Is there any finer tube than a GEC KT88?

Why not a kilobuck? They work, tbat's why.

??

Let me explain this cryptic thread-opener.
The GEC KT-88 was the original Gold Lion British-made tube from the late fifties through the late sixties. They are built like tanks, and have a life expectancy of - wait - 20,000 hours. Generally considered the Holy Grail of the high-power 6550/KT-88 etc. family, pristine specimens fetch an astronomical price.
Are they worth it?
Let's take into consideration, first, the simple math. A quad of the new Russian-made Gold Lions (a fine-sounding tube) costs $230 from Jim McShane. My experience over three years is that a year of rigorous use dulls them , so $230 a year. Not too bad.
A quad of the real NOS GECs runs (gasp) almost $1500. from Andy Bowman of Vintage Tube Services. Look him up. He's a Legend.
So if the GECs last six years (a very conservative estimate) they are running even with the new GLs.
This does not take into account relative day-to-day performance. The GECs are simply by far the finest sounding power tubes I've ever heard. In every way. EVERY WAY. Top to bottom, back to front, side to side, quiet to loud, etc.
There are no words. Deepee says "They fill all the holes". Close, but until you hear them....
If your system is optimized - well-matched, well set-up, in a room optimized for it, these GEC beasts, which might run as much $$$ as your power amp, are worth the outlay. Don't believe it? Visit me in Central Mass or Dave in Idaho and we'll prove it.

The original GEC KT88 will take your VTA (dare I say Dynaco?) amp into depths and heights heretofore unexplored.
Kently's math is spot-on, especially if one is trying to convince a spouse as to one's pecuniary brilliance. (They know better but are demur enough not to say so.)
There is a certain je na sai quois that the KT88 delivers beyond even what our venerated Newark-built 6650s are capable of. Bigger plates? The fact that they're black and can pack more juice? That side-getters were a mere afterthought 'cuz they didn't need them?
No mathematical equation here. Just, listen to a quad in your not too distant future. If you don't hear a difference, I might just take them off your hands.

I have used the GEC KT88s in my Dyna Mk IIIs for over 28 years. Not continuous but pretty regular use. I lost a few during that time so consider it two sets in 28 years. The key is lower the idle current. I adjust the Biaset for 1.4-1.42VDC. That reduces the power use at idle to 87% of the original setting. Tested the present set last winter and they read twice the minimum.

I think they sound great but have never rolled other tubes thru to evaluate. The amps originally came with 6550s but that was long ago and I do not remember the difference in sound quality.

I found a life time supply of these at older hamfests and pulls from beat up amps. Not so easy anymore. Highly recommended if you can find them at a reasonable price.

i have been schooled on the lion, wow. im sure they made kt66's too no?

dmagazz wrote: i have been schooled on the lion, wow. im sure they made kt66's too no?

Insofar as I know, same guys.

WLT wrote:I have used the GEC KT88s in my Dyna Mk IIIs for over 28 years. Not continuous but pretty regular use. I lost a few during that time so consider it two sets in 28 years. The key is lower the idle current. I adjust the Biaset for 1.4-1.42VDC. That reduces the power use at idle to 87% of the original setting. Tested the present set last winter and they read twice the minimum.

I think they sound great but have never rolled other tubes thru to evaluate. The amps originally came with 6550s but that was long ago and I do not remember the difference in sound quality.

I found a life time supply of these at older hamfests and pulls from beat up amps. Not so easy anymore. Highly recommended if you can find them at a reasonable price.

I got mine on the cheap because the alignment keys were broken off. Pretty easy fix as the nos. 7 and 2 are on the base as well. Still managed to screw one up but nothing went pear-shaped. I use nail polish now to align them.
Would love to hear why, from some technophiles, as these antiques so audibly best their peers. Or am I just daft?

Another option? The GEC and MOV production are almost identical, and the new production TAD KT88str is based on the MOV design, fat heavy glass and evarthang. A matched quad will set you back around $300US.



Life expectancy? I know it's not unheard of for the British MOVs to be going strong at 50k hours. I've had my TADs for a bit over a year now - check back, oh, say around 2025 ... ;-}

As to the question about Genalex KT66. Attached is a photo of the two boxes I have of them. It does state on the side that these are "made for Genelex by its associated company the M-O valve Co."

These super-premium tubes (GEC KT-88) have spent only about 32 hours in my ST-120, but already I am sold.
My decidedly un-techie ears tell me one thing which stands out - these tubes have a far more accurate transient response than any modern tube. We're talking about microseconds. The piano sounds more present because it, well, IS, by virtue of the instantaneous reproduction of the complex attack profile (thank you, Stanley Kubrick).
For me the question is best phrased backwards:
Why don't modern-production tubes all sound this good?

P.S. I've not been often impressed with "NOS" tubes. These are a notable exception. So this is no knee-jerk reaction. If anything, I'm pleasantly shocked.

sweeet!

They fill in the blanks and plug in holes. That's what's good about them. Try 'em and don't like ''em'? I will happily take them off your hands.

as soon as i am able to get a set,i will. i have a bluesbreaker amp also,and it uses kt66's. my st 70 has and is set up for el34's. and i just realized that pin 1 has to be separated using the kt 66 in the st70.also plate voltages are different right?
i guess the actual direct swap is a kt77.

Has anyone tried the new EAT KT-88s? They're ~ $1,700 a quad from Tube Despot and the Tube Store. Too rich for my blood and I'm not aware of any serious reviews on them.

and here is my humble opinion...I know....but the finest KT88 tube/s, or any other model tube for that matter, is the tube that sounds best to your ears in your system...period!
I have run the KT88 Lion in my system, love them. I have run the Russian made 'Mullard' KT88, great tube but needs a good while though and I have run the 'modest' EH KT88, actually currently in my system, again, after a good number of hours, a great sounding tube.
So the bottom line, to my ears, they all sound great.
On a side note, I did try some Shuguang and PS Vane KT88's on a trial basis from one of my suppliers.....really quite terrible, crackle, pop, noisy...right from the get go.

erhard-audio wrote:and here is my humble opinion...I know....but the finest KT88 tube/s, or any other model tube for that matter, is the tube that sounds best to your ears in your system...period!
I have run the KT88 Lion in my system, love them. I have run the Russian made 'Mullard' KT88, great tube but needs a good while though and I have run the 'modest' EH KT88, actually currently in my system, again, after a good number of hours, a great sounding tube.
So the bottom line, to my ears, they all sound great.
On a side note, I did try some Shuguang and PS Vane KT88's on a trial basis from one of my suppliers.....really quite terrible, crackle, pop, noisy...right from the get go.

Thanks for the post. I agree what one person hears another does not. I am not saying that all tubes are alike or am I.
This hobby has many conundrums that seem to be solved every day only to add more conundrums with people changing the formula.
When I am considering tubes or anything involved with this "hobby that never ends" I think of the value. What dollar amount is going to make me more content than I already am with my system.
Presently I have Sovtek KT 88's with another Quad as spares, Mullard rectifiers and Mullard driver tubes and GE 12BH7A in phase position. I have the m125's with my 803diamonds and I cannot be happier. Also I don't think it is JUST the tube, it's the entire system working harmoniously. The right combination makes the difference and once you found it DON't DO NOTHIN!
Just my 2cents

Unlike Erhard, I haven't the same miserable experience with Chinese tubes he has. They can be dreadful for the first 10 hours and aren't fully broken until they hit the 100-hour mark, but when they do, they're a very sweet-sounding valve. When considering them, keep in mind that about every 15th or so KT88 is going to be a lemon, and not worth the postage to return them. Chinese QC has improved over the past 5 years but they ain't there yet.

deepee99 wrote:Unlike Erhard, I haven't the same miserable experience with Chinese tubes he has. They can be dreadful for the first 10 hours and aren't fully broken until they hit the 100-hour mark, but when they do, they're a very sweet-sounding valve. When considering them, keep in mind that about every 15th or so KT88 is going to be a lemon, and not worth the postage to return them. Chinese QC has improved over the past 5 years but they ain't there yet.

I agree, to a point, that for the enthusiast/owner of a tube amp, a new out of the box 'noisy' tube might be acceptable, provided that it settles down after a number of hours of operation.
As a new equipment supplier, that is not acceptable to me. The amp I build for a client needs to work 100% when I ship it, including the new set of tubes. And I don't mind admitting, it has been a steep learning curve for me as a new equipment supplier to get to that 100%!
A new built amp will only run for X amount of hours before it is shipped, so even new out of the box tubes must sound and behave as a client expects them to when they first power up their new amp.

While back I emailed TAD to see what the next step up from their KT88str would be ... they recommended the KR Audio KT88. Around $2K US for a matched quad.

Holy smokes! I'll stick with my decrepit GECs. Besides, it's nice to have Marconi in the loop.

sKiZo wrote:While back I emailed TAD to see what the next step up from their KT88str would be ... they recommended the KR Audio KT88. Around $2K US for a matched quad.

NUTS!!!...