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Coriolis
Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark
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Posted: Wed Mar 18, 2009 12:44 am Post subject:
CGS ASR parts questions |
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I just finished building the ASR with a pcb from Ken, but didn't have the recommended grade caps for Cx. Instead, I used ceramic multilayer just for the heck of it. Also I forgot to match the 10k and 22k resistors.
Well, I figured I'd try it and see - and sofar nothing indicates performance problems. But then I'm not sure what to look for.
I like it as it is (but haven't used it much yet), but could could anyone here tell me what I might gain from using better caps and matched resistors?
Best,
C _________________ Some Rubber Stamp Sound Effects - and other sound effects Last edited by Coriolis on Wed Mar 18, 2009 9:22 am; edited 1 time in total |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Wed Mar 18, 2009 1:20 am Post subject:
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the cx caps are part of S&H subcircuits, so better quality caps will hold the voltage longer with less leakage. If you are running the ASR at fast speeds, maybe you will never notice a difference. Try running it very slowly and how much leakage you get.
having matched resistors on the output buffers ensures you get the same voltage from each stage as the S&H outputs are switched thru the different outputs buffers.
The resistors act as voltage dividers and set the gain for each output section. If they are different values a 1V input may result in 1.1V from stage 1, 0.9v from stage 2 and 1.05V from stage 3 (just for example).
if you are using the 1V/oct standard, and care about tuning, this will make a big difference.
All that being said, one of my ASRs has ceramic caps and 5% resistors...i like things getting a bit awry |
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Coriolis
Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark
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Posted: Wed Mar 18, 2009 9:21 am Post subject:
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Thanks Andrew!
I think I will live with these parts in my ASR for a while, and see if it makes a difference to me in the long run.
Edit: Oh - btw, I subbed a 741 opamp for the TL071 and it seems to be working fine FYI.
C _________________ Some Rubber Stamp Sound Effects - and other sound effects |
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