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I have a weird buzz issue; can you help me solve the problem?

Hi - my integrated amp has a 25db persistent buzzing noise; I need help figuring out how to solve this problem.

Here’s my system:
CODA CSiB integrated amp - custom tuned to produce 25w Class A power before switching to Class B
Lumin T2 streamer/DAC
Dynaudio Focus 380 speakers
Audience AR2-T2 power conditioner w/Audience power cable
Audience AU24 speaker cable
Cardas Clear M power cable
Purist Venustas Luminist Revision RCA interconnect
Synergistic Research TeslaPlex SE outlet
Shunyata Venom Defender

Some background:
I’ve had the CODA integrated for about 5 years. The remainder of my system has come on-line subsequently (I had different speakers initially). Within a few months of purchase, I noticed a buzzing noise coming from the speakers whenever the amp was powered on (bias “on”), but no noise in standby mode (bias off). I took it back to the manufacturer, who plugged the amp into their dedicated circuit and it was dead quiet. I had the same experience taking it to a local audio shop. Thinking that it might be a noisy circuit, the local shop loaned me a lesser priced solid-state amp (I forget which brand) to bring home. I hooked up the shop’s integrated to my system and.....it was dead quiet. Now I was confused. 

A dealer loaned me a completely different system with a tubed integrated, different speakers and cables. There was even a worse buzz coming from this system than from mine. I went back to living with my system and forgetting about the buzz.

Fast forward 4+ years. I have moved to a new house in a new state. Unfortunately, the buzz remains :-( I even tried plugging the system into what the electrician was sure was one dedicated line in the house (it was in the kitchen, so I had to run an extension cord to where my audio system lived). Still, the buzz remains.

I really love the sound of my system, but this persistent buzz is a (ahem) buzz kill (sorry for the predictable and bad pun). 

I would love to get some thoughts on what I can do to get rid of this damn noise. Please help!



mwsl
mwsl OP
64 posts
 
Did want to share some additional info:

I originally started with balanced interconnects (had a Sony HAPZ-1ES at the time), and the buzz was present. As far as I can determine, the buzz has been with me since I got the integrated. I switched to single ended cables as they sounded better with my Sony. Before I try to find the “right” cables for the Lumin T2 (which I just purchased) I thought I would try again to solve the buzz problem.

Someone a long time ago recommended shorting plugs in the empty inputs. Can anyone point me to some shorting plugs I can try?
atmasphere's avatar
atmasphere
12,099 posts
 
@mwsl , @imhififan  made a good suggestion above! Before you do anything else, simply run the amp with nothing other than the speakers connected. Does it buzz? No => ground loop issue is likely; yes => defect in the equipment or a noisy AC line is the issue.

wolf_garcia
6,767 posts
 
Simply listen to the Steely Dan song, "I'm through with Buzz" (Pretzel Logic). It likely won't help but could provide a brief distraction.
thenewguy007
38 posts
 
@ mwsl OP

 RCA plugs can be bought here
https://www.takefiveaudio.com/products/1416-rca-input-shorting-plugs
I think Cardas sells XLR shorting plugs & there are a ton of speaker shorting plugs on eBay.
mwsl OP
64 posts
 
Just tried the experiment; unplugged everything from the amp except speakers, ran OEM power cord directly into wall. As expected, the buzz still exists. It exists no matter which input is selected (Aux 1, Aux 2, etc) or what volume I have it set at. In fact, there is no change in volume of buzz, no matter what I do. As I soon as I turn the bias “off”, there is no further sound through the speakers.

So, does this in fact mean a noisy AC line? I would not suspect the equipment since I know that the amp was dead quiet when plugged into the AC at one audio store and the manufacturer. But, to be fair, this was about 4 or 5 years ago (I’ve been living with the buzz that long). 

FWIW.....someone asked who did the modification to increase amount of Class A power......it was the manufacturer at the time of purchase. 

Is it still worth trying grounding plugs?

Any other thoughts?


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