[hpamdr]

Odyssey could be the only amp with a dedicated EL11 sockets. Glad you think it's the best choice technically. Now I'm exploring getting adapters to use EL3N or EL33 in those sockets. Will be a challenge for @Deyan .

Or how about adapters for C3g into EL11 sockets. I've just given myself heaps of options.

The challenge with el11 socket is that it is not easy to get nude base. But you can find defective /unused tubes and then get the base by de-soldering from the pin using flux and pump.. To my experience EL3N are not better sounding than EL11, more prone to noise and very close spec. In odyssey you will have pure driver so medium mu tube 15~30 able to produce current should be the most effective.

@SonicTrance will give you more hint.

 

[UntilThen]

The challenge with el11 socket is that it is not easy to get nude base. But you can find defective /unused tubes and then get the base by de-soldering from the pin using flux and pump.. To my experience EL3N are not better sounding than EL11, more prone to noise and very close spec. In odyssey you will have pure driver so medium mu tube 15~30 able to produce current should be the most effective.

@SonicTrance will give you more hint.

Oh I know and much prefer EL11 over EL3N. I've use both sufficiently a lot in Elise, Euforia and GOTL. Just a thought on expanding the driver range that's all. However that will go against what I started out to do. Keep Odyssey simple.

It's also the reason why I've bought 7 NOS pairs of EL11 .... so I have enough to last me 2 life time. Maybe 3.

 

[OctavianH]

So, it began.

 

[OctavianH]

Something interesting for this thread, regarding tube rolling, biases and stuff I do not want to stress the original thread with. It seems what we measure (in my case with DuoVac) is not exactly what we will find when using the tube in the amplifier. For example, this pair of GEC L63 measured around -6.8V for 4mA @ 180V:

When inserted in Eternity it needs around -6.2V for the same 4mA. This means a possible formula for me would be "VgridEternity = VgridDuoVac+0.4V)"
On outputs it seems the reversed way. This pair of GEC KT66 measured on DuoVac -21V for 20mA @ 200V (left stronger one):

When inserted in Eternity I have around 20mA for -21.4V. So here it would be "VgridEternity = VgridDuoVac-0.4V)".
I am not sure about these but I'll keep an eye on them.

Other interesting thing is that after 10-15 minutes when the tubes are properly heated, the current decreases a little bit. When you start the amplifier, tubes start to raise current up to 4mA and 20mA perfectly biased by me. After 15 minutes of usage the current drops a bit around 3.9mA and 19mA.

Of course, not importat but I thought to share these as my impressions while rolling.

 

[triod750]

You get to know things us plug-and-play fools don't have a clue about .

 

[OctavianH]

You get to know things us plug-and-play fools don't have a clue about .

I am also a plug and play person, but I am lucky to benefit from the endless patience of Tomas which is always helping me to succeed.

Anyway, what many including me waited, KT88 on Eternity! The grid bias is, strangely, similay with my GEC KT66 (great stuff, these work on the fixed bias LOL, never thought)

The Psvane CV181T2, one of my favourite 6SN7, goes to -6.5V.

And what is quite nice, the sound si similar with Elise, more neutral than KT66, bass is punching harder. I recognize the signature, and since I am able to tell this, it means Eternity is receptive to tube rolling and changes, up to a point, the signature. Not as much as Elise, and it seems more on outputs than inputs. But again, big grain of salt.
We will talk about this much more in the future.

 

[hpamdr]

This is great for the tube rolling squad to have sonic change with different tube set. Like in Elise KT88 is a bassy tube with strong kick. I'm really waiting mine to test EL39, GU50 ... ECC32, EL11,fdd20....

 

[OctavianH]

This is great for the tube rolling squad to have sonic change with different tube set. Like in Elise KT88 is a bassy tube with strong kick. I'm really waiting mine to test EL39, GU50 ... ECC32, EL11,fdd20....

Exactly, KT88 is more neutral (not so sweet mids as KT66) but with strong bass, very punchy and defined. Since Eternity is warmer than Elise, a good pair for them is Psvane CV181T2 which are incredible detailed. I like this, since on Elise I wanted more bass and was using Foton 6H8C. Here Foton 6H8C was too warm for KT66 and I think it will be the same for KT88. But this combination is a very nice one.

 

[OctavianH]

Ok, biases for 6N7G were for me -3.3V and for 6L6GAY were -18.4V.

I started to write my biases measured directly on the amplifier. Might not be perfect but can be a starting point for others.

As a combo I do not like this, thin sound without enough power, but I just wanted to measure the biases.

Later edit: 6N7G in 6J5 slots with triodes in parallel. Don't take that bias for the double triode slot.

 

[OctavianH]

Ok, time for 6V6 and old GEC L63 grey glass. The 6V6 went about -14.5V and the L63 older type to -6V.

This sounds very good. Let's hope it is the merit of 6V6 because I have a lot.

 

[UntilThen]

Some very lovely options you have there. Great tubes.

 

[hpamdr]

Ok, time for 6V6 and old GEC L63 grey glass. The 6V6 went about -14.5V and the L63 older type to -6V.



This sounds very good. Let's hope it is the merit of 6V6 because I have a lot.

I have several matched pairs of russian 6n6c equivalent of 6V6 (not as nice) but sound great.
I'm also curious about how sound small tube like ECC83 or ECC88 in input socket ?

 

[OctavianH]

Ok, enough tube rolling for today. I got and idea about what bias I have to set for several types. My measurements revealed this and the surprise of my KT88 biasing at the same value like KT66 remains. I would be curious to know in the future other Eternity users what bias will find for KT88. For me this is very comfortable, since I can roll now several nice types without changing the bias. At the moment I set the tube rolling switches to OFF, I went on the fixed bias of -6.2V input and -21.4V output and just put my KT88 and the L63 clear glass to burn in.

Why KT66 and KT88 work at -21.4V? Hell knows, KT88 has to go around -22V or -23V and I doubt these were so heavily used or something. I have a pair of GE 6550A which measured around -25V. We will see, maybe others will come and test more KT88 in the future.

 

[OctavianH]

I have several matched pairs of russian 6n6c equivalent of 6V6 (not as nice) but sound great.
I'm also curious about how sound small tube like ECC83 or ECC88 in input socket ?

I have no idea and I have no ECC83 or ECC88. But 6V6 were great. I would say close to KT66 and at the price they can be bought, they might be a steal. I remember I found 6V6G around 25EUR/piece. Not bad, if you look about KT66.

 

[SonicTrance]

Love the detailed documentation @OctavianH keep up the good work!