jcm 800 mod question

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mikeanniston

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hey all, i have a 50 jcm 800. i beleive its a 2203 model. it has el 34s in it, and altho i love the way it sounds, i want just a little bit more balls. but i dont want to have to use pedals, etc etc. if i put kt-88s in the 800, would that beef it up a bit and give it more balls?
 
It depends on what you mean by 'balls'. The KT88's will not make it distort any more than it does now, it will distort less. However, the added headroom might give you more low end.

If you are looking for more distortion, you need to hit the front end with something or get a real modification like adding another preamp tube.
 
*more* balls? Turn it up, man! :D

how many power tubes does it have - 2 or 4? If it's a 50 watt head, seems like it would probably have 2, and it would be a 2204. I've got one. It's got a lot of f#*@+in' balls!

But seriously, try a boost pedal or something like tube screamer
 
ya it has 2 power tubes, i couldnt remember if it was a 2203 or 2204, its at the practice space, so i couldnt look. i know ive thought about that, but didnt really want to bring more pedals into the mix, i love the way it sounds just straight plugging it in. by more balls i just mean like taking it that extra notch. a little more gain, sustain, etc. ive looked into some splawn amps, which sound great, and the kerri king 800. which im not a metal head by any means, but ive played that amp before in a guitar center and it sounded great. unfortunately with many of the clubs i play, i cant really turn the volume past two, otherwise my stage volume would be just to loud. i guess something like a tubescreamer would be a safe bet, but i was just wondering if there was something besides like a serious mod that i could do to my head to achieve a but more umphhh.
 
A compressor/sustainer pedal will sometimes help without adding anymore distortion of it's own.

Most of the time you can just turn the drive control down and the output control all the way up and just get a boost which will do the trick.
 
  1. Take your amplifier to anyone who knows which end of a soldering iron to hold.
  2. Tell him he doesn't even plug in his iron just yet.
  3. Have him snip out the capacitor as shown in the photo blow. It is a 'Brite' cap across the Volume control.

    JCM800_input.jpg

  4. Enjoy your improved tone. When you refer to me, please address me as That guy who really freakin' knows his Marshalls ;).
 
o nice! thank you! what exactly will that do, like how will it change the tone?
 
With the 'Brite' cap left in, at lower volumes it is thinner and brighter. Without it, well, it will just be what I refer to as 'normal'. Usually with a JCM800 they sound great on '10', but at any lower volume they have that sound that you wish it was just a little more.
If you want to go one step further, between the 'Lo' jack and that Volume control is a 470K resistor with a 470pF capacitor piggy-backing along. Like so.....

JCM800_input2.jpg

.... now change that to whatever gives you the tone and extra gain you prefer. For this you need to plug in your soldering iron ;), but it's worth it. I often go with just a 68K resistor. You get more overdrive gain, and a fatter tone. As is, this is a treble peaking circuit, giving you more of that tone that is as thin as a politition's promise. Now you can get that 'cranked up' tone at a much lower volume. Try it, and remember my name.....

That guy who really freakin' knows his Marshalls!;)
 
Try it, and remember my name.....That guy who really freakin' knows his Marshalls!;)

Previously known as...That guy who really freakin' knows how to Google "Tone-Lizzard".! :D
 
well thanks all, i will for sure check it out and look into all of this!
 
Previously known as...That guy who really freakin' knows how to Google "Tone-Lizzard".! :D

Dude! I was trying to be incognito! Ah, well, I am still having a blast giving away advice. I sure don't make any money at it :o. But this is one instance where the free advice is worth more than you paid for it.
 
ranjam thanks for the mod info ;)

ocnor BIG thanks for the google hint ... :cool:

I`m in for some heavy reading by the looks of it ... :D

saved this page before the pics disapear..
 
OK - I saved off this thread and I just removed that bright cap from my JCM800 head (it was C5 - I've got the horizontal leads version, and so all the capacitors and resistors are on the board (as well as the pots and jacks), not like in the picture). Sounds a *lot* better! A lot less hiss, too. Doh! 25 years with the thing :o - ranjam (and if you're not the tone lizard, I'm pretending that you are), you could'a saved a lota ears a lota pain :D
 
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