New OT...

[909one]

So I had a problem with my Ceriatone 5e7 Bandmaster Clone having a huge volume drop. Some of you suggested it might be a blown OT. I had my friend check over the amp with a scope and we determined that was the cause. I ordered a new OT from Mercury Magnetics, put the tranny in and voila... it works!

I used the amp for the first time at practice yesterday and it sounds better with MM OT. The highs are much clearer, the mids are not as muddy, and the bass is not as flabby.

BUT, here's the problem... the headroom is now lower. Ceriatone must have been using an OT that has a little more output, and most likely the MM is closer to vintage specs. I unfortunately already cut the lead wires to transformer, so I can't return the transformer for something bigger, like a Bassman transformer.

I am thinking of trying the Paul C phase invertor mod. Anyone with experience on this?

Also, can I safely put a different rectifier tube in there to help increase headroom? Right now its a 5u4.

Any other ideas for suggestions to improve headroom at all?

[BP-Plickner]

The size of the OT transformer is real important for headroom. The 5e7 I built with a bassman OT is pretty loud and clean but breaks up earlier than a 5f6a bassman. It uses an GZ37 rectifier that runs about 430 volts on the plates of the 6l6 tubes. The GZ37 has a little less of a voltage drop than a 5U4 which equates to a little higher plate voltage
There is a mod that changes the PI to a long tail. But a big part of the sound of that amp is the phase inverter which I think is a split load phase inverter that uses 1/2 of the tube as opposed to both half's in a long tailed PI.

Here's a brief link on the subject
http://www.tdpri.com/forum/telecaster-discussion-forum/111870-5e7-bandmaster-questions.html

[Walter Broes]

Hey, that was me in that TDPRI thread, asking the question. Mine now has a SR output transformer, and I'm very happy with it.

[BP-Plickner]

:band:BEER
Cool!