Marshall 2555 Jubilee Mods

[zombitron]

Hello all, Ive been trying to track down some mods for an old 2555 I have. I'm pretty valve amp savvy and have a JCM800 I managed to mod with info from various resources but I cant seem to find anything for the 2555. I really dont want to destroy it by blindly experimenting so does anyone have a good place to start? Maybe even just direction on upping the Gain and altering the tone to something a little more suited to my tastes...

Morgan

 

[wkcchampion]

I personally wouldn't touch a screw on that amp

 

[zombitron]

Well, I personally would... It's my amp.

 

[jcmjmp]

What are you trying to improve or change on the amp? Are you wanting to mod it just for the sake of modding it?
If so, I would suggest getting a clone made up and have fun with that.

 

[monty john]

Dont do it!!! Sacrilidge....etc etc...

Really now as rare and hard to find as Jubilee's are and to OWN ONE!!!.... I own a 88 2550 and wouldn't dream of anything to this amp other than tube replacement & bias....she has "the sound" to die for...

The only thing I have read is jumper the effect loop (I have delay and other shit in the loop so forget that) and swap out clipping diodes to FRED's....

Better off messing with effects than the amp....its a collector's piece....

 

[jcmjmp]

The only thing I have read is jumper the effect loop (I have delay and other shit in the loop so forget that) and swap out clipping diodes to FRED's....

Better off messing with effects than the amp....its a collector's piece....

Do not swap the clipping diodes to FREDs - actually,do this this if you wish... but it'll sound like crap.

What gives the Jubilee its nice OD tone are the slow response LEDs in the clipping circuit in an asymmetric layout, along with the 1.45v forward bias voltage.

Some people use FRED (or just UF) diodes in the power supply to reduce power supply noise. Some techs have told me that the reduced switching transients can help prolong the life of the PT and other components in the power supply portion of the amp.

Jumpering the effects loop when not in use is a good idea on these to get a good connection between the two sections of the amp.

 

[monty john]

Thanks for clearing that up, I personally would never mess with the amp, just what I read....glad some guys on board know MORE than I!!!!

 

[zombitron]

It's bizarre how people consistantly try to talk people out of modding...
I modify everything I own in some way so for those people that think I'm going to spare this amp from a solder iron...just aint gonna happen. I have no dreams of reselling my amp for $10k, I have no plans of selling it at all. I'm not looking for advice on what pickups sound better with the Jubi, I'm looking to give a makeover...It will get new tubes and a rebuilt transformer, but if I don't hear any good ideas then I am just going to start experimenting...No, i dont want a clone...I want to use the spare amp, with the rust, ripped re-tolex job in what appears to be a slightly incorrect shade of silver and a replaced Neutrik input jack...The amp has no vintage value so get over it...it was someones kick around amp before it was my kick around amp so I figure I might as well tinker with it because its not like it gets played all that often...and again for all you jackasses...I BOUGHT IT FOR $500 w/no tubes or input jack already with the ripped up silver tolex...it's getting modded whether anyones interested in talking about it or not, I'm just looking to talk to those who are interested, that may have experience so I dont ruin a perfectly good amp by changing out the wrong thing because all I've worked on were single channels and doing simple mods, Im mostly into analogue synths...so for the last time, without rebuttals and negative opinions...

Anyone know of a good Jubill 2555 mods or maybe a resource where I may be able to find for info on the subject? Most owners dont seem to like to mod, but this is a good candidate and theres not much info about modding it (and in this day and age with a Marshall for F's sake). Any help is appreciated!

Morgan

 

[jcmjmp]

Anyone know of a good Jubill 2555 mods or maybe a resource where I may be able to find for info on the subject? Most owners dont seem to like to mod, but this is a good candidate and theres not much info about modding it (and in this day and age with a Marshall for F's sake). Any help is appreciated!

Morgan

But you never answered this simple question : What do you want to achieve with a mod? Is there a tonal goal or is it modding just for the sake of modding?

Post some pics of that amp. we always like to see Jubilees.

 

[Adwex]

Nice attitude for a new guy looking for help.
Do you always call people you just met jackasses?

 

[jcmjmp]

Nice attitude for a new guy looking for help.
Do you always call people you just met jackasses?

You're right... F**K it.

 

[monty john]

Simple answer: NO JACKASS

 

[manktelow]

It reminds me of something that Marty Strat wrote about some people come to the forum and do okay, while others within three posts have sealed their fate.

 

[BluesRocker]

Well if he was tone searching all he would have to do is just turn the damn thing on and crank it up. I mean I could understand modding a 900 or 800 or DSL or whatever. BUT A JUBILEE??? That would be like repainting the "Mona Lisa" to her leaning up against a tree. It may look good.. But its not the "Mona Lisa" anymore.

 

[Adwex]

Modding an already beat up Jubilee is not a crime, but there are friendlier ways to ask.

 

[jcmjmp]

Modding an already beat up Jubilee is not a crime, but there are friendlier ways to ask.

And I've been trying to figure out what he's trying to get out of a mod to be able to help him better... being helpful and all.

Who knows what kind of mod to suggest if you don't even know what the person is trying to accomplish with said mod? Ya know?

 

[wkcchampion]

And I've been trying to figure out what he's trying to get out of a mod to be able to help him better... being helpful and all.

Who knows what kind of mod to suggest if you don't even know what the person is trying to accomplish with said mod? Ya know?

well said bro. It's just a non-sense thread

 

[monty john]

Yeah if the dude would have xplained the amp in question was a basket case, I would perhaps say "build it back to original specs" as a unique project. Like restoring a muscle car back to original.........but this thread did not roll that way....

Not my problem anyway as I LOVE my setup....Jubilee Les Paul

what more can be said?

 

[RynoAZ]

Go to schematics heaven or drtube and look up the wiring diagrams for your amp. From there, find the sections you want to modify and change the values of certain components. You can raise or lower resistor values for more or less effect, and altering capacitor values can change frequencies that are sent to ground for a change in effect too.

FRED's are ultra fast diodes and sound like junk. Actually, they're tiny transistors and are very inappropriate as clipping/audio diodes. FRED's and UF diodes work great in the power section, like someone mentioned earlier. My best use of them is for the rectifier diodes - you may or may not notice the "sag" that vintage amps have - FRED's and better silicon diodes will reduce or eliminate that.

If you're into pedal modifications, you will know what can be done to clipping diodes, and you can use those practices to change the clipping section on your Marshall. I'm very familiar with pedal mods, and had asked around here if anyone had ever modded their diode-clipped Marshall like this and got no answers, so maybe you'll be the first. Have fun. Value is an arbitrary number - if I get no enjoyment from a $1mil amp, it's not worth $1mil to me.

 

[jcmjmp]

FRED's are ultra fast diodes and sound like junk. Actually, they're tiny transistors and are very inappropriate as clipping/audio diodes.

FRED diodes are not tiny transistors.... they're diodes.