[sdiy] A new Synth Project

[James Patchell]

Yeah, that filter is my take of the Paia 2720 bandpass filter.  I have 
been itching for a long time to do that filter with an implementation of 
a voltage controlled resistor done with an OTA.  And I agree, that band 
pass filter was the only good filter in the 2720, in fact, I have always 
liked the way it sounded.  Not really sure why I am calling this thing 
cheezy, but I was trying to go for a minimalist approach here, although, 
it looks like I was not very minimal. ;^)

-Jim

On 1/19/2012 12:34 PM, Harry Bissell wrote:
> yikes I don't see too well either anymore (at least not on my laptop screen...) I suppose i could download it
> to blow the pages up and get the page numbers but...
>
> is that your take on the bandpass filter from the PAiA2720 synth... with an LM13700 instead of diodes for tuning ?
> (its the transistor and twin-tee circuit...)
>
> Is that why its called Cheezy ?  Actually, the bandpass filter was the only good filter on the 2720... the LPF was nearly
> useless...
>
> H^) harry
>
>
> ----- Original Message -----
> From: James Patchell<patchell at cox.net>
> To: synthdiy diy<synth-diy at dropmix.xs4all.nl>
> Sent: Thu, 19 Jan 2012 15:01:21 -0500 (EST)
> Subject: [sdiy] A new Synth Project
>
>       When I lost most of my eyesight, I didn't think I would ever do
> something like this again...but here I go again.
>
>       Back around 1999, I did this project:
>
> http://www.noniandjim.com/Jim/smb1/smb.html
>
>       This board was huge (15" x 10").   And it was so big, building it
> was a real problem.  (Although, back then I could see).  I don't
> remember the component count, but it was a lot.
>
> Well, I got the hankering to give it another try.  But this time, I was
> going to keep it much smaller.  I have got the schematic about 95%
> complete at this time, and after counting the pages, it came to 32.
> Hmmm....not exactly as minimalist as I intended.  I call this one the
> SMBC, which stands for Synth Module Board - Cheezy.
>
>       It includes an AVR X-Mega controller which will do
> Midi/Sequencer/User Interface duties.  Anyway, here is a very prelim
> schematic.
>
> http://www.noniandjim.com/Jim/SMBCheezy/100-1059.pdf
>
> And the webpage is at:
>
> http://www.noniandjim.com/Jim/SMBCheezy/SMBCheese.html
>
> When I am done with this project, it will be "Open Source".
>
> -Jim
>
>
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