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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
keoliphant
keoliphant OP
86 posts
 
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.
erik_squires
16,057 posts
 
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.


https://amzn.to/2TzW7q1

Otherwise, advanced models add power regulation, and even balanced power for lots of $$$ though, as well as being more rack friendly.
jea48
4,425 posts
 
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.
https://www.hegel.com/products/integrated/h590

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.
https://avahifi.com/products/humdinger-dc-line-blocker

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

.

Jim

.


mrdecibel
3,063 posts
 
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.
oldears
386 posts
 
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?
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