[Ferstler]

On Jan 15, 12:08*am, Bret L wrote:
On Jan 14, 3:31 pm, Ferstler wrote:





On Jan 14, 2:49 am, Bret L wrote:

*Ferstler has never done any DIY projects. Nor is there any evidence
that he could.

*David Rich is another matter. In the old "Audio Critic" he would g
through commercial designs and essentially critique their component
engineering, always suggesting a better IC or other part for each
stage. Why he didn't simply design one "de novo" and publish a PCB
layout for us proles is my question, and one he never deigned to
answer.

Well, blast, I cannot let this one pass, even though my better
judgement says otherwise.

Not too long ago I sold off the Dunlavy Cantatas in my smaller system
(they were just too large for my wife's taste) and replaced them with
some home-built jobs. I used Allison tweeters and Tang Band mids in
vertical MTTM arrays with each system, and with a small Allison woofer
on the bottom of the slender, four-foot-tall cabinets. I designed the
crossover network myself (all second order, with polypropylene caps in
the tweeter and midrange high-pass networks, bipolars elsewhere,
chokes purchased from Parts Express, and with independent polyswitch
fuses installed to protect each driver array). All of the woodworking
and electrical assembly was done by me out in my workshop.

After they were done, I compared them to the Cantatas (level matched,
following guidelines I outlined in my recent AudioXpress article) and
they sounded quite similar, with the new systems being a bit more
spacious, thanks to the Allison tweeters and Tang Band mids and the
nature of the Dunlavy directional output design. I then hauled them
into my main system's listening room area and did a level-matched
comparison between them and my Allison IC-20 models. During some of
the A/B sequences, using mostly baroque and classical source materials
(music most of you people would not be able to comprehend), I could
hear no differences between my units and the Allison units at all.

*Yes, but you can't buy Allison tweeters, anymore can you? And how
efficient is this system?- Hide quoted text -

- Show quoted text -

I will answer you, because you post a valid question and seem
considerably more sane and honest than most of the other site members.

I have a stockpile of Allison drivers, but, yes, many old Allison fans
continue to scramble for spare parts. Fortunately, the drivers seem to
hold up very well, excepting the urethane foam woofer surrounds, which
deteriorate in a typical manner. I have replaced a lot of those
(several companies offer replacement kits), both on my own drivers and
on those belonging to friends. Fortunately, spare parts to refurbish
crossover networks are readily available, and, really, about the only
things there that might poop out would be the capacitors..

The smaller, main-channel systems I built have an 88 dB sensitivity
rating (2.83 volts applied, at a one-meter distance). That is about
the same as the bulk of the Allison speaker lineup (this varies, with
the company's 4-ohm models being 90 dB), as well as a lot of other
brands. The center speaker I built for my main system has an 87 dB
sensitivity rating, which is identical to that of the left and right
main Allison IC-20 units in the same installation.

Allison speakers have a reputation (like the old, classic AR line) of
being power hungry. However, you can get more than enough output with
a typical 100 wpc receiver. While I used to power all three front
systems with 250 watts apiece, I now use a receiver with 130 for each,
and get plenty of volume, even with movies. Of course, having an 18-
inch Velodyne subwoofer on hand to handle the bottom end takes
considerable pressure off of the satellite amps.

Howard Ferstler