Moog 904A lowpass filter Question

[Colin Fraser]

----- Original Message -----
From: "jh." <jhaible at t-online.de>
To: "Gerry Dahl" <gerryd at ntx-tech.com>; "Synth DIY"
<synth-diy at node12b53.a2000.nl>
Sent: Sunday, January 07, 2001 10:34 AM
Subject: Re: Moog 904A lowpass filter Question

> Apparently Moog used slightly different buffer amps
> for each VCF they made, and these will most likely affect the sound
> way more than all the above points.

Some time ago AHer Michael Caloroso put together a list of most variations
on the ladder Moog built, in order of his preference, and compared the
buffer amp design, and resonance feedback method (ac or dc coupled).

You'll find his mail in the AH archives at midiwall -
http://www.midiwall.com/archives/ah/lookit.cgi?-v1997-10.121

Very useful reading if you're interested in the differences between Moog
ladders.

Certainly in my experience, the filter in my mini, Prodigy and the Source's
I've borrowed or repaired all sound noticeably different.

Colin f