Tube noob here !I've heard that a KT88 tube has a harsh breakup that really grinds on your ears. Is that true? If so, is there an alternative for a KT88-ish tone with an "ear-friendly" breakup?

Also what can you tell me about the tone of KT66 and KT77 tubes relative to the classic El34 and 6L6?
Quote by blackflag49
Condoms, for all the copious amounts of pussy with which you will be inevitably bombarded from this moment onward.

KT88s and their sister tubes, 6550s, are for applications where you don't want any breakup. They provide tons of clean headroom, and that's it. That's why they're popular in metal amps--they want the power section totally clean, so it doesn't alter the distortion from the preamp. Literally any other tube will have a better breakup.
KT66s are (in my opinion--this is all very subjective) like a warmer, sweeter version of a 6L6. Same general tone profile, but you get a wee bit smoother midrange. When they break up, it seems a little thicker, a little more harmonically rich, and without such an edge.
KT77s are like if you cross a 6L6 with an EL34. They've got more bass than EL34s, a touch more brightness and a little more headroom. It's a bigger, stronger, more articulate sound, but they won't give you the same compressed crunch an EL34 will.
However [disclaimer] most of the time changing the output tubes in your amp makes less difference to the sound than turning a random knob. The effects are subtle. Sticking EL34s in a Twin Reverb won't turn it into a Marshall. [/disclaimer]
Last edited by AeolianSeventh at Apr 10, 2011,
KT88 / 6550 are used in slash's signature AFD head and Zakk Wylde's signature head.

Both those guys sound quite good to me.

It probably depends on your preferences, what music do you play? what sound are you going for?
if you've got kt88s in breakup you are playing way to loud.
Jumping on dat gear sig train.
PRS Hollowbody II / BKP Warpigs
Strandberg OS6T / BKP Aftermath
Strandberg OS7 / Lace Poopsticks
Skervesen Raptor 7FF / BKP Warpigs
Skervesen Raptor 6 NTB / BKP Juggernauts
Hapas Sludge 7 FF / Hapas Leviathan
Anderson Baritom / Motorcity Nuke BKP Sinner Anderson H2+
Warmoth Baritone / BKP Piledriver
Ibanez Rg2120x / BKP Nailbomb

Blackstar ID:Core Beam
Dr Z won an award for his KT66 Amp, the Route 66...


The Route 66 received the first ever "Editors' Pick Award" from Guitar Player Magazine.

As far as sound goes...

The Route 66 is an all original Dr. Z design based on the incredible KT-66 tube originally built by Genelex. This tube generates the "Milkshake Thick" tones, as heard on John Mayall’s "Bluesbreaker" album featuring Eric Clapton (the "Beano Album" as it is known to many).

Video files are on the page to hear it too.

The great thing about KT66s is how they make the sound of the guitar ‘bloom’.
Turn up the volume and the guitar doesn’t distort or overdrive in the traditional sense.
Rather, the sound becomes increasingly fatter and more dynamic.
Winding both tone controls to the max increases the overall gain and volume, but due to the amp’s ability to retain clean-ish headroom at fairly loud volumes, you’d be advised to cart along a good overdrive pedal to goose up the front end a bit – for solos, say.
Last edited by BurstBucker Pro at Apr 11, 2011,