Stereophile's Test CD 2 Track 10

Track Information, Track 10

[10] Mapping the Soundstage (ADD) 1:04
Larry Archibald (acoustic voice, footsteps, handclaps), John Atkinson (Cambridge Soundworks Ambiance loudspeaker)

Recording Venue: Universalist Unitarian Church, Santa Barbara, CA
Recording Date: January 29, 1990
Recording Engineer: Kavichandran Alexander (Water Lily Acoustics)
Microphones: two EAR The Mics set to figure-8 pattern, coincident at 90 degrees and spaced vertically by 2"
Microphone preamplifier: EAR 824M, Cardas microphone cables
Recorder: Ampex MR70 ½" open-reel recorder at 15ips
Tape: Ampex 456
Transfer to digital: Manley Analogue to Digital Converter, Aiwa HD-S1 DAT, Ampex ATR-100 open-reel recorder, AudioQuest Lapis balanced interconnects
Digital Transfer Engineer: John Atkinson

Before we embarked on the formal sessions for Stereophile's Intermezzo piano album, we recorded Larry Archibald "mapping" the soundstage in the church, illuminating the bounds of the acoustic to be later excited by the piano with his footfalls and handclaps (see fig.4). The Blumlein microphone technique, using two figure-8 microphones "crossed" at 90 degrees, accurately captures the directions of soundsources, though the slight degree of vertical spacing Kavi Alexander used somewhat widens the center of the stage.

Larry walks from the far left of the church to the far right, facing out from the altar (footnote 4), a total distance of about 35'. In both cases the position of the images should lie well outside the loudspeaker positions (if you have a pair of speakers that can image accurately). He then walks back to the center of the nave, then to the rear of the church about 60' from the microphone array. Clapping his hands, he then walks back up the nave to the microphone position and around the microphone (left to right), ending up in front of the piano. (Because stereo microphones cannot discriminate between soundsources in front of them and behind them, you should hear Larry move back behind the speakers rather than behind your listening chair.) JA's voice comes from a small foldback loudspeaker placed on a chair to the left of center of the stage, right behind the piano stool and next to the pulpit.

All through this track you should hear unambiguously where Larry and the loudspeaker are. You should hear Larry's image well beyond the speaker positions, when appropriate, and well back in the distance when he is at the back of the hall. When he walks around the microphone position, you should also hear his image lurch to the far left, then back again. If his position at any place seems confused or vague, then something in your system is not imaging as it should.

The microphones were left in the same position for both of the following tracks. In a sense, therefore, this "mapping" sets the context for the image of the 9'-long piano.

Footnote 4: As Larry was facing away from the altar, he correctly if confusingly refers to the listener's far left as "stage right" and far right as "stage left."