Marshall Artist 4203 c13 mod

[lefty64]

Has anyone here that owns this amp done this mod? I read that it can effect the boost channel and I don't want to mess w/ that. I would like to sweeten the normal channel however because even though I don't really consider that channel very clean, I do like the natural overdrive that it can produce. Right now I find I have to pretty much kill the treble to have it usable at all. Anyone who owns/has owned this amp what are your thoughts on this mod please.

 

[denwing]

I have one but it doesnt have the C13 mod.
This amp has a lot of potential. I'd like to be able to mod the OD channel with separate TMB controls.

 

[lefty64]

Same here. I may end up getting an eq pedal which I dont have just for that purpose and see how that works out.

 

[straightblues]

I did the mod. It is really easy. I did it, played the amp for about 20 minutes and then restored it back to the original spec. It does mess with the gain channel in a bad way to my ears.

 

[denwing]

A good EQ might help. Let me know your results if you try one.
I tried a cheap Behringer EQ pedal somebody had given to me to try & it sounded awful. Would like to try a Dano Fish & Chips or MXR.
Curious: What kind of tubes do you have in yours? I bought mine used & it has a Tungsram 12ax7 in the PI & no-name EL34's. Sounds dynamite but I was going to try experimenting since mine has the bias mod. Not sure if some good el34s would do anything, ....cant imagine anything better than the Tungsram.

 

[CaptBildad]

Mine had the mod when I bought it. I put it back to stock. To be honest, I don't remember that much of a difference. I just use mine as a power amp w/reverb these days going into the effects return with various preamp and modelling goodies. I also used an Rane EQ with it to good effect.

 

[lefty64]

I think I'm going to leave it alone. I do not want to mess w/ the drive channel. I absolutely love it. The gain has to be cranked to my ears for it to sound good, but it can "mellow out" by adjusting the guitar knobs. I like the gain on about 8, the channel volume 5-8 and then the master whatever. So nice this way. It is a little more high gain at times than what I prefer since I play alot of blues stuff. Sometimes I like just cranking it up and going back and playing 70's/80's stuff cause it sounds so freaking good on this amp! thanks for the input. Regarding tubes, The tubes are not marked in any way so I don't know what they are but the aren't real terrible. I have a set of JJ's ready to go in there when I pick up a bias meter to do it. I've never biased an amp so it will be my first shot at it. I'm also going to replace the 12ax7 but don't know if it will do much as it is really just a phase inverter on the amp.
Denwig, can you tell me about the bias mod yours has?

 

[denwing]

The stock 4203 bias is non-adjustable. I bought my amp from a local amp tech who had already installed the adjustable bias pot while he was using it. You're probably right that a tube change probably wont have that much affect.. but, there seems to be a lot of posts that claim different tubes in the PI position will alter the sound.

 

[lefty64]

So does that mean I can plug in the JJ's and I'm good to go??

 

[straightblues]

When I got mine it have Sovteks. I put in a pair a Amperex EL 34 and it was like night and day. Yes good power tubes make a big difference in this amp.

 

[lefty64]

Can someone tell me so I don't blow up my amp...I can just plug in my new set of JJ's and play away, or does it need to be biased by a tech. I apologize for being such a big dummy.:ganz

 

[denwing]

I would think you're ok to put in the JJ's because there's some allowance with bias settings and as long as the tubes are of similar ratings it should be within range. But, if you're uncomfortable with simply swapping you could have a tech check the current bias setting to give a basline reading, then swap the tubes & check it again. Or, you could buy a BiasRite & check it yourself.

 

[lefty64]

Thanks Denwing