[rollei_list] Re: Completely OT- Loudspeaker info a pop up question
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 17 Feb 2005 13:52:40 -0800
----- Original Message -----
From: "John Jensen" <jwjensen356@xxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, February 17, 2005 8:20 AM
Subject: [rollei_list] Re: Completely OT- Loudspeaker info a
pop up question
>I don't think that Altec Lansing had a Peerless line
> of speakers. However, there was a highly regarded
> transformer maker named Peerless that was acquired by
> Altec Lansing. Peerless output transformers were
> highly regarded back in the golden age of audio.
>
> Then along came David Hafler and Herbert Keroes
> (spelling?) and formed Acrosound with their
> transformers. Hafler later spun off from Acro forming
> Dynaco making audio output transformers which seemed
> to be a knockoff of Acros. Acro and Dynaco output
> transformers were also highly regarded.
>
> John
>
Acro transformers were excellent. In fact, they were used
in the amplifiers of the Westrex Stereo disc cutting system.
Haffler was one of the first to understand than the inherent
bandwidth of feedback amplifiers had to much wider than the
"usable" bandwidth. A powe amplifier with 20 db of feedback
(typical) must have a bandwidth of around 100khz to cover up
to 20khz. Few output transformers prior to the Acro would do
this. Frank McIntosh was another who understood the
requirement for transformers in feedback systems. His real
contribution was the design of an economical winding method
that allowed very tight coupling and very low parasitic
reactances in a transformer. The split load idea of the
McIntosh amplifier was actually an old idea. The Acoustical
Quad amplifier beat him to a commercial version of this.
McIntosh was able to run his first amplifiers in class B
because of the transformer but this really not a good idea
when feeding loudspeaker.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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