New JTM45 amp w RS trannies. Ideas?

[johan]

Hi there

A friend of mine built this JTM45 for me ( great friend huh?). Ceriatone chassis and parts with trannies from Marstran and Sozo vintage caps. I choose the Radio Spares transformers years ago based on some posts here more or less. Udo Pippers clips comes to mind. This amp has been in the works for years but now it's here.
So far so good. Sounds great. Loud ! Need to check the preamp tubes. It started to crack after some time. I have some old Mullards of unknown history in it. I'll use the amp with a closed back 212 cab w Scumback M75s

I've read some posts about mismatch transformer/speaker pairings, lead, PA and bass version etc.
With the RS transformers and the Udo clips in mind how would you set it up?
Ill have another friend over who knows what he's doing so who knows how it will end...
Any tips, tricks and recommendations are welcome? Or do YOU think this is the best set up me?

Lots more pics here
http://s279.photobucket.com/user/johanare/library/JTM45

[johan]

Found this info somewhere on this forum on th Udo amp. What's your opinion??

Note, that it has 1.5K screen grid resistors (for what Udo has decided for) and a common 1K screen pre resistor.
(1.5k at "2w" CC) - mix resistors 270k - PA specs.
removed the bright cap from vol 1, and removed the cap from the channel 1 mixer resistor

No cap across the mixer resistors, no cap on the Volumes!
http://www.larry-amplification.de/pixs/ ... 5-PA.2.jpg
http://www.larry-amplification.de/pixs/ ... 5-PA.1.jpg
http://www.marstran.com/RS%20OT%20wiring%20diagram.gif
http://marstran.com/JTM45.gif

The amp he's used was a '66 Marshall JTM45 PA-model with the RS Deluxe OT and still with the original GEC KT66 and Brimar ECC83 tubes in. PA-model means: No cap across the mixer resistors, which were 270K's

If you don't have GEC's kt66 use some 10k stoppers, they must be CC also. Try some Shuguang 11th gen kt66's
Tunsgram 12ax7 in V1 (early 70's) AND don't forget if those are NOS you must burn them in a good 20hrs before they really honks Same in V2 or a solid Ge, RCA, etc.. Tele Smooth plate in V3 is a huge plus also

You'll get that honk that way

The 10k are stoppers, they make the amp warmer and more stable, if your 5.6k are ok then leave it the way it is. 10k there will make your modern tubes sound a little more like the real thing...