Marshall jtm45 OT choice. (Edited title)

[dragonbat13]

Its time to put a marshall in the stable. I want to build a rather authentic jtm with kt66 tubes. I see a discussion between 8k and 6.6k primary OT. I want to use a standard 4 ohm can or whatever the amp would have used in its time. Only a half stack though.

I saw this transformer
https://www.mojotone.com/British-Style- ... ransformer

Gives the el84 option too. Is it any good?

This one's for blues and blues rock.

Any ideas on this or another transformer?

Really don't want to pay the mercury magnetics/NOS prices but will if it's worth it.

[Roe]

I dont like the 8k too much. the 6k6 is more powerful and has better bass, esp if you use 450-465v on the plates. The best replica transformers are generally believed to be marstran and merren but mojo is usually good too. In any case, the radiospares deluxe transformers are not intended for a 4/8/16 ohms switch

[pdf64]

I dont like the 8k too much. the 6k6 is more powerful and has better bass, esp if you use 450-465v on the plates. The best replica transformers are generally believed to be marstran and merren but mojo is usually good too…

I don’t like the linked OT.
It seems a crass misrepresentation to note the primary impedance as 3k4 or 6k8, without noting that the -3dB lower corner frequency will be moved up an octave in the 6k8 arrangement.
Mojo don’t seem to employ people with EE competence to review this sort of stuff.

[dragonbat13]

Would it be worth it for the extra coin for a mercury, or even a NOS?

I plan on doing this one "period correct". At least using the parts that attribute to the tone. It would be a nice challenge hunting down the parts.

[Roe]

Would it be worth it for the extra coin for a mercury, or even a NOS?

I plan on doing this one "period correct". At least using the parts that attribute to the tone. It would be a nice challenge hunting down the parts.

no not mercury. NOS is unobtainable

[martin manning]

Would it be worth it for the extra coin for a mercury, or even a NOS?
I plan on doing this one "period correct". At least using the parts that attribute to the tone. It would be a nice challenge hunting down the parts.

If that's your goal, I would contact Marstran about a JTM45 set. I believe Heyboer makes those, as well as many of the transformers Mojo sells.

[dragonbat13]

I just sent an email to marstran.

This is the info I have gathered this far. For what I want I believe I want to clone an amp that used the kt66/8k output primary.

The info, is it correct?
Use a 8k primary output transformer with kt66 tubes

784-128 output transformer is for el34 in the jtm 45/50 or jtm50 (3.5k to 4k primary)
784-103 output transformer is for the kt66 amps.(8k primary)

The 128 makes it a 67 jtm50 or 45/50. The first el34 amps had jtm45 faceplates

November of 1965 to mid 1967 jtm 45 used the 784-103 output transformer.