Yellow Jacket Converters?

[Guest]

[quote author="Greg"]I bought a reissue JCM 900 some time ago, and thought the tone was bit harsh and brittle. The power tubes were 6L6. I did a mod and changed them over the EL34, and the tone, IMO, improved dramatically. Still wasn't as good as the original JCM 900, but the midrange quality of the guitar tone was so much softer and lush. I don't know enough about tubes to comment on those exact conversions, just thought this would be slightly revelant to the topic.[/quote]
Had my JCM900 converted by Marshall (in Milton Keynes) last week
Fixed a few broken pots, changed over from 5881 to EL34s - valves plus 1 1/2 hours labour
£140 (including VAT)

And Greg - you are right the EL34s are soooooooooooooo much nicer
Been playing a 335 through them all weekend - very nice

 

[Kit]

Can we define the characteristic sound of the following amps by specifying the pre and power tubes?

Generally speaking:

Fender: pre-tubes(ecc83) power tubes( 6*6)


Vox: pre-tubes(ecc83) power tubes(EL84)


Marshall: pre-tubes(ecc83) power tubes(EL34)

Now, much of the sound differences of these amplifiers lies not only in the power amp stage, but very much in the pre amp EQ, and the preamp overload characteristics. Power amp clipping in a standard tube guitar amp is somewhat of a myth. Distortion? Yes, certainly. Clipping? No, not much. What youre hearing is mostly the PI plates hitting B+.

Traditionally, fenders has a very pronounced mid-dip which cant be dialed out without surgery. Marshall also has this but not as much.

Vox AC30 on the other hand when plugged into the "flat" channel (which is the only way it should be played) doesnt has this mid dip.

Personaly i got tired of this mid dip in my Marshall 50W head and i didnt want to mod it so i built my own amp with a simple shelving one knob tone control........been happy ever since.

Mid is the only thing that electric guitar has got going for it. Dont cut it.

IMHO.

Err.....sorry for the rant, what was the topic again?

 

[12afael]

Andy Marshall seem to be a really nice guy , and great designer too .
time ago I open up a univalve and is really well constructed.