Historic Princeton Reverb
- Thread starter AnalogPackrat
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Louie is an icon guitarist in the amount of albums he’s played on. That amp is cool. Look like the tremolo was use as an extra gain stage. The distortion is creamy and very studio 70s sounding. Very nice single 10” amp. I would love to find the circuit. And build a clone. It’s voiced nicely.
AnalogPackrat
Well-known member
Looks like push-pull pots also for bright switch maybe and perhaps the extra gain stages. Adding presence (feedback) is something I've found useful on my SFDR, but I repurposed the rear panel death switch for that. It's cool to know how the soup was made on all those old records.
He said there were labels on all the pots and two of the strips came off. So I would think switches were on all the pots. Then adding fat cathode caps would be used across the pot switches for thick tone. It’s got a tone with how fast he dialed in overdrive tones and using the master to control volume. It’s not a marshall thing so much as a boogie dumble versatility.
Fender ’68 Deluxe reissue modded by Paul Rivera | Rivera Amplification
He’s still doing these mods to the new deluxe. Tremolo is still used in the deluxe So he must add a stage
He’s still doing these mods to the new deluxe. Tremolo is still used in the deluxe So he must add a stage
AnalogPackrat
Well-known member
Lots of versatility there. It's strange because I never cared for his designs while he was at Fender (Champ-12, Super Champ). Seems like the notch switch just changes the "mid" resistor in the tone stack. So what's the mid switch doing?
I also was not a big fan of the fender amp changes made in those 80s amps.
Not sure what the mid switch notch switch difference would be. The tone stack lift increase gain and mids but dropping to 6.8k creates a notch. Just guessing. Playing with the slope resistor also changes the mids. 33k in a marshall. Guessing at this point.
Not sure what the mid switch notch switch difference would be. The tone stack lift increase gain and mids but dropping to 6.8k creates a notch. Just guessing. Playing with the slope resistor also changes the mids. 33k in a marshall. Guessing at this point.
Looking up Rivera amp schematics explains a lot of the circuit in this Princeton
Rivera Schematics - Tube amp Schematics
Notch, bright, gain
Rivera Schematics - Tube amp Schematics
Notch, bright, gain
AnalogPackrat
Well-known member
Ugh...the way he draws schematics makes them so hard to grok. The Clubster has a lot of the same stuff as the Champ-12. FETs, channel switching done with vactrols that simultaneously change the circuit at multiple points in the signal path, etc.
the schematic is messy showing all the optos but you can clearly make out the notch is the slope resistor changing and bright is 120pf across the vol ( no surprises). And the cold clipper switching is interesting. The presence is probably typical 5f6. The preamp is not sure but I would assume some version of what’s in the circuit. Knuckle head is the easier one to read for me. I’ll play around with this in the spring. It’s to cold here to be in my barn shop right now.
AnalogPackrat
Well-known member
I have a (rare?) red tolex Champ-12 with a few mods. Was planning to gut it and build something else in the chassis...but I see the plain black ones now going for $500+ on Reverb. Might be better off selling it and taking a different path.
Champ 12s are/were popular. Sell it to a person that appreciates it. Little amps are in. Build from a Chassis so you can change it to different designs when you want so as not to feel guilty cutting up a classic amp. I have a 5f2 tweed style SE Princeton I build last year and enjoy it. It has a 140 ma pwr trans and oversized output tranny 3k or 5k primary with 4,8,16 ohm output. I like it with different speakers. Speakers are so important to what your after. I like clean to mean with just a volume and tone control on your guitar. But volume is the thing to manage without sounding anemic neutered. It’s an endless quest. There is a SE build of a trainwreck that’s on my list of builds. It’s on ampgarage. Called the Wrong Horse.
SE Rocket build - The Wrong Horse Amp - The Amp Garage
There are some sound clips I thought were great.
SE Rocket build - The Wrong Horse Amp - The Amp Garage
There are some sound clips I thought were great.
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AnalogPackrat
Well-known member
I never considered the Champ 12 "classic." I have a SFDR and two SF Vibro Champs. Those are classics. Bought a Mesa TA-15 head to try to get more British tones. It's ok.
I've got some iron stashed away that I'd like to use. Nothing super fancy. Mostly low watt OT. We'll see. Too many other irons in the fire at the moment. I'll be lucky to find time to finish my fuzz face project.
I've got some iron stashed away that I'd like to use. Nothing super fancy. Mostly low watt OT. We'll see. Too many other irons in the fire at the moment. I'll be lucky to find time to finish my fuzz face project.
I know that feeling. Life on the property dictates priorities. I have a friend who is a rep and did very well. He’s the one that told me about the popularity of the champ 12 with different players. I had a black face Princeton back around 1970. I learned a lot of guitar on that amp. It’s a classic. The SFPR of Louie’s caught my attention. If I had my BFPR I would never want to touch it inside. I’m just saying a chassis is an open slate so you don’t mess up something that is a classic for someone else.
AnalogPackrat
Well-known member
BF and earlier are definitely restoration only AFIAC. I remember seeing a rig walk through of TPATH guitar rigs some years back. They had the big Vox Super Beatles on stage, but they were just props. Mike Campbell's main amp was a little BFPR tucked away back stage and miced up. I think he might have also had a tweed of some kind for a few tunes.
One of my Vibro Champs (both '77 models) is practically brand new. I will only touch electrolytics on that one. The other one was clearly used. Speaker was tired. I put a new 8" Alnico in it (Jensen, IIRC), recapped electros, rewired heaters with resistor "CT," and added an extra RC filter stage to B+ to drop voltage slightly and reduce hum. I might have tweaked the mid resistor, too. Nothing radical.
My SFDR, also a '77, was a tired player's amp that I got for $275 in 1991. Cabinet in good shape, Utah (?) speaker very tired. Someone had wired series strings of 1N4007 diodes across the 5U4 socket and B+ was something close to 500V.
Over time I undid the hacks, recapped it, mostly blackfaced it, then did the reverb & trem on both channels mod, then reworked the normal channel with a 12AY7 and less scooped midrange. I snipped the bright cap, too. Last thing was a vox cut control wired onto a plate covering the rear accessory outlet and repurposing of the death switch for a three position NFB control: BF (standard 820R), tweed (open--no NFB), and brownface (a few K--I did the calc to accomodate PI input differences, don't recall exact value).
I don't regret the changes. The amp is my favorite to play. NFB switch is a great mod. The amp can easily be restored to near BF spec in a couple of hours if desired.
I had a BF vibro champ I loved. I could use that to play with this acoustic group and not over power but still get a tone. Great amp. I traded it for a brown 1963 vibroverb amp no cabinet just chassis and no OT. The PT turned out to be bad also. It’s a work in progress. My old BF vibroverb has been my favorite amp but it’s heavy and loud. Small amps are where it’s at. Princeton reverbs and Deluxe are ideal IMO.
