Which OT for kt66 in jcm800

phil · Post by **phil** » Wed Nov 22, 2006 5:12 am

Hi! I've been a reader of this forum for almost half a year now and I really love it, so here is my first post:

I have a jcm800 4010 combo (1x12, 50w) from 1982 and recently changed from el34 to a pair of Ruby kt66 output tubes. There was definitly an improvement in tone but I read everywhere that you would have to change the output tranny to really let the kt66s shine (to a model with 8k primary impedance, if I remember it right).
Is it possible to just put in, let's say a MM radiospares model or do I have to perform other mods too?

For those who are interested: OT and PT are stock (drakes), the circuit is very similar to a 2204 head (a small mod was done on my amp for more gain), the plate voltage is 345V with the mains on 240V and the measured power of the amp is 43W at 1kHz. I biased the tubes to about 45 milamps.
I always use the low input to get an edgy clean tone and use a ZVEX Box of Rock as main distortion unit.

robert · Post by **robert** » Wed Nov 22, 2006 5:57 am

Hi phi,

order this one from Brian Wallace:

http://marstran.com/JTM45%20Output%20Transformer.htm

Regards

Robert

phil · Post by **phil** » Wed Nov 22, 2006 9:03 am

robert wrote:Hi phi,

order this one from Brian Wallace:

http://marstran.com/JTM45%20Output%20Transformer.htm

Regards

Robert

Should I worry about the Power Rating (30W) of this OT?