Modular Synth Panels

Very nice panel.  Not sure how often I would use both the AC and DC 
linear inputs at once.  I might swap the DC linear FM input for a second 
reversible CV input if I had to choose, or find a way to add an AC/DC 
switch.  But your large panel affords just about everything.

For a completely different and minimal approach, see the panel I've just 
uploaded to the same directory: dual-cgs-vco.fpd.  It is the VCO core 
that interests me.  I put two CGS VCOs into a 2U panel (1 in 1U would be 
just half).  I omit the Serge-lke CV inputs and the waveshapers.  The 
result is a VCO with features much like a MOTM-310, but with the 
addition of SYNC and linear FM, and with separate SAW and PULSE 
outputs.  I use switches to select whether the FM input is applied to 
one of the exponential control inputs or to the AC or DC linear input, 
MOTM-300 style.

My first try at this panel substituted a CV input for the FINE tuning.  
You can see it in the Richard Brewster Designs folder:  cgs-vco-2.fpd, a 
1U version.  It is a little awkward because with the additional CV input 
I had to use a switch to choose between SYNC and PWM input and also 
could only have AC linear FM.  The advantage it had was three total FM 
inputs, one of them being the cool reversible CV.  But after considering 
how much I use my FINE tune pots, I decided in favor of those, and as a 
bonus got separate jacks for SYNC and PWM inputs and could use the 
second switch for AC/DC linear FM.  Bye-bye cool reversible CV.  (Hey, 
but I have the Oakley Multimix!)  With a full featured panel you don't 
have this sort of dilemma.  Everything in design involves some sort of a 
tradeoff.  That is partly what makes it interesting.  The CGC circuits 
offer a lot of possibilities for different panel designs.  And Schaeffer 
let's us do our own thing.  1U, 2U, or 3U, it's a choice we can make.

I haven't built my CGS VCOs yet, but I think they will turn out nicely.  
I am going to use high quality parts throughout.

-Richard Brewster

Jeffrey Pontius wrote:

>Hi synth panelers,
>I've been working through my 'backlog' of cgs modules.  My recent
>completion (with a lot of great assistance from Ken Stone) is the cgs vco.
>I've uploaded a Schaeffer semi-motm 3U style panel to the
>ModularSynthPanels yahoo groups site under Files, Cat Girl Synth Designs,
>Schaeffer file: cgs.vco3U.4row.fpd.
>
>Basically the panel contains every  function from the pcb except a second
>cv in, and it contains attenuators for FM AC, FM DC, PWM, SUB CV IN and
>SHAPE CV IN.  Note that the pot holes are smaller than those for Spectrol
>or Bournes pots (I decided to use up some of my Alpha pots).  The design
>also has a FINE Tune pot location.
>
>In a 3U standard motm design I would have lost an output or input
>(excepting the 2nd cv in), so  I decided to use my 4 row style (that is,
>standard motm style has a total  of 8 rows of sockets vertically, but as
>Tony Allgood has shown us with the  410 filter companion, one can easily
>fit in 9 rows and still retain good  spacing for inserting jacks), since
>the standard motm socket spacing would  have required 4U (which I was not
>willing to do).  Adding in the 4th row increased the number of sockets
>beyond what I needed, hence the additional 1v/oct input (3 1v/oct inputs
>should prove interesting) was added.
>
>IMHO This is a nice companion vco to the motm and Blacet vcos that I
>already have (for example, I was after somewhat different waveforms).
>However, I haven't nailed down the subosc section yet.
>
>Constructive comments appreciated, Jeff
>
>
>  
>