[sdiy] TIS93, TIS92 availability/substitute?

[Paul Schreiber]

First off, there is absolutely *nothing special* about these parts. Moog bought 
50,000 of them surplus for 4 cents each back in the day.

The most important things are:

a) the top and bottom pair need to be matched. In the MOTM-490 VCF, these are 
SSM2210s.
b) the other NPNs can be just about anything: 2N3904, BC550C, CA3046, etc
c) use film caps for the ladder
d) a large portion of the 'Moog sound' is in the resonance feedback loop. The 
50K reverse log pot is part of that
e) the diff amp at the 'top' of the ladder needs to have 1% (0.1% better) 
resistors and a high CMRR (use a TL072 or better).

Paul S.

----- Original Message ----- 
From: "Jeff Farr" <moogah at gmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, July 24, 2005 11:22 PM
Subject: [sdiy] TIS93, TIS92 availability/substitute?


> I'd like to make a few MiniMoog VCF clones.  I've already gotten a
> pile of the tis97's for the matched pairs, but the 92&93's are more
> elusive.  Any suggestions?
>