Remembering My Marshall 2203

Inspector #20

Inspector #20

Ambassador of Tone
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I was thinking back on this today and trying to recall all the little details about it.

I got the amp around 1988 after telling Grover Jackson I was looking for one. Back then, Grover still did a lot of work out of his Covina garage and we would frequently stop by to raid his parts bin or to get advice.

I ended up getting hooked up with a guy named David (Morrison i think???) who was - at the time - working for Wayne Charvel as a painter.

The 2203 was a 1979 IIRC, and it was modified with an extra gain stage (extra tube as I recall) and something called a 'one wire mod.'

Other than that, I couldn't tell you much. I used that head continuously until I sold it in 2015 and started downsizing.

Maybe that explains my tendency towards higher gain???

Anybody ever heard of these mods???
 
What To Build . Plexi With One Wire Mod Or Jcm800

Neikeel knows his stuff too.

You can make it switchable too, then tune the cap/resistor values to your taste, if you like lots of gain.
Personally I lke the definition and tone of a very slightly warmed up 2204 so have a 2 in 1 plexi/2204 that I use for gigging. It has 8k2 on second stage cathode, 0.68uF/2k7 on first stage (ie stock 2204) and another 0.68uF over 820R on V2a, I like reasonably tight NFB (47k/8ohm).
 
Ampmadscientist too.

(cascading the gain stages ) make this amp compete with the jcm The one wire mod is Mickey Mouse. (it's a joke)
Use the 800 2203 schematic.
http://www.drtube.com/schematics/marshall/2203u.gif

The plexi has a problem...won't work right until the volume is pegged, producing output tube distortion.. Making the amp waaaaaaay too loud for most applications!

The plexi is a CLEAN amp which has no distortion until the output tubes overdrive. Face reality.

The 2203 adds one gain stage...to the plexi design...(it's the same amp w/ one extra stage).
This allows preamp distortion, to get a better sound at a low volume.

Plug into LOW input: you have a plexi (basically).
Plug into HIGH input: you have the extra stage.
The 2203 is much more practical versatile for lower volume (or all) applications.

Most people who "want" a plexi...don't really want a plexi....because they do not understand all of the above information....which is very important.

Add a master volume to the Plexi: It's a waste, it will never give you what you wanted or expected.

Add a master volume to the 2203: NOW you are talk'in.

And while I am on the subject of ppimv Master Volume: direct coupled (without capacitors) is way more accurate, and works much better.
Use a 1M audio pot, which has an insulation rating of 300-500 Volts. (there is bias voltage on the pot)
Recommended: PEC 1 Meg Pot, which has high voltage insulation.
r-vpec-250ka.png


Potentiometer - Precision Electronics, Audio, Slotted Shaft

As long as the pot has high voltage rating, there will be no problem whatsoever.
So...don't use a cheap pot to do this master volume.
images
 
Robert Herndon said:
I was thinking back on this today and trying to recall all the little details about it.

I got the amp around 1988 after telling Grover Jackson I was looking for one. Back then, Grover still did a lot of work out of his Covina garage and we would frequently stop by to raid his parts bin or to get advice.

I ended up getting hooked up with a guy named David (Morrison i think???) who was - at the time - working for Wayne Charvel as a painter.

The 2203 was a 1979 IIRC, and it was modified with an extra gain stage (extra tube as I recall) and something called a 'one wire mod.'

Other than that, I couldn't tell you much. I used that head continuously until I sold it in 2015 and started downsizing.

Maybe that explains my tendency towards higher gain???

Anybody ever heard of these mods???
Click to expand...

Mine was a 2205 and not modded. Never heard of that particular mod but people were doing all sorts of stuff to those amps back then.

But...it sounds like you still have a jones for that sound. Maybe track down one and have someone do the mod to it?
 
gball said:
Mine was a 2205 and not modded. Never heard of that particular mod but people were doing all sorts of stuff to those amps back then.

But...it sounds like you still have a jones for that sound. Maybe track down one and have someone do the mod to it?
Click to expand...

I never liked the bulk of a head/cabinet, but the tone is indeed killer. Nowadays, we can get by with a small combo.
 
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