[sdiy] Transistor help

[Harry Bissell Jr]

Transistor matching will show up the most in
control voltage breakthrough in a ladder filter.

using 'unmatched' transistors does not mean that
they are 'not' matched... just that you did not
test for that parameter.

Given the choice between unmatched transistors
in VCF, VCA etc... I go for matched. I'm mostly using
monolythic pairs, or arrays. They sound much better
than the dumb luck filters I've tried.

CA3046 is like $.25 each in quantity, so why not
use 'em. ARP and Moog both did...

H^) harry



--- Kevin Lightner <synthfool at synthfool.com> wrote:
> >Hi,
> >Whats the point of matching transistors (in expo
> converters and ladders),
> >beyond 2mV?
> >Is there really a sonic difference? Do we need
> expensive 0.5mV matched
> >arrays or just transistors from the same batch?
> >
> >Emperors new clothes? Or State of the Art?
> >
> >An E-mu Systems Resonant Filter I have recreated
> sounds better with
> >unmatched 2N3906's rather than a dual transistor
> pair (as per the
> >original).. any thoughts guys?
> >
> >Regards
> >Rob
> >www.emulatorarchive.com
> >
> >
> >One thing I have noted about modern batches of
> transistors is they sure
> >seem to be all very similar...I generally match
> about 10 pairs at a
> >time...out of 20 transistors (generally 2n3906) I
> always get 10 pairs...and
> >all of the transistors are within about 2mV of each
> other....30 years
> >ago...it wasn't like that...as I recall.
> 
> 
> I'm curious how the two were A/B'd unless you made
> duplicate filters. :)
> 
> However, transistor matching, in my opinion, is
> blown out of proportion.
> I'm not sure most people can hear a filter and say
> it sounds like the 
> transistors are unmatched or whatever. I've also
> built Moog filters 
> with completely unmatched transistors, even from
> different makers and 
> they sounded great.
> 
> It's funny about all the rumors out there in regards
> to matching too.
> For example, there's a rumor that only the early RA
> and Musonics 
> Minis used matched transistors in their ladders.
> I have 11 (count 'em!) Minis in and they ALL have a
> colored dot on 
> their transistors, which the other same numbered
> transistors don't 
> have. The reason, often overlooked, about the very
> early Minis is 
> that their electrolytic caps are older and of
> different values when 
> new anyways.
> 400uf, instead of the later 470. 80uf instead of
> 100uf and so on.
> Their carbon resistors are often *way* off too.
> I often measure the 820 ohm resistors at 1K-1.2K.
> 
> 
> -- 
> Regards,
> Kevin Lightner
> 
> Myself: http://www.synthfool.com
> Service and sales:
> http://www.moogmusic.com/service.php
> Sales: http://www.cluboftheknobs.com
>