another failed gainclone

[thomas997]

Have the same problems as you..

Built a 3886 that didnt even work, didnt really troubleshoot it though. Built a 3875t that worked, but really bad hum and static issues.

One of my problems was a mica capacitor I had used. Took them from an old TV, 4 were good, one made some very large staticy noises on the output..


Going to try again with a 3875TF, hopefully it will be better. Then basically screw around with components until it sounds best to me, and copy it a couple of times.


good luck

[theChris]

disconnecting the signal processor greatly reduces the amount of noise, but it is still present. i have a feeling i will build a new inverting gainclone -- my inverting gainclone seemed to be silent. it was 1 channel, and i need 4...

[Upupa Epops]

Chris, I will be quite sincerely : How I see in the picture, your work look like bird's nest and is miracle, that after switch on was not explodiert. Althought photo is not sharp, I see there for example bad soldered wire, which is touched ground ( ? ) beside etc. In this case we can't talk about quality of devices or correctness of schematic. Only one you can to do : disconnect all function blocks and test all one by one. When all will be OK, you may continue and gradually connect others. But you must have measuring machines, mainly scope, 'cos without this is work bull s... So don't worry and do it again. Pavel

[theChris]

a lot of the wire are soldered to ground. as for the hanging wire -- that was improv. the mute needed a resistor and i couldn't remove the one i place there incorectly. that one is soldered to a trace on the top and that is pretty bad. the wiring isn't too bad -- it just looks bad because of the angle. now i couldn't get a very good solder to the wire's connection to the top of the PCB -- this was impossible becuase my tip is to fine and i did the wiring last. I think i'm going to try to find some connectors.

my issue is that it takes me about a 6 weeks to get a PCB printed, so i wanted to know why the thing ossilates.

i also disconnected the mica caps, it worked worse without them.

the other amps i built looked worse but worked. this one looks a lot prettier but doens't work...