Princeton 1964 problems - weak tremolo and not loud enough

Make it loud here.
User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Mon Jan 15, 2018 10:48 am

Hi, everyone,

I have just bought a nice princeton 1964, with original circuit (according the seller untouched, but who can be sure, I haven t checked it yet), nice patriot cajun 10 speaker, which is one of louder speakers. Amp has 2 problems:

1.first problem is very weak tremolo, even at max level 10 is very weak.
2. Second problem is that the amp is not loud enough.

I have vibrochamp from the same year and I tried to put its tubes into my princeton (I replaced the fender marked 2 ax7 to 2 GT´s ax7 (which I have in my great working 64 vibrochamp), and I had only one available black glass tube 6v6 from my 64 vibrochamp that I put firstly instead of the first position RCA 6v6 tube and secondly to the second position 6v6 tube where amperex tube was ). After those swaps nothing changed significantly. Neither loudness nor vibrato.

Unfortunatley I don´t have onether GZ34 for princeton(I cannot take the 5Y3GT from Vibrochamp and put it into princeton instead of GZ34 to try the difference. Do you think this could be the reason for vibrato? I want to order TAD 5AR4 GZ34 Rectifier Tube Amp Doctor TAD PREMIUM SELECTED(which is promoted as a copy of Mullard/VALVO GZ34.)

Does anybody knows if this rectifier is good for 1964 vintage blackface princeton? Or any other advice? Many thanks!

Luke

User avatar
Squirrel
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 487
Joined: Tue Sep 03, 2013 3:55 am
Location: England

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Squirrel » Mon Jan 15, 2018 10:56 am

The GZ34 is probably fine, there's no way it could stop the vibrato from working correctly. Could be a lot of things but if the circuit is untouched I'd definitely replace all of the electrolytic caps. That'd be my first port of call anyway.

User avatar
mbene085
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 2857
Joined: Tue May 24, 2016 5:07 am

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by mbene085 » Mon Jan 15, 2018 11:02 am

Squirrel wrote:
Mon Jan 15, 2018 10:56 am
The GZ34 is probably fine, there's no way it could stop the vibrato from working correctly. Could be a lot of things but if the circuit is untouched I'd definitely replace all of the electrolytic caps. That'd be my first port of call anyway.
Yep, first step in using a 54 year old amp is to replace all electrolytic caps and then see what you're dealing with.

User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Mon Jan 15, 2018 11:05 am

Hi Squirell, many thanks for your quick reply, I have just plugged it in again and noticed that the problem number two (volume is already solved by replacing 2xax7 and one 6v6), but problem number 1(week vibrato) is still the same..
So also vibrato could be the caps?
Well for GZ34 I am sure it is fine for princeton 1964 in general but I dont know the particular product TAD 5AR4 GZ34 Rectifier Tube Amp Doctor TAD PREMIUM SELECTED, if it should be fine and will not burn the amp...

User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Mon Jan 15, 2018 11:21 am

mbene085 wrote:
Mon Jan 15, 2018 11:02 am
Squirrel wrote:
Mon Jan 15, 2018 10:56 am
The GZ34 is probably fine, there's no way it could stop the vibrato from working correctly. Could be a lot of things but if the circuit is untouched I'd definitely replace all of the electrolytic caps. That'd be my first port of call anyway.
Yep, first step in using a 54 year old amp is to replace all electrolytic caps and then see what you're dealing with.
Hi Squirell, many thanks for your quick reply, I have just plugged it in again and noticed that the problem number two (volume is already solved by replacing 2xax7 and one 6v6), but problem number 1(week vibrato) is still the same..
So also vibrato could be the caps?
Well for GZ34 I am sure it is fine for princeton 1964 in general but I dont know the particular product TAD 5AR4 GZ34 Rectifier Tube Amp Doctor TAD PREMIUM SELECTED, if it should be fine and will not burn the amp...

User avatar
andy_tchp
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5490
Joined: Fri Apr 02, 2010 1:36 am
Location: Brisbane

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by andy_tchp » Mon Jan 15, 2018 2:43 pm

No.

In these, weak vibrato = Power tubes need to be properly biased and are probably running too 'hot' at the moment.

Don't go replacing the rectifier tube just yet.

And yes, if those electrolytic caps are all original from 1964 get them replaced ASAP. I'd be hesitant to use the amp much until that's done.
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Mon Jan 15, 2018 3:21 pm

andy_tchp wrote:
Mon Jan 15, 2018 2:43 pm
No.

In these, weak vibrato = Power tubes need to be properly biased and are probably running too 'hot' at the moment.

Don't go replacing the rectifier tube just yet.

And yes, if those electrolytic caps are all original from 1964 get them replaced ASAP. I'd be hesitant to use the amp much until that's done.
Many thanks for your answer! How to biase the two 6v6 powertubes? How about just buying a pair of black glass 6v6 and putting into the amp? And for caps, do you think am I able to change them at home by myself? Do you have some recommandation which caps/website where I shoud search for? Many thanks to you all! Great points, I really appreciate it!

User avatar
derekstudt
PAT PEND
PAT PEND
Posts: 28
Joined: Mon Jan 15, 2018 6:08 am

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by derekstudt » Mon Jan 15, 2018 5:07 pm

It's certainly possible to change them yourself if you know what you're doing, however If you don't have a good understanding of working high voltage electronics, I would advise against attempting to replace the capacitors yourself. Those things can store voltage for quite a long time after being powered off.

This can be widely debated, but don't assume you must change out ALL of the capacitors at once. There's a chance some of them are still functioning properly. Will they need changed at some point? Yes. Will it be cheaper to have a tech change them out all at once? Likely. It just depends on which school of thought you subscribe to...keep it functional while being as original as possible (meaning change only the malfunctioning caps), or just give it an overhaul now because it will eventually need it.

User avatar
andy_tchp
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5490
Joined: Fri Apr 02, 2010 1:36 am
Location: Brisbane

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by andy_tchp » Mon Jan 15, 2018 7:11 pm

Take it to a reputable tech and have them carry out both jobs and give it a general once over.

Simply buying a 'matched' pair of 6V6s won't be enough; it's possible that the old tubes that came with it are fine and it just needs electrolytic caps and a bias. Tubes from that era are much more resilient/long-lived than current production items.
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

User avatar
kosmonautmayhem
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5673
Joined: Sun Mar 14, 2010 8:26 am
Location: Chicago

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by kosmonautmayhem » Mon Jan 15, 2018 7:45 pm

andy_tchp wrote:
Mon Jan 15, 2018 2:43 pm
No.

In these, weak vibrato = Power tubes need to be properly biased and are probably running too 'hot' at the moment.

Don't go replacing the rectifier tube just yet.

And yes, if those electrolytic caps are all original from 1964 get them replaced ASAP. I'd be hesitant to use the amp much until that's done.
This.

Get the amp serviced. Cap can and all electrolytics should be replaced. The power tube bias controls how deep the trem is. So if it's weak, chances are the tubes are just running too hot. These amps are pretty simple, shouldn't take a tech too much effort to get it running

I take it this is a BF Princeton, with treble and bass tone stack and not the earlier brownface (6G2) circuit?

PS - lets' see some pics! ;D

User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Tue Jan 16, 2018 4:52 am

kosmonautmayhem wrote:
Mon Jan 15, 2018 7:45 pm
andy_tchp wrote:
Mon Jan 15, 2018 2:43 pm
No.

In these, weak vibrato = Power tubes need to be properly biased and are probably running too 'hot' at the moment.

Don't go replacing the rectifier tube just yet.

And yes, if those electrolytic caps are all original from 1964 get them replaced ASAP. I'd be hesitant to use the amp much until that's done.
This.

Get the amp serviced. Cap can and all electrolytics should be replaced. The power tube bias controls how deep the trem is. So if it's weak, chances are the tubes are just running too hot. These amps are pretty simple, shouldn't take a tech too much effort to get it running

I take it this is a BF Princeton, with treble and bass tone stack and not the earlier brownface (6G2) circuit?

PS - lets' see some pics! ;D
Many thanks for your answer, it is black face (november and december 1964), NOT the brownface circuit. I will make some pictures as I come back home today.

User avatar
Guitarman555
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 88
Joined: Sun Jan 14, 2018 2:36 pm

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Guitarman555 » Tue Jan 16, 2018 2:22 pm

Unfortunately it is not possible ad images here, no"insert image", no upload, just "insert url"...

User avatar
kosmonautmayhem
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5673
Joined: Sun Mar 14, 2010 8:26 am
Location: Chicago

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by kosmonautmayhem » Tue Jan 16, 2018 6:38 pm

The non-verb Princetons are really cool. I only asked since I'm a huge Princeton fan. My main amps are a '72 SFPR and a '64 6G2 - brownface circuit but with blackface / tuxedo cosmetics.

Unfortunately you'll have to upload your pics to an image hosting site like imgur or flickr and then paste the image link into your post in order for them to show up.

For reference: Ye olde how to post an image on OSG thread.
viewtopic.php?f=5&t=202

User avatar
Witchburner
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 59
Joined: Fri Aug 18, 2017 12:09 pm
Location: 71st

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by Witchburner » Sat Jan 20, 2018 7:24 pm

kosmonautmayhem wrote:
Tue Jan 16, 2018 6:38 pm
The non-verb Princetons are really cool. I only asked since I'm a huge Princeton fan. My main amps are a '72 SFPR and a '64 6G2 - brownface circuit but with blackface / tuxedo cosmetics.
Why do you mention that? I'll pull up the schematics to see what you mean

I heard the head room and break up was completely different, I've never played a reverb version actually, so have no idea

What's your experience?

User avatar
sookwinder
Mods
Mods
Posts: 10141
Joined: Mon Sep 11, 2006 6:47 pm
Location: Melbourne Australia

Re: Princeton 1964 problems - weak tremolo and not loud enough

Post by sookwinder » Sat Jan 20, 2018 7:28 pm

The BF Princeton has one less gain stage than the BFPR. similar amps but effectively different amps.
relaxing alternative to doing actual work ...

Post Reply