[mordy]

I am interested in this as well, noting the KT88 - KT66 pairing requires higher volume settings to achieve similar loudness versus more conventional tubes in my Elise. It is not generally problematic but at times the sound feels a bit less robust than I'd like at lower volumes with the KT's. Is it likely this aspect will "self-correct" over time?

It appears to me that the mu (multiplifaction factor) is lower in these tubes and hence you need a higher volume setting to achieve the same loudness. Have not been able to find the mu for the KT tubes. As long as you get enough volume for your needs without distortion I don't think it matters.
I have made the same observation as cf on a number of occasions - as a tube burns in it operates at a lower temperature compared to when new.

 

[hypnos1]

It would be interesting perhaps a little later in the thread to see what we have all decided is our favourite combination 7581/KT66/KT88. And wether said combination is good for all genres. Personally I'm awaiting second pair of KT88's so still undecided.

Ah bt...the somewhat IMHO vexed question re. 'genre suitability/preference' of different tubes.

For a long time now I have thought this an often confusing/contradictory subject, and am fast coming to the suspicion that given tubes that can all basically do most things extremely well, it isn't in fact the tube/genre that should be the focus but the rest of one's gear and how it all interacts in final delivery...more so even than personal preference. When you have various tubes that are fairly equal in handling bass/treble/attack/speed/timing/dynamics etc., with masterly control and balance, then it would seem logical IMO to assume that it is actually the recording that will determine the overall sound effect...the degree depending, once again, upon the rest of one's system. This is my own take on the subject anyway...for what it's worth lol .

I am interested in this as well, noting the KT88 - KT66 pairing requires higher volume settings to achieve similar loudness versus more conventional tubes in my Elise. It is not generally problematic but at times the sound feels a bit less robust than I'd like at lower volumes with the KT's. Is it likely this aspect will "self-correct" over time?

Hi LW. These tubes do all need higher volume settings than those configured for, but as @connieflyer says, this may alter somewhat over time. The precise amount will also depend upon the input level from source/DAC of course (and which will probably also affect slightly the 'robustness' you mention, especially at low volume levels).
I also suspect this could be partly a factor in the difference between Elise and Euforia...such differences IMHO being greater than sometimes realised by folks lol! And as with my statements above, different systems are also surely going to be a factor in this aspect of sound delivery.... I myself for example have only ever been pleasantly surprised at maintenance of superlative performance even at low listening levels.

Whatever, I do hope that this aspect eventually moves closer to your own preferences...but I will say that the quad KT88 combo does take everything up at least 1 notch, and a good few areas more than 1 lol ...CHEERS!...CJ

 

[hypnos1]

I've used my IR thermometer to find out at what temps are these tubes operating. If the 6SN7 <-> 6AS7 combos were like 60C <-> 150C the KT66 <-> 7581A are around 90-100C <-> 60-70C. These measurements are not precise, but just to have an idea, I guess they are fine.
So the output tubes are 50% colder but the drivers go a little bit over the 6SN7. Measurements were made after 3 hours of listening, on this setup:

Hi OH...what really counts of course is the temperature of the amp and its internal components. My own amp (case) runs even cooler with these KT tubes than with the ELs which had every single internal component running 10 deg C cooler, and the area immediately below the trafo a massive 20 deg C cooler!! Something that appeals to me enormously...especially as an added bonus to all the KTs' other virtues lol .

 

[OctavianH]

I was just curious about the temps these are reaching, because after all, using adapters, I guess the impact of the heat on the amp is reduced. But indeed, these KT tubes have many virtues. I am a believer.

 

[LoryWiv]

Can’t keep up with you - thought that the KT88 was the end game, and now there are other alternatives already.....
ECC31/FDD20
EL3N
EL11
EL11N
EL32
EL38
EL39
KT66
KT88
TT21
It never ends! There are 13,000 types of tubes......
PS: Did I leave something out?

I'm actually considering KT77 driving KT88 powers as my next iteration to try. @Johnnysound had good things to say about a quad of these, thought I'd try 2 driving the KT88 before upping the ante.

 

[Scutey]

Quick update on the KT150. I would describe it as an impact tube, a super sub, not an all rounder, but get the genre/recording right and they sound spectacular, they seem to go well with hard rock/metal, well recorded contemporary jazz, and most types of electronica, as @Johnnysound mentioned they do need a warm driver, else they can sound too, clinical, aggressive, both the 7581A and GEC KT66, warm them up enough without sacrificing, the great drive they have. Also it's worth mentioning the Euforia chassis doesn't seem to get much warmer than with the KT88 either, I get the impression that despite the big muscular sound they're barely ticking over.

 

[Johnnysound]

Thank you for sharing these impressions. I have just installed and begun evaluating 2 GL KT88 powers driven by 2 GL KT66 into Elise. 1st impression is that these provide amazing clarity, detail, soundstage with by far the most realistic instrument placement I've ever encountered. In a string quartet recording each instrumental voice emanates from a distinct and well-defined space. Tonality is nicely musical but in this early stage a bit dry / clinical, hoping for a bit more euphony with further burn-in. If that doesn't occur I may try the TS 7581A as drivers, and of course per @hypnos1 amd @connieflyer at some point may acquire two more GL KT 88's to run as a quad.

it would be interesting to hear if anyone has tried KT88 as powers driven by KT77 in search of the best charactersitcs of KT88 (detail, stage, extension and overall "authority" for lack of a better word) with the KT77 midrange "magic" decribed above by @Johnnysound of the KT77. In any case, this journey with our amps is certainly great fun and musically rewarding. Thanks to all for the great input shared on this forum.

Yes LW, will surely test the KT77s/ KT88s combo as soon as I receive my new 88s, which btw are not GLs but the newest “super premium” Shuguang GEKT88...as much as I like the GLs, my PA is warm sounding itself, and the GEKT are supossedly very neutral, open and lively...we’ll see.

Those GL KT88 should warm/sweeten up after some decent burn in @LoryWiv , mine in the early stages sounded exactly as you've described, they now sound wonderfully sweet without loosing any clarity or detail. Also like you I'm interested in the KT77 too, especially after @Johnnysound excellent review, I must admit I might well get some next week.

On another note, again after @Johnnysound's review I've managed to pick up a used quad of TS KT150 in what appears to be excellent condition off you know where for £41, so far, they seem like a bargain, I can't really add much from what has been said but so far am really enjoying them, very clear, clean, big, full, muscular sound, and very dynamic,great extension at both ends, bass goes super deep, but is also very clean, no bloom/bloat,mids are also very detailed and full, less sweet than either KT66 or 88, I wouldn't call them refined but they are most certainly giving a fun sound!, also I have to say greatly improved when driven by a pair of NOS GEC KT66, which just give them a bit of extra body and tone.

Hi Scutey, a quad of KT150s for £41 is not a bargain, but a true gift !! And I concur absolutely with your impressions, exactly the same as mine: these are excellent sounding power tubes in Euforia, specially when driven by a pair of “classic” drivers that really improve their sound with more body and warmth. I wish I had a pair of NOS GEC KT66, but in the meantime a pair of Valvos EL11s did the job very nicely...

Hi J...and thanks for your very interesting comments on the GL KT77, and glad you love the sound as quartet in Euforia - yet another wonderful tube for our amps (and us!) to enjoy . Plus, from the sound of it, further grist to the KT77 vs KT88 debate lol!

I myself continue to be so enthralled with each and every one of my stalwart favourite test tracks/albums that I'm finally happy to say that my tube experimentation/testing is truly at an end...but I look forward to others' findings of perhaps a mix using these KT77s.

Once again, who would ever have dreamt that we could use these tubes to such great effect in our OTL amps...particularly as both driver or power, and especially as a quad lol!! And once again also, many thanks indeed must go to @ZRW0 for setting us on this trail by suggesting I try converting the 7581A...the rest is now history!

ps. Any thoughts about trying the KT88 yourself J? From the sound of it you've already got quite an arsenal of tubes lol!! ...CHEERS!...CJ

Hi CJ, as said above will soon try the 88s...only a “new” flavor, not exactly the GLs. Upon extended listening to the quad of GLKT77s, my initial impressions are confirmed, and I came to the conclusion that the 77 is a different animal from the classic EL34: yes, a good bit of the latter famous midrange, but the similarities end there. The 77s are NOT polite or “laid back” sounding in any way, not so dense but more nimble, lively and direct, very dynamic, detailed, with “fast” bass. Remarkable sound for a “new production” tube. While as a preamp this kind of sound was ideal to balance my tube PA slightly “warm” character, with my Senn HPs the sound was decidedly on the sharp, upfront, “hi rez” side of things: extremely clear, crisp, detailed, with soaring highs and deep, punchy bass. As tastes go, you may say a bit “forward”, maybe without that ultimate touch of refinement or “relaxation” of some NOS tubes, but a lot of fun !!

 

[LoryWiv]

Yes LW, will surely test the KT77s/ KT88s combo as soon as I receive my new 88s, which btw are not GLs but the newest “super premium” Shuguang GEKT88...as much as I like the GLs, my PA is warm sounding itself, and the GEKT are supossedly very neutral, open and lively...we’ll see.



Hi Scutey, a quad of KT150s for £41 is not a bargain, but a true gift !! And I concur absolutely with your impressions, exactly the same as mine: these are excellent sounding power tubes in Euforia, specially when driven by a pair of “classic” drivers that really improve their sound with more body and warmth. I wish I had a pair of NOS GEC KT66, but in the meantime a pair of Valvos EL11s did the job very nicely...



Hi CJ, as said above will soon try the 88s...only a “new” flavor, not exactly the GLs. Upon prolonged listening to the quad of GLKT77s, my initial impressions are confirmed, and I came to the conclusion that the 77 is a different animal from the classic EL34: yes, there is a lot of that famous midrange, but the similarities end there. The 77s are NOT polite or “laid back” sounding in any way, but lively and direct, very dynamic, detailed, with “fast” bass. While as a preamp this kind of sound was ideal to balance my tube PA slightly “warm” personality, with my Senn HPs the sound was decidedly on the sharp, “hi rez” side of things: extremely clear, crisp, detailed, with soaring highs and deep, punchy bass. As tastes go, maybe without that ultimate touch of refinement or “relaxation” of some NOS tubes, but a lot of fun !!

I went ahead and ordered a pair of GL KT77's to drive my GL KT88's and have high hopes for this combo. in Elise. I'll report out once they arrive and I have a bit of time to evaluate.

 

[Scutey]

Hi Scutey, a quad of KT150s for £41 is not a bargain, but a true gift !! And I concur absolutely with your impressions, exactly the same as mine: these are excellent sounding power tubes in Euforia, specially when driven by a pair of “classic” drivers that really improve their sound with more body and warmth. I wish I had a pair of NOS GEC KT66, but in the meantime a pair of Valvos EL11s did the job very nicely...

Indeed it is Johnnysound, for the price I paid I thought there had to be something wrong with them but no, so far, so very good, the seller also sold a quad of TS KT120's, they sold for £28!, I have a pair of Valvo EL11 and sound very good with them too, but if you have the chance, I will heartily recommend the GEC KT66 it has the classic, British tube sound, they give the 150, great weight and presence, whilst also being very detailed and holographic, they sort of polish the 150 without diluting what makes it such a great power tube.

 

[Johnnysound]

*

 

[Afsa]

Hello Guys

i would really like to try the KT88 on my Euforia. But i have no experience with tube rolling.
Do i need an Adapter to use the new tubes or can i just slot them in?
Thx for your help in advance

 

[Scutey]

Hello Guys

i would really like to try the KT88 on my Euforia. But i have no experience with tube rolling.
Do i need an Adapter to use the new tubes or can i just slot them in?
Thx for your help in advance

Hi Afsa, and welcome to the Euforia thread!. In answer to your question, yes, you will need adapters to use the KT88, or for that matter the KT66/77 (same adapter) etc, here's a link for the adapters.

https://www.ebay.co.uk/itm/1pc-Gold-6L6-7581-instead-6AS7-tube-converter-adapter-For-Elise-Euroria-amp/193142155772?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

[OctavianH]

Or if you prefer to order an adapter from Europe you can contact @Deyan

These are adapters made by him:

 

[Afsa]

Hi Afsa, and welcome to the Euforia thread!. In answer to your question, yes, you will need adapters to use the KT88, or for that matter the KT66/77 (same adapter) etc, here's a link for the adapters.

https://www.ebay.co.uk/itm/1pc-Gold-6L6-7581-instead-6AS7-tube-converter-adapter-For-Elise-Euroria-amp/193142155772?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Or if you prefer to order an adapter from Europe you can contact @Deyan

These are adapters made by him:

Thank you for your answers.
And can I just populate all 4 Slots with for example these tubes https://www.tubeampdoctor.com/gold-lion-kt88-genalex/russia?number=NN-GL-KT88-MQ ?
Or do i have to use different power and drivetubes?

 

[OctavianH]

Yes, you need to order 4 adapters and you can put 4 x KT88 Gold Lion on Euforia (the ones from your link). See here a post related to such a configuration:
https://www.head-fi.org/threads/fel...sheeps-clothing.831743/page-496#post-15343710