Sup GG@A, haven't been on UG in a while.

I have an Peavey VTM60, which runs 2 power tubes. I was told from the guy I got it from that it had two "new" JJ 6L6GC power tubes.

I noticed that the treble is disgustingly ear piercing, even when turned all the way down. I plan to do a mod to cut that out..

I just bought 2 Sovtek 6L6WXT tubes (Soviet Power!).

1) Will the 6L6 types match my amp?

2) They don't match, and my amp doesn't have a bias adjustment. (without mods)

Specs for tube 1:

lp: 43
Gm: 5,300

Specs for tube 2:

lp: 42
Gm: 4,900

(I don't know what lp and Gm mean by the way)

Will it be safe to replace the JJ's with the Sovteks?

3) I'm aiming for a really low-tuned dark, yet chunky and mid-filled tone, I was wondering if anyone can attest to the Sovtek's being better in that regard than the JJ's. If not, I guess I'll just keep them as spares.

You guys are the most helpful board (and my favourite) so thanks in advance for any help.
Last edited by Tedward at Apr 28, 2011,
if your treble is piercing and disgusting, just a tube change won't cure it i think. even if you swapped ALL the tubes with dark sounding tubes, u'll still have a bright amp. if you have "disgustingly ear piercing" treble, i would go about switching the cab. what speaker/cab are you running?

but yes, those tubes will still work. i don't think you'll hear much difference between the two tubes.

Ip is the plate current. I is current in electricity, and p = plate. Gm is the transconductance, measured probably in mili-mho/mili-siemens (siemens is inverse of ohm).

i like TungSol 6L6WGC-STR tubes for my 6L6GC applications myself. but that's just my opinion.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007

Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.

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Last edited by ECistheBest at Apr 28, 2011,
^aren't those going to add more treble?

Tedward - I'd also ask forsaknazrael too for his recommendation - he has the same amp.

Yes, what you have will work. Not sure what the specs stand for

If that lower number is the cathode bias in milliamps then they look really close. No sweat.

JJ preamp tubes should darken the amp up but yes the cab and speakers will make a difference as Shot said.
^^ thanks a lot man.

I plan on clipping one of the resistors ( I currently forgot which one but I have instructions somewhere) which apparently helps a lot of the treble problems.

I'm running a matching Peavey cab with 4 Celestion G12K-85's, made in England. I'm not that experienced with cabs or amps so I wouldn't really know the difference between different speakers. I could trade the 4x12 (overkill) for a 2x12 if the speakers are helping the icepick treble.


I have talked to forsaknazrael before about mods, I haven't seen him around in a while. Not since before my ban last summer anyways.
Last edited by Tedward at Apr 28, 2011,
I'm with Shot on this. I had the brightness problem, too, while running my amp with a V30 cab. Swapped the speakers and everything's great. The difference a new brand of tube will make is very small comparatively (unless your old tubes are borked).
G12K85s are the same as G12K100s (they just upped the wattage rating, but the speaker is actually the same), which are fairly dark, actually. They do still have some top-end going on and can get fizzy/shrill. Nothing I'd describe as ear-piercing though. This points to the problem being with the amp.
before u clip a resistor, tell me which one it is.

i like eminence cannabis rex with my amps. super bass response. smokey treble that doesn't kill things.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007

Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.

UG's Best DIY PedalBoard
Quote by forsaknazrael
I know what you mean by fizzy, but it's a very different fizzy quality IMO, than what I usually think of.

Oh, also make sure you have the gain switches down. Stock, I only like GAIN2 on, GAIN1 was poop.

Yeah, some people would say "sizzle". It's not really a bad thing, but some people don't like it.
It's nice to see you again forsakn

I have messed around quite a bit with the DIP switches, still haven't found a setting I REALLY love yet. Gain 1 and 2 at once is pretty nasty though.

So the bright cap is contained in the silver underside panel? It should be a small orange spherical thing right? And I just clip one leg/wire?

Thanks for all the help.

Also I do personally really like the cab/speakers.