Craftsman's Corner-- James Y. Pann's gargantuan speaker system.
James Y. Pann is a senior professional engineer, an amateur string player and audio hobbyist. His speaker systems are 6X4X2.5-feet that is. The top segments swivel to adjust for best sound response in the listening area. The enclosures are made of double thick 3 /<" plywood and particle board (plywood outside, particle board inside) front and sides and triple thick back.
Sized lumber two inches square provides the internal bracing. Each four-way units weighs about 650 pounds.
An electronic crossover (12dB/octave) divides the signal at 100Hz and a passive crossover (12dB/octave) further divides the spectrum at 350Hz and 5kHz (see photo). The subwoofers are ElectroVoice 30" drivers; the mid-bass is a 15" cone driver and the midrange and tweeter are horns. The latter three are Speakerlab products.
"Using the CBS pink noise record STR-140 and an SPL meter, the system is adjusted to correspond to a curve derived from the Fletcher-Munson data on hearing. 1 The optimum listening level is at around 70dB when the listener is 15 feet from the speaker system (R & L driven simultaneously). Chamber music at 65dB; symphonic music at 75dB (fff at 90dB)." the system builder reports.
The subwoofer is driven by a Dynaco Stereo 120 and the upper three channels by Dynaco Mark Ills.
Mr. Pann graciously invites listeners to visit him when in the Bay area. He lives in Richmond California 94804.
'Now superseded by the S. S. Stevens experiments. See Stevens /. Acoustical Soc. Am. Vol 51, No. 2, pt. 2 (1972) p. 575-601. Also Tomlinson Holman's excellent Preprint No. 1281, (D-4) from the Nov. 4-7, 1977 Audio Engineering Society Convention, titled "Loudness Compensations: Use and Abuse. "
Also see:
An Ambience Reproduction Speaker System
How to Improve That Small, Cheap Speaker --by Paul J. Stamler photos by the author