What are the best 6550/KT88 tubes for 2011?

[GregS]

But then a few people went off into the ozone talking about new age'y sort of ethereal traits of tubes that just was hogwash and is salesman or religious fanatic talk. It is one thing to like a brand of tubes but another to claim traits that are not part of the realm of things tubes can control. No one knows the amp the OP has, its condition, his playing style, the environment it works in etc, all of which are more influential in sound character than anything tubes can impart.

The problem is that there aren't words in the English language to describe different sound characteristics - so one does their best with what's available to try to communicate that. It's not about magical properties - there are real physical reasons behind why something sounds the way it does - but how do you communicate how something sounds in words?

[MstrB]

Thank you, I understand what you are trying to say. B.

[MstrB]

Thanks, I agree with you on these points. I have just had a lot of trouble with New Sensor power tubes shifting their bias point while on the probes. Have not had that problem with JJ or Svet. Since I need a matched octet for this amp the investment is significant.

[kg]

fwiw, i have found matching to be of little to no significance when talking about big power output stages with multiple parallel tubes.

in fact, i've found matching in general to be an overrated criteria for choosing tubes. (basically i balance each side's total q-currents +/- 10% and call it done.)

jm2c
ken

[mhuss]

Zombie thread alert!

I know this will produce anecdotal vs. statistically valid data, but which brand of KT-88s have proved reliable for you in the past couple of years?

I have a JJ KT-88 which gassed out (white snow globe) after 1.5 years of intermittent/light use in a practice room (Fender PS300), and the head was not not physically on top of the bass cabinet. It's only travels have been across the room between my workbench and the amp side. (Anecdote #1 )

[Leo_Gnardo]

No problems so far with JJ KT88 (in spite of JJ's spotty reputation for some other tube types.) OTOH I had a pair of EH KT88 showing signs of deep distress before the amp left the shop. Swapped in JJ's - no further problem, happy customer.

I'd like to hear from techs/musicians who have invested the extra $$ for supposed top grade Russian-made KT-88 GEC Gold Lion (another New Sensor label.) Are they really more rugged & less prone to failure? If so, that would be a reasonable trade-off for the extra cost.

[mhuss]

I was a bit disappointed by this failure, as I have also had pretty good luck with JJ overall (12AX7, EL34s and particularly 6V6), and their KT-88s seem well-built (thick glass, straight, ruggedly built).

[big_teee]

I have a small bit of power tube experience, but every JJ power tube I've bought has shortly developed problems.
I've had Good luck with JJ preamp tubes.
I have had no problems with New Sensor power tubes, EH & Sovetek.
Also had great luck with TAD power tubes.
It's a bad deal, because JJ power tubes always sound great!
T

[bob p]

I think that what JJ is selling as a 6V6 is a pretty strong tube. For a decade or so mine have had no problems dealing with plate voltages that strike fear into many a 6V6. But then I use rational screen voltages.

No recent experience with their EL34 or their 6550/KT88, but I've had zero problems recently with their 6L6, and I run a sextet of them in distributed load mode at 530 VDC. Ouch.

[bob p]

Funny that you necro'd this thread today, Mark. I was reading it last night.

[big_teee]

Funny that you necro'd this thread today, Mark. I was reading it last night.

I've been reading it also due to the new bass amp project!
Seems like a lot of bass amp activity lately!
T

[Bruce / Mission Amps]

I've been reading it also due to the new bass amp project!
Seems like a lot of bass amp activity lately!
T

I'm building a 100w lap steel 1X15 amp for a customer... he wants two KT88s. The PT I'm using will put about 600vdc into them.
Not sure which KT88 tubes to use either. I've had bad luck with nearly all of them over the years.

[Leo_Gnardo]

I'm building a 100w lap steel 1X15 amp for a customer... he wants two KT88s. The PT I'm using will put about 600vdc into them.

It's too bad the KT150 isn't out, tested & characterized as reliable yet - still a ways over the horizon. If the '150 turns out to be what it's supposed to, that would be the one for your project. I wouldn't trust any KT88 pair to make 100W @ clip with long term reliability. Better use 4, and you'll sail past the 100W mark with ease. It's that, or something a bit exotic like GM70 or EL156. Haven't used these last 2 so can't speak for their tone or reliability. I've been keeping an eye (and ear) out for the next big thing beyond KT88, and so far the KT120 doesn't seem to be it.

[bob p]

I wouldn't trust any KT88 pair to make 100W @ clip with long term reliability.

To get 100W out of a pair of KT88 I think the voltages would need to be pretty high -- like 670 or so, where the SVT puts them. I think you'd also need a driver circuit that means business -- something with enough current that it could push them into AB2 if it had to.

Reliability? why do you think a pair of them putting out 100W would be any less reliable than an SVT, using a sextet to put out 300W?

[big_teee]

To get 100W out of a pair of KT88 I think the voltages would need to be pretty high -- like 670 or so, where the SVT puts them. I think you'd also need a driver circuit that means business -- something with enough current that it could push them into AB2 if it had to.

Reliability? why do you think a pair of them putting out 100W would be any less reliable than an SVT, using a sextet to put out 300W?

Is that 300w a general term, or do you really get 300w output?
EBS sells a 2 6550 amp, and they call it 90 Watts.
http://ebssweden.com/
Does anyone know anything about the china made KT100?
It is supposed to be a beefed up KT88?