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Here is another mod i came up with. I haven't done the mod yet but will start on a layout today and wire it up soon after.
For this one you have to lose the effects loop (I dont use it) but you gain the ability to jumper the inputs for some marshall (well fender actually) magic. Here is the schemo.
Enjoy Johno

Looks like the classic Superlead Plexi circuit, should sound good......

Ok its all done now. Sounds heaps better and more versatile than it ever was.
It took some time to get the layout done but it came out good I think. No mods to the original board are necessary. R37 on the vht schematic needs to be removed from grid to ground on the output tube.
I put the pre amp volumes on the face of the amp where the original volumes were. The master is on the back (that sucks a bit) where the footswitch jack was, input's A for both channels are on the face of the amp where the originals were. Inputs B are on the back in the holes where the effect send and return were so i can just jumper those two inputs with a patch cable. I had to put the mid pot on the back where the line out was. No need to drill any new holes in the chassis.
Anyways heres the layout, resistor and cap values correspond with the VHT schematic
Shit just realized I didn't get all the resistor and cap numbers right. Opp's
Rock on, Johno

Just a quick update. I moved all 4 inputs to the back of the amp into where the effects, line and footswitch were. The pre gains, master and Eq knobs are all on the face of the amp. Still no need to drill any hole in the chassis.
The sound? Fucking amazing. It really nails those classic marshall sounds from the 70's when it's cranked.

JOHNO wrote: ↑11 Jun 2014, 04:17 Just a quick update. I moved all 4 inputs to the back of the amp into where the effects, line and footswitch were. The pre gains, master and Eq knobs are all on the face of the amp. Still no need to drill any hole in the chassis.
The sound? Fucking amazing. It really nails those classic marshall sounds from the 70's when it's cranked.

I'm looking for exactly this to use on my jcm800, do you have any videos, is it working correctly?

andregarcia57 wrote: ↑18 Apr 2022, 19:33

JOHNO wrote: ↑11 Jun 2014, 04:17 Just a quick update. I moved all 4 inputs to the back of the amp into where the effects, line and footswitch were. The pre gains, master and Eq knobs are all on the face of the amp. Still no need to drill any hole in the chassis.
The sound? Fucking amazing. It really nails those classic marshall sounds from the 70's when it's cranked.

I'm looking for exactly this to use on my jcm800, do you have any videos, is it working correctly?

I know jcm800's used to be less than $300 all day long. Before you mod it, check to see if that is the case