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Old 01-21-2013, 01:43 AM   #21
T7E
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Quote:
Originally Posted by 311ZOSOVHJH
This is what I don't get.

You say Mastodon tone is attainable with a Marshall Plexi but then you say 'run a suitable distortion pedal'

That doesn't count.

Anyone can run a distortion pedal to sound heavier. Most (lots) of people are more interested in attaining their tone with the amp.

The TS is asking if you can do Mastodon on a Plexi.

I can barely get there on my Splawn. I wouldn't want to be sitting there with just a Plexi.




Ok i get it.

Is the mastodon tone available on a plexi with no pedals or anything?
No
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Old 01-21-2013, 02:22 AM   #22
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A JCM800 is basically a modded plexi. You take the two triodes in V1 and wire them in series instead of breaking them up into two input buffers (or jumpering them in parallel). Add a master volume before the phase inverter and you're done.
Any half decent tech can do it for you, most will mount the master volume pot into one of the input plug's holes. Once you've done the mod you can't jumper the inputs any more so two of the inputs become obsolete.
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Old 01-21-2013, 02:31 AM   #23
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Quote:
Originally Posted by Cathbard
A JCM800 is basically a modded plexi. You take the two triodes in V1 and wire them in series instead of breaking them up into two input buffers (or jumpering them in parallel). Add a master volume before the phase inverter and you're done.
Any half decent tech can do it for you, most will mount the master volume pot into one of the input plug's holes. Once you've done the mod you can't jumper the inputs any more so two of the inputs become obsolete.


It's a little more complex than that, Cath. That's just the "one-wire" mod, but it sounds like shit due to stupid amounts of gain in so few stages. It really needs to be tweaked fairly heavily to sound any good, especially at lower volumes. I modded one of the PCB RIs 2-3 months back for a buddy. Wound up taking quite a few further mods, which wound up being a total PITA with the shit PCB design.
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Old 01-21-2013, 02:39 AM   #24
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You just shove a second gain knob to wash off some of the gain in the other input hole.
And **** lower volumes, it's a plexi.

If you want to do it right just add the components between V1a and V1b that are in the 800.
http://www.drtube.com/schematics/marshall/jcm800pr.gif
The bottom circuit of course.
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Last edited by Cathbard : 01-21-2013 at 02:50 AM.
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