You are not cloning an extant amp so there’s no off the shelf answer just different people's tastes, you just have to close your eyes and pick one. Or read through some forums and see what others did with 6V6 Plexis. Isn’t there a well documented Mark Huss 6V6 Plexi? Trinity? Peeps on TAG? (Be brave, fear not the malware).
Of course you want it to sound like a Marshall not a small tweed, so I would rule out the 108 Tweed Deluxe OT. Marshall used good interleaved iron, originally RS middling hifi iron, and as you said you want it to hold together. Fender, the 6V6 king, seemed to use 8K on the tweed cathode bias amps and 6.6k on the later fixed biased amps but that isn’t consistent either, 8K would suggest cleaner but maybe 6.6K has some mojo with fixed bias, or maybe it was about the higher voltages after the tweed era. Too big it can have too much bass and sound really wrong, or be too clear with buzzy saturation rather than grind.
I would look at the Allen BF Deluxe OTs, he has a couple versions of beefiness <http://www.allenamps.com/parts.php#transformers> I have not had good luck with the bigger Hammond 1600 HiFi OTs in guitar amps but the 1608 might be worth a try along with their BF Deluxe. Careful with the Edcors they are rated like the Hammond 1600s at 20Hz or 30Hz so they are bigger than you might expect, more like a 50W guitar OT, that’s why the 1608 might be a good choice here, it's more like 20W iron. The 30W might be too much transformer. The Edcors sound good but not like other vintage knock off trannies, i.e. it may sound good but not much like an old Marshall. I like them but they are not the best for cloning. The TW Express was made to run 6V6s along w/ EL34 so that would be a good option, a paper wound version might be a littler more vintage sounding maybe Classictone or Mojo Heyboer. All those Express OTs are supposedly copies of a Stancor but from the PA line not their Hifi line so it might not be too much iron and a good choice. There’s a JTM45 RS clone out there with both 8K and 6.6K taps that could work, that OT’s not all that big, like the Express in size. You'll have to decide whether M6 lams or not, always good on a PT, on an OT sometimes it's a good thing, sometimes not. Have fun, collect them all.
BTW you might never plug an other speaker in but for DIY it’s a really good idea to have 4/8/16 taps. You can also mismatch the secs to run EL34 if you like. All the trannies I ever had that got ebay’d or left on the shelf were the single secondary ones. Get something versatile and if you don't like it you can use it in an other build.
Topic: which OT? (Read 4876 times)