[LoryWiv]

Really good find. I feel the same about GEC KT88'S and have collected eight in various forms regular 88, TT21 and TT22. I've read in various forums that 500000 hrs is not beyond possibilities for this tube so I expect KT66 especially using our amps could also come close.

Don't TT21, TT22 variants require a different adapter due to top anode, and TT22 external heater to supply needed voltage? Wondering if you've tried 6550, 6550A which appear more "drop-in" compatable with KT88 using 6Vg to AS7 adapters such as those from Deyan.

Thanks, @barontan2418.

 

[barontan2418]

Hi LW.
Correct about adapters for TT21/22, Deyan made them for me. As for external 12 v psu this I already have for GU50's. I have both GE 6550's and Tung sol both of which I use along with GE 7581's for Elise. KT88's are being used in Euforia along with GU50'S. Like you I have so many tube combinations that work really well in our amps I shall only now buy replacements if or when needed.I can see your still enjoying your tube rolling so best of luck and enjoy.

 

[LoryWiv]

Hi LW.
Correct about adapters for TT21/22, Deyan made them for me. As for external 12 v psu this I already have for GU50's. I have both GE 6550's and Tung sol both of which I use along with GE 7581's for Elise. KT88's are being used in Euforia along with GU50'S. Like you I have so many tube combinations that work really well in our amps I shall only now buy replacements if or when needed.I can see your still enjoying your tube rolling so best of luck and enjoy.

Thanks, man, very helpful. Any sound quality differences between GE and Tung-Sol 6550's? I've been interested in trying 6550 to replace my new production GL KT88 but not sure which not sure or how they differ.

 

[OctavianH]

I own a pair of GE 6550A and the first word which comes into my mind is "clean". I was never very good at describing sound but I can say that these are for me like the TS 7236, less bass, very clear and clean sound on all the frequency range with a wide sound stage. This is why I thought about them when you described your VT-115A, I recognized what I heard in the GE 6550A in your description. I do not have the TS 6550A but from what I've read on several threads they are warmer than these, so more bass at a slight cost of clarity. Compared to KT88, I guess KT88 has a deeper bass but they are somehow drier and sterile compared to these. Well, I cannot describe more but maybe someone will add here some better descriptions.
I would pair the GE 6550A with warmer drivers to shine, for example I tried them with EL32 and liked what I heard.

 

[OctavianH]

1976. Black Sabbath was releasing Technical Ecstasy where the last track is Dirty Women. GEC was manufacturing these KT66 tubes used as powers in my amp.

44 years later I am here. The tubes have 44 years, the song the same. I am younger, but close. Time passes.

 

[OctavianH]

I read this article, which I find a little bit silly, but anyway, for those interested in KT88:
https://medialux.blog/2020/03/25/gec-kt88-the-king-of-power-tubes-part-1/

After reading this I wonder how an amp designed for KT66/77/88 sounds. Because I am sure that in our amps, via our adapters, we are not listening to the true sound of these tubes. Maybe we like it being distorted and if we buy such an amp, correctly biased for them, we will not like it. I would be very curious to know if someone tried KT tubes in Feliks amps and had the chance to listen to them in other amps built for them, to make a comparison.

 

[barontan2418]

I read this article, which I find a little bit silly, but anyway, for those interested in KT88:
https://medialux.blog/2020/03/25/gec-kt88-the-king-of-power-tubes-part-1/

After reading this I wonder how an amp designed for KT66/77/88 sounds. Because I am sure that in our amps, via our adapters, we are not listening to the true sound of these tubes. Maybe we like it being distorted and if we buy such an amp, correctly biased for them, we will not like it. I would be very curious to know if someone tried KT tubes in Feliks amps and had the chance to listen to them in other amps built for them, to make a comparison.

I've read this article in the past and have wondered the same. I'm using GEC KT88 of all three varieties, TT21/TT22 and regular KT88"S along side GU50'S as powers in different combinations and love the results. Like you I doubt we are hearing anything like their true capabilities. I might well in the future look out for a headphone amp that runs on KT88's most of the reading I've done has been associated with guitar amps but hopefully there are amps designed for headphones also?

 

[OctavianH]

I've read this article in the past and have wondered the same. I'm using GEC KT88 of all three varieties, TT21/TT22 and regular KT88"S along side GU50'S as powers in different combinations and love the results. Like you I doubt we are hearing anything like their true capabilities. I might well in the future look out for a headphone amp that runs on KT88's most of the reading I've done has been associated with guitar amps but hopefully there are amps designed for headphones also?

Yes, there are a few, but for a while I look at this one:
https://www.wbamp.com/product/virtus-01-headphones-otl-tube-amplifier/

However, I was never brave enough to order it, and I am quite pleased about Elise. Since I've discovered the KT66 and the GE 7581A everything changed for me, in a good way.

Later edit:

And when the weekend is starting and the good music alongside a good beer is the perfect way to embrace it, crap HAPPENS. Well, while listening and enjoying music everything stops. I said "The DAC died". Luckily me not. After several investigations I realized that the Sbooster is the problem. I use this Sbooster 5V LPS to power JCAT, the USB PCIex card which connects my music from my PC to the DAC. Well, this card is externally powered and it seems Sbooster is not providing it 5V. Why? It seems the fuse is the problem.
So yes, why to enjoy a nice evening with your tubes and a beer when you can start to measure stuff in your LPS to find the culprit.

And the Sbooster 5V inside:

 

[OctavianH]

But the best way to test your KT tubes is heavy metal.

 

[Scutey]

Yes, there are a few, but for a while I look at this one:
https://www.wbamp.com/product/virtus-01-headphones-otl-tube-amplifier/

However, I was never brave enough to order it, and I am quite pleased about Elise. Since I've discovered the KT66 and the GE 7581A everything changed for me, in a good way.

Later edit:

And when the weekend is starting and the good music alongside a good beer is the perfect way to embrace it, crap HAPPENS. Well, while listening and enjoying music everything stops. I said "The DAC died". Luckily me not. After several investigations I realized that the Sbooster is the problem. I use this Sbooster 5V LPS to power JCAT, the USB PCIex card which connects my music from my PC to the DAC. Well, this card is externally powered and it seems Sbooster is not providing it 5V. Why? It seems the fuse is the problem.
So yes, why to enjoy a nice evening with your tubes and a beer when you can start to measure stuff in your LPS to find the culprit.

And the Sbooster 5V inside:

That's a bummer, now I know why you've had a crappy day now, frustrating when all you want to do is chill out and listen to some wicked tunes, hope it doesn't mess things up for too long.

 

[OctavianH]

That's a bummer, now I know why you've had a crappy day now, frustrating when all you want to do is chill out and listen to some wicked tunes, hope it doesn't mess things up for too long.

I read the F.A.Q. on the Sbooster website and that fuse has to be an audio slow blow 20x5mm 250V 400mA but honestly, nothing seems to be audio about that LPS. So I guess any fuse is the same. Unfortunately I do not have one at home at the moment.

An article about guitars, amps and tubes:
https://www.samash.com/spotlight/tubes-and-tone-understanding-different-amplifier-tubes/

And an excerpt from the article:

KT66 Tubes

The KT66 tube was introduced by Marconi-Osram Valve Co. in 1937. In design it is very similar to the 6L6. KT66 tubes generally have thicker glass and are wider and taller than 6L6 tubes. While they work in any amp designed for a 6L6 (if it fits), the KT66 draws more current from the heater. It is a good idea to check with an amp tech to make sure your amp can handle the extra draw.

The tone is often described as “big” compared to a 6L6. Open and dynamic with little compression and smooth, singing sustain when pushed hard. Also, this tube is more robust than most.

KT88 Tubes

The KT88 tube was introduced by MO Valve Co. in 1956 as a larger variant of the KT66. It is still considered one of the best sounding power tubes for hifi audio amplifiers.

KT88 tubes are currently made by New Sensor, JJ and Shuguang.

Marshall used them in their 200 watt Marshall Major amps. KT88’s were also used in Hiwatt Custom 200 and 400 bass amps. They can be used as a substitute for 6550 or even EL34 tubes, if you’re looking for tighter, cleaner tone with less distortion.

 

[OctavianH]

Listening this morning to the Paradise Lost - One Second album is an absolutely incredible experience for me. The M Scaler is adding an incredible depth and edge to the sound.

If you really want to experience most of your CD collection, and I have a big one, you should add M Scaler. Incredible!

 

[OctavianH]

Anyone heard of the brand Tronix before? Seems related to Brimar or maybe some rebrands. I look and these wondering how they would sound on Elise. 6.3V/0.45A.

 

[LoryWiv]

Anyone heard of the brand Tronix before? Seems related to Brimar or maybe some rebrands. I look and these wondering how they would sound on Elise. 6.3V/0.45A.

Can't speak to this brand but I have several types of 6V6's that sound great as drivers in Elise, w/adapters of course.

 

[OctavianH]

I think we should go this path to try the 6V6 and all the related ones, but I am lazy and I promised my wallet to let it live.

In the meantime I needed some bass because I exchanged my interconnects to burn in an older pair I never liked enough and almost forgot about, so I just switched the powers: KT77 instead KT66. Problem solved, let the music flow

One thing I do not like at these KT77 is that they reach much higher temps than KT66 and it is not very clear for me why. In rest, all perfect.

Later edit:

So we discuss about 120C @ KT77 vs 60C @ 7581A and the KT66 are at the same level when used as powers.