Marshall 2203 - tweaks for more 80s sound?

[Jerri]

Hi there, i'm new to the forum. I wanted to ask some things about tweaks mods.

First of all, i've got an 84' 2203 (6cap/vertical inputs), which is at my amptech (who does usually mostly 2203/1959 type of amps) for new tubes and filter caps.
I asked him about the amp mods i wanted to do, and he was honest, and said, that he's more into the classic sounds, and nobody asked for that, besides me. But he told me, if i can name it, he does it with me, until i like it.
I don't want to set him in the wrong light, he had a few 2203s there, and i tried them, they sound really beautiful.

First tweak i asked for, is to get a Post PI MV instead of the Pre PI MV. My question for that is, if the stock Master gets disconnected, is the 2203 sound still there? (I always have the MV pot dimed, i dig that sound)

Second tweak (and that's for what i really need your help) i asked, was a more 80s sounding "gain structure". What i look for is that more liquid hifi-ish smoother sounding gain.
I don't want to alter the tone stack voicing or something that heavy, because i really like the 2203 sound.
Think a bit 80s Tony Macalpine or Chastain for example...

Any suggestions?

Thanks very much

Jerri

[toner]

Welcome.

If you usually dime the master then removing it and changing to a post PIMV won't alter the sound/feel much until you turn down the post MV below about 7. The usual negative effects of a PPIMV will be there (reduction of negative feedback, more "buzzy" distortion at low settings, etc.). I haven't ran a post PIMV with a cascaded 2203 preamp personally but several people do and seem to like it. I think its a key part of the "mod 5" too.

As for more "liquid smooth gain", a good starting place is the second gain stage cathode. Stock is an un-bypassed 10k, which adds a lot of odd-order harmonics and is a big part of the 2203's tight crunch sound. You can reduce that resistor to about 5k6 and/or add a bypass cap to add gain and smooth it out a little. Experiment with different bypass caps. 0.1uF is probably a good starting place.

[Jerri]

Hi Toner,

thanks for your answer, that really helps me .
So then i'll dump out the Pre PI MV and put an Post PI MV in that place, to keep it nice stock looking.
what i like about the open master, is that the amp get this "spongy feel" and that it thickens and gains up, without getting mushy hi end (think mesa rectifier distortion).

The last two days i studied some schematics here (UYI,AFD, 68spec,M-1000), and i saw something, that's maybe worth trying?
It's like putting down 0.22uf on V1A or V1B (don't know which is better) to 0.0022UF and pumping up the PI Coupling Caps to .1uf .
Does that give me a more "huge, but less flubby" bottom end? (think Savatage - Hall of the mountain King)

If anybody could answer that question, that would be all i wanted to know.
I'm searching for that 80s shredder thing , that almost no amp today nails . A Soldano SLO sounds quite good, but it's always like, could that thing sound more 2203 and a bit less saturated in the hi end?
That tone quest gives me headaches for years now

Thanks very much
Jerri

[Vince Neville]

If you are looking for an 80's shredder type setup, then check out the Slash amp thread (http://forum.metroamp.com/viewtopic.php?f=3&t=29759" onclick="window.open(this.href);return false;). There are many schematics of what people are trying out, and just as many people who can help figure it out. The amp Slash wanted to use for Appetite for Destruction was a modified Marshall which George Lynch and other prominent shredders at the time were renting and enjoying. It was the #39 amp at S.I.R. You may find that the common areas tweaked to get the Slash tone can lead you in the right direction, even if you don't like Slash's tone. Some guitarists simply use a boost pedal into the front end of an older Marshall, like Yngwie Malmsteen.

With regards to Master volumes, there is a simple option that may give you acceptable results before trying other more drastic approaches. You can simply add an isolation resistor (try 100k) in series with the output of the master volume pot wiper. You will notice more consistent tone from quiet to loud, I've done it, it works. You can't get any simpler, and it only costs one resistor. There are a number of things you could do to a pre-phase-inverter MV, and I am only learning them now, so I can't properly explain them. I am planning to install a type of bootstrapped MV created by Kevin O'Connor. You can buy a kit for it, the LP-MV kit at London Power's website (http://www.londonpower.com/catalog/prod ... ucts_id=77" onclick="window.open(this.href);return false;).

[Jerri]

Hey Vince,

thanks for your input, too, i really appreciate all info i can get. I'll memorize the idea with the "isolation resistor", sounds simple and easy.

For the Mod, maybe this sounds a bit stupid, but i don't want to add more gain (add a tube stage f.e.). I always boost my signal with and old '79 Tubescreamer. It's more like "the few %" are missing, so for me it's more a touch of fine tuning, than mod the thing until it shreds to hell.

Jerri

[stef]

Stock 2203 spec with a quad of eh6ca7's biased hot (65 -70% maximum dissipation..), china 12ax7's + strat with a dsd (or sh5 or dd) + xotic ep boost in front (or maxon 808 or mxr eq). No need for endless mods and techs -
http://forum.metroamp.com/viewtopic.php ... ng#p119884" onclick="window.open(this.href);return false;

[SteadyEddie]

The LP-MV looks interesting; if you install it, i'd like your opinion on it vs. the Lar/Mar PPIMV.

[Jerri]

Stock 2203 spec with a quad of eh6ca7's biased hot (65 -70% maximum dissipation..), china 12ax7's + strat with a dsd (or sh5 or dd) + xotic ep boost in front (or maxon 808 or mxr eq). No need for endless mods and techs -
http://forum.metroamp.com/viewtopic.php ... ng#p119884" onclick="window.open(this.href);return false;

I need my tech, because my power tubes are worn out. I like the stock 2203 spec, too, seriously, i can't get enough of it .
It's just loud as hell, if i want to get in the sound territory i like.
Mine's got Winged C SED's , Old Mullard I63/Tungsram 60s Military/Sylvania Long Plate 70s (V1/V2/V3).
Guitar is a Super Strat with Mahogany Body, JB and two SSL-1 Duncans in there.

For myself, like i said before, the tweaks are more like the icing on the cake, because the 2203 is my favorite amp ever .

Rock On, and thanks for your answer, too.

Jerri

[rocker77]

If you want a real #34 mod done by the original man himself look up Frank Levi he is working at "Rocket Studios"33-06 37th Avenue, Long Island City New York NY. 11101. If interested i can hook you up with him. I just got my amp back and it is freakin amazing. The afd has nothing on it because it is not even the same mod as frank's he done the original #34 it is the UYI tone and also on spaghetti incident. It isdefinately worth your money, trust me.

[Jerri]

Sorry, i've forgotten to answer, how the amp got tweaked. Really thanks again for all who answered, it helped quite alot.
I didn't have the PPIMV installed, my amptech and i tried some things together, and i liked the isolation resistor for the Pre PI Master best. But i went for a 220k instead of a 100k.
Then the bright cap on the Gain Pot was removed and we tweaked the second stage cathode to ~3k. With a .68 cap across it, it sounds very nice. The Gain is nicely Fluid and a bit Soldano like.

Jerri

[Did J]

The LP-MV looks interesting; if you install it, i'd like your opinion on it vs. the Lar/Mar PPIMV.

Quite interested by this review too