Power Amp transformer hum - intermittent and increases and decreases in a few seconds

FYI, One of my many power amps, a Smart Theater Systems TA 242 ( which is actually a beefed up Hafler 220 by design, and very musical ), experiences the transformer hum ( toroidal, chassis only ), when I use my OTR microwave. Have not tried a cheater plug during these times, as it is always in rotation with others. Enjoy ! MrD.

Some {not all} toroidal transformers can buzz when DC is present on the power line.

My Son of Ampzilla 2000 has a faint buzz when my Canon printer turns on, and when my Keurig brews a cup of coffee.

Otherwise it is dead silent.

My Pass Labs XA60.5 never buzzes and it has Toroids.

don_c55826 posts

03-11-2019 4:16pm

My Pass Labs XA60.5 never buzzes and it has Toroids.

Just a guess because Pass Labs incorporates a DC blocker in their power amps.



Bryston does......
https://www.diyaudio.com/forums/power-supplies/161428-variations-dc-main-filter-buzzing-toroid-trans...




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Mechanical hum is not always the result of DC offset. I have some DC offset on my mains and even two DC blockers in series couldn’t eliminate an obnoxious hum in one of my amps.

Anyhow, I own the CMX-2 but found the Audio By Van Alstine Humdinger works far better. I had a bucking transformer that still hummed loud when plugged into the CMX, but it ceased completely with the Humdinger.

Try a cheater plug.