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RE: Stereo Sub-Woofers

Bill,

Yes I had, twice before. It was originally inspired by an article in a small magazine full of DIY projects. This one involved use of the Electro-Voice 30" woofer in a 64 cubic foot cabinet. The showed the decrease of the in-box resonant frequency as they moved the cabinet closer to the wall. So I tried it with my 12" and it worked. The second time was helping a friend build up a good system. He had a pair of AR-3's that we drove with a Phase Linear 700. The AR's were on isolators and turned to the sidewalls, about 3' down the wall from the LS3/5a's that were the main speakers. They were placed about 1.75" inches from the wall (measured from the wall to the front molding). The owner then had finish panels made to cover the back of the AR's. Some of the best bass I've heard. The AR woofer is actually closer to an 11" driver.

In my case I'm using the same 1.75" spacing; but in my cabinet, the woofer is not recessed as on the AR, where the front panel is recessed at least and inch behind the from molding. More like an Advent cabinet. My friend's den had hardwood floors with an area rug, so the AR-3's sat on the hardwood. Without the isolators they made everything rattle and vibrate. The isolators were coil springs stuffed with polyurethane foam. We used 5 per speaker to handle the weight and to get the resonance high enough to get it away from the arm cartridge resonance on his Dual turntable. I coveted that turntable - direct drive and a heavy platter. Maybe a 714?

Some of the best low bass I've heard. The owner was an accomplished organist and collected recordings of famous organs, including several he made himself with a Nagra portable recorder. He wanted his own system to match the kind of bass he got out of a large pipe organ - we spent 2 years building and fine tuning the system.

One of the anecdotes about the system came when he hosted a dinner party at his home. He was in the kitchen mixing drink, while the system in the den was playing a Stravinsky number in which there was a very soft flute passage followed by a big crescendo. As he was fixing the drinks, the flute suddenly got a lot louder. Knowing the crescendo was coming he headed for the den - too late! As he got to the den door, there was this tremendous crash - and then silence. Next morning, a Sunday, he called me. Could I come over and see what was wrong? So I grabbed a bunch of stuff and drove the 15 miles. The electronics were all OK; but the woofer cones were stuck full inward, the voice coils jammed in the air gap. I pulled both woofers, got my fingers behind the cone and yanked. The cones popped back out and looked OK with no rubbing of the VC's, and continuity on the VC's. So I put it back together, and we tried the same Stravinsky piece. It worked fine. Those AR's were built tough.

The rest of the system was a Soundcraftsmen 2217 preamp/EQ with an Ortofon transformer for the MC cartridge. A Nakamichi Dragon cassette deck, and a Revox reel to reel. And a tweaked up Fisher FM tuner. Power for the Rogers was a Van Alstine Stereo 120 which matched the Rogers LS3/5a's quite well. Electronic crossover was a Phase Linear Series 20 (Pioneer). Most pieces were bought used or already on hand. Only the LS3/5a's, Van Alstine mods, the Ortofon transformer, the Dual TT and cartridge, and Crossover were bought new. Oh, and there was a huge Stromberg Carlson rim drive transcription TT in a lift top cabinet he used as a record cleaning machine. Boy, did it have torque!

Jerry


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  • RE: Stereo Sub-Woofers - Bold Eagle 20:04:43 01/02/17 (0)

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