How hard is to convert a JTM45/100 Metro 66 specs into a 67?

[Kazhi]

Can it be done and how hard is it?

[mightymike]

I'm not sure if there's a huge difference in the 66 2" Jtm45/100 OT and the Black flag 67 2" OT, but If you're looking to convert it to Black Flag/ 10000 series/67 spec, you could start by converting to EL34 by changing the bias range resister to get into the right range. The difference in PT is a different story. The original 66 had a 550v pt, ( The PT I bought from George for my JTM 45/100 kit was 500v) I can't remember what the typical Black Flag / 10000 series plate voltage is, but 500 will just be a little high..Other than that the values are pretty close. Just a different layout mostly. I say just change the bias range resister, put some El 34's that will handle 500v and see if you like it.

[mightymike]

Maybe someone in the know on the OT impedences, and any differences, can chime in

[waggclan]

I don't believe it involves changing the iron. Investigate an then change out some cap and resistor values. Your current PT and OT should get you there.

[Big Mike]

It absolutely needs a different OT unless you want to compensate and mismatch impedance.
And ditto mike on the power trans voltage.
Sorry Steve...

[Roe]

for early 67 you only need a 1202-119 Ot and 4xel34