Ampeg V4 / VT22 - Blurted Sound ??

[mercyhollow]

I hope one of you guys can help me before I get too much $ invested in the wrong parts. I have an ? 70s ampeg V4 / VT22 and I have been playing it for live gigs and practice for 5 years. My Bass player bought it new back in the day and until 6 years ago it had hardly been used. Up until about a year ago - It kicked all the time - every time. And now - progressively getting worse - it has a "blurty" not quite all there kind of sound - low voltage kind of sound - it comes and goes and now mostly comes and stays. I have some electronic knowledge and experience - but I am not fluent AT ALL - Do I possibly need to replace all 11 tubes ? If it is more serious than that - does anyone know of a repair place in Southern Indiana ?
I can check and repair lose / broken solder / tighten screws - bolts and ETC. But I do not know where to look for the problem for sure.

[Rob Mercure]

MH,

While these amps have many features no individual section is that electronically complicated. First off there are schematics available on the net - the "unofficial Ampeg" site has some (although there are a few variants). Secondly the amp probably suffers from dirty contols and jacks and probably needs the filter caps replaced. This is common with most amps of this vintage and especially the V-4 as it is a bit more "complicated." You might also have a poor solder joint on one of the PC boards or bad contacts on one of the 7027A output tubes. I've got a 1978 Master Volume V-4 that I restored a few years ago that I'm prepping for sale and all of the tubes are original 'cept the outputs. Of the dozen or so V-4s I've serviced the only tubes I've ever replaced, except the 7027As which may easily last 30 years in service, is the 6CG7/FQ7 reverb driver (and the reverb circuit does occasionally "eat" the coupling cap and associated resistors).

Search our the Tube Amp FAQ and if you're comfortable/confident with working around 500V go over the amp - but clean the controls, switches, jacks, and tube sockets - especially the outputs - first. Then post back to us. Ray Ivers is quite familiar with these, Enzo is our overall "genius" tech, and I've got a few under my belt so you won't lack help.

Rob

[stokes]

If the filter caps are original,it sounds like it could be time for new ones.If the tubes are original,same thing.By a "blurty" sound are you refering to an overtone kind of thing.If so that would be the caps.If they are almost 30 years old they likely need replacing.

[Enzo]

I are not a genius, but I would consider power tubes.