studio was set up by Telarc. Speakers are being monitored by Robert Friedrich checking the mix real time. Switching back and forth both the two channel mix and the SACD mixed could be monitored. Bob Woods and Robert also liked to use headphones about 50% of the time.

Bill setting mic levels

Microphone cables were run from the recording studio into the sanctuary, here Bill McKinney, chief technician monitors mic levels. Once set, there was not much to do, unlike recording musicians, a pipe organ will not surprise you with greater sound levels than initially established with all the stops pulled.

some of the crew

Part of the crew, Front Left: Robert Friedrich, Front Right: Robert Woods, Right Rear: Richard Torrence, Middle Rear: Cameron Carpenter, Right Rear: Bruce Thigpen

The Walker subwoofer system already installed in the church for the M&O Organ consisted of 6 refrigerator sized enclosures using dual 15" woofers powered by 500 watt amplifiers for each enclosure for a total of 12 fifteen inch woofers and 3000 watts of amplifier power. Three of these woofer boxes were located in the front pipe chamber and three in the rear balcony. In the middle of the sanctuary, usable response measured down to 27Hz. On a 32' stop, about two thirds of the bottom notes C(0) to F(0) would be missing. Bob Woods, Telarc's President and Richard Torrence of Torrence and Yaeger who markets M&O organs asked Eminent Technology to participate in the recording.

M&O console

The stage console was used for the recording. The Eminent Technology TRW-17 rotary woofer provided the foundation for the Marshall and Ogletree organ for the first time creating a virtual organ that enabled true acoustic reproduction of 32', 64', and even 128' foot stops at realistic sound levels. The instruments existing sampled 32' stops were divided by two to create 64' stops and sine wave stops were created and added to instruments ranks at 32', 64' and 128' to create a low frequency foundation for other stops. Cameron Carpenter interpreted and added these stops to the score in real time.

M&O Balconey Console programming new stops

The Marshall and Ogletree organ adapted easily to its new low frequency capability. Doug Marshall and David Ogletree took existing 32' samples and also added "sine wave stops" with ranges matching 32, 64, and 128 foot pipes. This created a musical instrument for the recording that produced the lowest audible tones of any instrument in the world. (Today you can hear a M&O Organ with two rotary woofers permanently installed at Middle Collegiate Church in Manhattan)

door opening

Installing the rotary woofers: These doors formed the opening to a porch backspace volume used for the temporary rotary woofer installation. As you enter the main doors into the sanctuary the porch doors are located on the right.

outside view

Outside view of the porch which became the rotary woofers' "box" or backspace volume for this temporary installation.

rotary woofer baffles

Two TRW-17 rotary woofers (home versions) were used to fill the sanctuary volume estimated to be about 1 million cubic feet. Temporary OSB baffles were installed in the doorway between the side porch and the sanctuary.

finished installation inside view

Once the rotary woofers were added, this is the installation appearance from inside the sanctuary.

behind the baffles

The finished temporary installation from behind the baffles constructed by Winston Wright and Bruce Thigpen. The electric motors are 1/3 horsepower, 1725 rpm, each controlled by a frequency drive motor cotroller operating on 120vac. The blades were spinning approximately 800RPM. One 150 watt direct coupled audio amplifier was used driving both woofers in parallel. A balanced line level signal came from the M&O organ controllers sound card.

bracing ballast

The baffles were held in place by 240 pounds of ballast.

sine wanve stop E-1 slightly over 10Hz at 105dB

The sound pressure levels were set such that the lowest freqeuncy tones in these stops were approximately 10dB louder than the instrument's middle registers or about 105dB sound pressure level. Telarc placed the LFE microphone (Bruel and Kjaer 4007) about 30 feet from the temporary rotary woofer installation, where the measured response was +/- 3dB from from 6.5Hz to 24Hz. For the recording this is the only electronic pipe organ in the world with a 64' stop and the only organ of any type that could reproduce sounds from a 128' stop. During the recording the Marshall and Olgetree organ produced the lowest tones and had more octaves and range than any other pipe organ in the world.

Pink Noise frequency response

The frequency response of the woofer system using pink noise. The sound pressure levels were set such that the lowest freqeuncy tones in these stops were approximately 10dB louder than the instruments middle registers. Telarc placed the LFE microphone (Bruel and Kjaer 4007) about 30 feet from the temporary rotary woofer installation, where the measured response was flat from 6.5Hz to about 25Hz.

rear definitive array

The midrange and high frequencies from the organ are produced from two arrays of Definitive Technology speaker systems. This photo is of the array in the balcony. The arrays were powered by Carver Amplifiers. It was anticipated that this array was going to be used for the recording. Telarc spent approximately 14 hours testing microphone types and positions trying different microphone locations at the front, middle and rear of the sanctuary. A smaller array of speakers near the stage area ended up being chosen as the main left and right channels for the recording with surround mics closer to the rear speaker array.

20Hz 110dB SPL

The rotary woofer levels were set to 105dB between 7Hz and 25Hz rolling off on either side of this frequency range. The system capability was a little over 110dB measured in the middle of the sanctuary. Shown is the 20Hz distortion with a sine wave from a signal generator (about 3%). Out of respect for the structure and in keeping with the tonal balance of the instrument it was felt that 105dB at the lowest notes was desireable. The settings for the fundamental tone levels relative to the harmonics were patterned after the amplitudes of Atlantic City Convention Hall organ's 64 foot stop.


We would like to thank Robert Woods, Richard Torrence, Robert Friedrich, Bill McKinney, Susan Slaymaker, the church and church security staff who stayed with us for some very long days and of course Cameron Carpenter who wanted to use the rotary woofers in his first recording. You owe it to yourself to listen to this recording and if you get the chance you should definitely see Cameron perform live.