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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
 
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. 
oldhvymec
5,101 posts
 
I got a funny feeling routing a PC or changing it will fix the problem..
It's got to be.  I've never seen a noise issue I couldn't fix. EVER.
If the noise is not there somewhere else, and got louder with another valve amp, but quieter with a SS, why is that? I think it's where you set it, and the power cord you used. You have a routing issue, an IC is picking up noise because of a PC being to close, and not enough shielding. I don't like shielding. I get rid of noise by routing.. All of it.

The only problem is if you have a ground loop issue. Get an adaptor, to remove the ground from you amp. See if the noise goes away. If it does you know how to fix that too.. Don't leave the adaptor installed.. Just for a test..

Get a jumper wire, hook between components, see if there is a voltage offset. The noise will stop, if there is. Make up a perm. ground wire.

There you go..

I got a few more, but I bet it's routing, or voltage difference between components.

Regards
millercarbon's avatar
millercarbon
12,531 posts
 
Here’s my system:
CODA CSiB integrated amp - custom tuned 

Custom tuned. When and by whom?
Within a few months of purchase

There's a clue. What else happened 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).

Possible clue. Does the amp mute output in standby?
Thinking that it might be a noisy circuit, 

Yes and if the amp doesn't mute output then guess which one.

I've never been one to shotgun a problem throwing parts at it but if the amp doesn't mute the output and its quiet in standby without tube bias then the odds-on favorite is the bias circuit.

Coincidentally (?) the very circuit one would think likely needs to be modified or adjusted in an amp custom tuned to alter the power at which it switches class.
imhififan's avatar
imhififan
2,146 posts
 
Plug the CSiB directly to the mains without any conditioner, and only connect the outputs to speakers, no connection to any input, the buzz still remains if bias is on?
jackd
1,044 posts
 
If you are using SE cables between the Lumin and the Coda try a pair of Balanced cables.
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