Ampeg SVT (Vintage)
With plate voltages at 660 volts and multi section fp type can caps this one wins the most expensive to restore award. If it’s an old one and the caps are original, it’s definitely time to replace them.
The tube compliment is about half obsolete types (preamp) and the power amp uses a sextet of 6550’s or perhaps 6146B’s these should be a well matched sextet. There are 3 more obsolete or at least semi obsolete types in the power amp drive stage (12DW7 & 12BH7).
It’s a beast to work on and probably takes about 5 hours to clean out the soot, recap, replace the plate, screen & bias sampling (cathode) resistors w/1% types, de-hum, re-tube, clean and/or replace the noisy pots and switches, make sure the speaker jack w/ impedance selector contacts are ok, replace the burned up filament balance pot, and put on a new heavy duty AC cord and put on some new feet!
If an entire set of tubes is needed they will run upwards of $300.00 We can mod some of the circuitry to run on more common tube types if you prefer which can save you a few bucks on NOS obsolete tubes.
This is one bad mutha’ bass amp when it’s in good working order. We see a lot of them lately.