Princeton Reverb build

[Opry Audio]

Hey guys, sorry for starting another thread so quickly. My project changed and I’m now putting together what I need to do a Princeton reverb build. I have a chassis without the angled front panel, just a 90 degree one that I got for cheap. I know it would be more cost affective to buy a normal PR chassis so I can buy a mojotone cab or something, but I have this and would like for the amp not to have PR looks :)

So, one big decision I’m trying to make is lower B+-higher mA or or higher B+. There are so many threads on this, I know. The old PR transformers are overworked. Something with higher current wouldn’t mind modern 6V6’s. I’m looking at the low B+ MM transformer.

Any recs would be helpful. I’m going for a tighter sound that’s clean but when cranked sounds like a TW. Avoiding some of the voltage sag sounds of the originals. So, PR based but not true PR is ok.

I think for coupling and tone caps ideally I would love to use Jupiter’s, but the Hoffman boards won’t really fit them it looks like. Is it possible to move the lugs down to make room for axial caps? Mallorys have fit in leu of the xicons in my experience. Plus, they are much cheaper.

I’ll be using a Weber 10f150t 50w I think, apparently everyone agrees they sound really good.

Anything else to consider?

[jordan86]

I got the Hammond 290ax. $60. Two options - low or high B+. Or both if you put it on a switch.

Also 100ma

[ac427v]

Another thumbs up for Hammond. I used a DPDT switch to choose which PT taps to use. I never switch when hot tho--not tempting fate.I've done a bunch of mods you can ignore but the schematic shows actual B+ values with the two sets of taps and a variety of rectifiers.

[Opry Audio]

Another thumbs up for Hammond. I used a DPDT switch to choose which PT taps to use. I never switch when hot tho--not tempting fate.I've done a bunch of mods you can ignore but the schematic shows actual B+ values with the two sets of taps and a variety of rectifiers.

This is pretty helpful. I did check out the Hammond, but I’m also interested in the Allen TP25 because it has 310-CT-310 150ma. No sag possible. Id imagine there’s a significant difference in the way the amp breaks up with an extra 50mA in the B+. Hi power low power switch concept seems cool. If it was a different chassis that had room for a 3 position standby switch I would probably incorporate something like that.

[mresistor]

I used the TP25 in my first PR build, and used a Hoffman turret board.  If you are going after lots of headroom it would be the choice.  Also can use 6L6 family of power tubes..  I also used a Deluxe Reverb OT.
The Hammond 290AX is better for more conventional build.  Switching the HV secondary windings is interesting.

[Opry Audio]

I used the TP25 in my first PR build, and used a Hoffman turret board.  If you are going after lots of headroom it would be the choice.  Also can use 6L6 family of power tubes..  I also used a Deluxe Reverb OT.
The Hammond 290AX is better for more conventional build.  Switching the HV secondary windings is interesting.

Did you ultimately end up liking one or the other more?

[drew]

It seems like you want an amp that doesn’t look like a Princeton Reverb and doesn’t behave like a Princeton Reverb. What is the point of even using the Princeton Reverb as the jumping off point?

[jordan86]

I was going to also ask...is your chassis already punched for a Princeton PT? May be cheaper to just go with a Deluxe PT. Dave Allen is fantastic and would happily give him my business again (I have a TO20), but if you’re not looking to make it look like a Princeton and not using a Princeton chassis you can probably find more power for less cost with a different PT

[mresistor]

I used the TP25 in my first PR build, and used a Hoffman turret board.  If you are going after lots of headroom it would be the choice.  Also can use 6L6 family of power tubes..  I also used a Deluxe Reverb OT.
The Hammond 290AX is better for more conventional build.  Switching the HV secondary windings is interesting.

Did you ultimately end up liking one or the other more?

I like them both.   I have built stock AA1164 Princeton Reverbs with the 290AX and love the result, have one here that I'm playing accaisionally now. I really like the Hoffman PR with the TP25 and DR OT. I built it as a head and its a beast. I would say it is a very powerful and cleaner amp than the AA1164s.  Like the OP says he's going for less sag in the power supply so the TP25 is going to be a better choice, especially if powering 6V6s. I select the Hammond PT over others because of it's rating and the cost.  It's a win-win in my book.

[mresistor]

When I use the Hammond 290AX in an 1164 Princeton reverb I also use the Hammond 1750E or 1760E. 

[Opry Audio]

It seems like you want an amp that doesn’t look like a Princeton Reverb and doesn’t behave like a Princeton Reverb. What is the point of even using the Princeton Reverb as the jumping off point?

Well, at the end of the day I want to build a Princeton reverb type of amp but choose iron that makes it a bit different from a typical one. It’s pretty common knowledge that the original PR’s are underpowered and would like for it to put my own twist on it

[Opry Audio]

I was going to also ask...is your chassis already punched for a Princeton PT? May be cheaper to just go with a Deluxe PT. Dave Allen is fantastic and would happily give him my business again (I have a TO20), but if you’re not looking to make it look like a Princeton and not using a Princeton chassis you can probably find more power for less cost with a different PT

Yeah it is! I bought a right angle chassis a while back, and would like to use it. I’m having a cabinet made that’s a Princeton reverb but with without the angled front, so that already looks different enough for me, and still has the convenience of the small size of the PR, if that makes sense. The PT hole is already cut, but I have a classic tone tweed deluxe transformer I’d consider using. Good idea, bad idea?

[jordan86]

TP25 is probably the best choice then if you need more power and your PT footprint is already established.

[labb]

FWIW-I just built a version of the Princeton Reverb that was with out the reverb. used the PR circuit. I used classictone PT and OT that are sized for the Deluxe. I could look up the numbers if you like. I included the Raw switch in the amp. The guy I built it for uses it in the Raw Switch mode and controls tone from his pedals. If he wants reverb he does it with his pedal. He loves the amp.

[mikhett]

I Built a PR clone using a PT and OT from a junked 66 Ampeg RR ABOUT 22 WATTS.I USED 6V6S.

[Opry Audio]

I haven’t heard from Mr. Allen so I just bought a pair of Hammond transformers.

Anyway, I have all the parts ordered so should be done early next month. Has anyone build this amp on the Hoffman board with orange drops? I was looking at using Jupiter’s but they won’t fit on this board.

[sluckey]

Hoffman's boards were designed to use Xicon chicklets that he sells. You can shove orange drops in some places but it won't be pretty and the amp will lose that Hoffman mojo.