68 Custom Princeton Reverb - 240v mod?

SunDevil

Having read this thread from cover to cover, it looks like for all of the 68s, swapping the black and black / white wires is what I need to do on the 68 Pro?

Is it sufficiently standardised, that I co do this irrespective of which slots these wires are in and without access to the schematic to confirm?

ICBM

SunDevil said:

Having read this thread from cover to cover, it looks like for all of the 68s, swapping the black and black / white wires is what I need to do on the 68 Pro?

Is it sufficiently standardised, that I co do this irrespective of which slots these wires are in and without access to the schematic to confirm?

I'm not certain. I think it's likely since all the models other than the Princeton should share the same PCB, but if you don't have a means of checking the mains voltage on both those connections safely, it's better not to swap them until you have confirmation.

SunDevil

Cheers @ICBM - seems there's nothing on Fender support to help with this at present and they weren't in the slightest interested in sharing the schematic with me - wonder if maybe I can get a code off the Power Transformer and confirm the taps that way

godders

RiftAmps said:

Yes, these need swapping over too.

Locate P8 (White) and P17 (White/Black) on the board, and swap.

Obviously, disconnect the amp from the mains first.

Hi, @RiftAmps ;you wouldn't happen to have the schematic for a 68 Vibro Champ reverb would you?

Keen to do this on that amp but don't want to assume colour coding of wires is common across all amps!

ICBM

godders said:

Keen to do this on that amp but don't want to assume colour coding of wires is common across all amps!

This is precisely why you can't - on some of the amps it's the black wire and the white/black stripe one, whereas on these it's the *white* and white/black.

Without a schematic, the best method is to measure the voltages on the taps after having traced which ones go to the unconnected terminals on the PCB.

The first time I come across a new Vibro-Champ I will be certain to do this and post the result, but I haven't yet...

godders

ICBM said:

The first time I come across a new Vibro-Champ I will be certain to do this and post the result, but I haven't yet...

Thanks, much appreciated.

tomajoha

Necrobump: I’m having trouble finding a schematic for the Deluxe Reverb 64 handwired version, has anyone done this mod on that amp and can help?

tomajoha

tomajoha said:

Necrobump: I’m having trouble finding a schematic for the Deluxe Reverb 64 handwired version, has anyone done this mod on that amp and can help?

Anyone ? @ICBM have you fettled the handwired version?

delab

Apologies for resurrecting this old thread however for the benefit of others..... reading here about the benefits of adjusting 230v amps to 240v I thought I'd add the following.

I recently bought a 64 Princeton reissue and having read about cooking the the tubes at 230v I got my local amp tech to adjust it accordingly.  What I wasn't expecting was for the noise floor to almost disappear.  

Previously with volume set at around 3 there was noticeable hissing and background noise.  Now?  Nothing.... I have to turn the volume to around 8 to hear anything.  I'd swear the amp also sounds sweater.... less edgy.

Based upon my experience I'd highly recommend the 230v to 240v 'modification'.  Saves tubes and problems in the long term and gives immediate sound benefits.

Cirrus

delab said:

Based upon my experience I'd highly recommend the 230v to 240v 'modification'.  Saves tubes and problems in the long term and gives immediate sound benefits.

I feel the same - I actually went as far as getting a small transformer maker to build me ac30 power transformers with 245 volt primaries, because I was fed up with red plating el84s and yes, going from 340 to 315 volts made an audible difference for the better - less edgy sounding

tomajoha

@delab Interesting, yours is the handwired version, Ive been trying to find out how to do this mod on the handwired verison of the deluxe to no avail. Did you tech show you which connectors he swapped?

delab

tomajoha said:

@delab Interesting, yours is the handwired version, Ive been trying to find out how to do this mod on the handwired verison of the deluxe to no avail. Did you tech show you which connectors he swapped?

Sadly no... I left the amp with him for a couple of hours.  

ghad

Hello '68 custom owners. I need some help, and I don't think it's worth an entire thread. My 68 CPRRI is bone stock and I'd like to put a diff speaker in. It has the 8ohm Celestion 10/30 in currently. Can I replace it with a 16ohm without problems? I've attached a pic of the amp rear, if it helps, I'm not sure if "8ohm min total" rules out anything over 8ohm or under 8ohm!!  

 

RiftAmps

tomajoha said:

@delab Interesting, yours is the handwired version, Ive been trying to find out how to do this mod on the handwired verison of the deluxe to no avail. Did you tech show you which connectors he swapped?

If you're ever passing the workshop, I'll happily take a peek inside the amp and tell you if it is possible. No charge.

ICBM

ghad said:

My 68 CPRRI is bone stock and I'd like to put a diff speaker in. It has the 8ohm Celestion 10/30 in currently. Can I replace it with a 16ohm without problems? I've attached a pic of the amp rear, if it helps, I'm not sure if "8ohm min total" rules out anything over 8ohm or under 8ohm!! 

In common with all older Fender amp designs, that's misleading. Fender intended them to run into either the internal speaker (8 ohms) or that plus an extension cabinet of the same impedance - ie a total load of 4 ohms... which is safe despite it saying '8 ohms min total'. 16 ohms is also probably safe, although it's less so than a mismatch below the correct impedance. (With a valve amp.) A mismatch in either direction will reduce the power, typically by about 20-30%.

As always, it only really matters if you're cranking it right up. At anything less than full power - ie when the amp is still clean, or at no louder volume than the maximum it can produce clean if you're using a pedal for overdrive - then it's not critical at all.

ghad

ICBM said:

ghad said:

My 68 CPRRI is bone stock and I'd like to put a diff speaker in. It has the 8ohm Celestion 10/30 in currently. Can I replace it with a 16ohm without problems? I've attached a pic of the amp rear, if it helps, I'm not sure if "8ohm min total" rules out anything over 8ohm or under 8ohm!! 

In common with all older Fender amp designs, that's misleading. Fender intended them to run into either the internal speaker (8 ohms) or that plus an extension cabinet of the same impedance - ie a total load of 4 ohms... which is safe despite it saying '8 ohms min total'. 16 ohms is also probably safe, although it's less so than a mismatch below the correct impedance. (With a valve amp.) A mismatch in either direction will reduce the power, typically by about 20-30%.

As always, it only really matters if you're cranking it right up. At anything less than full power - ie when the amp is still clean, or at no louder volume than the maximum it can produce clean if you're using a pedal for overdrive - then it's not critical at all.

Thank you very much for the response. Good to hear a 16ohm internal speaker is feasible.

tomajoha

RiftAmps said:

tomajoha said:

@delab Interesting, yours is the handwired version, Ive been trying to find out how to do this mod on the handwired verison of the deluxe to no avail. Did you tech show you which connectors he swapped?

If you're ever passing the workshop, I'll happily take a peek inside the amp and tell you if it is possible. No charge.

Thank you kindly @RiftAmps unfortunately I’m in the wilds of North Yorkshire 

tomajoha

Heres some shots of the HW64 internals if it helps @RiftAmps ;

RiftAmps

tomajoha said:

Heres some shots of the HW64 internals if it helps @RiftAmps ;

It has a multi-tap primary but without either a schematic or measuring them I cannot say what wire (if any) is correct

tomajoha

RiftAmps said:

tomajoha said:

Heres some shots of the HW64 internals if it helps @RiftAmps ;

It has a multi-tap primary but without either a schematic or measuring them I cannot say what wire (if any) is correct

Ah no probs thanks for looking @RiftAmps ;