2. misc-audio
  3. 1197248387

Transformer hum with AC fluctuations

I was about to buy an isolation transformer (Tripp Lite) in hopes of cleaning up my inexpensive CDP's sound a bit (Tobias's rec on the cables forum), and now I've run into another AC-related problem.

I live in an old, small rural town in PA, and this time of year power demands start overwhelming our grid: our lights dim for brief moments (a second or so) and then come back to normal all evening long. Coinciding with that--and only at high-usage times on the grid--the transformer of my NAD C325BEE has started making a hum that's audible from across the room. The trannie has always hummed faintly (had to put my ear above the amp to hear), but now it's hard being in the room with it. It doesn't come through the speakers or headphones.

I have two questions: is an isolation transformer likely to hum just as much as my NAD's transformer? and is there a better route to cleaning up my AC (the kicker: within a $200 budget)? I appreciate any other suggestions/solutions. Thanks in advance.
ablang
ablang OP
165 posts
 
Well, I said I'd post again if the thing worked--and it does. Even the usual quiet transformer hum is reduced to practically nothing, my TT strobes at the steadiest speed I've seen, and sound has improved subtly but noticeably--better resolution of low-level detail, a slightly tighter bottom end, and improved soundstaging, especially front to back. The EMI/RFI filtration has a good bit to do with all that, I'm guessing. It's the only AC cond I've tried, but I'm pleased--it works, it's cheap, and it's a tank. Thanks for the leads, one and all.
mrjstark
1,112 posts
 
Hi,
I have also a problem with my 2nd system.
Noise/hum in both spks. but a specialy in left.
Disconnected everythig but amps and spks, still there.
Used power stabilizer, quantum 800, PS ult. outlet and
Granit Audio Ground Zero. Nothing helps.
It is a real pain in the neck. By adj. gain on Supratek preamp I get it down somewhat but not 100%.
I am giving up now.
Was thinking about running new line from the basement but not sure if it is going to help.
I am not sure if any of you guy have any ideas how to fix it.
Thanks

P.S
Sorry for coming in without knucking.

Mariusz
johnmcalpin
57 posts
 
Thanks, Tvad.

My amp's massive transformers hum from time to time. I've got the amp powered through an Equi-Tech balanced power unit which runs off a dedicated 20 amp line. The hum is definitely audible and varies. It was there in my old place and here in a new house. Plugged into the wall directly or through all sorts of power boxes. But the sound of the amp is still amazing.

A friend who designs and builds large scale manufacturing machines told horror stories of transformer hum, with some folks resorting to hand wiring and other techniques. He said old timers believed some times there was a harmonic built into the transformer through the wiring and nothing would rid it.
tvad
9,467 posts
 
John, it's interesting to me that your Rogue Zeus' transformer hums. I have never owned a tube amp that had a problem with a humming transformer. Also informative to me that the Equitech has not solved the hum problem, as I was considering a balanced isolation transformer to address my problem.
johnmcalpin
57 posts
 
It certainly is odd. I figured the Equitech would take care of it, but it's still there. But, and more frustratingly odd, is that it is intermittent. It's a head scratcher.

I also have the amp -- and every other component -- sitting on a Sistrum platform. I wonder if setting it on something else might do the trick.

Don't get me wrong, this amp is amazing and in the grand scheme of my system the hum is a very minor flaw. And while I go through all sorts of system do-over fantasies -- like the one I'm in now -- I know the Zeus is a keeper.
More to discover