Paul C mod for PR

MikeT · 08-31-2009, 03:43 PM

Does anyone know where I can get a schematic of the Paul C mod? There a couple of links on google, weber and cornell, but they have both been taken down-BTW ..... RIP Ted.....I found a text description that Paul C himself wrote and I can probably follow that and be OK, but I would like to see it in a schematic if possible....anyone? Thanks....

Mike

txstrat · 08-31-2009, 09:25 PM

Here you go.
Would be nice if you could tell us what it sounds like after you tried it.

loudthud · 09-01-2009, 12:23 AM

Anyone who wants to experiment, try this mod. Tweek the pot and note how "warm" it sounds when the volume goes down. Ooohhh aahhh no headroom! As you may have guessed, I'm not a fan of the Paul C mod as it's usually done. Change that 2.2 meg to 4.7 meg.

MikeT · 09-01-2009, 12:31 AM

Thanks.. I already did it by the text description but I will check my work with these schematics. The sound: These are my first impressions and could become more defined as I use it more.....Headroom is improved. I had already done the voltage mod on the PI (....moving the B+ supply for the PI back one leg for a little higher voltage..a real impressive mod) so I don't perceive much of a volume boost. But the headroom is greater and as the breakup happens it comes on very slightly a little bit earlier but much more evenly as it gets more intense and so feels like more headroom. The bottom remains more defined throughout. It seems the fidelity is effected the same way a long tailed PI effects it. I get heavy long tailed PI vibe from this mod.

Mike

MikeT · 09-01-2009, 01:18 AM

I heard about the 2m2 to 4m7 mod somewhere else too, so I tried it. Can't really do volume tonight though...I'll get back to you tomorrow...

hasserl · 09-02-2009, 03:33 PM

I've employed this on a couple of cathodyne PI amps, one of them being a Princeton Reverb. IMO the result is a smoother distortion, less compressed. I like it.

TheElectricMoron · 09-03-2009, 06:57 PM

I have done this to several PR's and ASAIC it has just become part of the standard package for me like moding the tonestack. Together with the Stokes bump the voltage mod, any old Deluxe OT, and a 12" speaker and you have a total killer amp in a really compact package. Maybe I don't run mine at a low enough vol to notice the limitations of the 2.2meg resistor but I'm certainly gonna do that 4.7meg swap to see how that works.
JIC you feel the urge - To cut a 12" into a fixed baffle you have to put the speaker as far down and to the left (looking at the front of the cab) as possible to clear the OT.
The one PR that I try all the new stuff will be by my bed when I die. I love that amp. And thru a 2x10" box ....... almost orgasmic. I'm in the process of refurbing a trashed 70's DR cab and 2 10"'s will fit in there just fine.

JMO of course YMMV

Charlie

porge · 09-22-2009, 02:53 AM

Hey Charlie,

When you say "any old deluxe OT", are we talking 5E3 or DR? I have a SFPR that I'm thinking of modding this way, and wanted to be sure before I start ordering parts.

I've read that the Stokes mod and Paul C mod can put some pressure on the PT in Princeton Reverbs - what do you guys think?

TIA

Andrew

TheElectricMoron · 09-23-2009, 12:38 AM

Andrew-
any BF/SF OT will be fine. The Weber OT rocks.

Those mods do nothing to the PT. There was in ancient times some concern about the v's getting dumped on the PI, but if you look at the v's on the 12at7 in a Fender reverb, and know that a 12ax7 will live in there too the PR v's are small potatoes. I've never seen over the so-called 100v limit on the cathode anyway.

I run mine cranked all the time - never a problem.

Charlie

porge · 09-23-2009, 01:59 AM

Thanks - I was about to try and hop from the PR to DR for gigs (DR's are hard to come by here in Australia), but will give the PR another go.

Will keep my eyes open for a Deluxe OT. Might try the weber one, but shipping is getting ridiculous from the US.

Regis · 09-25-2009, 01:35 AM

I did that mod to a friends SF Princeton and we both thought it sounded like ass. I reversed it.

JDW3 · 09-25-2009, 03:51 AM

I did the Stokes and the PaulC. I undid the PaulC and the amp still sounds horrible. Not Fender like at all. This was a '73 NR Princeton.

TheElectricMoron · 09-25-2009, 04:51 PM

The only thing I can say is that if you haven't up-graded to a quality 12" in there you prolly will have wasted your time. Even with a replacement 10" I never had any inclination to undo the mods. I have had players with decades of experience tell me that (even with the 10" in it) it was the best sounding PR they had ever heard. I also run it thru two different 2x10 cabs, one open and one closed. I haven't been able to make it sound bad.
But it don't woof and fart no more. And if that is the sound you like then what you say makes a lot of sense.

And of course - YMMV

Charlie

08-31-2009, 03:43 PM	#1
MikeT Member Join Date: Jul 2006 Location: Upstate NY Posts: 26	Paul C mod for PR Does anyone know where I can get a schematic of the Paul C mod? There a couple of links on google, weber and cornell, but they have both been taken down-BTW ..... RIP Ted.....I found a text description that Paul C himself wrote and I can probably follow that and be OK, but I would like to see it in a schematic if possible....anyone? Thanks.... Mike

09-25-2009, 01:35 AM	#11
Regis Senior Member Join Date: May 2006 Location: Atlanta Posts: 396	I did that mod to a friends SF Princeton and we both thought it sounded like ass. I reversed it. __________________ Stop by my web page!

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09-01-2009, 12:31 AM	#4
MikeT Member Join Date: Jul 2006 Location: Upstate NY Posts: 26	Thanks.. I already did it by the text description but I will check my work with these schematics. The sound: These are my first impressions and could become more defined as I use it more.....Headroom is improved. I had already done the voltage mod on the PI (....moving the B+ supply for the PI back one leg for a little higher voltage..a real impressive mod) so I don't perceive much of a volume boost. But the headroom is greater and as the breakup happens it comes on very slightly a little bit earlier but much more evenly as it gets more intense and so feels like more headroom. The bottom remains more defined throughout. It seems the fidelity is effected the same way a long tailed PI effects it. I get heavy long tailed PI vibe from this mod. Mike

09-01-2009, 01:18 AM	#5
MikeT Member Join Date: Jul 2006 Location: Upstate NY Posts: 26	I heard about the 2m2 to 4m7 mod somewhere else too, so I tried it. Can't really do volume tonight though...I'll get back to you tomorrow...

09-02-2009, 03:33 PM	#6
hasserl Senior Member Join Date: May 2006 Posts: 724	I've employed this on a couple of cathodyne PI amps, one of them being a Princeton Reverb. IMO the result is a smoother distortion, less compressed. I like it.

09-03-2009, 06:57 PM	#7
TheElectricMoron Member Join Date: Jun 2006 Posts: 27	I have done this to several PR's and ASAIC it has just become part of the standard package for me like moding the tonestack. Together with the Stokes bump the voltage mod, any old Deluxe OT, and a 12" speaker and you have a total killer amp in a really compact package. Maybe I don't run mine at a low enough vol to notice the limitations of the 2.2meg resistor but I'm certainly gonna do that 4.7meg swap to see how that works. JIC you feel the urge - To cut a 12" into a fixed baffle you have to put the speaker as far down and to the left (looking at the front of the cab) as possible to clear the OT. The one PR that I try all the new stuff will be by my bed when I die. I love that amp. And thru a 2x10" box ....... almost orgasmic. I'm in the process of refurbing a trashed 70's DR cab and 2 10"'s will fit in there just fine. JMO of course YMMV Charlie

09-22-2009, 02:53 AM	#8
porge Junior Member Join Date: Jan 2007 Posts: 14	Hey Charlie, When you say "any old deluxe OT", are we talking 5E3 or DR? I have a SFPR that I'm thinking of modding this way, and wanted to be sure before I start ordering parts. I've read that the Stokes mod and Paul C mod can put some pressure on the PT in Princeton Reverbs - what do you guys think? TIA Andrew

09-23-2009, 12:38 AM	#9
TheElectricMoron Member Join Date: Jun 2006 Posts: 27	Andrew- any BF/SF OT will be fine. The Weber OT rocks. Those mods do nothing to the PT. There was in ancient times some concern about the v's getting dumped on the PI, but if you look at the v's on the 12at7 in a Fender reverb, and know that a 12ax7 will live in there too the PR v's are small potatoes. I've never seen over the so-called 100v limit on the cathode anyway. I run mine cranked all the time - never a problem. Charlie

09-23-2009, 01:59 AM	#10
porge Junior Member Join Date: Jan 2007 Posts: 14	Thanks - I was about to try and hop from the PR to DR for gigs (DR's are hard to come by here in Australia), but will give the PR another go. Will keep my eyes open for a Deluxe OT. Might try the weber one, but shipping is getting ridiculous from the US.

09-25-2009, 03:51 AM	#12
JDW3 Junior Member Join Date: Sep 2009 Posts: 12	I did the Stokes and the PaulC. I undid the PaulC and the amp still sounds horrible. Not Fender like at all. This was a '73 NR Princeton.

09-25-2009, 04:51 PM	#13
TheElectricMoron Member Join Date: Jun 2006 Posts: 27	The only thing I can say is that if you haven't up-graded to a quality 12" in there you prolly will have wasted your time. Even with a replacement 10" I never had any inclination to undo the mods. I have had players with decades of experience tell me that (even with the 10" in it) it was the best sounding PR they had ever heard. I also run it thru two different 2x10 cabs, one open and one closed. I haven't been able to make it sound bad. But it don't woof and fart no more. And if that is the sound you like then what you say makes a lot of sense. And of course - YMMV Charlie

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