[hpamdr]

I didn't mix them. Does this look like it's 1/3 gone?

WHat's the next song !

you got sword back !

 

[UntilThen]

you got sword back !

You have no idea.... after a bit of whiskey how I manage to take such pictures.

 

[OctavianH]

Guys, just found out that KT55 exists. There is a pair selling on Ebay in US at a small price compared to KT66.
I think this might be compatible with Eternity but biases at -30V for 20mA/200V?

I have to admit I never heard about this tube before.

Later edit: WOW 50 Volt heater?

 

[triod750]

50 volt heater?

 

[OctavianH]

50 volt heater?

This is exactly what I was looking. I have to admit that looking at the picture and pin layout I did not pay attention to the Vh. 52V. WOW.

 

[hpamdr]

Guys, just found out that KT55 exists. There is a pair selling on Ebay in US at a small price compared to KT66.
I think this might be compatible with Eternity but biases at -30V for 20mA/200V?


I have to admit I never heard about this tube before.

Just have to heat at 52V, hope you did not clicked on the ebay link !

 

[OctavianH]

Just have to heat at 52V, hope you did not clicked on the ebay link !

Absolutely not. I was looking and when I saw the picture said to myself "hmm, these look identical with GEC KT66 grey glass". Then I saw the KT55 on the boxes and googled it, found the datasheet on Valve museum and looked a little bit on the pinout, seemed similar to KT66. What I have not done because I was not paying attention, was to look at Vh. I have to admit my brain somehow associated the shape to KT66 and never thought that these are not 6.3V. Interesting anyway.

 

[triod750]

But you could afford 52 volt, could you not? You are full of volt, ampere and beer. This isn't much of a problem!

 

[OctavianH]

But you could afford 52 volt, could you not? You are full of volt, ampere and beer. This isn't much of a problem!

I would not combine beer with volts or ampere, can be dangerous.

 

[triod750]

I would not combine beer with volts or ampere, can be dangerous.

Just remove the ampere then .

I know that you are careful.

 

[OctavianH]

Gaining confidence in EL32 from the previous experiment with the Mullards, I have decided to measure and try the Marconi EL32. I have 4 pieces of these and I remembered from the past that these sound different than the others, towards a more neutral sound. With EL3N these were harsh, but with 6J5 they start to sound better.

What was strange measuring these 4 pieces was that 3 of them were around -16.x and one measured -18.5V for 20mA. It was not a problem for me to find a matched pair, but the question arises: If we plan to make a table with recommended values for each tube type and the tube tolerances are so wide, how can we be sure someone will not damage the amplifier? I mean, that tube measuring -18.5 at the -17V which I would propose as bias, would exceed 24mA. If we raised the value of bias around -18V to be sure no pair exceeds the limit these go much under what we desire. According to the datasheet, these should bias around -17V.

 

[OctavianH]

Victory!

After hours of thinking, measurements and so on, I managed to make one mixed pair of KT77 work safely in Eternity! KT77 works! It is the strong pair, biased so both tubes are in decent range and no danger for the amplifier is possible. I monitor via the meter the stronger piece from the pair.

And what a beautiful tone, KT77 are incredible! Warm and relaxed, yet very rich in tone, exactly like I was hearing on Elise on Friday. But on Eternity this kind of tone complements the analytical/clean sound of the amplifier and sounds much better than on the already warm Elise.

Ok, I will stop here, today I learned several things, it was a day full of surprises and experiences. Now it is time to relax and listen to ... the music.

 

[OctavianH]

I have to come back with some more details about the GEC KT77 in Eternity at 200V/20mA. It seems these reach over 100C and even the logo starts to degrade. These were NOS but it seems after several hours at 100C the logo starts to burn slowly. I carefully monitor the temps and also the currents, the amplifier works fine, however, these seem to be the hottest tubes used by me until now.

The logo looks darker and with some black points on it compared to yesterday, this is the reason so many have no logo at all on Ebay or other collections:

The glow is incredible, these are some of my most beautiful tubes. I love them. The sound is creamy, warm but very rich in the mid section, emotional and lively. I start to become very curious about EL34 because it has to be in the same area and I start to realize I am totally into this kind of magic. I remember what @UntilThen said yesterday on the Destiny thread that he liked most the RFT EL34 and then KT88. I start to think if he was also enjoying such kind of sound I hear now and honestly, tops everything I heard until now. Ok, might be excitement of the moment because I wanted so much to listen to KT77, but I think it is also a very good synergy of this clean and fast amplifier with a very creamy and romantic tube. Many wrote on different forums that EL34 is incredible, I have a feeling I start to understand.

 

[hpamdr]

I have to come back with some more details about the GEC KT77 in Eternity at 200V/20mA. It seems these reach over 100C and even the logo starts to degrade. These were NOS but it seems after several hours at 100C the logo starts to burn slowly. I carefully monitor the temps and also the currents, the amplifier works fine, however, these seem to be the hottest tubes used by me until now.



The logo looks darker and with some black points on it compared to yesterday, this is the reason so many have no logo at all on Ebay or other collections:



The glow is incredible, these are some of my most beautiful tubes. I love them. The sound is creamy, warm but very rich in the mid section, emotional and lively. I start to become very curious about EL34 because it has to be in the same area and I start to realize I am totally into this kind of magic. I remember what @UntilThen said yesterday on the Destiny thread that he liked most the RFT EL34 and then KT88. I start to think if he was also enjoying such kind of sound I hear now and honestly, tops everything I heard until now. Ok, might be excitement of the moment because I wanted so much to listen to KT77, but I think it is also a very good synergy of this clean and fast amplifier with a very creamy and romantic tube. Many wrote on different forums that EL34 is incredible, I have a feeling I start to understand.

Glad you fixed the issues with KT77, so many experiment is really great !
My excitement to get my amp increase so much... (I will not experiment with so "aristocratic" tube as i do not have any but my list of potential good combination still grow.)

Rolling with manual bias seems to not be so painful if you use the right parameter ! Eternity is a flexible beast in fact

Finally the conclusion is that Eternity gives precise, cleaner and more dynamic sound than Elise. But it is a bit more sensible to tubes as sonic is less hidden by too warm tonality.

 

[OctavianH]

Glad you fixed the issues with KT77, so many experiment is really great !
My excitement to get my amp increase so much... (I will not experiment with so "aristocratic" tube as i do not have any but my list of potential good combination still grow.)

I would say you should not worry because your pair of NOS Tesla EL34 might be the best possible output in the world. KT77 destroys everything in it's path and it is, in my view, a good EL34. The amplifier sings, there is life in every note, I never heard something like this in my life. I am totally blown away. Lightwise, I have no words:

The GEC L63 inputs are very clean and full bodied and somehow complement the KT77 even if I would have said before trying them that a good match would be a more neutral input. I will try these with other variants in the next days, at the moment I cannot stop and change anything.