My Hoffman Princeton Reverb Build

[p2pAmps]

I thought i would share my Princeton Reverb build that I am working on.  I still have a ways to go as I am waiting on a few more parts to arrive.  I am pretty excited to hear this bad-boy and A/B it next to my friends 65 PR.

[sluckey]

Nice start. Hope to see some updates.

[p2pAmps]

Nice start. Hope to see some updates.

Thanks Sluckey.  I am waiting on a few key things to move on.  I kinda was thinking if I should pull the wires off the turrets and solder them underneath for a super clean look?  Any thoughts to that?

[sluckey]

I would not do that. One bad connection on an underboard jumper will ruin your day! And your super clean look! You likely won't find it until you power up.

I don't like underboard jumpers but sometimes you cannot avoid them. When I do underboard jumpers I like to do them like this pic. Then I don't have to wonder if the jumper will fall out of the turret when I add components later. I highly recommend this technique.

[p2pAmps]

I would not do that. One bad connection on an underboard jumper will ruin your day! And your super clean look! You likely won't find it until you power up.

I don't like underboard jumpers but sometimes you cannot avoid them. When I do underboard jumpers I like to do them like this pic. Then I don't have to wonder if the jumper will fall out of the turret when I add components later. I highly recommend this technique.

Great tip and makes complete sense.  I am not so far along that I can't make mine like yours, thank you

[p2pAmps]

Here are a few updated pics

http://www.p2pamps.com/pr1/

[EL34]

Looking good Mike

[p2pAmps]

Looking good Mike

That means a lot to me Doug, thank you

[Fresh_Start]

Really nice looking build.

I had some noise problems on my Princeton Reverb builds. Shielded cable to and from reverb pot helped, along with keeping tremolo wires away from everything else. Don't do anything different until you start playing.  I'm just relaying my experience.

Cheers,

Chip

[p2pAmps]

Really nice looking build.

I had some noise problems on my Princeton Reverb builds. Shielded cable to and from reverb pot helped, along with keeping tremolo wires away from everything else. Don't do anything different until you start playing.  I'm just relaying my experience.

Cheers,

Chip

Thanks Chip.  This is my first PR so I will be learning a few things along the way.  Thank you for the tips. 

[lego4040]

Holy Smokes is that super clean. Lock-tite as well, what made you pick the WGS speaker? I have a older out of production one I like as well. Thanks for the tip with shielded cable to reverb pot and tremolo wire path. Can't wait for more pics

[p2pAmps]

Holy Smokes is that super clean. Lock-tite as well, what made you pick the WGS speaker? I have a older out of production one I like as well. Thanks for the tip with shielded cable to reverb pot and tremolo wire path. Can't wait for more pics

You know I thought i would start with the WGS speaker since I already had one.  I have a few others too to try, thats part of the journey for me.  I'm also going to start out with some Juniper caps and see how they do...  Thanks for the note

[lego4040]

  Jupiter Caps, straight to the top shelf I see. I don't know how many are on your circuit but that's a easy buck fifty with shipping I bet

[p2pAmps]

Jupiter Caps, straight to the top shelf I see. I don't know how many are on your circuit but that's a easy buck fifty with shipping I bet

Nah, not that much.  I use Mylars on the trem circuit.  The Junipers are around 5/6 bucks each...  Come on Doug, get us some so we can buy from you :)

The signal caps needed for a PR:
3 x .1
1 x .05 (=.047)
2 x .02

[lego4040]

That's not bad for their yellow mylars, the red "astrons" are $$. I see they have speakers as well now? I'm gonna have t look into their reviews, I'd buy jupiters if you stocked them Doug

[EL34]

The Junipers are around 5/6 bucks each...  Come on Doug, get us some so we can buy from you :)

Where are you buying these?

[p2pAmps]

The Junipers are around 5/6 bucks each...  Come on Doug, get us some so we can buy from you :)

Where are you buying these?

http://vintagefenderamprepair.com/maintenance/signal-cap-upgrades/jupiter-vintage-tone-premium-caps/jupiter-signal-caps-singles/

[EL34]

I see they have a red astron and a yellow vintage tone cap
http://jupitercondenser.com/product-category/capacitors/


I don't mind stocking them


looks like the red astrons are really expensive


You guys interested in just the yellow ones?

[p2pAmps]

I see they have a red astron and a yellow vintage tone cap
http://jupitercondenser.com/product-category/capacitors/


I don't mind stocking them


looks like the red astrons are really expensive


You guys interested in just the yellow ones?

I would probably use more yellows than reds.  I would buy from you 100% when needed Doug...  I have all but left Mojo to be honest.  Your parts are just better quality

[EL34]

I'll inquire with them and see about dealer pricing

[Ed_Chambley]

Nice work.  Did you get the faceplate from Dr Tube?  If you don't mind me asking where and also how much coin?

She might be a little woofey with that ceramic speaker, but I'll bet you know just what to do.  I can tell this ain't your first rodeo.

I have a huge stockpile of Caps.  Doubt I would be buying any Jupiters Doug, but I would think some would like to try them.  A load of guys are using them and I have seen the Red ones in a lot of Tweed Clones.
 

[p2pAmps]

Nice work.  Did you get the faceplate from Dr Tube?  If you don't mind me asking where and also how much coin?

She might be a little woofey with that ceramic speaker, but I'll bet you know just what to do.  I can tell this ain't your first rodeo.

I have a huge stockpile of Caps.  Doubt I would be buying any Jupiters Doug, but I would think some would like to try them.  A load of guys are using them and I have seen the Red ones in a lot of Tweed Clones.

The faceplate was an ebay buy and the backplate including the brass ground plate in front of the pots came from a guy in Thailand named Songwut.  His email is noojwut@yahoo.com  I think I have about 150.00 in all...  Little high but I really wanted it since its going to be my personal amp.  Cabinet came from Mather (1st class)...  I kinda discovered Hoffman along the way and now I'm sold 100%.

[p2pAmps]

Nice work.  Did you get the faceplate from Dr Tube?  If you don't mind me asking where and also how much coin?

She might be a little woofey with that ceramic speaker, but I'll bet you know just what to do.  I can tell this ain't your first rodeo.

I have a huge stockpile of Caps.  Doubt I would be buying any Jupiters Doug, but I would think some would like to try them.  A load of guys are using them and I have seen the Red ones in a lot of Tweed Clones.

Also Ed, you're right, this ain't my first rodeo but I still have tons to learn and am humbled daily by the large number of good tube amp guys. 

[Ed_Chambley]

Yes, and what is nice about the Forum here is I have yet to work on anything that Sluckey and or PRR cannot help with.  I mean anything, even a tractor blower motor switch.

But with amps, my God, if you think it someone can tell you how to do it.  BWT, I love the Princeton Reverb.  I use a Dual amp setup and for small places I use a 2, 10 Princeton Reverb and the Head version of the AC15 that Sluckey revised the layout.  2 Great sounding low watt amps.  Plenty loud for me and I actually get to turn them up to their sweet spots.

Rock on!

[lego4040]

Id buy the yellow ones for my next build, those red ones are 2xs the price as the red ones

[EL34]

Thanks for the feedback
I emailed Jupiter and inquired about becoming a dealer

[sluckey]

--- going to ground
Y on cap going to A on the board, pin 8 on the rectifier, Y to the OT

First, is this right?

Yes, that's right.

Next does it really matter where O,U, and X on the cap go on the board B,C,D?

No.

[p2pAmps]

--- going to ground
Y on cap going to A on the board, pin 8 on the rectifier, Y to the OT

First, is this right?

Yes, that's right.

Next does it really matter where O,U, and X on the cap go on the board B,C,D?

No.

Thank you Sluckey...  I hate it when I second guess myself...  Getting really close now

[Willabe]

I see they have a red astron and a yellow vintage tone cap

looks like the red astrons are really expensive

Yes, VERY!     

But I think they are going after the vintage 'look' with them? For the 'vintage' guys who have to replace an old Fender tweed coupling cap or 2, or 3, or.... they are the closets look. The yellows they have made for them, I think.... are the same cap internally, but are just 'tape wrapped' no molded shell.

I just bought a few of the astron 'clones' yellows and reds @ .02 to test in a Champ against SoZo yellows/blues, Mallorie's 150's and Orange drops 715 and 415(?) the OD caps Tubenit uses. 

I think...... that the only difference between the yellow/red astron 'clones' is that the reds have a molded exterior shell, like the old Fender BF blue caps????? I think... the yellow/red astron 'clones' are both film/foil, as are the SoZo's, as apposed to metalized polyprop's, no foil.     

[purpletele]

I would not do that. One bad connection on an underboard jumper will ruin your day! And your super clean look! You likely won't find it until you power up.

I don't like underboard jumpers but sometimes you cannot avoid them. When I do underboard jumpers I like to do them like this pic. Then I don't have to wonder if the jumper will fall out of the turret when I add components later. I highly recommend this technique.

That is a great tip.  I have struggled with jumpers.

[eleventeen]

Looks terrific, very nice work!


Excellent pix, too. Eagerly awaiting the A/B vs the '65 PR!


The only thing I would do differently is on your e-cap, generally I like to have ground connnections *under* the B+ wires. Or, I might slip a piece of ins tubing over the B+ wire (to prevent abrasion) if you want to use the bare ground wire to keep the B+ wire close to the chassis. That's about 1/57th of one nit I could pick on your excellent work.

[p2pAmps]

Looks terrific, very nice work!


Excellent pix, too. Eagerly awaiting the A/B vs the '65 PR!


The only thing I would do differently is on your e-cap, generally I like to have ground connections *under* the B+ wires. Or, I might slip a piece of ins tubing over the B+ wire (to prevent abrasion) if you want to use the bare ground wire to keep the B+ wire close to the chassis. That's about 1/57th of one nit I could pick on your excellent work.

Thanks so much, and yes I am waiting patiently myself to A/B with the 65.  It's killin me LOL

It's funny what you said about that ground wire as I saw that and changed it right before your post!  Good times

[EL34]

I uploaded a new PR PDF file this morning.
The power supply page still showed 22uf x 4 for the caps

The new PDf shows 40x20x20x20
http://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf

[p2pAmps]

I uploaded a new PR PDF file this morning.
The power supply page still showed 22uf x 4 for the caps

The new PDf shows 40x20x20x20
http://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf

Thanks Doug.  I also noticed on that layout that the PT blue and brown were reversed...  I used brown on pin 3 on V6 and blue on pin 3 V5. 

[EL34]

That would depend on the OT transformer you used

[sluckey]

I used brown on pin 3 on V6 and blue on pin 3 V5. 

There is usually a 50/50 chance you'll need to reverse the brown and blue wires since this amp uses NFB.

[p2pAmps]

That would depend on the OT transformer you used

I am using a Classic Tone Deluxe Reverb output tranny:
"Fender Style 20W Output Transformer 4/8 ohm 40-18038"

[EL34]

I  was using a different brand and so my hookup was different than yours


Like Steve said, it's a 50/50 dice roll
It's just one of the things that you adjust when firing up an amp for the first time


I never cut the the OT wires going to the power tubes until I know which way is correct

[p2pAmps]

I  was using a different brand and so my hookup was different than yours


Like Steve said, it's a 50/50 dice roll
It's just one of the things that you adjust when firing up an amp for the first time


I never cut the the OT wires going to the power tubes until I know which way is correct

I'll hold my ears LOL....

So is there a way to test before hand so I get it right?  Or is this just like you said, fire it and see what happens?

[EL34]

You fire it up after doing all the voltage checks, etc
Set the volume on low and you know right away


If you are using the same OT for multiple builds, then you already know which way is the correct way

[p2pAmps]

You fire it up after doing all the voltage checks, etc
Set the volume on low and you know right away

[Fresh_Start]

You fire it up after doing all the voltage checks, etc
Set the volume on low and you know right away


If you are using the same OT for multiple builds, then you already know which way is the correct way

IIRC another approach is to leave the negative feedback disconnected for initial power-up. That way you can check voltages, etc. before worrying about the output transformer leads.

Cheers,
Chip

[PRR]

> leave the negative feedback disconnected for initial power-up.

+1

Also, when the amp works no-NFB, you can then *tap* the NFB wire to where it should go. If the small hum gets smaller, that's correct. If it HOWLS, it is probably not correct. And with the "tap" you can un-NFB it instantly, instead of suffering while you wait for the power to bleed down.

[HotBluePlates]

I thought i would share my Princeton Reverb build that I am working on.  ...  I am pretty excited to hear this bad-boy and A/B it next to my friends 65 PR.

Looking great!!


I'm somewhat partial to the blackface Princeton Reverb, as that was my first good tube amp. I've had a number of black- and silver-face Princetons over the years.


I'd suggest you not completely judge your work until you also hear your amp through the old Jensen in your friend's amp. Hopefuly the speaker cord/plug will reach when your two amps are back-to-back.

[p2pAmps]

Well I finally got my caps in and fired her up this morning.  Sure enough the blue and brown in the OT were backwards.  Quick change up and 2nd fire.  Set the bias around 27mA. 

[p2pAmps]

Sound check
WOOT WOOT

https://www.youtube.com/watch?v=3mb3ig0S11U&feature=youtu.be

[EL34]

Sounds great Mike
I guess you nailed down the reverb issue

[p2pAmps]

Sounds great Mike
I guess you nailed down the reverb issue

Yeah, really dumb mistake, plugged in backwards LOL...  some kids I swear

[HotBluePlates]

Sounds perfect! And the cab, grill cloth, faceplates, etc look so spot-on it's a near-forgery! 


Really great job!

[Willabe]

Yeah, really dumb mistake, plugged in backwards LOL...  some kids I swear

     Can happen to the best of them.

Really, really, nice looking build!