2. amps-preamps
  3. 1069258983

Please advise - volume-variable buzz in spkrs

Introduced a new (used) tubed preamp into the system yesterday. Having had tubes before, I was prepared for a tube hiss, but what I got was a buzz that increases with volume. It is in both speakers and seems to be about the same level in each. It definitely gets in the way of the music and during a late-nite session could be heard even farther away than the listening position.
Nothing else in the system has changed. I use Chris VH power cords on the cdp, amp and preamp. I tried lifting the ground on the pre and amp (separately); tried a cheap 2-prong cable; no change. The HT comes through this system, so I disconnected that including the cable tv. No change. The only thing I haven't tried, I think, is changing tubes, and that's because I don't have replacements on hand.
Any ideas? I've been thru the forums here and on AA (but not fully; my DSL chose this morning to crap out as well!).
kck
newbee
4,093 posts
 
Well, you can start from scratch. Disconnect everything from your preamp (except amp) and see if you have a buzz. If you don't add each source, one at a time, when the buzz appears you have your culprit.
kck OP
184 posts
 
Did a lot of experimenting, and found that I could eliminate 75% of the buzz by rerouting cables. There was a set of ICs touching and partly intersecting the path of a power cable. Lifting it in my hand reduced it quite a bit. As the rat's nest did not allow for too much tweaking there, I just moved components around.
There is still that 25% or so left. I will try more fiddling tonight.
Try that, Clydemetz!
djohnson54
372 posts
 
Swap the right and left channel tubes. If the buzz moves with them then you have your answer.

Dick
phild
603 posts
 
I doubt this is your situation, but I was using my amp and DAC with a SS pre and it was dead silent. Switched to a tube pre and a similar noise appeared. Tried everything to no avail. Eventually found out that a connection inside of my amp was bad. It was fixed and the noise went away. For some reason, the problem only manifested itself with the tube pre and not the SS pre.
kck OP
184 posts
 
Phild, that is interesting. I have the exact same symptoms, and in fact I did have an SS pre that had no hiss. What was the guilty item and how did you find it? Of course my amp would be different from yours but it is worth a try.
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