[sdiy] Moog ladder filter transistor pairs matched or not..??

[Tom Wiltshire]

I thought it was the other way around - the top and bottom pairs need matching, but the ones in the middle don't matter so much. That's why the schematics that use the 3046 use it for those pairs. For example, The Elby version of Paul Maddox's Monowave:

http://www.elby-designs.com/webtek/monowave/MonoWave-V12.PDF

HTH,
Tom

On 18 Feb 2014, at 13:50, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:

> Hi list,
> 
> i'm about to build some VCF modules for my DOTCOM synth
> in the next weeks. I'm gonna use the nice Moog ladder type VCF
> like this one:
> http://www.experimentalistsanonymous.com/diy/Schematics/Filters%20Wahs%20and%20VCFs/Minimoog%20ladder%20VCF%202.gif
> 
> Some DIYers used that Moog design and adapted it to their needs..
> But when I check the info about the matching or not
> of some of the ladder transistors, opinions differ from one
> guy to another.
> In fact, looking at the transistor ladder there are 5 pairs
> of transistors stacked on each other. We'll call them
> row 1 to row 5.
> Most forums I browsed talk about transistor pairs rows 2,3,4
> that need to be matched. Pairs on rows 1 and 5 need no matching.
> But some DIYers say even rows 2,3,4 need not to be matched
> for the VCF to work correctly..
> 
> What should I keep as a good info ??
> JP
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