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CMOY Distortion

post #1 of 5
5/8/09 at 5:23pm
Thread Starter 
Hello All,

I've just finished a CMOY amp and I'm getting a strange problem that I haven't been able to find on here nor google.

When the amp is turned on with no source connected, I hear nothing other than the device powering up. However, when I have a source connected and playing, I get loud distorted music. The signal IS being amplified to a louder volume though.

Thanks for any ideas that you kind folks may have.

I've linked to pictures of the front and back of the cmoy.


Back:
solder on Flickr - Photo Sharing!

Front:
front on Flickr - Photo Sharing!
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post #2 of 5
5/8/09 at 5:56pm
I also just finished mine recently.
How are your C1 capacitors lined? (positive, negative)
Does one need to be oriented the other way?

edit: oh wait it looks like they are set up right, I must've made mine wrong.
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post #3 of 5
5/9/09 at 12:14am
You appear to have put in resistors in the R5 spot. They appear to be 1k resistors, but I could be wrong? If they are 1k, that is much too large. Remove them and jumper them with resistor leads or whatever and see if your distortion persists. The 1st two Cmoys I built I mistakenly put 470 ohm resistors in for R5... result was massive distortion.
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post #4 of 5
5/9/09 at 1:44am
Thread Starter 
I've followed your tip (good eyes btw) and removed the R5 resistors and popped in jumpers. There is till distortion but it is much less than before. However, thee is sill quite a bit of distortion on the low notes.

could the type of solder affect anything? i'm using electrical 4% silver.

i've built a breadboard version and it sounds fantastic...
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post #5 of 5
5/9/09 at 1:50am
The only other thing I see is a bit heavy on the solder, particularly on the opamp socket pins. You might try running an xacto knife or similar down between the pins to ensure you don't have any small solder bridges. Heavy on the solder on those boards is preferable to too little btw.
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