PV12L whine/ringing issue
Posted: Fri Dec 23, 2016 2:00 pm
A few weeks ago my PV12 (linestage only) developed an occasional and intermittent very high pitched whine through the speakers. It was really only audible when no music was playing.
I thought it may be the preamp tubes so I replaced them which only made it worse. (I had checked the tubes that I used as replacements and they tested good.) Yesterday I decided to try yet another set of tubes.
With no music playing I turned on the system (MC2100 amp) and all was fine for a couple of minutes. Then a very static like sound came from the right channel. Not constant, but fairly loud and unaffected by volume control. It sounded like the static you might get as you're trying to tune in a radio station.
Turned things off, tried installing the last set of tubes that had been in place and the same thing happened.
I had previously tried a different preamp to make sure the high pitched sounds were the preamp, and it seems that was the case since I had no problems with the other preamp in place.
I asked for some input over on Audiokarma and a member suggested seeing if moving the tubes a bit made a difference. I tried wiggling the tubes a bit.
The static sound had just been on the right channel as far as I could tell, and moving that tube around did seem to help. However, while I was doing that I started getting a whine out of the left channel. Wiggled that tube a bit and while it did seem to make a difference, I also noticed that both tubes were extremely microphonic.
Another member suggested cleaning he tube sockets so I cleaned the sockets (with the handy dandy Caig tube maintenance kit). Cleaned the pins of the original tubes that I first noticed the high pitched noise with.
Fired 'er up. Dead quiet for about 2 minutes, then the whine and some "whooshing" from the speakers (unaffected by the volume control or input choice). That lasts for about a minute and during that time it may subside a bit and then get louder, subside, get louder. Also during that time and tapping on the preamp at all can be heard through the speakers, as can any movement of the controls.
After a minute, maybe 2, that all goes away and things are back to normal.
Last night I went through several album sides with no further issues.
I'm concerned if I keep using it I'm going to cause a real problem. Any suggestions?
I thought it may be the preamp tubes so I replaced them which only made it worse. (I had checked the tubes that I used as replacements and they tested good.) Yesterday I decided to try yet another set of tubes.
With no music playing I turned on the system (MC2100 amp) and all was fine for a couple of minutes. Then a very static like sound came from the right channel. Not constant, but fairly loud and unaffected by volume control. It sounded like the static you might get as you're trying to tune in a radio station.
Turned things off, tried installing the last set of tubes that had been in place and the same thing happened.
I had previously tried a different preamp to make sure the high pitched sounds were the preamp, and it seems that was the case since I had no problems with the other preamp in place.
I asked for some input over on Audiokarma and a member suggested seeing if moving the tubes a bit made a difference. I tried wiggling the tubes a bit.
The static sound had just been on the right channel as far as I could tell, and moving that tube around did seem to help. However, while I was doing that I started getting a whine out of the left channel. Wiggled that tube a bit and while it did seem to make a difference, I also noticed that both tubes were extremely microphonic.
Another member suggested cleaning he tube sockets so I cleaned the sockets (with the handy dandy Caig tube maintenance kit). Cleaned the pins of the original tubes that I first noticed the high pitched noise with.
Fired 'er up. Dead quiet for about 2 minutes, then the whine and some "whooshing" from the speakers (unaffected by the volume control or input choice). That lasts for about a minute and during that time it may subside a bit and then get louder, subside, get louder. Also during that time and tapping on the preamp at all can be heard through the speakers, as can any movement of the controls.
After a minute, maybe 2, that all goes away and things are back to normal.
Last night I went through several album sides with no further issues.
I'm concerned if I keep using it I'm going to cause a real problem. Any suggestions?