[sdiy] simmons sds800

[WeAreAs1 at aol.com]

In a message dated 8/18/04 11:24:06 AM, zifcak at hotmail.com writes:

<< hi,


the decay envelopes in my sds800 behave differently than other synths i 

have. they are generated by a fairly standard looking circuit, using a 

section of a tl084. the strange thing is, at shorter decay times, the 

initial peak of the envelope is lower. as the decay time is increased, peak 

voltage increases. any ideas as to what might cause this? i'd really like to 

alter the circuit to have a uniform peak level over the range of the decay, 

as it makes it easier to adjust sounds without having to constantly 

compensate for differences in volume etc. i have scans of the schematic if 

anyone would like to take a look. i wondered if it might be the response of 

the cem, but my akai ax73 also uses the 3394 and doesn't act like this. >>

Hello Greg,

Keep in mind that the SDS800 creates its envelope by analog means, and the 
AX73 creates all its modulation (envelopes, LFO's, etc) in the digital realm.  
This may partially explain the difference in response.  Sometimes the amplitude 
and/or shape of analog envelopes will become strange or unpredictable under 
certain conditions (such as rapidly repeated notes and attacks), whereas the 
same conditions will not at all effect digital envelopes.  I'm not sure that I 
would be able to help solve your problem, but I certainly would like to see the 
SDS800 schematics, since I also have one of those units.  Would it be 
possible for you to email the schematic to me?

Best regards,
Michael Bacich