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Re: RETICON SAD1024 CHIP QUESTION


 :
9/7/2000 12:34 PM
CJ Landry
Re: RETICON SAD1024 CHIP QUESTION
Good point Mike! Most of the FX pedals do have a trim pot and on some units tweaking this pot squashes the squeal. (Hey, I just found a name for my next song, "Squash the Squeal") However, I have seen where it attenuates for a certain range of the delay setting. Then usually at the faster delay settings the squeal can be faintly heard. Especially at higher amplifier volumes. Replacing the SAD1024 was the only remedy.  
 
Unfortunately, I have not had the time to investigate what causes this or I should say what might solve the problem without replacing the BBD.  
 
This is the exact problem I fouind on a delay pedal and I beleive I kept the SAD1024 to play with other ways to "Squash the Squeal".  
 
CJ
 
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9/7/2000 3:59 PM
Mike Irwin

Hi C.J.,  
I've seen the same thing - null the clock for faster clock speeds and the clock signal reappears in the output when the clock freq is lowered. Or null it for lower clock speeds and it reappears when the clock speed is increased. Probably best to null it for low clock speeds and let the output low pass filter take care of the clock signal at shorter delays. That is interesting that some SAD1024's do not show this behavior. Wish I had a bag of them to sort into bins.
 
9/7/2000 6:34 AM
friday
MUCH APPRECIATED!
Thank you everyone. I love these forums!  
I will endever to get some chips to substitute. In the meantime I'll try swapping them around. I am checking out a source here in Canada, if it comes through I will post the info.  
 
To answer Anders question, Yes, the whine does change pitch when the delay time is shifted.  
I actually had quite a bit of fun recording "regeneration frenzies" with the Ross into an additional delay line last night. The whine sat nicely in the high frequencies! Admitedly a limited application for most.  
Thanks again to all.
 
9/8/2000 6:44 AM
friday
PROBLEM SOLVED
Hows this for cheap and dirty!  
 
I swapped the first two SAD1024A's around and the background whine has ceased entirely! I have put the Ross to the test and the whine is 100% gone.  
I got lucky I guess. I wasn't looking forward to messing with the 5 trimmers  
Interestingly, the 3 Reticon chips had a slightly different code number in the bottom corner but otherwise were identical in marking. I wonder what that's about?
 
9/8/2000 9:56 AM
Anders Westerberg

Congratulations!  
 
I have no explanation to this, but maybe the adjustments have drifted over the years and you were lucky to get each chip in a more suitable posistion. In that case, you could probably have got rid of the problem by tweaking the trimmers but since everything works fine now: JUST DON'T TOUCH IT ANYMORE!!! ;-)  
 
 
Anders
 
9/8/2000 12:40 PM
CJ Landry

Great news! My best guess is dirty socket contacts causing an added resistance.  
 
Glad to hear it is working,  
CJ
 
9/8/2000 1:02 PM
Anders Westerberg

CJ, your explanation seems more likely than mine (previous posting).  
 
 
 
Anders
 

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