MOTM

Check out:

www.expresspcb.com

I am so happy to have found this place. You choose the level of circuit 
board quality. All boards have plated throguh holes, but if you pay the 
difference you can also get solder mask ans top side silkscreen. They even 
let you write stuff in the copper if you want to go the lower cost route. I 
will label my board side componenets this way.

I want to do a board layout for Barry Kleins CEM3320 Lowpass VCF circuit 
(fig.5-20 in the book) from Electronic Music Circuits. It will end up a 
lowpass similar in sound and features to the 440 with the same inputs and VC 
resonance control. I have already started the pcb design and I hope to be 
able to find a couple of guys who are down to make a custom MOTM filter 
module with me. This is the classic filter from the sequential 
Pro-1/Oberheim misc and has the bass compensation when resonance is 
increased like the 440 (but on chip) The circuit takes a small amount of 
parts and the CEM is readily available from Paul.

You can get Paul-like circuit boards, but the cost for these is much more 
expensive with a solder mask or silkscreen. If you pay the difference you 
will end up with a quality board for sure so I would like to go the more 
expensive route, but cost then becomes a factor. 4 4 x PCB's of my design on 
the standard boards is about $110 total. The nice solder masked boards with 
silkscreen make the total about $350 for 4 boards, but its only $400 for 20 
boards so if we can come together on some sort of module we could all share 
the costs and end up with $20 PCB's of a high order.

Even if no one is interested I will go the cheap route wich ends up being 
about $25 per pcb (when ordering 4). If I end up going through with it I 
will post the results to you all. Thanks

Thomas White

PS. Quiet list this weekend right?

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> I want to do a board layout for Barry Kleins CEM3320 Lowpass VCF circuit
> (fig.5-20 in the book) from Electronic Music Circuits. It will end up a
> lowpass similar in sound and features to the 440

You won't.
Or more precisely, you might - if you always run it at signal levels where
nonlinearities are not important. Which is a small subset of interesting
applications.
You will come be able to emulate a Pro-1 filter, of course. But you won't
come close to a MOTM-440 - not closer than a revision 3 Prophet comes
to a rev. 2.

> This is the classic filter from the sequential
> Pro-1/Oberheim misc and has the bass compensation when resonance is
> increased like the 440 (but on chip)

"Bass compensation" is just what's going on "on the outside".  The similar
bass compensation has very different sonic qualities on a SSM "chip",
a CEM chip. (Or on a Roland chip for that matter. The Juno-6 has a similar
thing as well, but a filter circuit different to both SSM and CEM.)

JH.

Good find - I'll probably give them a try for some of my designs too!

Moe

>>>>>> 
Check out:
www.expresspcb.com

I am so happy to have found this place. You choose the level of 
circuit board quality. All boards have plated throguh holes, but if 
you pay the difference you can also get solder mask ans top side 
silkscreen. They even let you write stuff in the copper if you want 
to go the lower cost route. I will label my board side componenets 
this way.
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