2. amps-preamps
  3. 157077-6156

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
 
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?
imhififan's avatar
imhififan
2,180 posts
 
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.
mwsl OP
52 posts
 
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.
oldhvymec
5,101 posts
 
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..


Regards
mwsl OP
52 posts
 
To oldhvymec: 
“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 suspect, but do not know for certain, that my previous house did have an AC noise issue. So that when I tried the second system in the house, it too was noisy. 

Yes, I put up with the buzz for a long time. I had a lot of other things going on in my life, but now, with COVID, I have more time to dig into issues that have been put on hold for a while.

Will be calling CODA tomorrow morning.
More to discover