[hpamdr]

The different sound shouldn’t be too much of a surprise really.

Your Odyssey is using "standard SET design". The synergy between driver and output is much more critical than with the Eternity using input (not driver) and output tubes using @MrCurwen design.
With Odyssey, you always have to find a good matching combo as the input will give a lot of flavor and also critical to feed output tube.
With our design, the most important is to have good gain matching. We can ear effect of inputs to outputs, but it is always subtil for me in the same range of gain and noise.

 

[OctavianH]

We can ear effect of inputs to outputs, but it is always subtil for me in the same range of gain and noise.

I hear easily the difference between different input tubes, but it's true that the overall shape of the signature is given by the output and the input adds some salt and pepper. Anyway, it's there and I can differentiate between them.

 

[Isaacc7]

Your Odyssey is using "standard SET design". The synergy between driver and output is much more critical than with the Eternity using input (not driver) and output tubes using @MrCurwen design.
With Odyssey, you always have to find a good matching combo as the input will give a lot of flavor and also critical to feed output tube.
With our design, the most important is to have good gain matching. We can ear effect of inputs to outputs, but it is always subtil for me in the same range of gain and noise.

My Odyssey is actually push pull, the only one Tomas made I think. But yes, your point still stands. When he asked me what I wanted in an amp I specifically told him I want to hear the differences between tubes so he suggested the old school approach to the circuit. Not too old school though. First of all I wanted a good solid state power supply. Secondly I wanted to avoid using a phase splitter. I have always been struck at the compromises phase splitters cause designers to make. They can’t split it perfectly, add distortions, and add a little bit more complexity to the power supply. Since my preamps already had split the phase via transformers why duplicate that in the amp? It’s a little more purist approach to amplification.

 

[triod750]

I guess you need to hear all these differences yourself in order to understand what they mean in the real world. Difficult to do.

 

[Isaacc7]

I tried some GEC KT61 here on input and sounded OK (I know this does not say much but I do not remember exactly how, it was just fine form my point of view). If I remember correctly it was with KT66 grey glass on output. I have a quad of KT61 here somewhere, in the storage. From what I have experienced here, pentodes in input strapped as triodes tend to sound more open. I am unsure why, I just can say that KT61, EL38, EBL1, EL3 have all something in common when used in input. But the problem of these is usually the low gain, I would not go under 20 in input because it just does not sound right on my amp.

Have you tried el90 as an input? Like I said earlier, that family of tubes has been used quite a bit in that role. You’d still be face with the low gain situation though. So maybe not worth getting new adapters.

 

[OctavianH]

Have you tried el90 as an input? Like I said earlier, that family of tubes has been used quite a bit in that role. You’d still be face with the low gain situation though. So maybe not worth getting new adapters.

I cannot bias it. On input I can go maximum around -13V and this is not enough for EL90.

 

[hpamdr]

I cannot bias it. On input I can go maximum around -13V and this is not enough for EL90.

Thomas suggested to have a bigger bias range up to -30V to be able to use more penthode in input. It is less precise and i remember that it was not a huge modification on his side...

 

[OctavianH]

Thomas suggested to have a bigger bias range up to -30V to be able to use more penthode in input. It is less precise and i remember that it was not a huge modification on his side...

Yes, he asked me if I wanted and refused, I am not into low gain input. So basically it was my decision. I know you have it.

 

[OctavianH]

I have to admit it's quite addicting this GEC sound of A2293 combining GEC flavour with the EL84 sound. Even if you know it's veiled and forced somehow, you like it especially on specific records where exaggerated mids can be fun. For example the latest Judas Priest album, it's a charm with these.

But I also observed these got quite hot.

I haven't seen such temps in a while, I remember the 5998 and 6080 days on Elise. 6080 was getting very hot.

 

[OctavianH]

Is there a specific triode sound? I doubt. When we triode strap beam tetrodes or pentodes we basically put G2 and G3 out of operation. So a triode strapped pentode is basically a triode. But I have no idea why I have a feeling that the sound of A2293 on output, making Eternity to use exclusivelly triodes in both stages, makes me think about older Elise days.

Elise was my former amplifier using double 6SN7 and 6AS7 double triodes in parallel. A very inefficient design from my view, but this is another story. However, when listening to this "all triode" setup I have a feeling I am going back in time. Placebo? Most probably yes.

 

[OctavianH]

And since we have these nice triodes on the amp, we need some music.

The latest Harakiri for the Sky albums are perfect. I heard they already record something for 2024. Excellent, I hardly wait.

 

[Isaacc7]

Is there a specific triode sound? I doubt. When we triode strap beam tetrodes or pentodes we basically put G2 and G3 out of operation. So a triode strapped pentode is basically a triode. But I have no idea why I have a feeling that the sound of A2293 on output, making Eternity to use exclusivelly triodes in both stages, makes me think about older Elise days.



Elise was my former amplifier using double 6SN7 and 6AS7 double triodes in parallel. A very inefficient design from my view, but this is another story. However, when listening to this "all triode" setup I have a feeling I am going back in time. Placebo? Most probably yes.

I dunno, the a2293 were advertised as a regulator tube just like the 6080. Do they comparable specs to a single triode from the 6080?

 

[OctavianH]

I dunno, the a2293 were advertised as a regulator tube just like the 6080. Do they comparable specs to a single triode from the 6080?

Excellent question. I have no idea. But they get hot.

 

[OctavianH]

Let's go to the CD wall... later:

And then:

Piece by piece. LOL

 

[LobalWarming]

Excellent question. I have no idea. But they get hot.

Not that hot compared to my Bendix 6080WBs with graphite plates. Their heaters can hit 218c on a cool day. My normal TS/RCA 6080s run around 180-188c.

I find the A2293/CV4079 more efficient and sweeter sounding than most in the AC motor regulator family.

The specs of A2293/CV4079 are better than a single section of most any 6080/6AS7 in terms of output impedance. Plus they're Twins so they're way more adorable with beautiful curves.