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simple mods for marshalls


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3/4/1999 7:30 PM
j burt
simple mods for marshalls
im screwing around with my 78 marshall mk2 master lead 100 watt 2203 trying to see what i can do to it to make it sound really good-really cheap. i am experimenting with presence capacitor and resistor values and input to gain capacitor. so any ideas? what can i do to the gain stages? any ideas would be appreciated.
 
3/5/1999 12:11 AM
Richie
J: Its hard to know what your after in tone or sound your looking for.What one likes,another may not. There are quite a few things to change these amps.Trace has been doing alot of experimenting with one of these.As far as gain,it should have plenty already.Or do you want less? The tone of the amp is what counts.There are quite a few on here that have their own taste of mods to change the sound of these. Some small things are to change the .022 caps in the PI/driver to .1uf and change the tone slope resistor and cap from 33k to 56k and 500pf to 250pf. Make it a bass amp,they sound thicker like this,and change the middle control from 25k to 50k.This will give alot more range in the middle section.Just do a little at a time. see what you like.You can leave the cap alone for the presence control, but in the feedback, add a .01 cap to the resistor.I'm sure there are others that will give you their recipe. Alot depends on how you like your amp set, or tone you want. This will give it alot more range and won't sound so thin. There are some small caps you can change on the preamp that will make it less bright,but the amp will still have enough bite! And differences for the one on the volume control.Give us more info of what your after, and i'm sure their will be plenty of answers.Oh does yours have 6550? Change them to EL34 and rebias if you haven't done this yet. [Richie]
 
3/5/1999 3:36 AM
Niek

The 2203 preamp design is known to be a bit too bright for many people. I recently build an amp using a preamp similar to the Pignose G40 amp. It uses a 2203 preamp with a few tweaks. You only have one input, less interstage attenuation, a 1000pF treble cap in the tone stack and a cap across the mastervolume to bleed some highs of to ground. I have been experimenting with this cap and found it greatly responisble for the preamp's brown sound. Steve Ahola has schematics of this amp on his cool site along with tips & tricks for serious modding. This should give you plenty of ideas on modding your 2203.  
the url is of steve's site is: http://www.techaccessinc.com/blueguitar/  
 
Cheers,  
Niek
 
3/5/1999 6:49 AM
Liam

All of the above are good info. Here's my thoughts. (I love the 2203, it's one of my favourite amps). Try changing the first pre-amp valve to a 5751. They're a bit lower gain and a bit warmer. That makes the whole set-up very touch sensitive. I also moved the presence control to the tone stack, and grounded the PI through a resistor. If you want values I'll let you know.  
 
I'd love to hear from Trace on this matter. He has good taste in tone!  
 
Liam
 
3/5/1999 8:21 AM
Niek

Liam,  
 
Please send us those values (presence & PI mod).  
 
Cheers,  
Niek
 
3/6/1999 3:12 AM
Mark Cameron

Everybody has ther tricks to getting the best tone out of a Marshall. So hears my2cents.  
I dont like taking out the caps, thats what makes that Marshall crunch. Try this, lower the feedback resistor to 27k if its too brite. This takes the icepick treble out, but you still have that classec sound,Or you could use a 250k pot in place of this resistor(boogie presence cont.). also play with the presence cap I like the .68 cap over the .1 cap (this ads more high mids)  
Need more bass,look at the purple wire going from the impedance selector to the 100k feedback resistor, Disconect it from the impedance selector, now get a .0033 cap connect 1 lead of the cap to whare the purple wire went and take the other lead and conect the purple to this, BOOM more tight bass (adding bass in the preamp makes the amp turn to mush and you lose gain on higher notes).  
Try all of these ideas (not just mine)if you can. Let us know what works best for you.  
.......Mark Cameron
 
3/5/1999 12:23 PM
j burt

it has el34s. i like a nice crunch sound. it seems when i go to do a lead i have a drastic loss in gain. i know there is not a lot i can do about that. i want it to sound beefy and full. i bypassed the cap and resistor from the input to the gain pot and that made a world of difference- much more full. i want the eq controls to more sensitive. on my dual recto they are really sensitive and give me a lot of control. i dont need that much control but i would like some. maybe more control in the mid & bass sections- but i want crunch like a jcm 800- not super saturated though. i want tonte that mill make my lespaul scream with joy. is this possible?
 

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