Need advice for simple JTM 45 mod to make amp more balanced

Moshaholic

New member
Hi All!

I have a JTM 45 reissue that I only want to use for a pedal platform amp period. All dirt tones coming from pedals and no where else.

The amp is somewhat working out for me for what I want to do and I get the whole Marshall plexi thing. I also get the whole "jump the channels together" and all...

But to my ears it's like jumping a bees nest to a wad of mud and trying to mix both together to balance it all out.

Unfortunately jumping the channels in different ways, trying different inputs, etc does not give me the exact desired effect for a "smooth and balanced canvas" for a pedal platform to my ears.

Is there a simple way to mod the amp so one (or both channels) can just sound "NORMAL"...??? By NORMAL I mean no extreme BEE HIVE and NO extreme muddy, ear fatiguing bassy low-mid darknesss...

It's like the channels are really extreme in opposite directions and I just really want a more balanced tone what you EQ on the amp can run dirt pedals through and then still get a great CLEAN tone when you bypass the dirt pedals...

I not scared of a solder iron per say, but If I cant do this mod myself or it is too complicated I am willing to PAY someone who is experienced to take care of this for me.

Also I have read that when you turn up the bright channel volume to 10 the bright cap goes away...? Is this the same as just removing the bright cap altogether and the bright cap will be gone at all/lower volumes?

THANKS!
 
For the bass problem, some of the caps are probably too big. the 330uF/25V V1 cathode bypass or the .1 output tube coupling caps. You could replace with 25uF/25V or smaller and .022 output coupling caps for less bass response. The harsh treble could be from 500pF caps on the volume pots or grid resistors to V2. Or from a .0022 coupling cap on the 1st stage. You can omit the 500p and swap .0022 for .022. Experiment with the cathode resistor values in the preamp as well.

The only way to your goal is swap and listen. Over and over. I personally like the trebley caps and blending channels.

Some people refuse to roll back the tone controls. Sometimes the gain and treble need to be at 5 and bass at 2.
 
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