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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
 
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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imhififan's avatar
imhififan
2,180 posts
 
If buzz on both channel, I suspect the CSiB power supply section or internal grounding has issue, my suggestion is send it to a tech to diagnose.
mwsl OP
52 posts
 
Jea48: I will try ground cheater tomorrow. Mute button does not change anything either.
oldhvymec
5,101 posts
 
Again, you took it to a repair man, they hooked it up, and there was NO NOISE. You brought home a whole different system, WITH speakers.
The noise was even louder. 

Shorting plugs, la - te - da. IT WENT AWAY.....It was gone... It was fixed.
at the repairmans, WHAT did they do?

You moved, you still have the noise...

You have the answer. Think!! 

The repairman, do you know if they simply had NO ground hooked up? NO.

Get the cheater plugs. 1.00 dollar each. Get more than one. Use them on every plug for a test, ONLY.
If it goes away, you have a difference in voltage between the unit and a component.
Remove the cheater plugs, all of them.
Take a jumper, and hook between components.
You can not have to many, BUT you might not have enough of them. Hook them to EVERYTHING, between all components, until the noise goes away. Once you've isolated the noise. Make or buy a ground wire, clean to bare metal, on both ends. Check to make sure the grounds are common. Check!!!

If the noise is still there after the checks, it is a routing issue as I said..

Does the noise Yo Yo.. If you move cables, does the noise go up and down. Be aggressive moving the cables, not rough, but move them more than an inch, move them a foot 12" not 1/2". Then you've checked..
No Check No fix.. Or a Train ticket, I'll come and fix it for you.. My fingers are getting tired...

Regards
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