PAT-4 >> to ULTIMATE tube preamp

OK, next project, hopefully done in a week or so if not too busy.
I'll be converting a stock Dynaco PAT-4 solid state preamp into the ULTIMATE mod for the PAS-4 - an SP12 tube preamp.
I've done several of these using my PAS3 mods, but wanted to do something nicer and better with this chassis. Cost was $60.
Add an SP12 board, throw in a couple of leftover power transformers from other projects, about $300 worth of parts total,
and a budget SP12 in a vintage style chassis . . .
OR, you could do the exact same thing but using an SP9 board if you want tone controls, the PCB is the same size and price.

This is an infinitesmal better idea then to destroy an existing PAS2/3 !
Well written!

OK, it's about 3/4 done now, about an hour left to wire up the selector, volume, balance, power switch,
and connections to the PCB.
So we've got the SP12 PCB kit ($179), the PAT4 I-O board with all new RCA jacks ($70), ALPs volume & balance ($50), selector $8,
and two DPDT switches $10, one for SOURCE-TAPE and one for POWER On-Off. All that's left is a tube set $70, so $387 in parts,
plus the cost of the PAT4 (which I got for $60, now they go for $80-100). It will be done in just under 4 hours.
That beats paying $990 for a new assembled/tested SP12 preamp.
Also BTW, available with the stock PAT4 front panel as shown in the first post, or with a brand new custom machined/engraved front panel.

How is the PSU designed ? Is it the 2 transformers to the right ?

it's a stock SP12 board, just using some leftover transformers that had the right voltages.
If I was building this with new transformers, I'd use a single toroid or a couple of flatpaks like the ones I use for the PAS3 PS upgrade.

OK, so all done wiring, here are the finished photos, and the very bottom photo is a "mock-up" of the custom panel I ordered to use,
or I can finish it off with the original PAT4 faceplate, as shown on the first photo at the top of the orignal post.
4 inputs on the selector plus a tape in (or any other source), a tape out, and two preamp outputs (use one for a sub if you want).
No phono board, sorry. Now posting for sale in the FOR SALE section of the forum.