A question about KT88's vs KT66's

[blasure82]

I know there are million and one topics on the subject of tubes and certainly these have been debated to death. Right now I'm running my RM100 on 50w as the dreaded failed tube light has went up one of the tubes after three years.

I've secretly been hoping for this day to come because now it's time for me to experiment with the sound of the amp a bit more and I'm trying to decide what tubes would be better. My amp came with JJ 6L6's and I originally wanted to replace them with KT88s. I play lead guitar in a black-thrash metal band.

No a few have pointed out to me that KT88s, while having great midrange tone, require higher volume levels to break up. If true would this be significantly higher? I'm currently running the master volume at 12'o'clock. Sorry if I sound like a newb but I'm used to 6L6s.

A few friends have said that KT66's might be the way to go as they have a good tone for my style of play. Anyone with any experience using these in a gig setting?

 

[GtrGear]

I don't think you should push KT88 into distortion!
KT88 feel stiffer, cleaner, thicker lows, topped highend.
Probably good if you use lots of preamp gain.
6L6 is more punch to me, smaller Q-factor of lows, cut thru highend.
KT66 more bluesier, vibe, nice for clean and breakup.

Amp design shouldn't be overlooked. Although you can hear differences
between powertubes, a VHT 2:50:2 with KT88 will never sound like a VHT 2:90:2 and vice versa. My 0,02 ct

 

[Bukak65]

I agree with Gtrgear on the description of the tubes. You might want to try the Eurotubes Big bottle 6CA7. It's a cross between a 6L6 and a EL34. I didn't like the 88's in the RM100. Seems to me the amp is really made for 34's or 6L6's. I've only use KT66's in a Marshall Plexi. I hope that helps?

 

[blasure82]

Thanks for your replies guys. After doing some research I think I will in stick with the 6L6s although I haven't ruled KT66's out completely either. Anyone know anything about them vs 6L6s?

 

[joey_truelove]

Thanks for your replies guys. After doing some research I think I will in stick with the 6L6s although I haven't ruled KT66's out completely either. Anyone know anything about them vs 6L6s?

Definitely do not rule out the KT66s. I prefer them to 6L6GCs any time of day, espec if treated like 30W bottles, as that give them the right amount of compression with no edgy trebles when 'clean'. Does marvels to your pedal or pre-amp distortion as to me they are the thickest and woodiest kind of outputs out there.

Then pushed into outputdistortion they're still kind of 'clean' yet barking with good separation although not as edgy as 6550s, 6CA7s, KT88s and those 'KT6L6s'. 6L6GCs sound ratty and oddly nassal by comparison, EL34s are more breathy and compress like mad.

Mind that the main difference between the KT66 and 88 is on one hand the Gm that is far higher on the KT88 so the rise time is higher, and on the other it has higher headroom, which as you know makes it harder sounding and less valvey even if running on full. Wouldn't use the 88s unless I wanted maximum headroom or if the amp eats 66s for breakfast.

 

[hmic10]

Just Replaced KT88s to Kt 66s
INCREDIBLE
They compress they can be clean, very warm better than 34s to my mind and defiently better than 6l6

 

[rblyn]

I still SWEAR by the KT88's, especially if you getting most/all of your gain from your preamp. Its the cleanest, thickest and punchiest tube I've ever used. Lately, I've been using two KT88's with two Winged C EL34's and and very, very happy with that too. Talk about mid range CRUNCH! The high end is NEVER brittle- The low end holds together- no flub whatsoever. I dont shoot for any power tube distortion- Im looking for depth and cut in the mix of my band. They can play a little stiffer than 34's but still very nice response. The KT88/EL34 combo might be the best- I keep going back and forth between that and running four GT KT88's. I've also heard good things about KT66 tubes but no so much for metal or high gain but as a nice bluesy type of tube. I think they are more related to the 6L6 sound so if you lean that way, the KT66's might be the way to go.