# how much does this mod normally cost?



## Budda (May 29, 2007)

I have a stock Canadian JCM800 2203. My bandmate has a similar 2203, only he runs 6550's. I'm thinking about doing this mod in future, and I'm wondering what the fine folks here would deem a reasonable price for the mod? We play loud and clean - his volume is on 5, mine is nearly on 8.

Thanks!'


----------



## jb welder (Sep 14, 2010)

Basically just a few resistor changes and bias adjustment. They may also want to do routine clean & check-up. I would guess a couple bucks for resistors, an hour to 90 minutes labour charge, plus the 6550's.

But I wouldn't go by how the volume knobs are sitting. Crank them both up till they start to distort. Is the other amp still significantly louder?


----------



## JCM50 (Oct 5, 2011)

The instructions for doing the mod can be found here:
http://www.lydian.ca/Marshall_Misc.html

Pretty simple but frankly, EL34s sound best in the 2203 IMO. 
Count approx 1 hour of labour + the parts.


----------



## jb welder (Sep 14, 2010)

JCM50 said:


> The instructions for doing the mod can be found here:
> http://www.lydian.ca/Marshall_Misc.html


That is for converting to 5881/6L6. He wants to go to 6550.
There is a nice writeup with pics here (just in reverse): http://www.marshallheads.com/viewtopic.php?f=32&t=346
You want to change _to_ the US version parts. In the text he talks about the feedback wire, you could try it either way, or see which way it is on the other amp and change accordingly.
The one resistor he ignored I would also change: shown above the bias pot in the schematic, next to the lower "grid leak resistor", and appearing below the bias pot in the photo.
So, the "grid leak resistors" become 150K, the "bias range resistor" becomes 15K, and the resistor connected to the bias pot becomes 47K.


----------



## Disbeat (Jul 30, 2011)

Do you run ever run through the low input?
I have a 1976 JMP 2203 and with the low input you get loads of clean headroom in my opinion.
Just a thought anyways.


----------



## Budda (May 29, 2007)

Disbeat said:


> Do you run ever run through the low input?
> I have a 1976 JMP 2203 and with the low input you get loads of clean headroom in my opinion.
> Just a thought anyways.


It's clean, but quieter. My gain is set at the edge of breakup, his is clean. I think its basically a 200W amp vs. A 100W amp at this point. He's clean and a lower volume whereas I'm cranked and trying to stay clean. I figured the tubes would be the big expense.

That said, i have a friend in town with a modded 2203(?) 112 and its so damn loud. But he doesnt know exactly what mods were done.


----------



## Disbeat (Jul 30, 2011)

Yea your right it definitely is quieter. 
The 6550's is probably your best choice then to keep up for sure, like the others said not a super involved or expensive mod either.
You could just trump him and pick up a Marshall Major though haha


----------



## Budda (May 29, 2007)

If I had the scratch haha. But i just had a flight case made, so this amp stays!


----------

