Post by thetragichero on Sept 27, 2020 21:10:29 GMT -5
rectifiers can create noise. whether that is being picked up or not who knows hum regardless of guitar pickups? humming while put back together or is the chassis out in the open? there is likely shielding when it's all put back together that isn't there when you're working on the chassis
Post by blademaster2 on Sept 28, 2020 14:07:42 GMT -5
I have used the NE5532 and it is wonderful for low noise, high fidelity operation. Its distortion was not at all pleasing when I tried it in place of another op amp in a solid state amplifier, but this application is also not driving it into overload conditions.
However the TL072 devices are also pretty low noise, so it is not a surprise to me that both sounded good when used in a clean application like this. The primary source of noise I get from a guitar comes from the guitar itself and is usually a hum or a buzz from power lines, which would be better handled by the low pass filtering of that capacitor.
Guys, With regard to this subject, I was wondering if anyone has tried a variable cap in conjunction with good shielding connected to a signal earth to prevent or reduce receiving. I find adjusting a variable cap to work well with eliminating hum.👻🎃👻🎃
Post by thetragichero on Sept 28, 2020 19:35:22 GMT -5
hum can come from so many causes it's better to try to figure out the cause than add a bandaid it could've been present in the amp already (just hidden by smaller coupling caps) sometimes i just get to the point where it might hum or buzz when I'm not playing so just keep playing and turn it off when I'm not
The hum is there with no guitar plugged in and the amp input is shorted. I measured the speaker output and the hum is 120hz, not 60hz. Sorry, I should have measured it before my last post. I isolated the filter caps and measured them and here is what I got.
Tolerance on the caps is -10% so the main power supply filter is right on the edge of tolerance. Do you all think replacing the filter caps will make a difference?
Fortunately I have another amp to play while this project is going. Unfortunately I have another amp to play so I'm not feeling the pressure to finish this project and I might have unrealistic expectations.
Post by thetragichero on Oct 1, 2020 12:10:07 GMT -5
120hz so power supply filtering, lead dress, grounding are likely culprits might be a bad solder joint. being adjusted by the volume pot means it's coming from before that control I'd check your solder joints could it be the power supply caps? possibly. depending on the of the amp might not be a bad idea anyway