Princeton Reverb issues

[Andre Dardeau]

My late seventies Princeton Reverb has started acting up pretty bad. It’s suddenly gotten very quiet/clean and the tremolo stopped working. I swapped everything other than the power tubes with stuff that I know works (no spare 6v6s). The ones in there don’t have a ton of hours on them. It seems like the bias suddenly went very cold. Anything quick before I take it to the tech?

[Tim Marcus]

if its original - it would be very common for the cap in the bias circuit to need replacing. That cap would affect both the volume and tremolo

[Eric Philippsen]

Old tech here.

Sounds like your PR needs service. Think about it, the amp is around 45-or-so years old. Few things can go that long w/o maintenance. As for old amps, yeah, there are still owners who love to say theirs “is all original and still working as good as the day it was bought new.”

The correct response to that is, “No it isn’t.”

Get your amp to a good tech. As for older Princeton Reverbs, in addition to new electrolytic capacitors have the tech put in an adjustable bias. Fender left that out on their lower end models to save money.

Last, I would say the older blackface and silver face Princeton Reverbs and Deluxe Reverbs are the hottest vintage amps out there. You got one? Don’t sell it.

[Andre Dardeau]

It’s been serviced within the last six months or so. The capacitor in the bias circuit has definitely been replaced. If you see the earlier version of this post I misread Tim Marcus’ post

[Dave Mudgett]

It’s been serviced within the last six months or so. The capacitor in the bias circuit has definitely been replaced. If you see the earlier version of this post I misread Tim Marcus’ post

What earlier version of this post?

I agree with Eric and Tim. In fact, the latest possible late-70s Princeton Reverb (1979) is 45 years old. What exactly did the tech do 6 months ago? A 45+ year old amp can have lots of components go bad or drift to the point of messing up things. I have had to replace trem parts on virtually every blackface/silverface Fender with trem I've ever owned. Practically any electrolytic cap is dead after 45 years. I totally agree on adding an adjustable bias. If a tube or some other bias component drifts, the bias may need to be adjusted. Because the Princeton Reverb's trem is based on bias modulation, it is more sensitive to bias issues than trems on the larger blackface/silverface amps that use a bug. But again - I (or one of my buddies, who is a tremendous tech) have frequently had to go in and replace resistors and/or caps in the trem section of practically every one of these I've ever owned at some point.

[Andre Dardeau]

All the electrolytic caps should be replaced already, and I believe that there has been a bias pot added. The last time I brought it in the push pull pot crapped out and was replaced with a normal pot. I’ve had this amp for probably five or six years and it’s been serviced several times since I got it. I was just curious if this is a common problem.

[J Fletcher]

Too bad you don't have a spare set of output tubes , that would be easy to sub a pair in .

[Ricky Davis]

Just what Tim said:
CAPS
Ricky

[Andre Dardeau]

I’m just gonna take it in, I’ll let y’all know where the problem is!

[Tony Prior]

IF you say its been serviced, fine, but go back and take a look at what was serviced to CONFIRM.

I'm gonna go on a limb here, after being a service tech my entire life and starting with TUBES. If you brought this amp to me the first thing I would look at is the Power Supply.

[Dave Mudgett]

All the electrolytic caps should be replaced already, and I believe that there has been a bias pot added.

IF you say its been serviced, fine, but go back and take a look at what was serviced to CONFIRM.

Absolutely confirm what was done. If you're comfortable pulling the chassis, it's easy to see what components were replaced. Or if you still have service receipts available, they should state what was done.

As far as not having a spare set of power tubes goes - I strongly recommend always keeping a spare full set of tubes for an amp. They are the easiest thing to check - if you have spares.

[Ken Fox]

From some old files on my computer

[Rick Hearne]

I just got back my '65 original blackface after having been gone over by George Allesandro. I've never heard a sweeter or more powerful Princeton. He's a true tube wizard.