I am fairly new to tubes so I will ask this question in the hope I don't sound to silly. I just bought a new set of tubes for my CJ PV2 and I am getting alot of noise and what I can only describe as uncontrollable volume. Do new tubes need to be ran a while before they settle in?
Tim

No...new tubes should work fine right out of the box...I am not familiar with amp you describe but if older amp there could be bad capacitors or maybe bad resistors...the only time I have seen noise from tubes is with very old tubes that were microphonic and would pick up noise when tapped or vibrated by sound from a speaker.
Also check that there is not oxidation on the sockets...if the tubes are moved slightly in the sockets (carefully if hot) while power is on does the noise change?

Yup you may need to clean and tighten the connections inside the tube sockets. I take this unit was working properly before you replaced the tubes?

Craig

Yep it sounded great then I put in new lights and wam.

Yea what happens is the old tube pins were contacting a different area of the contact inside the tube socket. So the new tube pins are contacting a area that is oxidized. Get some contact cleaner and give them a cleaning your problem should disapear.

Craig

My tubes are OK, I found the balance pot is acting wacky, needs changed. Thanks all for the help

If the amp worked fine before the tube change its highly unlikely that the balance pot just all the sudden failed. Something seems strange.

sounds like the tube is fried and playing wide open. i had a similar problem with a preamp. a 6dj8 tube was brand new but bad and i had no control over vol, just played full blast no matter what. just put the old tube back in and see if that fixes the prob.

Well now the rest of the story. Not so strange is I had removed the face plate to clean it up and put in new tubes. I reinstalled the face plate not giving any notice to the pots and I assume I over torqued the nuts and damaged the pot. I can wiggle the pot and all performs as advertised.

Check the solder connections to the pot since tightening the nut could have put stress on them.

I have one of these as well; it works ok but has a bit more 60hz hum than I would like. I was using it to record LPs into the computer.

How exactly could he check for bad resistors?

Could my AC hum be caused by AC sneaking past the rectifier diode or somewhere else in the power supply? Forgive me, I don't know THAT much about this sort of thing...

Usually hum is bad filter caps, but if you have solid state rectifiers, they could be failing as well. The early types were known to be a bit problematic.

The Conrad Johnson preamp described in the original post in this thread ended up in my hands and I forwarded it to dr*audio who found the rectified/filtered/regulated filament power supply had gone bad, hence the hum when I had it.

Check the DC voltage across the filaments and also check for AC ripple(o-scope if you have one) to see what is going on.

Ron

While it's probably not the problem with the units in this thread, one thing to keep in mind is that sometimes people tend to substitute the WRONG tubes into these CJ preamps. These preamps use some rather unique variations of the 12AX7 family... different gains. If someone just plugs in 12AX7s into the sockets, the preamp will basically WORK, it'll just have the WRONG gain structure (TOO MUCH gain). This will cause various problems... noise, tonal balance problems, and such...

Basically, the idea is that you have to make sure any replacement tubes have the SAME GAIN as the originals. There are retrofit/replacement tubes that'll work... you just have to have the RIGHT ones...

Regards,
Gordon.

How exactly could he check for bad resistors?

With a multimeter, the power off, and capacitors drained.