Pro Reverb mystery

[scr@tchy]

Hi all,
I have an early 70's Fender Pro Reverb with no master volume or mid controls. It sounds not so good. The bass is not tight and really not all that present. When I adjust the EQ to get the bass in the ball park, the treble strings are ice pick bright. It's not the guitar or the speakers. I just did a recap and it didn't really have any impact on this problem. Any ideas?

Also,
Where can I go to get schematics for this or the blackface version? Someone told me that it is the same as the Super Reverb but when I compared them my parts didn't match up.
Thanks

[Jag]

Try here

http://www.schematicheaven.com/fender.htm

or here

http://www.ampwares.com/ffg/

for schematics.

[scr@tchy]

Thanks.

[scr@tchy]

bump.

Still would appreciate some trouble shooting tips, tubes are good, speakers good, just did recap... so why is it so dull sounding?

[Enzo]

I'd gop through the amp stage by stage to see where it loses tone. An open coupling cap or connection thereto would remove a lot of bottom, since all you'd be hearing was the crosstalk.

[Satamax]

May be simply the .1 cap in the tone stack. Does it on both chanels? Or just one?

[Paleo Pete]

Someone told me that it is the same as the Super Reverb but when I compared them my parts didn't match up

According to the page for this amp on the Fender Amp Field Guide, (2nd link above) the Pro Reverb used two circuits, AB 668 and AA 1069. The AA 1069 is identical to my Super Reverb except for one or two resistors and an electrolytic cap if I remember right, almost identical anyway. I'm pretty sure mine is the AA 270. So if yours does not match the AA 1069, it could be the AB 668. Also the AA165 was used for blacface Pro Reverb, and Fender was notorious for changing things in their circuits to tweak the amps, Leo Fender was the head tweaker...so it might not be exactly like anything...

Inside the amp, on one side wall should be a paper sticker with the tube ID on it, that should also have the circuit used printed at top. If not, check the rectifier tube. The AB668 circuit used a GZ34 and the AA 1069 used a 5U4. They use entirely different transformers, and are not interchangeable, so the rectifier tube should be a good indicator of which circuit you're dealing with.

A silver face Fender without any bass is definitely not right, most have way too much boomy, out of control bass. I had to modify the tone section of mine to get the bass under control, changed out one cap and it's great. So I would say enzo is on the money, I was thinking tone section caps too but I'm no amp tech...and if the "Bright" switch is on, yeah that thing is going to be really bright...I can't run the treble above about 5 or 6 onstage and it's running enough treble to just about cut glass...