Originally Posted by Charles Hansen
The Beveridge website still appears to be active:
The letters in RM-3 stand for Roger Modjeski, who still makes tube amps:
You may be able to find resources there. A ported loudspeaker such as the KEF LS50 will have a 4th-order rolloff at the low end. This normally will create its own natural acoustic crossover. The subwoofer should be used to augment below the limits of the main speakers. The chief reason to add a high-pass filter to the main speaker is to reduce the power sent to the small woofer, in an attempt to reduce distortion and/or power dissipation. This is normally only a problem if you are playing the system extremely loud. Creating a high-pass filter for the main speakers is a complex engineering project in itself. In addition, any extra electronics in the signal path of the main speaker will be quite noticeable. As long as you are not hosting large dance parties, you should be in good shape.
First off let me say that while I have never owned Ayre equipment I have always been impressed by the designs and enjoy listening to Ayre systems at the audio shows. Don has been a friend of mine since my days in Santa Barbara and I have known Roger Modjeski since then and now work with him up in the Bay Area. He was the Chief Designer for Beveridge electronics, including the amplifiers that powered those ESLs you heard, as well as the Beveridge RM 1 & 2 (12 tube preamp with separate power supply).
Your comments on the Beveridge speakers are very much appreciated. The "Beveridge Lens" made them unlike any other ESL and even today many ESL manufacturers cannot achieve the dispersion characteristics of Beveridge ESLs. It made them sound so realistic and three dimensional.
Today I use Quad ESL 57s in a biamp setup with an RM-3, where the low pass (4th order Linkwitz/Riley, 100 Hz cutoff) is sent to a vintage Luxman M-02 that powers four passive 8" woofers placed asymmetrically around the room. The high pass (4th order Linkwitz/Riley, 100 Hz cutoff) feeds a Music Reference RM-10 (single ended set up) or Atma-Sphere M-60 OTLs (my balanced differential set up).
I'd be interest in you expanding on the differences (if any) you see in biamping using the method I have in my set up versus running the Quad ESL 57s full range and just feeding the low pass to passive woofers or subs.