My next Princeton Reverb Build

[Opry Audio]

Hey!

I’m in the midst of planning my next Princeton Reverb build. My last one was a pretty true Hoffman layout (and turret board) I managed to get some of the last PR classic tone txmrs— a little sad they won’t be in this one! I used mojotone chassis and cab, which was pretty cost effective. It came out great!

I want to try some things on this next round that are pretty new to me design wise and looking for some advice. I plan to build essentially the same amp with the changes I had made. I am considering designing my own tweed style config and get a cabinet made for a 12”.  I am really trying to build a more unique looking amp. At least not PR looking. I have good reasons for doing so— and since I’m designing this chassis, I’m exploring doing a true PTP layout. Any projects out there like that, that turned out well?

I reached out to Heyboer about getting a TP25 and TO20 made in stand up config.

Is there any major downside for PTP in a PR with this type of chassis? Spacing? I really love the way supro’s were built this way and going for that style.

And can I ask where everyone is sourcing components for reasonable prices? Components, Jupiter caps, carbon comp .5w.. trying to use quality stuff. It’s looking like $1,000usd atm to build.

I understand not buying in bulk can be that way, but how do I lower the cost and maintain exactly the amp I want to build? How much should I expect to pay for a custom cut chassis, faceplate and cabinet? I am ordering at wholesale prices for components from CE and mojotone

Thanks for reading and I’ll post my progress here.

[AlNewman]

I think the main difference between PTP vs a board, is there's no available layouts to follow.  So either you have to be very smart with your initial plan, or you need to leave yourself room and extra points for connections, (which you will use).

The PR has a lot of circuits and tie in points.  So if you aren't careful in how you plan your space, it will look and sound like a jungle.

That being said, again, if you're thinking ahead, you can use a PTP layout to save space as well. 

The best thing you could do to discover the 'joys' of PTP is refurbish an old radio.

[dogburn]

That's a lot of questions asked in one post, but I'll start by saying I find that ordering parts from as few places as possible is my preference. If you get components from 5 different vendors, the shipping charges all add up to a lot more than the savings you might get on individual parts. I tend to order more than I need of caps, resistors, etc., because it's not much more and then next time around, I've got extras lying around (or if something gets broken, goes bad, etc.). I tend to buy from Mouser, Amp Parts Direct, Mojo Tone, and of course Doug Hoffman himself.

**edit: I don't know how that Youtube link got in there, but I've now deleted it.

[labb]

Hard to beat the original Fender layout with the eyelet board. I would move the components for tremble, bass and mid off board to strip mounted right under the pots. Saves some board space. Always check tubes and more and tube depot for prices. I have use Tubes and More’s Mod electrolic caps on a couple of builds with no issues. Will save you some $$.

[mresistor]

A standup PT could save a bunch of interior space.

[Opry Audio]

Part of the reason why I’m not using the fender style layout is because of preamp / power supply grounding mostly. Plus I get to add modern niceties like an IEC, and a 1/4” footswitch with a few led’s. I’d love to try Merlin Blencowe’s grounding theory of each stage being grounded at the ps- and flowing through the chassis to earth.

I decided now is a good time to learn fusion 360 for chassis and cabinet design. One being much more involved than the other… I also decided that a top mounted chassis is still going to be best for the layout, but now I get to move tube sockets around :). I’ll update my sketches and progress here.

One thing I’m thinking of trying to replicate is the look of the late 70’s traynor YGM. I think the look of those amps are super cool with the tubing on the side panels (anyone know exactly how they did that?), rocker switches, led indicator, and possibly using their design for the top cabinet piece coming off for easy access to the inside. I’ve always thought it was a great idea, convenient, and keeps the tolex and baffle from getting chewed up removing the chassis.

 

[Opry Audio]

It’s looking like having the chassis and cabinet parts cut by CNC and assembling at my shop is going to save a good chunk of that 1k parts price tag.

[bmccowan]

I have rebuilt several true PTP amps (component to component, no tag strips) and built some simple PTP amps. I would advise against that type of build for more complex amps. Older capacitors and resistors had much heavier leads. The leads could be bent to fit and they would stay that way. Not so with new components - the flimsy leads will be a hassle. Also, in order to do true PTP in a PR, you would want to locate the tube sockets, pots, jacks, etc. closer together than the standard layout in order to get the leads to reach.
I am wondering what you mean by, "I really love the way supro’s were built this way and going for that style." Only the earliest Supros were built true PTP - they soon transitioned to tag strips.

Part of the reason why I’m not using the fender style layout is because of preamp / power supply grounding mostly. Plus I get to add modern niceties like an IEC, and a 1/4” footswitch with a few led’s. I’d love to try Merlin Blencowe’s grounding theory of each stage being grounded at the ps- and flowing through the chassis to earth.

All of that can be accomplished with a turret or eyelet board and fender type layout. No need to use the Fender style chassis, or the brass plate grounding scheme - just make sure the board will fit, eh?
I predict that if you go ahead and build a PR true PTP, as some point you will mutter, or scream, "what was I thinking?"