Help - I've Got the Dreaded Transformer Growl....

I'm on week 3 with my new office amplifier - Hegel H590 integrated amplifier driving KEF Reference 1's. Absolutely killer thus far. Dynamic, powerful, detailed, smooth and dead quiet at the speaker. One problem - the amp sometimes produces a buzz/hum at the amplifier. It's typically dead quiet during the evening/weekends but buzzes during the day. The Hegel is dead silent at the dealer so he’s telling me that I either have DC on the line or excessive harmonic distortion on the power line. The dealer says that it’s time to go for a power conditioner.

I’m considering the following power conditioners:

1. Audioquest Niagra
2. Shunyata Hydra or Denali
3. Torus RM 20
4. PS Audio P15 or P20

Does anyone have experience with transformer buzzing caused by DC on the line and did the power conditioner properly address the issue? Also wondering if I should first try the Emotiva CMX-2 AC line filter with DC offset eliminator. A very cheap option at $129. Anyone tried one and did it work and/or degrade your system sound?

Thanks for your help!Ken
DC on the line is not expensive to fix and you don't need a conditioner for it- just a DC Blocker.

That is likely the number one reason for transformers (in particular toroidal transformers) getting mechanically noisy.
Thanks atmasphere - any recommendations for a quality DC blocker / line conditioner?
As Ralph  mentioned you need a DC blocker.  I have a PS Audio UPC-200 HB (Humbuster) version. It works great. I also have a DIY single outlet DC blocker.
If you do for a Filtering Power conditioner I found my Transparent Reference PIMM 2 eliminated the transformer hum in one of my amps that you could hear in the next room.  My Shunyata V-ray didn't remove the Hum.  Try a DC blocker first it sounds like. Office power is polluted with all the computer gear interference. 
It's really just two choices. DC blocker or balanced power conditioner.

I prefer Furman for all things conditioning, because I knwo their filters so well.

Thanks for the responses. I went ahead with the cheap option first - purchased the Emotiva CMX-2 AC line filter with DC offset eliminator ($129). Fingers crossed it does the trick. If that doesn't work, I'll either (1)  look at the Furman power conditioners or (2) become a vampire and only work in the evenings and wee hours of the night when no amplifier buzz is occurring!

I'll let you know.
I'll submit a 3rd choice. If it has a toroidial transformer, see if you can find a technician to reorient the transformer to a minimum noise position.
Back to the drawing board. The Emotiva CMX-2 didn't help at all so it's being returned tomorrow.

@cytocycle - can you send a link for the Transparent Reference PIMM 2? I'm not seeing anything by that name when I do a web search.

@erik_squires - since the DC blocker was a no go, think i simply have  dirty power? Do you have a preferred Furman model for power conditioning? My system's at the office. Early morning & late night equals dead quiet. People start showing up, the transformer starts to buzz. 

@oldears - Interesting suggestion. I don't want to modify the amp as it's brand new plus I don't want to void the warranty.
It is really weird the DC blocker didn't help. It could be you just have some weird transformer resonance which is better fixed mechanically.

The two key features for Furman's are LiFT and SMP. Combined they are the most cost effective noise reduction I know of. Fortunately, this comes in relatively inexpensive models.

Otherwise, advanced models add power regulation, and even balanced power for lots of $$$ though, as well as being more rack friendly.
keoliphant OP50 posts

03-13-2019 5:52pm

Back to the drawing board. The Emotiva CMX-2 didn’t help at all so it’s being returned tomorrow.

The DC blocker must have an ampere rating as big or bigger than the amplifier idle ampere rating as well as the FLA rating of the amplifier.

Check out this unit.

Give them a call and ask them if their unit is rated big enough for your amp. If not ask them what they would charge to build you one that is.

Audio by Van Alstine

2665 Brittany Lane
Woodbury, MN 55125
(651) 330-9871




A couple days ago another thread just like this appeared. " Power Amp Transformer Hum ". See if there were any answers for you. Good luck. MrD.
I had a BAT tube preamp with hum so bad, I quit using it and went back to SS. I gave it to a tech to check. When I returned home he called and had put it on his test equipment and told me it was better than spec. I told him it was mostly a mechanical hum from one of the toroidal transformers, and he replied," I know about that". He loosened the central transformer bolt, rotated it on axis for minimum noise and gently retightened the bolt and fixed the noise while I was on line with him. I had, like you tried everything. You may be able to do the same thing, with a little luck......or it may be some other problem. This should have no effect on your warranty, but if you have a warranty, why are you worrying about this?
OP, I think that I'd try what oldears and others are saying.  Rotate the transformer.  If you haven't worked inside an amp before be sure to turn it off, unplug it and let it discharge for an hour. 
Based on the DC stuff not working, I am not sure my Transparent Reference Powersisolator MM Power conditioner will work.  So if you can borrow one great but it's a lot of money.  Mine is the older series and I didn't find the equivalent on Transparents site
To the OP did you ever get a resolution to this issue for the H590?
Yes, amazingly good now. I brought old line conditioner from my currently dismantled home theater setup and it wired like a charm. It's an old Monster Power rack style product from about 15 years ago.

I really like this new Hegel H590. Great 1 box solution.
Darn autocorrect.....Worked like a charm.