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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
52 posts
 
I want to add the following:
I measured the buzz with an app on my iphone held within a few inches of the speakers.
I can hear the buzz from my listening position which is about 12 feet away from the speakers.
roxy54's avatar
roxy54
7,977 posts
 
Did you have a detailed discussion with the guys at Coda since that first time they tested it?
stringreen's avatar
stringreen
6,468 posts
 
It sounds like a grounding issue......a very illusive problem.   It can take a long time to find it, but if you do, it will go away.   Try inverting plugs, listen if the the noise appears when the tv is on, refrigerator, etc.
mwsl OP
52 posts
 
Roxy - it’s been so long since I took the int to CODA, I can’t remember the specifics of what was discussed. I do remember that: 1) no noise was heard on their dedicated circuit, 2) they said that it was very unusual for one of their products to elicit the buzz I told them I was hearing.

Stringreen - can you be more specific about “inverting plugs”? The noise is constant, no matter what other electrical devices are on or off anywhere in both my current and previous homes. 
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