I scored big time when I bought this amp: A 1968 Pro Reverb for a very low price, less than half of what it is worth. The guy's story was that he was unemployed, his truck needed tires, his mama was sick and he was on the lam from his mortgage company for his unpaid doublewide payments. I am not making this up.
The amp is a Silverface drip edge. He brought it over and it looked good but didn't sound all that good, the power tubes looked and sounded worn. I was going to open it up and look inside but decided it was worth the risk and did the deal.
After I paid him and he left I opened it up and was found that it was essentially like it was the day it left the factory! Dunno if the tubes were original but this is what was in it: RCA 12AX7 preamp tubes, Telefunken 12AX7 reverb and driver tubes, RCA 6L6GC's, and a Mullard GZ34 rectifier.
The amp was an odd combination of pre-CBS and post-CBS technology, with the cloth wiring and blue caps from the Leo years, but also the snubber caps and an odd combination of both fixed and cathode bias from the CBS years. It also had the original Utah orange backed speakers, but one of them was partially blown because it sounded weak and fuzzy. I sent both of the them to Ted Weber for reconing.
The reverb didn't work but I took it over to my friend Kerry and he fixed it, one of the reverb spring retainers was broken and he had an old tank he cannibalized one from. The pots were scratchy but that was easily fixed with contact cleaner. The power tubes were worn out and I replaced them with a of JJ 6L6GC's I had in my tube collection, leaving the RCA's and Telefunkens in place.
There was never a "Pre CBS " version of this amp, but there was a blackface version, and I did a few mods to move it in that direction.
Removed snubber caps from power tubes
Replaced old AC cord with grounded one.
Cleaned pots
New electrolytic caps
Changed to BF bias and removed cathode bias resisters from power tubes
JJ power tubes biased to 36 ma
5U4 rectifier tube instead of GZ34 for earlier breakup
Swapped caps in tone stack for silver micas
Changed one of the caps in the tremolo to .025 slow it down
Changed .047 tone cap in Vibrato channel to .033 for Super Reverb/Vibroverb tone
Other blackface parts and layout changes
Speakers: Utah orange backs, reconed by Ted Weber
This amp has the classic Fender Tone Of The Gods. Everything ever described about clean Fender tone is there, and when dimed it has the sweetest overdrive ever. With an overdrive like a Tube Screamer it rocks.
It was seriously dusty inside the cabinet, and while I was vacuuming it out there were a few other bonus items I found. A guitar cord that didn't function, a few picks, and, well... see the pictures below to check it out to see what else I found.
It has the cool wire cloth wiring, the good blue caps, and the original Utah orange back speakers.
All 12AX7's: RCA preamp tubes and Telefunken driver tubes!!
Hmm.... Wonder where this amp has been in the past?
