Troubleshooting Tone on a 78 JMP 2203

[Joey Voltage]

Any internal modifications to put that thing in or is all you need the adapter?

No, It's plug n' play, but it only sounded good with particular amps although thats subjective of course. it was designed primarily for use with 2203/4's and 1987/59's, and you can only use it in amps that run 6.3V heaters. They can be hard to come by too (the socket that is)

 

[Lucky]

Right you are sir, although Mr. Wilder hit it right, it is a NOS 6K11 that was what I got with it.

 

[Lucky]

I bought this off of e-bay many years ago...Lets just say that now I run the preamp on about 5 or so and it has a little more gain than if I was to run it on 10 with a regular 12AX7

 

[Joey Voltage]

Right you are sir, although Mr. Wilder hit it right, it is a NOS 6K11 that was what I got with it.

The two are interchangeable, I just like busting Jons nuts a little. A lot of them were shipped with 6c10's. which will give you more gain.

the difference between the two is that the 6K11 has a lower mu triode as triode 1, has a amplification between a 12Au7, and a 12AY7 IIRC about maximum of 17 (which you will never get out of it), and the other two bottles are 12AX7 types with a higher Mu. the 6c10 has all 12ax7 like triodes

 

[Lucky]

Ahhh! Busting his balls huh! Although, I thought the SLO comment was funny! Thanks for telling me that, I never knew about the 6C10, when I got this it was shipped with a 6K11. So I ordered a NOS 6K11, now I will order a 6C10 and see what the difference is...

 

[Joey Voltage]

Ahhh! Busting his balls huh! Although, I thought the SLO comment was funny! Thanks for telling me that, I never knew about the 6C10, when I got this it was shipped with a 6K11. So I ordered a NOS 6K11, now I will order a 6C10 and see what the difference is...

http://www.schematicheaven.com/newamps/soldano_hot-mod.pdf

 

[Jonathan Wilder]

I just like busting Jons nuts.

So now the truth comes out...:eek2::eek2::eek2:

 

[krokit]

Well the only thing your original OT would've been needed for was to have MM wind you an EXACT DUPLICATE of the amp's original OT. Since transformers were fairly inconsistent back then this ideally would've allowed them to exactly copy the exact transformer that came out of your amp.

However, all hope is not lost. Mercury's transformer upgrades for your amp are copied from transformers that came out of some of the absolute best sounding vintage Marshalls. They went through a whole pile of Marshalls until they found the ones that had THE tone, and copied the transformers from those models.

I just checked their site and it looks like they make a "Late 70s higher gain" model, which is what your JMP 2203 would effectively be. I will call MM tomorrow and ask them exactly which one they would recommend for your amp.

Also, if you order from me I can get it to you a little cheaper than what MM will sell it to you for as well.

Just wondering if you found out what replacement output transformer is recommended for a 78 2203?

Cheers