Try the JJ KT77. Just popped them in and biased, here are my first impressions (this is directly quoted from an e-mail I just sent, just thought I'd share it):

Very EL34-like but with way more tight controllable bass that didn't fart or get boomy - fatter, rounder, much clearer, more focused, less harsh and less "boxy" mids and very nice strong clear detailed cutting treble that wasn't harsh or grainy, and not ear-tiring. The pinch harmonics really cut and scream as an effect of the great mids and the strong treble. I used to scoop out lots of mids, now i dialed them back in because they sounded very sweet, chunky and raw and not horrible and honky like with the old chinese EL34s, and no matter how much mids you add your tone remains punchy.

Instead of jerking around playing random crap and get tired of it like I used to do I just became addicted to the tone coming out of MY cab and I played and played and played till my wrists hurt. Remember; i still have utterly shitty pickups, my good (hopefully) pickups should arrive in a week or two.. I can't wait..

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sounds sweet... do you think KT66's will have the same effect with my marshall (with 5881's right now).

I'm looking for more bass, more gain, and more overall crunch and clarity... right now its kinda flubby sounding... palm mutes are not tight at all.

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i went from chinese el34's to jj kt77's in my pittbull 100/cl. worlds different.


the power tubes arent going to have a big impact on the gain. but i'd say 6l6's or kt66's will have a little more low end than 5881's. as far as tightness and clarity goes though. i really liked that about the tung sol 5881's.

what marshall is it? i'd say to have it set up with el34, e34l, or kt77's since those are the tube types that marshalls are built around.

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KT66 is like a 6L6 but with a bit more mids.. very "flat", hi-fi tube.

If it's a 6L6 amp I'd recommend the SED 6L6.. great clarity, huge and tight bass, sweet tone.

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6100lm 30th anniversary lead mod. Would el34s/kt77's open it up? I just want a heavier sound, my mesa/sovtek 5881's are pretty sad sounding to me. Not enough bass, gain or clarity.

and about the gain, i notice HUGE differences in gain when i run it in triode or half power mode which is what makes me think that powertubes would have an effect.

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never heard a marshall with 6l6 type tubes that i liked. some jj e34l's would be my reccomendation. basically el34's but a little thicker on the bottom end. and not as much headroom as the kt77's.

as far as gain and the power section goes. its all about headroom, the half power mode may cut low end a little, but it'll distort the power section alot faster because less wattage = less headroom. 6l6 type tubes have alot more headroom than el34 type tubes and dont break up as smoothly. so by switching to el34's or e34l's your amp will saturate a bit faster.

have you changed the preamp tubes? some higher gain preamp tubes like tung sol 12ax7 reissues, high gain graded jj ecc83s's, or sovtek 12ax7lps's may help out a bit.

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i'm getting on that, i have 7 slots to fill.

V1 for clean
V2 shared between crunch and lead
v3,4,5 for lead (yet lead barely has more gain than crunch...)
v6 for crunch
v7 phase inverter

I just dont know what tubes to get, and if i should put them in certain places. Or should i just get a full set of a single type?

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If you want a bassier and clearer sound try KT88's or 6550's.. won't distort too soon though.

And for your preamp mostly anything will do.. Tung-Sol, JJ, Chinese.. just give us a description of what you feel lacking in each channel.

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cleans arent chimy or fat... theyre kinda dull, even with the bright switch on. If i cant get both out of a single tube, i'd go for more chime.

crunch is pretty good, but i'd like more gritty crunch and less fuzz... which i think can be achieved with something to give me more mids. I always keep them dimed because there just isnt enough.

lead... its basically a mushy, fuzzy, less vintage/more modern sounding version of the crunch channel. I want it to be more suitable for metal... tighter bass, less fuzz, more grit, and more aggressive/tighter attack

thanks so much guys

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You'd be disappointed with a tube swap.. change the amp..

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i dont think theres anything dissapointing from changing 14 year old chinese pretubes...

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14?? =)

V1: JAN GE 5751
V2, V4, V6: High-gain JJ ECC83S
V3, V5, V7: Chinese 9th gen (Some say balanced for V7.. I'm pretty neutral on this)

Power tubes: SED Winged C 6L6

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the jan 5751 is a pretty low gain tube. i used one in my old powerball to calm the amp down...

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Mu is about 70 for a 5751... Based on his explanation it is solely for the clean channel, so gain might not be an issue. Tone is beyond godly, very bright, chimey, fat & sweet at the same time. A bargain at the measly 20$ is goes for nowadays.. hehe i remember 5-6 years ago when you could buy a box full of NOS RCA 6L6's at 50$.. if i had only seen today coming i would stock up like a madman

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Awesome report on the KT77's, im looking at going balls to the wall and selling a bulk of extra gear to get an Egnater MOD100 and I was thinking what kind of tubes I would like to put in it. Each tube has its own adjustable bias so I can pretty much put whatever the fuck I want in there! Within reason of course.

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