My Dumble-modded '63 Princeton

ICBM

RiftAmps said:

Both of those tone control caps have been replaced. The amp is too late to have a domino bright cap and that OD is too large for 5nf or less.

That's what I thought, but wasn't sure other than that those types aren't original.

RiftAmps said:

If he did mod it, you'd have thought he'd add some screen stoppers!

Given the way the standby switch has been done with the disconnected wire just 'insulated' with tape, and the unnecessary wire from the cap to the switch (much easier to just link it to the rectifier directly - you could even reuse the other wire!) then anything is possible.

Not sure who did the 3-wire mains cable conversion either. Death cap left in place (albeit disconnected) and earth wire not properly attached... hmmm.

RiftAmps said:

Pretty sure I've seen the A.D. stamp on unmodded Fenders but I could be wrong.

I thought so too, but having it on what is obviously a patch from a removed transistor on the Bandmaster cap cover does make me think it's probably not Fender.

danny_777

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

danny_777

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

Rob Livesey here.

I’m a bit out of the loop on prices these days, but the amp has all the hallmarks of a Dumble modded amp. It’s worth what it’s worth to the man who will buy it, but prices even for modded amps were silly a few years ago. A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. Whether or not it would sell at that is speculation, but there are collectors who will pay a LOT of money for these things. An ODS is £100k now.

What I would do first of all though is take very detailed pictures of EVERYTHING. Then get the circuit drawn out to see what’s been changed. Even that drawing is worth money!

Nice amp, wish I had it.

Rob

Thanks for your input Rob - I believe the pics I linked to above were from your page!! 

I am surprised by the value, which somewhat dissuades me from putting this amp on a freight container for two months

I'll do my best to get some better pictures! Absolutely clueless on the circuitry though, I was dreadful at electronics at school...

danny_777

newi123 said:

Hattigol said:

Forgive my ignorance but what might he have done to have improved the sound so much? And how much of it could only be done by him rather than someone else with tech knowledge?

And herein lies the magic. The mods are carefully graded in terms of sonic improvement by the level of his involvement:

1) `Might` have worked on it - sounds better than anything Leo did
2) Actually been in the same room as him - the kind of amp Beethoven dreamt of hearing
3) Touched by him - like hearing a chorus of Welsh close harmony Unicorns on a sunny day
4) Actually modded by him - better than full on choirs of Biblical Angels eulogising over the birth of the baby Jesus

Obviously the above can be closely replicated by buying a $20 clone of a pedal such as a Zen drive (the hint at sonic revelation is in the name!) or by purchasing an amp kit from a man in a shed on the other side of the world who`s carefully replicated an amp he`s never actually seen.

(nb - really I`m deeply jealous - this is a poke at the legend, not the work of the man himself. I`d personally love to own this amp, and I bet it sounds glorious!)

Hah!!! Very accurate!

Anecdotally, pretty much everyone who's ever played this amp has offered to buy it on the spot. The hype and values look to be silly, but it really does have something very special about it.

danny_777

ICBM said:

Can you take a pic of the back of the controls and the components on them? The main board looks completely stock apart from a couple of changed cathode caps (normal maintenance), but I can see at least one ‘orange drop’ cap on the controls, which isn’t.

The standby switch mod is a bit crude!

Here you go mate:

Hattigol

Ossyrocks said:

A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

At which end?

ICBM

danny_777 said:

Here you go mate: 

Thanks, that's what I expected... stock circuit, with the two tone caps changed.

Any chance you could read the values on the caps?

Ddigger

Don't tell him Pike!

danny_777

ICBM said:

danny_777 said:

Here you go mate: 

Thanks, that's what I expected... stock circuit, with the two tone caps changed.

Any chance you could read the values on the caps?

Sorry, tone caps, values... I'm a total newbie on electronics. Which bits are you referring to?

exocet

ICBM said:

danny_777 said:

Here you go mate: 

Thanks, that's what I expected... stock circuit, with the two tone caps changed.

Any chance you could read the values on the caps?

All I know is that at some point Alex Dumble became very particular about the components that he used - certainly was the case in the Overdrive Special amps, no idea if he applied the same to "mods".

So, the resistors used on the anodes became exclusively Metal Film for noise performance - he favoured this specific type:

https://ie.rs-online.com/web/p/through-hole-fixed-resistors/8500937/

For capacitors in the tone circuit he favoured Polyester Sprague 6PS - generically referred to as "Orange Drops" however, not all Orange Drops are from the 6PS range.

https://modulusamplification.com/Orange-Drop-Capacitors-6PS-418P-Polyester-600v-P5536653.aspx

Ossyrocks

danny_777 said:

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

Yes, really. 

https://reverb.com/uk/item/38950606-1979-dumble-deluxe-reverb-amp?show_sold=true

ICBM

danny_777 said:

Sorry, tone caps, values... I'm a total newbie on electronics. Which bits are you referring to?

What's printed on the orange and red caps on the tone control pots. The orange drop will be something like this - 



The number that's important is either printed as (eg) .047 on the one at the bottom right, or 103K/223K/333K on the other three. The voltage rating doesn't really matter in this application.

The red cap has a colour dot code (which is why they're called 'domino' caps) which is more complex to read.



Changing these values from the stock ones will change the voicing of the amp. Changing the type, for the treble pass cap (the 'domino' one) might also change the tone subtly - the original type would have been a ceramic I think, the 'domino' is mica.

Ddigger

I hear there is some bloke near Edinburgh who is about to start selling copies...

danny_777

ICBM said:

danny_777 said:

Sorry, tone caps, values... I'm a total newbie on electronics. Which bits are you referring to?

What's printed on the orange and red caps on the tone control pots. The orange drop will be something like this - 


The number that's important is either printed as (eg) .047 on the one at the bottom right, or 103K/223K/333K on the other three. The voltage rating doesn't really matter in this application.

The red cap has a colour dot code (which is why they're called 'domino' caps) which is more complex to read.



Changing these values from the stock ones will change the voicing of the amp. Changing the type, for the treble pass cap (the 'domino' one) might also change the tone subtly - the original type would have been a ceramic I think, the 'domino' is mica.

Thanks mate - I'll take it apart again tonight and get some closer pics!

ToneControl

Ossyrocks said:

danny_777 said:

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

Yes, really. 

https://reverb.com/uk/item/38950606-1979-dumble-deluxe-reverb-amp?show_sold=true

isn't that one from when he rebuilt the amp to the ODS design, rather than just a few tweaks?

Ossyrocks

ToneControl said:

Ossyrocks said:

danny_777 said:

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

Yes, really. 

https://reverb.com/uk/item/38950606-1979-dumble-deluxe-reverb-amp?show_sold=true

isn't that one from when he rebuilt the amp to the ODS design, rather than just a few tweaks?

Maybe, but it’s not a scratch build, it’s a modified Deluxe Reverb for £50k!  You potentially have a Dumble modified Princeton. If it turns out to be real, you potentially have a £five figure amp. The Japanese are mad for them. 

ICBM

Ddigger said:

I hear there is some bloke near Edinburgh who is about to start selling copies...

lol

No, just genuinely curious .

What's hilarious is that without the Dumble connection, this is just an old Princeton with a couple of caps changed and a rather crude standby switch mod, and it would in fact be worth marginally less than if it was original, no matter how good it sounded.

But because the great wizard Dumble touched it, it's worth thousands. That's not to say it doesn't sound great, and it may even sound noticeably better than stock, which is why I'm interested in those two caps - since they're the only parts that could be responsible. Although from memory, this model is extremely good-sounding anyway.

What's been done on the front panel between the volume and tone knobs by the way? Has there been a sticker or something, or an extra pot hole drilled and somehow filled again?

danny_777

Ossyrocks said:

ToneControl said:

Ossyrocks said:

danny_777 said:

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

Yes, really. 

https://reverb.com/uk/item/38950606-1979-dumble-deluxe-reverb-amp?show_sold=true

isn't that one from when he rebuilt the amp to the ODS design, rather than just a few tweaks?

Maybe, but it’s not a scratch build, it’s a modified Deluxe Reverb for £50k!  You potentially have a Dumble modified Princeton. If it turns out to be real, you potentially have a £five figure amp. The Japanese are mad for them. 

This is bonkers. It's been sitting in the corner of my room for the past two years.

ToneControl

Ossyrocks said:

ToneControl said:

Ossyrocks said:

danny_777 said:

Ossyrocks said:

PeteC said:

Rob Livesey (UK) or Scott Lerner (US) will be able to tell you., if you can locate their details.  

 A standard Princeton is worth maybe £1400, but I reckon if this amp was with a dealer, he would add a zero to that. 

Sorry WHAT.

Yes, really. 

https://reverb.com/uk/item/38950606-1979-dumble-deluxe-reverb-amp?show_sold=true

isn't that one from when he rebuilt the amp to the ODS design, rather than just a few tweaks?

Maybe, but it’s not a scratch build, it’s a modified Deluxe Reverb for £50k!  You potentially have a Dumble modified Princeton. If it turns out to be real, you potentially have a £five figure amp. The Japanese are mad for them. 

I suspect the reverb advert is for when he used the output amp, and built an ODS style preamp for it, hence using the logo on the front panel? It has all the ODS switches

If that is correct, and the OP's amp is just a preamp tweak (rather than a replacement), I'd assume it would be more like £10k than £50k, but I'm just guessing.

danny_777

ToneControl said:

If that is correct, and the OP's amp is just a preamp tweak (rather than a replacement), I'd assume it would be more like £10k than £50k, but I'm just guessing.

That's still about five times what I thought it was worth - I'd be pretty chuffed!!