Thoughts on dropping B+ in Ampeg V4 (another blasted V4!)

[Chuck H]

And now you know 17mA is low. And the Vp would probably come into the same range you just dealt with if you biased them a little hotter. If you're replacing the power tubes I'd handle it the same way. The only possible rub would be clipping where the tubes will see considerable voltage dynamics. I blew up a brand new pair of Tung Sol EL34's at 470Vp when the clipping reached a square wave.

[g1]

V2 B+ is higher than V4 at 595V stock .

[nsubulysses]

Not sure what to do with this one.......... I was told it "crapped out" during a recording session. Seems to work fine to me clipping at 64W.

It is all original except the new 470 ohm screen grid resistors someone put in. I put 1K and added a bias pot. Maybe that's it.

[g1]

So if 17mA bias gives 585 plate volts, you have about 33% idle dissipation. That would appear to be stock value, do you hear objectionable crossover distortion?
Was it brought in for a fault?

[nsubulysses]

Havent' listened to it yet a band is recording

I put it at 27mA at 578Va and I have set it aside for now. Maybe i'll play it tomorrow.

Also I realized when putting in the trimpot that R49 is supposed to be 75K and it was changed to 68K. so one more unoriginal part. I think the rest is stock.

[g1]

Do the wiggle test on the preamp tubes to check for dirty sockets or bad solder at sockets.

[The Dude]

Not sure what to do with this one.......... I was told it "crapped out" during a recording session. Seems to work fine to me clipping at 64W.

It is all original except the new 470 ohm screen grid resistors someone put in. I put 1K and added a bias pot. Maybe that's it.

Maybe it was just playing the wrong notes.

[nsubulysses]

WIll do. Thanks G, and everyone else for your thoughtful comments and nice conversation

[g1]

Maybe it was just playing the wrong notes.

Try that one on the customer:
User: "it crapped out"
Tech: "maybe it was just faithfully reproducing what appeared at the input"