Jcm 900 extreme mod

[covil]

Finally decided to do something to my Jcm 900!! Sorry for shitty riff and shitty sound!
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[covil]

Sorry but the legends are in portuguese and clip only starts near the end.

 

[AllanD]

Sounds good! Which model is this? Also I wish there were before the mod clips!

 

[covil]

Just a regular Jcm 900 4100 with 6L6gc pwer tubes!! The sound of the amp wasn´t very good probably the worst amp Marshall made!! Most of the sound was from transistors!! The valves weren´t doing very much!

 

[covil]

So decided to strip it all apart and built a new preamp section with an extra preamp tube!

 

[dfer]

So decided to strip it all apart and built a new preamp section with an extra preamp tube!

What kind of tone stack did you go for? Info on the preamp circuit? I assume the extra pre tubes a EEC83..... yeah?

 

[covil]

It´s a marshall based eq, like most amps do, with an extra knob for the range, just like a krank. The preamp section is based on nothing in particular. Just built it first with no highpass and no lowpass in any stage and went from there!!

 

[covil]

Some of the stages ended up having litlle or now low end at all!! Definitly it´s not a mesa preamp based! More like an Engl or 5150 style of preamp.

 

[kaomao]

sounds good