[connieflyer]

Well said,and spot on

 

[Scutey]

If anybody fancies a NOS pair of GEC KT88, how about these, a snip at £1,500
https://www.ebay.co.uk/itm/TWO-BOXE...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

[connieflyer]

And used besides

 

[DecentLevi]

Or how about this GEC TT21 for only $3,000 per tube - if you negotiate the cost down. It's a KT88 with a top cap which would need special adapter, and I presume it must do something special at these prices.


This and the above post are only the extreme examples but cheaper deals do pup up from time to time.

Meanwhile I've just found the black metal tubes RCA 6N7 / VT-96 to have SENSATIONAL synergy as drivers with KT66's as powers. Liquid mids, smooth highs, bass that's both controlled, earthshakingly strong and deep as the sea, and for a first time ever on my system it's a combination that synergises well with both my open and closed headphoens! I even tested it for you folks as a 'conventional' setup and the aforementioned system dependent issues while still present it was obvious top fidelity.

 

[Johnnysound]

..

 

[Johnnysound]

Tour of KT powers: First, Genalex Gold Lion KT77s...already burned in 100 hours plus



To reduce variables, decided to use well known and excellent sounding Valvos EL11 as drivers



Now fasten your seat belts, please



The Tung-Sol KT150 animals: Extremely fast, detailed, super Hi-rez, “big” sounding combo for which ultra deep bass was simply no problem at all...the deepest bass I have ever heard from Euforia. I think the EL11s drivers offered a much needed touch of warmth, refinement, “humanity” to the sound of these real beasts...that BTW behaved very nice, politely in Euforia, sounding much better as triodes than as pentodes. The KT77s, on the other hand, are really natural, kind of sweet sounding, very dynamic and musical tubes with nice bass, astounding mids & highs, like an EL34 on steroids (which they really are). And last but not least, I really liked the 7581As a lot in the same slots: a wide, accurate, different kind of sound (they say 6L6 family sound) that also has a nice touch of naturalness and refinement to it.

All preliminary impressions, of course: tried all of them as preamp tubes and in HP duties, and the KT150s proved that my modest Senn 579s were capable of MUCH deeper and tighter bass than I ever imagined, without a hint of distortion. The frecuency extension was enormous, up and above the very limit of the cans, but undistorted, very impressive. With top cans...the sky is the limit, I guess.

I bet that KT88s will offer more or less the same sonic picture, which is super accurate, with the strongest bass ever in Euforia...but it will be very different from the 7581A, KT66 (6L6 family) or the KT77 (EL34 family), each with its own, nice sounding signature. KT88 belongs to a different, proper “KT family” of high power pentodes (along with KT 90, 120 and 150) that go for great accuracy and power more than nuance, refinement...and in an HP amp (or preamp) like Euforia there are other important sonic variables to think about.

 

[DecentLevi]

Oh rats, expensive is better this time - this thread's getting more costly by the day but I don't think you're to blame alone, LOL.

CONGRATULATIONS on your super combo. It looks like you must be getting the utmost potential out of this wolf of an amp! Does the KT150 run very hot? Temperature measurements don't mean much to me, so as just a general idea is it getting hotter than, say, 6080 tubes? And if so by about how much? (2x more, etc.) Your bass descriptors sound amazing, but what about the top end / treble quality? And those HD-579's were my recommendation right?

 

[DecentLevi]

Also it's worth mentioning that most of these recent sensational results we've been having with the likes of KT66, 77, 150 as powers, 6N7 as drivers, etc. have been with adapters from Ms. Xuling most of which use brass pins and/or copper sockets (correct me if I'm wrong), which are far from the best conductor material, so these fine new discoveries could sound even better.

Brass may be badass but aint' no match for higher jazz like UP-OCC Single crystal silver.

 

[hypnos1]

Tour of KT powers: First, Genalex Gold Lion KT77s...already burned in 100 hours plus



To reduce variables, decided to use well known and excellent sounding Valvos EL11 as drivers



Now fasten your seat belts, please



The Tung-Sol KT150 animals: Extremely fast, detailed, super Hi-rez, “big” sounding combo for which ultra deep bass was simply no problem at all...the deepest bass I have ever heard from Euforia. I think the EL11s drivers offered a much needed touch of warmth, refinement, “humanity” to the sound of these real beasts...that BTW behaved very nice, politely in Euforia, sounding much better as triodes than as pentodes. The KT77s, on the other hand, are really natural, kind of sweet sounding, very dynamic and musical tubes with nice bass, astounding mids & highs, like an EL34 on steroids (which they really are). And last but not least, I really liked the 7581As a lot in the same slots: a wide, accurate, different kind of sound (they say 6L6 family sound) that also has a nice touch of naturalness and refinement to it.

All preliminary impressions, of course: tried all of them as preamp tubes and in HP duties, and the KT150s proved that my modest Senn 579s were capable of MUCH deeper and tighter bass than I ever imagined, without a hint of distortion. The frecuency extension was enormous, up and above the very limit of the cans, but undistorted, very impressive. With top cans...the sky is the limit, I guess.

I bet that KT88s will offer more or less the same sonic picture, which is super accurate, with the strongest bass ever in Euforia...but it will be very different from the 7581A, KT66 (6L6 family) or the KT77 (EL34 family), each with its own, nice sounding signature. KT88 belongs to a different, proper “KT family” of high power pentodes (along with KT 90, 120 and 150) that go for great accuracy and power more than nuance, refinement...and in an HP amp (or preamp) like Euforia there are other important sonic variables to think about.

Very interesting info there J...thanks.

It's once again evident that, as usual, so much is going to depend upon the rest of one's system as to the final results. For example, it's interesting to hear from DL that the inexpensive metal-encased 6N7 drives the KT very well, and that you found the 7581A so good in your own setup...the 6N7 not generally regarded as a top flight tube, good though it is, and myself and @connieflyer finding the KT66 appreciably better than the 7581A in all departments lol!

And so it certainly looks like the 7581A and/or KT66 is a tube that can - and should IMHO! - be included somewhere in anyone's system...they are both exceptional alternatives to any 6SN7/6N7/7N7/6AS7G/6080 etc....no question!! And now with well over 100hrs on all my 3 KT66s (2 as drivers to 1 as power along with an EL39 at present), their performance in my own system is so far ahead (objectively) of anything else before (especially with the Meze Empyreans), that if one has top flight gear elsewhere I suggest folks don't settle for less and just bite the bullet...go for the KT66 as both drivers and powers...But as usual, the choice is yours lol!

ps. From what you say about the KT88 J, I'm now much more interested than before even to see how it performs in my system. Perhaps the KT66s as drivers might well bring a tad more of the 'nuance and refinement' you spoke of. I suspect my Empyreans especially will have a good deal to play in this scenario lol ...CHEERS!...CJ

pps. And it would appear the best 'reasonably' priced KT66 is the Russian reissue Genalex Gold Lion...I personally can't fault this tube in any way whatsoever...

 

[hypnos1]

OK guys, wakey wakey....................KT88s in da house!!....................

First, I'm glad to say that Euforia has taken them - or, rather, one at the moment as partner to an EL39 for comparison purposes - in from the cold and with a warm and hearty welcome lol, just as with the KT66...And once again, just as if this amp was actually made for these tubes!

Even with only a few hours on it, this KT88 is already showing its true colours - more quickly than the KT66 in fact. Can't believe it really, so early in proceedings. But I suspect that although new and unused, these too have had pre-burn-in before shipment from the factory/wholesaler...nice!

Driven by the KT66, it's quite clear that this driver/power combination exceeds all expectations...and, in fact, I can't recall such a combination ever being tried before. I'm sure this is yet another discovery unique to our unconventional explorations...especially in a headphone amp! Although too early for definitive statements of course, already I would say it takes all the virtues of the KT66 and simply augments them. Bass - as expected - is even more thunderous, without being 'bloomy'/soft; stage is on course to be even more 3-dimensional; treble is still sweet, without losing 'spice'/bite, plus just the right balance of mids (for me, anyway) all combine to give an even more dynamic overall presentation.

And all this from just one as power (with the EL39)...can't wait to see how things are with the second 88 in place of the EL39. Plus, it's still in Mrsx's adapter, with my 2x 66s as drivers also in adapters, so things can only get better when I do away with the adapters and convert the tubes directly.

And so this result has brought a sudden halt to any idea of my approaching a manufacturer to (hopefully!) make a headphone amp specifically configured for these tubes...absolutely no need whatsoever. We already have a perfectly good vehicle for them IMHO...here in the Euforia! By some incredible fortune, its 6SN7/6AS7G circuitry is ideal for running tubes one could never have envisaged even not all that long ago, and to a standard that echoes everything one reads about them from high-end users...especially in line with each and every upgrade made to the rest of one's system. And the icing on the cake is that we don't really need to spend silly amounts of money on hallowed NOS examples - these Russian reissue Genalex Gold Lions take Euforia to levels never reached before (even though I've said this a good few times already with other tube discoveries lol!! ...these KT tubes truly are in a class of their own, and not, obviously, just for esteemed power amps!!).

And so @teknorob23 , you'd better get things hurried along with your new SE amp! And it looks like you're gonna have to add to your bursting tube collection after all @connieflyer ...best get selling off some more of 'em, mon ami!! And if more 'meat' is what you're after, @OctavianH and @LoryWiv , then any more than these tubes provide would surely lead to dangerous indigestion as far as I'm concerned! ...(but perhaps wait for others' findings first lol!).

Just a couple of not-very-good photos I'm afraid for now...low light levels (my excuse, anyway...) :



And one comparing the 88 on the right, to a 66 on the left.....no difference in size!!...most unexpected .



HAPPY LISTENING folks!...CJ

ps. IMPORTANT WARNING/ADVICE...even though being careful, I managed to insert the tube into Mrsx's adapter without the tube's locating lug fitting/staying nicely in the socket's hole...no wonder it didn't light up!!! And when trying to remove, it was in so tight that levering it out gently still broke off the lug!

I should have suspected something wasn't right while having to push the tube in much harder than usual...so be warned folks. Make absolutely sure the tube's locating lug fits snugly in its hole, and if it feels extra 'stiff', take it out, check for position and try again...This applies to all tubes when fitting into an adapter...just in case!...CJ

 

[connieflyer]

Can not wait to hear how the pair compare in powers to the KT66 as powers, might just have to go back on my word, one last time!

 

[connieflyer]

Noticed one thing with Mr.s X's adapters, with these KT66's they were a very tight fit. Don't know if it was the tubes or the adapters. Did you have the same?

 

[connieflyer]

Okay, so why are you continually twisting my arm? Okay, Okay I just bought a pair. Paid a little extra, they burn in all their power tubes for 72 hours so will have a head start on them.

 

[hypnos1]

Noticed one thing with Mr.s X's adapters, with these KT66's they were a very tight fit. Don't know if it was the tubes or the adapters. Did you have the same?

As I just mentioned cf (probably crossing your own post), the main problem (with the KT88's base at least) was its locating lug being able to be pushed into the adapter's socket without seating properly therein. But to be fair, I've found this in other situations in the past...hence the need to always be extra careful when inserting IMHO lol!!

And yes, both KTs are quite a tight fit in those adapters, but better that than too loose IMO!! But it can mean having to use the 'levering' out method to remove the tube, and this also requires great care not to lever one part too much at a time, in case the locating lug breaks!!...ie. lever all round the tube's base with a flat-bladed screwdriver a little at a time, and finish off with a pull (by the base, not the glass bulb, especially if an old tube!).

 

[connieflyer]

Had to do this with with 7581a's when I took them out to insert the KT 66's, so had to use a jewelers screwdriver carefully around the tube, a little at a time. Did you see my email to you?