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Weird Cmoy distortion when loaded

post #1 of 5
7/28/11 at 6:20pm
Thread Starter 

My Cmoy produces a perfect sine wave when unloaded. When I plug in headphones, the top half of the sinewave becomes horribly distorted.

 

Imagine chopping off the top of the waveform and replacing it with an egg-shaped thing.

 

It is a Tangent-style Cmoy, but with these modifications:

 

TLE2426

No input caps

Sloppy custom layout with lots of jumpers

AMB Sigma 25 also on protoboard, acting as a voltage regulator fed by a wall wart

Gain of 4

 

 

The power supply seems solid.

 

I've checked the wiring on the amplifier and it seems okay. The resistances between the input and output, input and ground, etc. etc. all seem on target.

 

 


Edited by levigoulet - 7/28/11 at 6:21pm
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post #2 of 5
7/28/11 at 7:23pm

Are you using a bipolar chip? if so the virtual ground could be pulled over to one side when the amp is loaded

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post #3 of 5
7/28/11 at 7:34pm

What are the rail voltages when the distortion happens?

What op amp are you using?

Is there any DC offset?

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post #4 of 5
7/29/11 at 6:14pm
Thread Starter 

I found a tiny solder bridge between V+ and one of the outputs of the OPA2134 and removed it, and also added input caps. Now the rails are really unbalanced, so I'll try to replace the TLE next.

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post #5 of 5
7/30/11 at 9:50am

pictures?  a drawing of your signal flow?

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