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Re: Doc: would you comment on the sound.....

I heard a Bastanis Prometheus system at the 2004 RFAF driven by Brian Cherry's DIYaudio 300B amps. This was in the BAULS Audio Room. Heard many of the rooms at this show, but not all, because I was busy promoting my VTAF (Vertical Tracking Angle on the Fly) tone arm mod. Of the systems I did hear, this room was my "best-of-show." Very transparent. Very musical. Great imaging, even off axis. Some of the tautest deep bass I've heard.

Robert Bastani explained to me that the Promethius woofer operates in the region below resonance (he calls it subresonant operation). This is accomplished by installing a large high efficiency woofer in a sealed cabinet small enough to move the resonant frequency up to 100 Hz. In the Promethius, the woofer is used only below 60 Hz. Below the 100 Hz. resonant frequency, and characteristic of sealed box speakers, the unequalized response falls at 12 dB per octave with decreasing frequency. This is equalized out by a filter with a 12 dB per octave rise as the frequency falls (you can get this by double integration of the signal).

The Prometheus was selling at that time as a kit with the woofer filter and amp and all the drivers and crossover components, no cabinets, for $1625.

Another woofer system using the subresonant principle is the one by Jan Plummer of Atlanta. The company was Virtual Bass Technologies a couple of years ago, but has undergone a name change. This uses a different baffle configuration, but does use the subresonant operating principle. Like the Bastani woofer system, this too has unusual bass tautness and clarity.

On the basis of these two experiences, I've become a big fan of subresonant woofer operation.

If going the Prometheus route, it will be important to obtain the Bastani bass equalization electronics, or the equivalent.

Pete Riggle www.vtaf.com



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  • Re: Doc: would you comment on the sound..... - PeteRiggleAudio 10/9/0522:08:20 10/9/05 (0)


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