Phoenix Gold M50 DC Voltage Problem

mithatcann · Post by **mithatcann** » Mon May 12, 2025 2:53 am

For M50 , Even no music is playing, I can hear a crackling sound from speakers if they are connected to the speaker terminal. It still does it with the RCA’s unplugged so Speakers connected but no rca signal.

We measure each channel (L and R) voltage. DC voltage is not under 50mV. I think 50mV is still considered acceptable.

Check all the fused resistors in the channels. So problem is continue for both channels.

We hear turn on and or turn off pops too. The m50 is a powerful and beautiful sounding amp if it’s working properly.

We did not see any of the fused resistors opened. They are the dull/matte resistors and have an extra stripe on them. Maybe diff pair transistors or current source transistors are leaking.

We applied a solution like this for left channel. And the DC voltage in this channel dropped to <20mV.

But unfortunately we could not solve the problem of the other channel.

Would anyone support us on this matter? Additionally, how recommend we adjust the Bias setting?

We took your time, thank you very much.