18w JCM800

M Fowler · Post by **M Fowler** » Thu Apr 11, 2013 2:15 am

I built a Matchless Lightning but didn't like it so I gutted that amp, Weber 6MX chassis, Modulus faceplate, kept the Watts 18w Marshall tranny set and choke, and kept the 5AR4 recto.

It's a mess from all the rework plus trying figure out a layout.

Mark

Post by **Colossal** » Thu Apr 11, 2013 2:28 am

Sweet Mark. How do you like it? What values did you go with for the grid leaks in the power section?

M Fowler · Post by **M Fowler** » Thu Apr 11, 2013 2:30 am

Oh crap I went to low 1k5 when I should have used 5k1 at least, I'll change those out. Stock 50w JCM values 220k/220k, 100k/82k, 470/10k tail all these should be changed more to 18w values.

I like it but I haven't had opportunity to drive the shit out of it yet

Bob S · Post by **Bob S** » Thu Apr 11, 2013 2:55 am

Very cool Mark.
Another way to use the 6Mx is born.
Looks good - how's the noise floor with V1 over there next to the input jack?
I'm betting it's quiet.
Well done.

M Fowler · Post by **M Fowler** » Thu Apr 11, 2013 2:59 am

Thanks Bob, not very pretty but I like way better then the Lightning.

Noise is very low for sitting on top of my bench open. I didn't want to do it that way but didn't have much choice. I didn't want to add a can cap between the EL84's not much room so I used the end wall.

I wanted to know if building 18w JCM800's would be worth it, perhaps 6V6 version would be better.

Mark

Reeltarded · Post by **Reeltarded** » Thu Apr 11, 2013 6:16 am

Love!

I like the umm.. patch.

cbass · Post by **cbass** » Thu Apr 11, 2013 11:57 am

Cool diggin the green knobs.

Reeltarded wrote:
I like the umm.. patch.

Its a Pirate amp YARRRR!

How do you make your faceplates?

Reeltarded · Post by **Reeltarded** » Thu Apr 11, 2013 4:59 pm

Me? I walk over to the buffet and usually start with mashed potatos.

M Fowler · Post by **M Fowler** » Thu Apr 11, 2013 7:12 pm

It's a misfit amp for sure and the patch job will have to stay until I get to Lowe's for correct size hole plug

M Fowler · Post by **M Fowler** » Fri Apr 12, 2013 1:59 am

Reeltarded wrote:Me? I walk over to the buffet and usually start with mashed potatos.

M Fowler · Post by **M Fowler** » Mon Aug 05, 2013 4:31 am

Changed to 470k/470k bias resistors and 5k1 grid resisters. Also, using 5AR4 recto to push more voltage that did the trick.

Mark

mark enger · Post by **mark enger** » Mon Aug 05, 2013 9:23 pm

Nice mark, did you make the faceplate? mark

Blackburn · Post by **Blackburn** » Mon Aug 05, 2013 11:03 pm

Cool amp, Mark! I bet yours sounds better than the Friedman.

M Fowler · Post by **M Fowler** » Tue Aug 06, 2013 4:20 pm

Thanks guys, the faceplate was made by Modulus and this amp is cleaner sounding then the Friedman. That Friedman sounded like it gets much more distortion. Hope that helps.

ampmike · Post by **ampmike** » Wed Aug 14, 2013 11:43 am

Nice Mark,Beautiful clean build,What did you use to mount the cap against the sidewall of the chassis.There is a zip tye on it.Looks like a neat way to
use the side wall,Ahh I need more coffee cant articulate yet,Mikey

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18w JCM800

18w JCM800

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Nice