[sdiy] New long term project

[cheater cheater]

The Synthacon is from the 70s. The differences between parts from the
same batch back then were bigger than differences between models of
parts nowadays. In other news, if it works, it works.

That's all I have to say regarding subs. :^)

On Tue, Aug 11, 2009 at 2:53 AM, David
Ingebretsen<dingebre at 3dphysics.net> wrote:
> For purely nostalgic reasons (short history below if you are interested) I
> want to build a Steiner-Parker Synthasystem/Synthacon clone. Nyle gave me
> schematics to his modules in 74, but (long story) they are gone. I found
> some Synthacon schematics which nearly fit the bill but I have some
> questions.
>
> While I can read a schematic, and I took upper level EE classes as an
> undergrad and some more in grad school, I am -not- pretending to be an
> analog guru.
>
> In the schematics, the matched NPN pair (2N5172, I still have a boatload of
> them and the PNP's Nyle used from when I was building an SP in 74, but alas,
> no FET's) is a pair of discreet transistors which were bent over and a
> thermistor stretched across the both of them.
>
>        1a.     Can this pair be replaced by an SSM chip? What
> characteristics would be important when trying to see if I can substitute
> the SSM chip?
>
>        1b.     Is it your experience that making this substitution will
> somehow change the character of the oscillation? I hated matching transistor
> pairs back then, and don't think I'll like it any better now but will do it
> if it will preserve some audio quality.
>
>        2.      Next, as I lamented, I don't have the old 2N5163 FET. I have
> found some cross references, but am unsure again which parameters I need to
> compare to match them. Can I just trust the cross reference charts and
> blindly substitute the one recommended?
>
> For what it's worth, this is not for profit, or sale. I just want to say I
> finished what I started as a 17 year old so many years ago.
>
> Thanks
> David
>
>
> ***********************************
> Historical note:
> Nyle was my neighbor and I don't know how, but I got his name as I was
> becoming interested in synthesizers. I called him and he invited me over. I
> left with a fistful of schematics and was totally inspired. Over the course
> of the next 9 months or so, he gave me more help, demonstrations, and even a
> summer job soldering PCB's in his shop. I only ever got a VCO and keyboard
> working. Life happened, I was gone for a couple of years and my brother
> threw it all out, schematics and all. All I have left are a handful of pots,
> and some transistors.
>
> So, with my mid-life crisis in full gear, I am now at a point where I want
> to finish the thing that really got me started. I want to build a true
> Steiner-Parker synthesizer voice. VCO, VCA, VCF, EG at the least.
>
> I don't know what I'll do with it other than look at it and feel happy :)
>
> ************************************
>
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