[sdiy] Buchla VC Bandpass (with proper header)

[mark verbos]

The Buchla 291 bandpass is more like a state variable than a sallen-key. 
In fact, there are points that you can tap to get the lopass and high 
pass out of it. Ask Scott Sites.

BTW. you can replace the dual FET buffer stages with OP Amps. Check out 
my page.

Mark





Aaron Lanterman wrote:
> 
> [Ooops, sorry I sent this without a subject last time...]
> 
> OK, I think I've (more or less) cracked the Buchla LPG; I'm going to 
> present it in class tomorrow, along with the Korg MS-20 LPF and Rene's 
> version (I'm going to start with Rene's since it's easier to see what's 
> going on on his schematic).
> 
> Next curiosity - anyone have a clue what's going on in the Buchla VC 
> _Bandpass_ filter?
> 
> I conjectured he might use a bandpass Sallen-Key; I tried tracing one 
> out, but failed utterly; I don't think that's what's going on. There's 
> clearly some JFET buffers in there; beyond that, I dunno...
> 
> - Aaron
> 
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