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!

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.
Did you have a detailed discussion with the guys at Coda since that first time they tested it?
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.
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. 
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.

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.
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?
If you are using SE cables between the Lumin and the Coda try a pair of Balanced cables.
Another quick one turn off all the breakers but the one you're using...
If it's still there.

Fix the ground loop, or routing issue, it can be a component to close to another.  Have you tried moving cables to see if the noise yo yo s. UP and down, up and down, while you move cables?

But you do have to try it.. They never heal on their own, unless you have a fiendish house guest. LOL

It did work right somewhere else. right? Another system with speakers, was NOISER... It's you... not the equipment... Route the cables and check for ground loops, listen to the OLD wore out mechanic.... get rid of the noise, once and for all...

Happy hunting....

Ok off to feed the chickens...

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Thanks for all the suggestions. I was busy today walking the dog then doing some interior painting. I will dig into this tomorrow and give you some feedback. 

I agree, given that I have the same problem in a second house, it seems unlikely to be the electrical system at my new home. OK, all for now.

Thanks again.
Did want to share some additional info:

I originally started with balanced interconnects (had a Sony HAPZ-1ES at the time), and the buzz was present. As far as I can determine, the buzz has been with me since I got the integrated. I switched to single ended cables as they sounded better with my Sony. Before I try to find the “right” cables for the Lumin T2 (which I just purchased) I thought I would try again to solve the buzz problem.

Someone a long time ago recommended shorting plugs in the empty inputs. Can anyone point me to some shorting plugs I can try?
@mwsl , @imhififan  made a good suggestion above! Before you do anything else, simply run the amp with nothing other than the speakers connected. Does it buzz? No => ground loop issue is likely; yes => defect in the equipment or a noisy AC line is the issue.

Simply listen to the Steely Dan song, "I'm through with Buzz" (Pretzel Logic). It likely won't help but could provide a brief distraction.
@ mwsl OP

RCA plugs can be bought here
I think Cardas sells XLR shorting plugs & there are a ton of speaker shorting plugs on eBay.
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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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.
Jea48: I will try ground cheater tomorrow. Mute button does not change anything either.
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...

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Very interesting and strange. It would appear from what I have read that you have covered all the bases except one. The speakers. Please try another pair of speakers disconnecting the ones you have and let us know what happens. I have seen this with powered speakers but not passive ones. Stranger things have happened. 

I feel for you, Sh-t like this drives me crazy. In my own little world everything has to be perfect. No buzzes, no dents, no imperfections.
It's like having a splinter in your hand. When the splinter comes out there is this sense of relief that one gets that is inherent in all of us.

Good luck,
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. 
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.

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.
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?
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.
If your amp is humming or buzzing with nothing connected either it is broken or you have noise or DC offset in your AC line.  You could try an isolation transformer.  Or you could just sell the amp and but something with a design that isn't susceptible to such things.  Many higher end components are designed by barely competent engineers.
Had a problem with an earthing hum years ago. It ended up that I had sent my TT arm away as it had a bearing issue. The bearing was replaced and shortly after a hum developed in my system. After quite a few expensive repair shops saying they had fixed it (they soldered a wire onto the deck of the TT  to create a ground when it was plugged in) it didn't work. I finally found someone who knew what they were doing. The bearing repairers had pinched the arm cable creating an earth hum. The specialist repairer I sent it to left town with my turntable and I never saw it again. Back to your problem. Get back to Coda the changes they made seem to be the genesis of your problem. It may be intermittent (the worst kind )and when you had them test it the movement may have temporarily given the problem a short term reprieve. If there is anyone from Coda on this forum they may be able to help. If Coda is a good corporate citizen I'm sure they may be able to assist you with this. My story reflects the fact that sometimes you have to find the right person to diagnose the problem as plenty of technicians go for a quick easy fix to get you out the door. It really is a job for someone that has the proper understanding of amplifier circuits. Even though it has been five years I'm sure if you rang CODA you might find someone with a sympathetic ear. As for me, I'm still tracking down that turntable and one day I might find it. If anyone has seen a Logic DM101 with a Datum 2 arm and a Garrott  P 77 cartridge let me know. ( : 
Many higher end components are designed by barely competent engineers.
Eric Lauchli?
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.
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..

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.
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. 
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..

This is a great thread.  I have a buzzing problem but I know what's causing it.  Can someone explain in greater detail how to make it stop?

My 2.1 channel listening system is part of my 5.1 home theater.  There is a quiet buzz coming through my 2 main speakers which are powered from a Parasound amp.  All I have to do to make the buzzing stop is unplug the cable box HDMI cable from the TV.  This seems strange because the cable box is still connected to my receiver for audio.  The TV is still connected by HDMI to the Blu-Ray player and directly by HDMI to my Mac Mini music server.

So, jumper wires, shorting plugs, ground cheaters?  Can you explain in greater detail?  I believe all units are currently plugged into the same power conditioner (which I bought used for $100 on Craigslist many years ago).

For now I just leave the HDMI cable from the cable box unplugged because it's amazing how LITTLE regular television we watch any more.  Most of our viewing these days is Amazon Prime/Netflix streaming from the Blu-Ray player, or MasterClass watched through the Mac Mini web browser.
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To cakyol: I tried your suggestion of plugging the amp and streamer directly into the wall (no power conditioner). It made no difference, the buzz was still there. I also tried just the amp alone into a regular outlet (no streamer); the buzz remained. I vaguely remember that I purchased the power conditioner in the hopes that it would eliminate the buzz, and even though it didn’t, it had a positive effect on the sonic quality of my system.

So where, in your opinion, does this leave me?
To oldhvymec: my speakers only have one pair of binding posts, not two, thus I could not try your suggestion. 

I have multiple built in appliances in my house and thus could not unplug everything as you suggest. A previous suggestion was to turn off all the breakers except for the one to the stereo. Will this work as well as what you suggested?
It sounds like a ground problem.   Integrated amp, plugged with a cheater ( no ground ) directly to the plug, no inputs, nothing else, and you get a low level buzz that is leaking into the amp circuits.

Perhaps the outlet is wired backwards, it happens.   So, the "neutral" is on the wrong side.   That can wreck havoc depending how the power supply is designed.

Have you tried other outlets in the house?   I think you said you ran one to the kitchen...  You can't always trust the electricians.

Get an AC outlet checker at a hardware store.  Check to see if the outlet is wired backwards.  It's cheap and easy to use.  It is possible that your old house was also wired off.   
I have multiple built in appliances in my house and thus could not unplug everything as you suggest. A previous suggestion was to turn off all the breakers except for the one to the stereo. Will this work as well as what you suggested?

Yes, but in the event it does go away, you'll be doing what I said to isolate the offender, anyway.. Either way.. will work for the test though.

Built in, I'm not worried about, too much. WHY. because you brought your noise with you, you've moved.. Not saying a common appliance isn't a problem.. chances are slim, though.. just saying..

I suggest an extension cord, only to get away from whatever is in the room. Turn all the breakers off including the room the stereo is in.
The room you choose turn back on and plug into. Make darn sure, nothing is plugged in, in that room, except the extension cord, back to your stereo..

After that only thing is drop the voltage down.. If It was a tube unit, we would have looked at possible noisy valves too.

Your getting there..hang in there. one way or the other...

Oh and BTW I bought a plane ticket to come fix it. My ticket is for Cancun Mexico... Oh you don't live there.... opps.. can you meet me there..LOL

The next step would then be to make sure that all the signal cables you have are shielded like a coax cable. I had a problem like that once and it got fixed when i changed the signal cable. I presume your cables are good but just be sure. 
You can also try moving JUST the amp to another mains plug in another room, put headphones on and WITHOUT anything connected to its inputs see if you also get the buzz. I have a feeling your streamer and amp are having a ground loop issue.
The next step would then be to make sure that all the signal cables you have are shielded like a coax cable.

This is the problem. It's integrated. That's the issue. Speakers, IC and an Integrated amp. Nada, nothing else is hooked up, or shouldn't be.

Suppose to swapped out to a cheap pair of speakers and zip cord, that's on the, try out list.  No cost anyway..

OP, HAY OP One other thing.. That IA, does it have LEDs in it anywhere,
Little buzzin' baster^&. I forgot about them. They can wreak havoc, too.

It’ the amp. Send it to Coda. Tell them it buzzes with bias switch on, and is quiet when off. Or just buy another amp. 
UPDATE: I had the chance to borrow a new Prima Luna EL 300 integrated tube amp this morning. The amp was dead quiet! Clearly, I have a problem with my integrated amp. I will call CODA and inquire about repair. 

QUESTION: The Prima Luna had both 4 & 8 Ohm speaker inputs; I used the 4 ohm inputs as that is what my Dynaudio Focus 380’s are rated at. The CODA only has one set of speaker inputs. Is there any chance at all that there is a mis-match between the CODA and the speakers due to impedance difference?
The Prima Luna had both 4 & 8 Ohm speaker inputs; I used the 4 ohm inputs as that is what my Dynaudio Focus 380’s are rated at. The CODA only has one set of speaker inputs. Is there any chance at all that there is a mis-match between the CODA and the speakers due to impedance difference?
No, although I have no experience with Dynaudio Focus 380, but I've use the CSiB to drive power hungry Thiel CS2.4 and CS3.6 without any issue.
The Prima Luna had both 4 & 8 Ohm speaker taps because it is output transformer coupled.
To imhififan: thanks for the explanation. I didn’t think this was an issue, but thought it worth asking the question. I was really surprised by how well the tube integrated drove my speakers......and it was almost a brand new unit with minimal burn in time. If coda can’t fix my issue, I may switch to a tube integrated.
You know what is strange, when you had a complete system swap a few years back it was even noiser. How does that play into it..

I'm glad to see your getting somewhere, finally..

For some reason, I keep thinking a variac, would have told you a story.
What can cause it?.. It's just the mechanic in me.  The bias is incorrect, a picky transformer?   Be interesting to know what the fix is.. Not just an amp returned, with no noise..  5 years...is a long time, to put up with noise.

I can't take the noises. LOL,  I never stop until I get the sucker.
I had a few in 45 years of hunting.. oh yea...

Neighbors, wife would use a sewing machine, and caused the problem.. 
Not when using it, all the time. If it was plugged in, the stereo was noisy.
Took two months, until I came over and unplugged the WHOLE house.
Plugged that old machine in and there it was... It was the light on the sewing machine... Turn the work light on, noise, off no noise.. push the peddle, quiet as a mouse. 

It  took two months, and 2 hours to figure it out..