[sdiy] CA3086 - was ARP Pots / Sequencer

[jhaible]

> Judging from the archives, JH has had pretty good luck with the 3086 in
his
> Quadra Phaser clone.

Well I think I just used what ARP used. (;->)


>  I think ARP probably used the CA3086 in some of their
> ladder filter designs as well.  Seems like I read somewhere that there
were
> 3086's in the MoogerFooger filters, but I'm not sure IIRC.

The 3086 is a cheap way to get fairly matched transistor pairs.
If you want well-matched, low noise transistor pairs, you can either
select low noise transistors, or buy expensive transistor pairs.
For the ARP Phaser, noise is not so important, because the ladder
is used with a compander / noise reduction system.
For a VCF that's driven with raw VCO waveforms at high and constant
amplitude, noise isn't much of a problem anyway. However, if
you run complex audio material thru a filter, where noise matters
and headroom is critical, it certainly can make a difference.

I have *not* compared a Mooger Fooger filter and an old Moog
Modular VCF myself, but I would not be surprised if the Modular
filter with its discreete transistors would have a better SNR.
(Same for the Phaser, BTW. The classic Moog Phaser has
a nice opto electronic compander system to reduce the noise from
the CA3094 OTAs. No such compander in the MoogerFooger
version. But then again, no compander in a Small Stone phaser,
either.)

JH.