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Clipping diodes modification...on my Marshall


KRAA!!

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I know this isn't the amp forum, but I just did something to my amp that I should have done years ago. I removed the silicon clipping diodes from the circuit in the lead channel of my Marshall JTM-312. I always liked the voicing of the lead channel vs. the clean channel since the clean is way too bright. NOW though the lead channel has very little gain in comparison (a little more than my Epiphone Valve Jr.), and GONE is the grainy fizzy brittle distortion. The amp is quite a bit louder also, and this apparently did nothing to the clean channel at all. I have basically a new amp and ALL the distortion pedals I have sound ridiculously huge through it. Holy {censored}. Has anyone else done this to a Marshall? I'm aware that many new Marshalls have diode clipping like a distortion pedal even though they also have tubes.

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It's only the second time I've had it out in 11 years so I'm not planning on doing it again. Actually you can't miss the clipping diodes. They're labelled on the board to which the preamp tubes are attached. D101 D102 D103 D104 Just clip the wires with scissors or pliers leading to D101 and D102 or D103 and D104. That's it. You're looking for these:

 

1N4148.jpg

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you just left them clipped? thats the rectifier


i would imagine you'd want to put some LEDs in there. i know someone who replaced with leds and it was way clearer with strong mids

 

 

Thanks for the suggestion. LEDs might work well but I think I like using my pedals to add distortion. To unsolder them I'd pretty much have to pull the board out and take apart half of the amp, that would be more effort than it's worth. I kind of did it on a whim and I like how it sounds as is. I basically have two clean channels on the amp now with two different voicings.

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Cool trick I've wanted to try on a JCM900 instead my guitar player sold it and got the 2203 800. BE CERTAIN YOU DISCHARGE THE CAPS FIRST.
:thu:

 

That's actually the main reason I don't want to mess with it any more, just in case I didn't.

 

I'm surprised just how drastic the change was, the lead channel is completely transformed. Is a 900 just an 800 with more gain stages (more or less)?

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