• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Transformer humming while using Microwave ?



Active Member
Forum Donor
May 3, 2021
Just to be clear, do you mean the transformer hum is back?
A ground loop if the hum is from the speakers, but not if it's transformer hum.

Yes...I am not talking about speaker hum.
This is transformer hum so the hum is from the amplifier transformer itself (not speaker).

I ordered the proposed solution (CMX-2) to DC offset: https://www.pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html
CMX-2 has two outlets , so initially I used one for the AMP (with transformer hum) and the other one connect to power strip for pre-amp, players, etc). That did not eliminate the transformer hum.
Only when I connect just the AMP to CMX-2 , leave the other outlet alone/unused , then the AMP transformer hum is gone.:)


Senior Member
Nov 15, 2018
When hum appears using two different outlets, ground loop is a common cause.
This is not like connecting to two different wall outlets. It is using two outlets on the CMX-2 (equivalent to using two outlets on the same power strip).

Anyway, we are talking about mechanical transformer hum (typically caused by DC offset). Ground loops are usually associated with hum in the audio signal (heard through the speakers). The article you linked earlier does not discuss mechanical transformer hum.
Top Bottom