Start by swapping op-amps, you can use all the op-amps that are used with Tubescreamers and they can all be found on ebay. Change the pots to mil spec as the replacements have a life of about 5 years.

I use 3 turn pots that let me dial in the tone allot more precise. Free Ecu Flashing Software. Same exact amount of resistance on the eq just it now takes 3 turns from 0-10, I use my ear to more finely dial it in where I want.

I wire the line outs to an American made Iron core transformer that knocks all signals down to 150 ohm. Balanced out and I add the XLR on the back. This makes a world of difference in the amount of hum I get when I use the XLR to go into a DAW.

Those are the beginner mods I have been doing for 20 years on these amps, if you want to move on to pro mods you can change the EQ by varying the pot values and you can always change the filter caps in the power supply section to be on the safe side, since they may be from 1985. The jacks need to be changed on older units and again using the same jacks they used is going to have a very definite life span, I would venture into using some high quality panel mount stuff and mount the pots to the board with wire so you can float the board in the chassis and use any replacement parts you want as opposed to being stuck with specialized PC board mounted NOS parts. I have seen the same pot values used on almost all the amps made and I tend to think they had been chosen on the lines of what the factory had tons of and not what the circuit warranted. Then again I could be a little crazy from playing loud guitar all my life, I am not by any means a trained electronics engineer, I am just a tinkerer. My short list of favorite op-amps: TI MC1458p (The original) LF353n (a higher quality amp that some people like) RC4558p (typcal TS type op-amp but purists want the JRC only. JRC4558p (the original TS-808 amp) I love the RC4558p.

The Marshall Super Lead Model 1959 is a guitar amplifier head made by Marshall. One of the famous Marshall Plexis, it was introduced in 1965 and with its associated 4×12' cabinets gave rise to the 'Marshall stack'. 1.1 Reissues. 2 Technical specifications; 3 Notable early users.

Don't know if that is what you mean, but email and I will explain all the mods that I have done on all teh solid state stuff, when you deal in Solid State it is very lonely and you feel very left out of the tube talk.j/k! The pots on this specific amp are 22k and 4.7K the closest real world pots are 20k and 5k respectively. These are easy as pie to find. Make a decision of what is important to you, as for me keeping original knobs is not important so I can use almost any pot, if you want the exact pot I believe it is a 16mm with a quarter inch post.You can go on ebay and see the exact replacement, it is a pc board pot, I hate these, I use pots I buy from a mil surplus dealer and I solder 3 wires per pot to the board and then the other end to the pot, this lets me use any pot I want. Again it depends on what is important to you.

3 turn pots are just annoying for most people because they want a visual reference of where it is set, I don't care about that, I know the amp well enough to know if it needs more mids or less by ear, but most want a visual ref and 3 turn pots do not have this, it is 3 turns from 0-10 but lets me dial the tone in a little finer. Look up google articles on 808 op-amps and you will find to much info for anyones own use, at 10 cents a piece get as many as you can and switch them out and see the one you like best, for me the differences are in the amount of noise when the amp is set at full throttle, the 353n have less noice the JRC has the best overdrive, the 4558 has the best distortion and so on, just plug and play. If you want to record this sound into a DAW, that is another set of mods, let me know how you do and feel free to email me I am the promoter for the largest guitar builders event in the country in Miami this April, come by and lets talk solid state anytime. Start by swapping op-amps, you can use all the op-amps that are used with Tubescreamers and they can all be found on ebay. Change the pots to mil spec as the replacements have a life of about 5 years. I use 3 turn pots that let me dial in the tone allot more precise.

Same exact amount of resistance on the eq just it now takes 3 turns from 0-10, I use my ear to more finely dial it in where I want. I wire the line outs to an American made Iron core transformer that knocks all signals down to 150 ohm. Balanced out and I add the XLR on the back.

This makes a world of difference in the amount of hum I get when I use the XLR to go into a DAW. Those are the beginner mods I have been doing for 20 years on these amps, if you want to move on to pro mods you can change the EQ by varying the pot values and you can always change the filter caps in the power supply section to be on the safe side, since they may be from 1985.

The jacks need to be changed on older units and again using the same jacks they used is going to have a very definite life span, I would venture into using some high quality panel mount stuff and mount the pots to the board with wire so you can float the board in the chassis and use any replacement parts you want as opposed to being stuck with specialized PC board mounted NOS parts. I have seen the same pot values used on almost all the amps made and I tend to think they had been chosen on the lines of what the factory had tons of and not what the circuit warranted. Then again I could be a little crazy from playing loud guitar all my life, I am not by any means a trained electronics engineer, I am just a tinkerer. My short list of favorite op-amps: TI MC1458p (The original) LF353n (a higher quality amp that some people like) RC4558p (typcal TS type op-amp but purists want the JRC only. JRC4558p (the original TS-808 amp) I love the RC4558p. Don't know if that is what you mean, but email and I will explain all the mods that I have done on all teh solid state stuff, when you deal in Solid State it is very lonely and you feel very left out of the tube talk.j/k! Click to expand.Interesting!

I'm trying to do some work on my Lead 12 Combo and the board closely resembles the board in the center of the three you have (labeled? Old old board). I do not have any line out or headphone jacks and when I look for a schematic, I notice I don't have as many transistors and I have a few additional diodes. There's probably other differences too. My serial number ends in 'P'. Read somewhere this means the amp was built in 1982 (A = 1967, B = 1968.), but other research suggests the 5005 was produced starting in 1985.

Yes, I also have a 1982 serial number Marshall Lead 12, a 10' combo. No output jacks of any kind, two inputs one high one low. And yes, the board is exactly like the one labeled as old board on the post by 5005_Owner. The board is marked as JM73 (?) Quality is above any other Marshall 12 I've seen. Brushed gold metal front, plywood instead of particle board, knobs with fitting screws, handle with brass/gold platted fittings, and the back panels are also plywood covered with tolex, not just painted cheapboard or particle board.

Celestion G10D-25 stamped frame Made in England inside. The words/number Lead 12 are printed larger on the front (it doesn't have any output jacks) and serial number is stamped/engraved on the metal just below them. It has been confirmed as 1982 built by Marshall UK, but they didn't provide any other info. Said that, they offered sending the schematics to a registered repair workshop after it developed a fault in one of the inputs (now solved).

There's a dude in youtube playing one of these: [ame=- Marshall Lead 12 Clean[/ame] So yes, all info pointing out that these started to be built around 1984 is wrong. And the one referred as the 'old' model, could well be this, not the one output vs two outputs later model. It is a wonderful little amp. I had a buddy of mine help me.

He desoldered the existing opamp using some copper braid and soldered in a socket (I ordered the socket off digikey.com). I ordered a couple of other opamps from them too, and the new capacitors. The original opamp actually ended up sounding best, although one of the others (can't remember the model number) had a lot more gain. But that other opamp really just made this amp sound like other solid state amps I've heard, so I am keeping the original opamp in there. Replacing the capacitors seems to have made the sound cleaner at high volumes (that is, less noise--still sounds dirty in a good way!). I can turn the thing up to 10, with gain at 10, and it sounds great. Just need to replace the speaker though (or get a 2-12 or 4-12 cab)--sounds like it could sound a lot better with some better speaker action.

Was planning on going 50 watt. Never heard a JMP in person, I'll have to hit the local pawn shops and see if I can check one out.

This would be my first 'vintage' gear purchase, b c I hate buying old equipment that I'm not very familiar with. I don't know how to recognize mods or other aspects that should be turnoffs about used vintage gear. Just basically looking for a step up from the tsl602 combo we have at the studio, doesn't do much for me. Any other suggestions? Might have to check out the plexi's also. The JCM800 2203 and 2204 are great recording amps.

I'm not a fan of using mine live but for studio work they're damn cool. The 2203 is the 100w version and gives you a great crunch. The 2204 (50w) is nice for getting gain at lower volumes. Both work great for AC/DC style crunch. Both also pair up great with most distortion or overdrive pedals. Now the JMP is a sweet amp. It's full out Marshall sound with a nice sweet twist too it.

It's sounds juicier if that's a good way to put it. If you want straight ahead crunch, go with the 800's. If you want the crunch plus a nice warp to the sound, go with the JMP. As for other Marshalls, I've never been a fan of 900's and I think the TSL is the fuzziest POS I've ever heard. Now the DSL was nice but I didn't try it for long.

As far as the other tube Marshalls, I've had little to no experience with them. Can't go wrong with tracking a JCM800 with a Mesa Dual or Peavey 5150 Block Letter. I have an early 80's JCM800 50 watt 2x12 combo. At first I thought it did not have enough gain, then I figured out how to push it with an overdrive pedal. Then, I started to use it for other tones, semi dirty, clean.

Now, no matter what other rig I try, I always think. I can get this tone, only better with the JCM. Just check one thing, I believe in the later models they used diodes in the preamp to get more gain.

Good idea on the surface, but it made for gritty tones in reality. Better off with a lower gain older model and Tube Screamer type bix infront, if you need the extra juice. Get a Hotplate, use the cabinet simulator in NI Guitar Rig and you have a silent studio amp, with touch senstivity! What I dont like about the JCM 800 is how the tone and the pre amp gain interact.

If you don't use alot of pre amp the JCM is kinda bright. The JMP tone controls act more like the plexi marshall, warmer when the amp is cleaner.those are the same circuits. Maybe age of the components has something to do with it, or maybe those JMP's had some caps clipped (sounds like it - as the pre gain is rolled back more highs pass through). Don't know, but there's no difference amongst 2203 and 2204 circuits until 85, respectively.

If you want the classic JCM800 sound, get a 2204 head. Equally important is the cab choice. You can get the regular JCM800 slant cab that's the 300w version, but for more choices, it'd be nice to have something loaded with Greenbacks or the Vintage 30 speakers. I think I've got the best of everything for the studio, as I took an older cab and have two Greenbacks and two of the Vintage 30s in it. I can mic one of each speaker and use the best or blend the two.

Very cool indeed. If you do run across an older JMP, they're great, but are more expensive and are going to give you more of an older, more vintage marshall sound.

Think Aerosmith 'get your wings' vs. GNR 'Appetive for Destruction' on the JCM series. If you really want a cool studio amp, look for one of the little JCM800 combos like the 4010. It's the 80s JCM 50 watt head in a single 12' combo.

It's great as is for a cool sound, but you can plug into a regular 4x12 cab for that sound as well. The prices are skyrocketing on these so get them while you can. I got mine a few years back and LOVE IT. I sold my 81 2204 and my reissue 1987x.which is the 4 input 50 watt plexi reissue I liked this little combo so much. I never really cared much for the 800 series. They seemed to have a lack of.magic, I guess.

And, the 900? Now, Marshall kept the same model number for the 800 (2203, 2204), but for my money the original 2203/2204's are the way to go. I believe the first master volume Marshall was made in '76 (possibly '75). You want one of those.before they started calling them JCM800. I had a '77 50w 2x12 combo that was absolutely incredible.

I'm still not sure why I sold it. Put some JJ/Tesla EL34's in there and WHOA NELLY! Sweet, sweet tone. If you want a killer Marshall sound, though, you can't beat a 50w Super Lead (model# 1987). Crank it and adjust your gain from your guitar's volume knob. Oh man.now I'm going to have to find me an old Marshall. There is an 80's model called the Artist 3203.

Most 'Artist' Marshalls were designed NOT to distort; they are infamously NON-Marshall. But this model is a little 25-30W head, two channels. The 'clean' channel is almost exactly what the pre-Master volume Marshalls from the 70's sound like. And a LOW-power tube head - perfect for studio. The distorted channel is way too thick - it actually uses some solid state crunch.

Decent, not great. But the 'clean' channel is a REAL monster. I have a 1966 Plexi Marshall and cab, but this little Artist gets used more!!!

Some of my very best guitar tones have come from it. It actually sounds better recorded than it does in person! What I dont like about the JCM 800 is how the tone and the pre amp gain interact. If you don't use alot of pre amp the JCM is kinda bright.

The JMP tone controls act more like the plexi marshall, warmer when the amp is cleaner.I read about the over-bright sound of the JCM 800 from time to time, but I just don't see it. I just bought a 1983 2203 and love the sound. It's glassy, crunchy, pure, rough, pretty much whatever I want to get out of it. Depending on which guitar I use, the tone changes slightly. I'm not sure what is causing the tone issues, but I'm not having any of it. I have a decent collection to compare the JCM 800 sound to.

I have an '86 Mesa Boogie Mark III, a '93 Fender Blues Deluxe, '65 Fender Vibro Champ, 2007 Peavey Penta Head, a new custom point-to-point hand wired 50 watt tube, '76 Fender Bassman 70 and have others over my 40+ years of playing. This Marshall is one of the best, richest sounding amps I've ever played through.