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Right now Im using the following equipment:
1982 Marshall JCM 800 2203 with 3 JJ ECC83S and 4 JJ KT88
1960A Lead Cabinet with G12T-75 Celestions
Epiphone Les Paul with JB pickups
Zakk Wylde Overdrive pedal for boosting.

I like the way my chords sound, but the high notes sound very piercing.
Does anyone know what the problem could be?
Ive been recommended to do one of two things: Change the pickup volume pots to 250K or clip the bright cap on the JCM 800.
Which would you guys recommend?

use the neck pickup?, sorry i dont think that was helpfull, i would try changing the volume/tone pots, probably cheaper and easier job than doing the amp

I don't think the amp needs any tweaking, I'd try out 300k pots first, and if that doesn't solve it, do 250.

Ive also been recommended to change the JJ KT88 tubes to JJ EL34 or E34Ls. If I did that, which JJ would you choose, the EL34 or the E34L? Thanks!

i dunno which type of el34 but definutly you should do that, the EL34 and EL84 is the sound of marshall, preferably the EL34 for me, but my Jcm800 preamp runs into a 6L6 poweramp which sounds amazing.

'bout the JJs:
the E34L is just a higher level version of the EL34. soundwise they are pretty much equal, you can just push the E34L quot;up to 20%quot; harder (that's what JJ says). They won't sound louder, you can just crank them up a bit more.

Keep in mind, that KT88 sound different than the EL34. The EL34 give you overdriven a rather quot;british tonequot; while the KT88 is considered to deliver quot;californian tonequot;. Also you have to adjust the bias when changing from KT88 to EL34 - they have the same socket but require different idlecurrent!

I would also give the Electro Harmonix EL34 a try, I like their sound better than the JJ E34L...

I'd also try changing the pot first - tube exchangement is a rather radical thing for your overall sound

greetz
grams

I agree that untamed, the JB can get piercing for high gain leads. I've found that when I do use my JBb for leads that it's best to roll the tone knob back to about 5-6. That's enough to take the edge off. I'm also running 300k pots, so swapping pots might not be a bad idea. I definatly prefer the tweek first, replace second methodology, and when I do replace things, start simple (such as pots).


Originally Posted by lit31686Right now Im using the following equipment:
1982 Marshall JCM 800 2203 with 3 JJ ECC83S and 4 JJ KT88
1960A Lead Cabinet with G12T-75 Celestions
Epiphone Les Paul with JB pickups
Zakk Wylde Overdrive pedal for boosting.

I like the way my chords sound, but the high notes sound very piercing.
Does anyone know what the problem could be?
Ive been recommended to do one of two things: Change the pickup volume pots to 250K or clip the bright cap on the JCM 800.
Which would you guys recommend?

The 50 watt version of that amp is one of my favorite amps of all time!

'82 is possibly the very best year for those amps.

I am not a fan of the G12T-75 Celestions...but it'd be pretty expensive to change all four. I do prefer G12H30's though: smoother, chunkier tone, IMO.

The very piercing tone you're getting must be when you use the JB...right?

Some ears do respond to the upper mids in the JB that way. Mine do too.

Seymour uses his JB with 250K pots and that does smooth out the JB but at the same time it throws away some of the sparkle...which is unfortunate, IMO. Makes it sound like there's a blanket over the speakers to me!

But that's the simplest cure.

You could try experimenting with the value of that bright cap on the volume control of your Marshall. You could just clip it...and if that makes the amp lose to much sparkle then experiment with differant values until you get the sparkle you want. I'd use silver mica caps and try 47 pf, 120 pf, etc. until you find the tone you want.

Lew

another thing about the speakers, i have the same cabintet running G12T-75 speakers with my 5150 and the cab itself is very bright in comparision to the much warmer 1x12 celestion im using for my Jcm800(not sure the speaker type). if i plug my Jcm800 into the Marshall 4x12 i have to really turn down the treble on the amp, where as id have it near full on the 1x12 i ussualy use with it.

I've had a bridge position JB come standard in a couple of guitars that I've owned, and I found them to be overly bright for my taste. They have this dentist's drill thing going in the highs that I really don't like. I would first try a different pup, then the 250K pots, amp tweak as an absolute last resort.

From brighter to warmer: Custom 5, Custom Custom, or Pearly Gates would be my choices for replacement.

I hate to deviate from Duncan, but the Rio Grande BBQ is like a fatter and warmer JB - think of the JB with the EQ shifted toward the lows with an overall warmer tone.

Different pickup. Not all pickups sound good in all guitars.