November 27th, 2008, 08:53 PM
Are there any simple mods to add some gain to this amp and make it louder or should I just sell it and move on to something else?? I got it for nearly free form a friend but in its present form, it's barely louder than a Champ. I hoped it would sound similar to my old Princeton Reverb, but no dice so far.
November 27th, 2008, 09:43 PM
Don't hack mod the damn thing. First off make sure it is healthy (caps, tubes, etc.) Put in a more efficient speaker like a Weber 10F125. If it still needs "more", use a drive pedal. If that still does not cut it for you, get a different amp.
Don't do anything that will overstress the already maxed-out PT or it will fry. Read the other threads on Princeton power transformers.
November 27th, 2008, 09:46 PM
Listen to the man!
A good clean boost pedal will do everything you're asking, and won't mess with the amp.
November 27th, 2008, 09:48 PM
Put in a more efficient speaker
+1! What speaker is in it?
First off make sure it is healthy (caps, tubes, etc.)
+2! Don't throw the baby put with the bath water! Those are great amps and should have more SPL than a champ. Make sure it's bits are in good order before selling.
November 27th, 2008, 09:54 PM
I had a really great, really toneful 1966 BF Princeton (non-reverb), and it really wasn't very loud, compared to a Princeton Reverb. On 10, it was about the same as 6-7 on a PR. And it stayed pretty clean, as well. Damn, though, was it TONEFUL!
November 27th, 2008, 09:57 PM
A PNR on 5-7 is still much bigger than champ. Just saying.
November 28th, 2008, 01:56 AM
The PNR has several dB less preamp gain than a PR. Hence my suggestion for a drive pedal to make up the discrepency. It has the same/identical power output section so it's max power out is the same.
Stock speaker in these amps, IMO, sux. Oxfart 10J4. A Weber 10F125 is *way* more efficient.
If you have an older one with the screw mount baffle, you can buy an aftermarket baffle (or make one yourself like I did) that holds a 12. Again, massive improvement over the stock speaker. I put a Weber 12F150 in mine.
Lastly, if you'll notice, there are actually 3 screw holes for mounting the OT. The stock OT uses the closest spaced pair. It just so happens that a DR OT fits perfectly in the wide spaced pair. No drilling. If you are going to go to the trouble of replacing an OT in a Princeton with anything aftermarket, why not go with the bigger DR type?
Done all the above on mine. It's as loud as my DR.
November 28th, 2008, 03:07 PM
IF the amp does have the Oxford speaker, it is indeed a low-efficiency speaker. STarting in the mid-60's 1966? or so, Oxford started buidling a sider gap in their speaker which decreased the efficiency. EArlier OXfords do not suffer from this and can be good speakers.
It is probably time to get a tech analysis of the amp. Worst case scenario, your OT is not performing up to spec. THat amp should be a bit louder than a Champ. Hey, put the PRinceton through the Champ speaker for a few seconds and compare the output through the same speaker. THat should give a clue as to what is going on. Best comparison would be through a 4 ohm load that is separate from either amp....just to be safe with the Champ's speaker.
November 28th, 2008, 03:18 PM
We are in exactly the same boat--I found a pristine '69 Princeton NR. I was really surprised that it wasn't as loud as my '71 VibroChamp, but I wanted a cleaner sounding amp. With a clean boost, it's great--I have a SexDrive and a Keeley Katana. The Katana is darker sounding, but really gives a nice bit of hair around the edges. I have had a hard time finding an OD pedal that didn't sound fizzy, but am using a Barber LTD and its a great combo.
As for mods, mine is in the shop now to add an adjustable bias, which should help with the relatively weak trem, and I'm also doing the Paul C and Stokes mods. They each involve only moving a wire--they aren't going to ruin the amp--and my understanding is that they will add both volume and some oomph to the amp. I'll let you know how they sound...
November 28th, 2008, 03:44 PM
If it were mine, I'd sell it and buy an amp that did what I wanted. The Paul C and Stokes mods can take there tolls on the PT.
If it were a player amp and not a collector piece, I'd add a Mid/raw control, the raw takes the tone stack out of the circuit and increases gain.
November 28th, 2008, 05:17 PM
A few comments:
First, thanks to the missing reverb circuit, the PT on a non-reverb Princeton is not as stressed as the same PT on a Princeton Reverb.
Second, I owned both blackface and silverface non-reverb Princetons, and though I had heard about the extra hole in the chassis for a Deluxe-size OT, I didn't find those holes on my amps. Perhaps those extra holes are only on Princeton Reverb chasses?
Last, to second, third, and fourth what others have said: in the end, you might consider letting this amp be what it is. It is a delightfully toneful little package, especially with the right speaker. The 10F125 is a good choice. If you were to keep things clean, a new Jensen C10R sounds wonderful in a straight Princeton. Eminence Copperhead, Ragin Cajun, and Legend 105 speakers would also be good choices with louder voices than the stock speaker.
November 28th, 2008, 11:19 PM
If you want it dirtier, install a 1K resistor in parallel with the 1.5K cathode resistor (tied to ground on the control-panel side). That will lower the total resistance on the first triode of the 12AX7, increasing gain. I just did this on my 5F1 after alligator-clipping different resistors in that position, settling on 1K. This lowers the resistance to ~ 700 ohms, and it'll dirty up the mids a bit and add a little volume.