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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
 
Ordered grounding plugs for RCA and XLR inputs. Should arrive in a few days. Will try this experiment as well as the one with the breaker and report back early next week. I’m expecting that none of these will solve the issue and that I’ll need to send the amp back to CODA. I hope to be pleasantly surprised.
oldhvymec
5,101 posts
 
Shorting plugs are real good for Point To Point, cross talk.. That I do know..Buzz, Hum.. It would be a new one, but not to expensive to try.

I been reading back through the post, a couple things. A goner posed speakers? something about powered speakers. Point is, unhook ONE speaker and see if the noise goes away. Just one. Hook it back up and do the other side.

If it goes away with one but not the other,  you're CLOSE!

If the speakers are bi ampable? PULL the jumpers, ok Bear with me..

Again one at a time. First top (highs) then the bottoms 

I'm noisy, bare with me.

Clean the jumpers, get zip cord, I don't care BUT change the jumpers
clean the post all of them

If none of that works. Cost nothing, right.


The Second a Variac, you happen to know anybody with one?

You need to have a variac, though.
It didn't dawn on me to try.  It's kind of second nature for me, tinkering to use a variac.. I've had transformer noise, and speaker noise, and stopped it with a Variac. It WAS NOT the cure but it lead to one. A pair of filter caps, and a cheap pair of mismatched bridge rectifiers. They acted up with 120 VAC but shut right up at 110 or so.

You would start at say 101-5, and really start listening and paying attention.  Again ya never know.. and it doesn't cost a dime, just time.

Gee! tough one for sure.. Plane ticket time... I'd like to try, just to see what the mystery was.. 2 hours..Tops.. I bet we could figure it out ..With a  DMM, couple wires, clips and a variac.

Happier hunting.. you'll get it...Eye of the Tiger... all that stuff..

Regards..
mwsl OP
52 posts
 
OK oldhvymec: did the following:

unhooked right speaker - buzz on left speaker
unhooked left speaker - buzz on right speaker
unhooked red leads to speaker - quiet!
reattached red leads to speaker, unhooked black leads - quiet!

What does this mean??

Had to look up what a variac was......don’t have access to one.
cakyol's avatar
cakyol
940 posts
 
You have a ground loop. Get rid of the power conditioner. Plug ALL your devices to the SAME outlet (star configuration). Basically the grounds of all your devices must be at exactly the same potential. Any resistance between different grounds will cause hum or buzz. It is impossible to get it to zero resistance but minimizing it is the goal.  Get rid of all esoteric plugs and power conditioners. You dont need them unless you live somewhere with a lot of lightning strikes. 
If that does not work you should make sure all your signal cables are shielded (like coax cables) and are not close to higher current cables like the mains and speaker cables. 
oldhvymec
5,101 posts
 
I want to see if your speakers had two sets of binding post. If they did I wanted to isolate top from bottom. Red, or black disconnected..its gonna stop making the noise, has to.

If one speaker STOPPED the noise in the other, we would have been close..

A small set of different speakers is easy.. and different speaker cable, zip cord is perfect.. Swap them out.. if no change, and without a Variac, there is one other freebie.

Unplug everything in the house, everything.. Home security, electrical, especially 220. Everything that has a plug, UNPLUG it. From RJ11 to RJ45, phone land lines, network cables, cable boxes, unscrew, unhook, undo EVERYTHING. Turn off all battery powered led, if they have a monitor light, take out the batteries, turn off your cell phone, WiFi EVERYTHING in that house OFF, and unplugged, and power removed, batteries too.

Get a long extension cord.. Start plugging in all over the house, see if the noise changes or goes away.

If by chance it’s gone, leave it plugged in wherever it’s quiet, and start plugging in a room at a time. Then any 220 plugs, then the land lines, network cable.. Isolate then fix.. ok

Now you can turn your cell phone and pacemaker back on. If the noise starts then, you really got a problem..

If you can’t get a variac and drop the voltage... it’s Shop time.

I ran out of no cost test..

Hang in there, after all this time.. you’ll get it..

Regards
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