[sdiy] Project using CEM3394's

[David Moylan]

This is off the top of my head but if you're not using a CPU you'll 
probably need scale trimmers for the OSC freq CVs and either manual tune 
knobs or timmers for each oscillator.  The six trak had a tune function 
whereby the CVs were adjusted in software.  This chip was designed with 
a CPU in mind and there is a note in the datasheet that nonlinearities 
exist in the freq CV ranges at the extremes.  These were intended to be 
corrected for in software.  Depending on your intended use this may or 
may not be a problem.

One of the best features of the SixTrak and some other SCI synths of 
that era was the stack mode, where it became a multi-timbral mono synth 
with each of the six voices assigned a different program.  I think 
that's much more useful (or at least more versatile) than just a six 
oscillator mono-synth, but don't know how deep into the software you're 
able to get.

Good Luck.

Dave Moylan

Travis Shire wrote:

> Hey kids
>  
> I have a project in the works for a (up to) 6 osc monosynth using the 
> 3394 ic mainly as an oscillator. I will be using a seperate multimode 
> filter and have some SSM2056 to use for env gens. LFO's are up in the 
> air as of now.
>  
> What I am wondering about is when paralelling these voice ic's, will 
> there be a need for buffering ctrl voltages? I'm not sure if these 
> will interfere with each other but I've not worked with these before. 
> Actually this will be my first building project so I'm sure there'll 
> be a wrong turn or two.
>  
> I am taking a bit of a shortcut tho. I have a pcb with the 6 3394's 
> already on it that was OEM'd by Sequential for another company in the 
> early 80s. It is *very* similar to a sixtrak. Main difference being a 
> 2764 program eprom instead of the 6trk's 12128, and one less 6116 ram. 
> Responds to midi input with an optocoupler interface  (on voice 1 only).
>  
> Input/ideas welcome.
>  
> Travis
>  


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