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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
 
Ground cheater installed. No effect. Buzz still exists. 

To Jea48: definitely the buzz, not a hum. 

Should I now order and try input shorting plugs? If so, can someone send me a link for viable ones that are inexpensive? Will I need them for both RCA and balanced inputs?

Thanks again to all - this IS very frustrating. I so like the overall sound of my system, but this has been a persistent problem that I would really like to get solved. 
imhififan's avatar
imhififan
2,180 posts
 
I have a CODA CSiB v3 integrated plugged directly to the wall, without any shorting plug installed, no buzz, hum or any kind of noise while bias “ON” at any selected input.

I think the last thing you can try is to turn off all circuit breaker except the one for your amp, unplug everything from that circuit. power up the amp and see if the buzz still exist, if yes then the amp need to send for repair, if no buzz then you can plug back all electrical device one by one and see if buzz exist. If no buzz then turn on all circuit breakers one by one until buzz exists again so you will know what caused the issue.


imhififan's avatar
imhififan
2,180 posts
 
I also like to add that something like a cold solder joint can caused intermittent problem like this, that explain why the amp was dead quiet when plugged into the mains at audio store and the manufacturer.
mwsl OP
52 posts
 
Thanks imhififan. Given that you have a dead quiet amp, and mine has been “noisy” in two separate homes, I have to think that despite it being quiet at manufacturer and audio store, something is likely amiss with the amp itself. I will try your experiment, and then contact CODA for repair. 

Just out of curiosity, did you have CODA bump up the amount of Class A watts?
imhififan's avatar
imhififan
2,180 posts
 
Just out of curiosity, did you have CODA bump up the amount of Class A watts?
I wish I could, but I need most of the class B power to feed the power hungry Thiel.
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