The amplifier hum noise is not strange to every one. The source of hum noise may come from different factors such as bad tubes, bad filter capacitors, low heater voltage or amplifier locates next to a high power electric device, bad layout design (some sensitive compenents are locating close to the high power trace), ect. To find the amplifier hum noise source, we need to isolate one by one factor until we can find where the problem is.
For the hum noise source comes from amplifier itself, you need to check the preamp section or power section is making noise. If your amp has fx loop (send/return), then connect SEND to another amplifier to see if you can hear the hum noise or not. After that, try to short RETURN to ground then check if you can hear hum from speaker or not. By doing this trick, you can quickly determine the hum noise source is from preamp section or power section or due to power supply.
In case your amplifier has no fx loop, then try to connect some points on the signal path to ground to find the hum noise source as what i have done with Fender Pro Junior. When I got this amp, it was very noisy. It could produce its sound along with loud hum. It looked like 50Hz/60Hz hum noise. In this video, i show you how easy to find the hum noise source.
Visit [ Ссылка ] for more details. The schematic of this amp is also available there.
Thank you.
#friendlymusician
