Marshall Artist 3203 Mods

[Marshall Man]

I have a 87 3203 that I did the traditional C13 mod and it really helped the clean channel out a lot as it takes pedals much better and is not so harsh. Anyone know about additional mods for the clean or boost channels? I'm wondering about the 4 red LEDs, what are they used for? Thanks.

[stump]

The LED's are the diode clipping section of the lead channel I believe.

[Steve Ouimette]

I'm about to embark on some mods with my tech later this week on my 4203. When I go through it and see what changes make a good difference I'll be sure to post here. Should be fun...amp already sounds really good on the gain channel but the clean is pretty lifeless.

[rastaman]

Great amp, I had one for quite a while and AB'd it with an amp that had a good clean sound. I loved that dirty channel. I did the C13 mod but never anything else and I finally got rid of it. Good luck.

[dughaze]

After owning two of them, my theory is that the lead channel is the cats meow with a good speaker cab, some overdrive, and roll back the volume for some warm and gritty cleans. It's in the JCM800 family, who buys a JCM800 for good cleans? An overdrive will thicken up the clean channel also if one must go there.

[Marshall Man]

The cleans are now really good with the C13 mod and takes pedals well. The overdrive is thick and dark and does not come on until about 8 on the dial. I was just wondering if there were any mods to the overdrive channel to tighten it up etc. since it is a SS pre section. Additionally, this amp runs totally cold as there is no bias pot. I tried several pairs of EL-34's before I finally found a set that gets somewhat close. Anyone know where the bias resister is so I can put in a pot?

[nickyjoe]

It was my first Grab And Go... It was "almost close" to having a special kind of tone. Good luck on the mods. There's a petty good grab and go amp...not quite what one would expect for 30w.

[Steve Ouimette]

Just back from doing the mods and this thing is now a total fire breather! The clean channel isn't great even with the C13 mod but it sounds like a rolled-back Marshall gain channel. That's OK because as Dughaze mentioned, who buys a Marshall for cleans!?

As for what we did, here's a list.
1. Changed out all of the 3 op amps to different ones. I need to get the # on the ones I chose but now there are op-amp sockets in place so they can easily be swapped out.
2. Added a Presence control. Removed the Line-Out on the back (useless to me) and out a 25K pot in place. Killer!
3. Added a trimmer pot to the Gain channel for more drive. Now the amp has the ability to tap into more distortion and thus becoming a fire breather.
4. C13 cap lifted. This helps but still not loving the cleans.
5. Put a trimmer pot on clean side to back down the added gain from the Gain channel (they work together).

6. Changed the slope resistor. Again, need to get the value of the new one but that tightened up the bass.

The Op Amp change was phenomenal. Since all 3 were swapped out we could listen for the changes or keep it stock. I tended to like one particular op amp that gave a tighter bottom end, more width, more clarity and better definition. The standard ones weren't bad but once you start playing with it the changes are obvious.

The presence circuit makes it a real Marshall to me and also really opened up the sound. Because the Gain channel only has a tone knob sometimes it was too bright when cranked but too dull in the position that sounded the thickest. Presence circuit nailed it.

For a $300 amp and a few bucks in parts and tech time the amp is a solid contender for any budget. It has way more gain than an 800 but still sounds like one. If I had my eyes closed I'd think this was a Marshall but would wonder which one or who modded it because it retained all of the character of a great Marshall but still doesn't sound like a boutique copy.

Let me get the specifics and I'll post them. Also will be doing some clips soon. This has been the coolest experience modding an amp for me in a long time.

[Rupe]

Originally Posted by Steve Ouimette

Just back from doing the mods and this thing is now a total fire breather! The clean channel isn't great even with the C13 mod but it sounds like a rolled-back Marshall gain channel. That's OK because as Dughaze mentioned, who buys a Marshall for cleans!?

As for what we did, here's a list.
1. Changed out all of the 3 op amps to different ones. I need to get the # on the ones I chose but now there are op-amp sockets in place so they can easily be swapped out.
2. Added a Presence control. Removed the Line-Out on the back (useless to me) and out a 25K pot in place. Killer!
3. Added a trimmer pot to the Gain channel for more drive. Now the amp has the ability to tap into more distortion and thus becoming a fire breather.
4. C13 cap lifted. This helps but still not loving the cleans.
5. Put a trimmer pot on clean side to back down the added gain from the Gain channel (they work together).

6. Changed the slope resistor. Again, need to get the value of the new one but that tightened up the bass.

The Op Amp change was phenomenal. Since all 3 were swapped out we could listen for the changes or keep it stock. I tended to like one particular op amp that gave a tighter bottom end, more width, more clarity and better definition. The standard ones weren't bad but once you start playing with it the changes are obvious.

The presence circuit makes it a real Marshall to me and also really opened up the sound. Because the Gain channel only has a tone knob sometimes it was too bright when cranked but too dull in the position that sounded the thickest. Presence circuit nailed it.

For a $300 amp and a few bucks in parts and tech time the amp is a solid contender for any budget. It has way more gain than an 800 but still sounds like one. If I had my eyes closed I'd think this was a Marshall but would wonder which one or who modded it because it retained all of the character of a great Marshall but still doesn't sound like a boutique copy.

Let me get the specifics and I'll post them. Also will be doing some clips soon. This has been the coolest experience modding an amp for me in a long time.

Thanks for this...looking forward to the specifics
The 3203 was my first "good" amp back in '86 and I actually still have it in storage. I did the C13 years ago but would love to kick it up a notch on the dirty side and use it for rehearsals.

[straightblues]

I would like to find out more about your mods. Are you interested in doing them for others? I have always liked this amp. I would love to get some more out of it.

[franksguitar]

I have a 4203 combo I bought it years ago with the C13 mod and it also may have a hotter transformer. It is a loud 30 watter, great clean headroom and great Jubilee sounded drive. It was was once owned by an instructor noted for tone at the Atlanta GIT. I also once owned in the 80's 2, 3203 double stacks with dual 4-10" bottoms

[Marshall Man]

Steve, I would be interested in what you did as well. Thanks.

[Steve Ouimette]

I'm not personally doing mods because I'm not a tech...I understand just enough to see what's going on (reading schematics, soldering, basic amp technology) but I wouldn't feel comfortable doing mods since I'd just be copying my tech's work.

That said the Op Amps were ST Micro TL072's that we replaced in all 3 spots.

Let me take some pix of the guts so we can discuss. It's an incredible upgrade.

[Marshall Man]

Sounds good. Thanks!

[Guitarfool]

This sounds interesting - Any chance of getting a clip, even a short 30 sec or 1 minute quickie? i would love to hear how the mods really changed or altered the amps tone