So i've ended up with a few of these things & went feral on making at least something that works as an amplifier. Cue Pete Millett's design & project for a couple of monoblocks using a couple in parallel push-pull... (link: pmillett.com/807pp_amp.htm)... I already have Pete's HV power supply about to assemble that uses 807s as series pass elements which i think may be relegated to the junk bin in favour for five the 5B/254Ms....

I've been cooking a couple on my eTrace curve tracer to get my head around their performance. I'd an interesting experience & learned the proper way to extract a loctal from its socket! The other query but trivial issue i need an answer for is why so many 5B/254Ms appeared in NZ back in the 1980s i believe. I faintly recall seeing cartons of boxes of the things at the Queen St Surplustronics waaaay back then! Perhaps is was ex-military (NZ Navy) warehouse stock... ? (It's be neat to know, a bit of a conversation piece to go with the story of the amplifier).

I've bent hell out of my credit card on Hammond transformers for the monoblocks & most the other main big cost items like Pete's 'red' PCBs for the powersupply section & the p-p universal driver boards.

Then this project stalled BADLY.... The (it would seem infamous) 450W, 40W IXCP10M45S driver/current regulator is unobtainium until late next year for whatever reason... No one has stocks of these critters & indept study revealed just how well the devices are regarded. Very strange why the things are now virtually rocking horse poop even considering the fallout of a Pandemic! Ebay is of course an avenue but at over USD $15 each for what could be fake parts... even i'm not that silly....

So eventually i'll be (with luck) making some glorious sounds with some obscure tubes... i hope...

IXCP10M45S In stock at Infinity Electronic.

AMR-iFi R&D

I haven't watched the YouTube link yet but I remember those at Surplustronics and still have 10-12 of them.
Long time back burner project of mine to make a stereo PP amp around them. Thanks for the link!
I have Hammond 5k 100W transformers stashed along with several and pairs of HT transformers, and chokes and heater transformers, and saved chassis.

I might have a clue about where 2-3 of those boxes ended up, I'd have to make inquiries - but I bet that they are or will be still able to be found.
When I tested one on the Taylor 45C it was superbly in spec.

And yes, extracting a loctal valve correctly!

I almost think we need a refresher or a link.

Cheers

Ross

I hesitate to ask, since I'm nowhere near progress on mine, but how are you going on yours?

pmillett.com/807pp_amp.htm

I have a couple of early Sansui 8K 30W potted OPTs with octal base connection stashed for an amplifier as well.

Some pics of my valves collected from 2008.

5B/254M loctal on the far left. As I wrote, I have maybe 10-12 on hand. Maybe 6 or so 813 of different manufacture. And bases for them all.

Also in comparison with 807 & 829B & equivalents, dual tetrodes also possibly able to be used (pressed into service as?) in audio circuits.

I have a bundle of those too. But I sense that I'm running out of time to implement some of those ideas ...

Maybe some will have to go on sale.

But I still hope to be building something.

In the future !!!

;=}))

For the record, my build has at this time is stalled out seriously over being unable to source the parts it needs. Things like the trimmer pots of the proper wattage & for the footprint of the PCB are no show... Physical size of 3W wirewound resistors etc... For now the entire project is confined to a storage bin. I've now turned to my p-p 6B4G project instead...