1980 Marshall JMP 2203 - Stock or Mods?

Troy T. Blues

Comstock Station
Messages
2,523
Hi guys,

Not too long ago I acquired this amp from a good friend of mine and it came with these Tone Lizard Mods:

Tales From The Tone Lounge; The Ultimate JCM800?

Since I got the amp, I got a cap job (F&T) and retubed it, but I left with the mods. I was gonna have my tech undo the mods, but I liked the tone and figured I'd leave it alone at that point. Now my curiosity has piqued and I've decided to go through with it. If I don't like it stock, we can always go back. When my tech had it last, he said that three of the four mods were done...#4 is stock I think. It was also converted to EL34's. So, I am curious if anybody has any experience with these mods vs. stock in a 2203 or similar amp. Any thoughts?

I am looking at various schematics and I think this one would be the correct one to reference for the stock values right? Marshall JCM800 Master Volume M2203 100W Schematic - KBapps.com

Any comments would be appreciated. Thank You! :)
 
Last edited:

sickboy79

Member
Messages
13,068
I've heard the Tone Lizard mods do sound great but, I've never personally heard them. That said - I've got a super 1979 JMP 2204 50w head that us just awesome! Just right stock - except I did have her converted to EL34s. To me - Marshalls are EL34s. Nothing wrong with 6550s - just not for me. Too much headroom, and a bit hard to my ears when overdriven. A JMP w/EL34s just gets a wonderful warm crunch going when you push it.

Hope it helps a bit.
 

Chevyvan

Member
Messages
369
I use exactly the same amp, an 1980 JMP2203 with EL34's completely stock and it sounds amazing. It sounds woody and thick and has more than enough gain for me.

To me it works best just to crank the preamp knob, set your master and eq and use the volume on your guitar to clean it up.
Lowering the preamp knob results in thinner tone and I didn't get good results with clipping that bright cap...and it also seemed to affect my overall sound with the knob on full and although it was very slightly changed....I put the cap back en Oh Yeah Baby...I will never mod this thing!!! This thing eats every boutique amp that comes near!
 

GrecoVee

Member
Messages
880
Hi guys,

Not too long ago I acquired this amp from a good friend of mine and it came with these Tone Lizard Mods:

Tales From The Tone Lounge; The Ultimate JCM800?

Since I got the amp, I got a cap job (F&T) and retubed it, but I left with the mods. I was gonna have my tech undo the mods, but I liked the tone and figured I'd leave it alone at that point. Now my curiosity has piqued and I've decided to go through with it. If I don't like it stock, we can always go back. When my tech had it last, he said that three of the four mods were done...#4 is stock I think. It was also converted to EL34's. So, I am curious if anybody has any experience with these mods vs. stock in a 2203 or similar amp. Any thoughts?

I am looking at various schematics and I think this one would be the correct one to reference for the stock values right? Marshall JCM800 Master Volume M2203 100W Schematic - KBapps.com

Any comments would be appreciated. Thank You! :)
I have a`77 JMP 2204 (50 watt) that I had my amp tech do some of the Tone Lizard mods to and it was definatly an improvement in tone! I know he boosted the low end to the max recommended on the site and bumped up the tone stack in the midrange area. He also at first changed the gain to almost the maximum but I ended up taking it back to him to reduce it some. That was all it took to "improve on" the tone of an already great sounding amp. Definally worth having these mods done and they are very easily reversiable.
 

Rex Nomad

Member
Messages
584
I have a few 2203 heads and have done all kinds of mods to them. I like some of the Tone Lizard mods. I did not like the 68k for the treble peaking circuit (#1 in his picture). I do like cutting or reducing the bright cap. I use 150pf on one and it's cut out completely on the others. Reducing the cathode to 4k7 works for me too. The rest of the mods I didn't care for.

One mod that I don't think he mentions that I really like is to reduce the negative feedback resistor from 100k down to 68-75K. To my ear this really sweetens up the amp. You get a bit more low end response and the highs are a little softer. The best thing would be to make that resistor a pot and be able to vary it. I haven't tried that yet but it's on my list.

The other important mod for a 2203 isn't a mod at all - it's getting the right speakers for your cab. My experience is that a little bit warmer sounding speakers work better with this head. But that's a whole other conversation.
 

Chevyvan

Member
Messages
369
Great info, thank you Chevyvan! :aok
Thanks Troy T. Blues. Thing is, you got a great amp there and like Rex said....speakers...very important.
For me the head seems to work awesome in conjunction with either greenbacks (25 watts, uk from around '95), marshalls Vintage 30's and Boogie's Vintage 30's. I also found that the combination of a Koch cabinet filled with Jensen 90 watt speakers was really great.

I didn't like it with EV and Alnico's like the Blue Bulldog and the Gold.

Taste...it's all about personal taste.

Use your ears to find the sweet spot and stick to it. :)
 
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lespaul6

Senior Member
Messages
1,334
I have a few 2203 heads and have done all kinds of mods to them. I like some of the Tone Lizard mods. I did not like the 68k for the treble peaking circuit (#1 in his picture). I do like cutting or reducing the bright cap. I use 150pf on one and it's cut out completely on the others. Reducing the cathode to 4k7 works for me too. The rest of the mods I didn't care for.

One mod that I don't think he mentions that I really like is to reduce the negative feedback resistor from 100k down to 68-75K. To my ear this really sweetens up the amp. You get a bit more low end response and the highs are a little softer. The best thing would be to make that resistor a pot and be able to vary it. I haven't tried that yet but it's on my list.

The other important mod for a 2203 isn't a mod at all - it's getting the right speakers for your cab. My experience is that a little bit warmer sounding speakers work better with this head. But that's a whole other conversation.
this...

Just mod it for el-34's and undo everything that was done to "tame the brightness"...why anyone would want to throw a blanket over a marshall and call it tone is beyond me!!! also, I would take out all that gain building crap and keep it stock...just use a boss sd 1 or a tube screamer if you need more gain. just my humble opinion
 

Troy T. Blues

Comstock Station
Messages
2,523
this...

Just mod it for el-34's and undo everything that was done to "tame the brightness"...why anyone would want to throw a blanket over a marshall and call it tone is beyond me!!! also, I would take out all that gain building crap and keep it stock...just use a boss sd 1 or a tube screamer if you need more gain. just my humble opinion
Right on. This was my goal, especially since I've never heard the amp stock before. I've listened to some other stock 2203's via clips or YouTube and I like what I've heard. I don't have a problem with using an OD pedal for more gain and I like that versatility. I just want the amp to sound it's best and I would like to hear the amp in it's stock form to ultimately decide.

Right now I'm using an early JCM800 1936 2x12 Cab (ca. '82 first version, shallow depth) with '96 UK Vintage 30's.
 

lespaul6

Senior Member
Messages
1,334
Yes, I use vintage 30's as well...love those speakers! I also run my master volume at about 4 or 5 so it is loud with plenty of push back and kerrang factor! With the SD 1 off and a strat I get a good SRV/ David Bowie China Girl guitar solo tone..with the sd 1 engaged with a humbucker I get whitesnake!!
 

Troy T. Blues

Comstock Station
Messages
2,523
Yes, I use vintage 30's as well...love those speakers! I also run my master volume at about 4 or 5 so it is loud with plenty of push back and kerrang factor! With the SD 1 off and a strat I get a good SRV/ David Bowie China Girl guitar solo tone..with the sd 1 engaged with a humbucker I get whitesnake!!
:aok

Bump :)
 

panhead5

Gold Supporting Member
Messages
425
Ok --I 'm jumpimg in here.I spent several hours yesterday with my MV JMP and 800 and ran them through 8 different Marshall and Bogner cabinets I own.They all sounded good but my hands down favorite was the Bogner OS 2x12 with Vintage 30's.I think I'm posting this out of guilt due to the fact I liked them better than my Greenbacks ,65's and G12H30's.

Now if I could play like the dudes from whitesnake .....
 

Troy T. Blues

Comstock Station
Messages
2,523
Ok --I 'm jumpimg in here.I spent several hours yesterday with my MV JMP and 800 and ran them through 8 different Marshall and Bogner cabinets I own.They all sounded good but my hands down favorite was the Bogner OS 2x12 with Vintage 30's.I think I'm posting this out of guilt due to the fact I liked them better than my Greenbacks ,65's and G12H30's.

Now if I could play like the dudes from whitesnake .....
Ha! Cool! Thanks for posting.
 

GrecoVee

Member
Messages
880
Cool Greco, thanks. What do feel was the greatest improvement?
I would say a fatter and more Low end is what I noticed the most, there seems to be more of an overall thickness to the midrange as well.
Isn't a vast amount of more gain on tap, I still use a Tubescreamer to boost it but I don't have to crank up the pedal as much but like I said, if you have the gain mods done to the max or almost the max, the amp gain sounds like crap, it's too much. Just have the gain mods (mostly resistor values) increased a little at a time. I think I actually took the amp to my tech three times to get the gain where I liked it without it sounding to mushy. Also go with having the brite cap clipped, it will sound better for when you're playing at lower volumes.
 

Troy T. Blues

Comstock Station
Messages
2,523
Thanks again Greco. Yup, mine sounds like that (thickness) and at times, I most think it's almost too much. We'll see....I plan to have it brought back to stock values this week.
 

Griz

Member
Messages
2,834
It might be just sentimental on my part, but the sound of a stock 2203 with the master opened up a bit...

:aok:love:

It's a wonderful thing.

Enjoy the amp.
 

Troy T. Blues

Comstock Station
Messages
2,523
It might be just sentimental on my part, but the sound of a stock 2203 with the master opened up a bit...

:aok:love:

It's a wonderful thing.

Enjoy the amp.
I bet! What is your usual master and pre-amp settings? With the mods, my rhythm drive is master at 4ish and preamp at 5-6.
 




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