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Wingherder · June 22nd, 2011, 12:35 PM

I apologize in advance for asking stupid questions. Seems to be a talent of mine.

I did use the search function, and haven't found anything on point.

I've got an old Princeton Chorus amp that is having volume variation issues, and I don't really think is economically repairable. I'm wondering if I can use the cabinet for the PC as is, as an extension speaker cabinet for a Twin Reverb II (The 2x12 combo version). The manual on the PC is here:
http://support.fender.com/manuals/gu...rus_manual.pdf

Shows the cabinet with 2 8 ohm speakers. I'm not where the amp is right now, but I believe each speaker is wired separately to the amp (the double amp 2 channel feature of the PC). I also believe the TR II's extension cab output jack is labeled "4 ohms or greater" but again, I'm not looking at it right now. Would use the PC "cabinet" as an additional cab, along with the 2x12's of the TRII. Really more of a "what would that sound like?" project. Is this possible to do without damaging anything? Other than eardrums?

If so, how would the PC cabinet need to be wired? Thanks!

Wally · June 22nd, 2011, 12:53 PM

Wing,, you need to wire those two 8 ohm speakers in parallel for a 4 ohm impedance. Then, when you plug into the TR's Ext Spkr jack, which is in parallel with the Main spkr jack, the amp will see a 2 ohm load. FEnder provided for this mismatch, and the amp will have no problem with it.
I don't know if those speakers are up to everything a TR can throw at them, but used 'sensibly', they should be alright. Max the volume on the TR and those speakers won't be alive long.

Wingherder · June 22nd, 2011, 12:58 PM

Thanks, Wally!

Stupid question alert #2:

Parallel wiring would be to tie the two "+" terminals together on the speakers, and the two "-" terminals together, correct?

Wally · June 22nd, 2011, 01:01 PM

Yepssir, Mike..that would be the way....and tip to +, ring to -.

Wally · June 22nd, 2011, 01:02 PM

OH, and uselss info....imho, that would be the best service that Princeton Chorus will ever have given you! (;^)

Wingherder · June 22nd, 2011, 01:08 PM

Definitely be much louder than the ol' PC ever managed before.......

Wingherder · June 22nd, 2011, 01:10 PM

A kinda related question: Any advice on how to fabricate or build a "close up" piece to go in the PC cab to replace where the faceplate of the amp was? And, as a bit of useful background, I suck at carpentry/fabrication skills.

Wally · June 22nd, 2011, 01:15 PM

???? cut a piece of board to fit, paint it black and stick it in with some Liquid Nails???

Louder??? Not just louder, but more musical at any volume level, imo.

SamClemons · June 22nd, 2011, 02:09 PM

Buy something like a Furman Power conditioner and mount it in the slot where the amp was, then use that to plug all your gear in and turn it on and off.

broncstomper · June 22nd, 2011, 08:01 PM

I'll bet that some contact cleaner in the volume pot would fix that variation problem. just sayin.

Wingherder · June 23rd, 2011, 11:26 AM

I've tried some Deoxit in both volume pots. The volume drop occurs after the amp has warmed up (10-15 minutes), and affects both channels equally. I'm probably gonna try a few more little things like that before giving up, but they haven't worked so far.

Wally · June 23rd, 2011, 12:15 PM

Mike, the best way to resolve all of the sonic problems with that amp is to do what you are proposing....pull the chassis out and make good use of the cab.
Imho, it is not worht hte expense of working on it. That said, it is a heat realated problem.
Some 'cold spray'...I forget the name of the products... that will chill components while they are exhibiting the problem might help locate the problem...might not. I would guess that there is a problem with electrolytics, transistors, resistor, other caps.....long list, right?

DOGMA Dunn · June 23rd, 2011, 06:11 PM

Quote:

Originally Posted by Wingherder

I've tried some Deoxit in both volume pots. The volume drop occurs after the amp has warmed up (10-15 minutes), and affects both channels equally. I'm probably gonna try a few more little things like that before giving up, but they haven't worked so far.

Does it have any leaky capacitors?

new2twang · June 27th, 2011, 08:29 PM

I've been looking at getting one of these amps in a trade, and was thinking about wiring it for a couple of 8 ohm outs (keeping the stereo) and then rewiring a 4x12 as an 8 ohm stereo cab. Anyway, in doing so, I came across this, which might be worth looking at before/while/after you tear things up:

http://music-electronics-forum.com/t17705/

June 22nd, 2011, 12:35 PM	#1 (permalink)
Wingherder TDPRI Member Join Date: Apr 2009 Location: Texas Posts: 39	Princeton Chorus as TRII ext. Cab - Stupid? I apologize in advance for asking stupid questions. Seems to be a talent of mine. I did use the search function, and haven't found anything on point. I've got an old Princeton Chorus amp that is having volume variation issues, and I don't really think is economically repairable. I'm wondering if I can use the cabinet for the PC as is, as an extension speaker cabinet for a Twin Reverb II (The 2x12 combo version). The manual on the PC is here: http://support.fender.com/manuals/gu...rus_manual.pdf Shows the cabinet with 2 8 ohm speakers. I'm not where the amp is right now, but I believe each speaker is wired separately to the amp (the double amp 2 channel feature of the PC). I also believe the TR II's extension cab output jack is labeled "4 ohms or greater" but again, I'm not looking at it right now. Would use the PC "cabinet" as an additional cab, along with the 2x12's of the TRII. Really more of a "what would that sound like?" project. Is this possible to do without damaging anything? Other than eardrums? If so, how would the PC cabinet need to be wired? Thanks!

June 22nd, 2011, 08:01 PM	#10 (permalink)
broncstomper Tele-Meister Join Date: Dec 2009 Location: GA Posts: 155	I'll bet that some contact cleaner in the volume pot would fix that variation problem. just sayin. __________________ "I invented the R chord"

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June 22nd, 2011, 12:53 PM	#2 (permalink)
Wally Doctor of Teleocity Join Date: Mar 2003 Location: Lubbock, TX Posts: 13,730	Wing,, you need to wire those two 8 ohm speakers in parallel for a 4 ohm impedance. Then, when you plug into the TR's Ext Spkr jack, which is in parallel with the Main spkr jack, the amp will see a 2 ohm load. FEnder provided for this mismatch, and the amp will have no problem with it. I don't know if those speakers are up to everything a TR can throw at them, but used 'sensibly', they should be alright. Max the volume on the TR and those speakers won't be alive long.

June 22nd, 2011, 12:58 PM	#3 (permalink)
Wingherder TDPRI Member Join Date: Apr 2009 Location: Texas Posts: 39	Thanks, Wally! Stupid question alert #2: Parallel wiring would be to tie the two "+" terminals together on the speakers, and the two "-" terminals together, correct?

June 22nd, 2011, 01:01 PM	#4 (permalink)
Wally Doctor of Teleocity Join Date: Mar 2003 Location: Lubbock, TX Posts: 13,730	Yepssir, Mike..that would be the way....and tip to +, ring to -.

June 22nd, 2011, 01:02 PM	#5 (permalink)
Wally Doctor of Teleocity Join Date: Mar 2003 Location: Lubbock, TX Posts: 13,730	OH, and uselss info....imho, that would be the best service that Princeton Chorus will ever have given you! (;^)

June 22nd, 2011, 01:08 PM	#6 (permalink)
Wingherder TDPRI Member Join Date: Apr 2009 Location: Texas Posts: 39	Definitely be much louder than the ol' PC ever managed before.......

June 22nd, 2011, 01:10 PM	#7 (permalink)
Wingherder TDPRI Member Join Date: Apr 2009 Location: Texas Posts: 39	A kinda related question: Any advice on how to fabricate or build a "close up" piece to go in the PC cab to replace where the faceplate of the amp was? And, as a bit of useful background, I suck at carpentry/fabrication skills.

June 22nd, 2011, 01:15 PM	#8 (permalink)
Wally Doctor of Teleocity Join Date: Mar 2003 Location: Lubbock, TX Posts: 13,730	???? cut a piece of board to fit, paint it black and stick it in with some Liquid Nails??? Louder??? Not just louder, but more musical at any volume level, imo.

June 22nd, 2011, 02:09 PM	#9 (permalink)
SamClemons Friend of Leo's Join Date: Jan 2011 Location: Jasper, TN Posts: 2,805	Buy something like a Furman Power conditioner and mount it in the slot where the amp was, then use that to plug all your gear in and turn it on and off.

June 23rd, 2011, 11:26 AM	#11 (permalink)
Wingherder TDPRI Member Join Date: Apr 2009 Location: Texas Posts: 39	I've tried some Deoxit in both volume pots. The volume drop occurs after the amp has warmed up (10-15 minutes), and affects both channels equally. I'm probably gonna try a few more little things like that before giving up, but they haven't worked so far.

June 23rd, 2011, 12:15 PM	#12 (permalink)
Wally Doctor of Teleocity Join Date: Mar 2003 Location: Lubbock, TX Posts: 13,730	Mike, the best way to resolve all of the sonic problems with that amp is to do what you are proposing....pull the chassis out and make good use of the cab. Imho, it is not worht hte expense of working on it. That said, it is a heat realated problem. Some 'cold spray'...I forget the name of the products... that will chill components while they are exhibiting the problem might help locate the problem...might not. I would guess that there is a problem with electrolytics, transistors, resistor, other caps.....long list, right?

June 27th, 2011, 08:29 PM	#14 (permalink)
new2twang Tele-Meister Join Date: Sep 2010 Location: SFBay Posts: 139	I've been looking at getting one of these amps in a trade, and was thinking about wiring it for a couple of 8 ohm outs (keeping the stereo) and then rewiring a 4x12 as an 8 ohm stereo cab. Anyway, in doing so, I came across this, which might be worth looking at before/while/after you tear things up: http://music-electronics-forum.com/t17705/

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