Low notes weak and static-y through amp

The tubes are easy to get http://thetubestore.com/fender-65-princeton-reverb.html , the amp is practically bullet proof, I think but am not not sure that the capacitors are flat brown ceramic discs in that one, and they last. One of the tubes, and I suspect pre-amp 12AX7, (because they can usually run on just one 6V6 power tube) could be going bad, if the scratchiness and lack of contact is not in the BASS control/potentiometer; or it is sometimes a dried out, cracked and broken resistor where the big power tubes plug in, but behind, where it gets absolutely high voltage and shocking! Look up biasing procedures as well, or the kit, since they are fixed bias. http://www.torresengineering.com/newfenprinre.html

Sure, test the tubes if you are in the radio hobby, or try to spot one with a weaker glowing cathode. If they look all right, hook up another remote speaker/cab or other amp as a slave speaker only to the thing.

The amp's a Fender Princeton Reverb (1968, probably). The speaker cone looks undamaged. Only the lowest notes from a guitar seem to be attenuated. Doesn't seem to matter too much where the bass control is set too much.

I haven't ever done anything with a guitar amp before, I bought the thing from a coworker 10 years ago and am only now getting around to learning to play. I haven't tested any of the tubes yet. My first thought is a tube is getting weak and just can't supply enough current for the bass notes, but are there any other obvious things I can check before tearing things apart? I imagine there could be a bad cap in the filter for the bass control or something...

It will be an adventure looking for replacement tubes if I need them - I should have replacements for everything, but they're just loose and unsorted in grocery bags. :P Hooray for an antique radio hobby.

It's a 43 year old amp. If it's been sitting unused for 10 years then it's almost certain that the filter capacitors need replacing or reforming, especially if they are the original ones. If you have an antique radio hobby, then you probably know that you're dealing with lethal voltages and know how to avoid killing yourself. There should be a sticker inside the cabinet that details the circuit revision, and the tube specs. You can find the schematic here for the aa1164 circuit, and here for the B1270 circuit

It's a 43 year old amp. If it's been sitting unused for 10 years then it's almost certain that the filter capacitors need replacing or reforming, especially if they are the original ones. If you have an antique radio hobby, then you probably know that you're dealing with lethal voltages and know how to avoid killing yourself. There should be a sticker inside the cabinet that details the circuit revision, and the tube specs. You can find the schematic here for the aa1164 circuit, and here for the B1270 circuit

Thanks for the links. I took a quick look and it's the AA1164, so the schematic should be a big help. Even if I'm a total beginner with a guitar I still love how this thing sounds. I've always liked the sound of a Fender amp with a spring reverb. Everything sounds like surfer music.

Thanks for the links. I took a quick look and it's the AA1164, so the schematic should be a big help. Even if I'm a total beginner with a guitar I still love how this thing sounds. I've always liked the sound of a Fender amp with a spring reverb. Everything sounds like surfer music.

With that circuit you have a blackface amp with silverface cosmetics. If you think it sounds good now, wait 'til you bring it back up to spec.

I remember the guy who I got it from telling me it was a '67, but I've never quite believed him because when I read articles about the amp everything about it is '68-69 - silverface, metal strip around the grill cloth... Maybe it used a leftover amp with the redesigned cabinet.

On a happy note, I started pulling tubes and testing them. The rectifier was borderline, but all of the other tubes tested really strong. I put the tubes back in and all of the problems were gone. I can't believe that reseating the tubes fixed everything, boy do I feel dumb. :D

I'm pretty much just working on open chords and basic scales right now, but it was pretty fun playing around with the reverb while playing blues scales.

Makes me even more excited to start lessons ten days from now.

I remember the guy who I got it from telling me it was a '67, but I've never quite believed him because when I read articles about the amp everything about it is '68-69 - silverface, metal strip around the grill cloth... Maybe it used a leftover amp with the redesigned cabinet.

They didn't change to the B1270 circuit until 1970 or so. The only minor change they made before then was subbing a GZ34 rectifier for the 5U4. You can use either, just re-bias when you swap.

Reseating the tubes - nice going! :lol:

Enjoy that baby, wish I still had mine. :cry:

Can't have 'em all, I switched to Blues Deluxe.