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Today I brought my amp to a tech get everything checked out and cleaned beacause of the problems I have been getting recently. When I was there I saw that I have pre-amps tubes with the marshall signature on them. I assume they are ecc83s, but I'm not sure what kind they are. I know marshall uses most svetlana tubes, but I think I heard about them using sovteks when they started to switch to 5881 power tubes. I just wanted to know so I could try some other pre-amp tubes out.

prolly sovteks...my 1994/95 1987X has sovteks

Yep. Sovteks. Throw some EH 12AX7's in there. Turn it up and hang on. If you're changing the power tubes and getting it biased, I like Svetlana EL34's.

Do you guys know which sovteks are in there? I know there's a couple versions of the 12AX7s. I just guessing that pre-amp tube farthest from the power tubes provide most of the pre-amp tone right?

I can't remember which ones came in those. Probably the same as what they put in the Dual Reverbs, which I think were WXT or something like that. The 12AX7 closest to the input jack is V1 and is the first part of the tone. You have 3 in the pre-amp plus 1 more for the phase inverter.

Buy 3 GT12AX7C's for it. If you change power tubes, the Svetlana =C= logo 6L6's would sound best in that amp. Do all that, with a perfect bias, and that amp will sound better than it ever did.


Originally Posted by GearjoneserBuy 3 GT12AX7C's for it. If you change power tubes, the Svetlana =C= logo 6L6's would sound best in that amp. Do all that, with a perfect bias, and that amp will sound better than it ever did.

Wait a minute. You can't put 6L6's in the SL-X without changing some resistors and a rebias.

Im sticking with el-34's in my amp.

I Really like the Sovtek WXT EL34's in my JCM900 2100 MKIII. I also run Sovtek LPS 12AX7's in there also!!! I have tried JJ's and EH's and the Sovteks I have are by far the best!!!!

Which positions would give tone changes? I'm not sure cause I never did this before. Does the phase inverter effect tone?

No the PI doesn't directly effect the tone, but it drives the power tubes, and depending on it's gain structure, it can make slight tone differences,just by how hard it drives the power tubes, but the majority of tone shaping stages are V1,V2, and V3, (if your amp has 3 pre tubes) with V1 having the most effect on tone.

i ran GT12ax7-C in the 4 preamp spots and JJel-34L's in the power amp to cut down some of the brightness of the amp it sounded very good