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Ringing from the tweeter

Hello fellow Audiogoners,

The ringing began about a year ago or longer in the left tweeter. It sounded like tuning in to radio stations in the old days, which I attributed to my Rogue Audio 99 preamp's tubes going bad. At first it was intermittent, then more and more present. It was audible and annoying when changing sides or records, even with the volume all the way down, but not apparently audible with the music. I had a rare listening session when the ringing was not there, but once it began it was pretty much always there. Muting the preamp would get rid of the noise so I assumed the problem was the preamp tubes, not my M-180 tube monoblocks.

About a month ago, I installed new tubes in the preamp, four NOS hand-picked and thoroughly tested by Andy from the VTS. The tubes are dead quiet and sound terrific, but just a week or two after I put them in, the ringing from the right tweeter this time began again, first intermittent, now pretty much constant, just as before. Again, muting the preamp gets rid of it.

Andy told me that the 6SN7 tubes should last years so I'm quite upset the problem returned so fast. Any idea what may be causing the ringing other than the new tubes going bad so fast? Is the preamp somehow “overstressing” the tubes, for lack of a better word, and needs to be checked out? The tubes are the type that can handle higher voltage, btw. The only other source would be my solid state phono preamp or the cartridge, which I think is rather unlikely.

I’d appreciate your opinion or suggestions.
actusreus
actusreus OP
733 posts
 
Mofimadness,

Thank you for your generous offer. Alas, I live in San Diego!
I did consider the tweeter may be an issue. I'm going to swap the left and right speakers this weekend to see if the ringing moves with the speaker.
tls49's avatar
tls49
1,318 posts
 

Agree with Zd that swapping left and right channel tubes would determine if there is a tube problem. As far as swapping speakers, just swap the speaker cables on the back of the amp. If the problem doesn't move, then it is the speaker.
actusreus OP
733 posts
 
Well, as I said in my original post, it is highly unlikely that it's the tubes as I just put in four NOS that were thoroughly tested by Andy at the VTS. Especially given the fact that I experienced the same issue before, and the current tubes are dead quiet as far as the typical hiss associated with microphonic tubes. The same symptom with two different set of tubes worries me that something else is going on. I was hoping that some of the A-gon experts were familiar with the problem.
zd542
5,339 posts
 
"I was hoping that some of the A-gon experts were familiar with the problem."

I'm familiar with this type of problem. In my expert opinion, I would tell you to swap the tubes from both channels.

"The only other source would be my solid state phono preamp or the cartridge, which I think is rather unlikely."

"Well, as I said in my original post, it is highly unlikely that it's the tubes as I just put in four NOS that were thoroughly tested by Andy at the VTS."

Just because you think something is highly unlikely, doesn't mean it is. If you don't explore all of your options, its highly unlikely you'll find your problem.
daveyf's avatar
daveyf
1,174 posts
 
Actusreus, your problem is most likely stemming from your tube preamp. I noticed with my CAT ( tubed preamp) that depending on the tube, there can be noise from the tweeter IF the tube is at all microphonic. Just because you acquired new tubes, unfortunately does not mean they are not microphonic! I would do as Zd542 suggests, swap tubes out left for right and see if the noise changes channel.
BTW, I'm in San Diego, therefore I might suggest a visit with Bruce at Stereo Unlimited, he can probably suss the problem.
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