Unfortunately the C3g's are back in their boxes. The reason was that I have switched the interconnect cables from Chord C-Line to Chord Clearway which was a sensitive upgrade. Clearway are much better cables but the sound they provide is darker. Having new cables I added again the ISO Regen and now it seems it provided this time an improvement. This was the reason for me to search for a more detailed and better match and I found it in the CV181T1 + 7236. These have less bass than the 5998 but are very clean and detailed, and added to my setup exactly what I was needing. Now, honestly, I do not really understand why a pair of 5998 is priced somewhere at 250 EUR and a pair of 7236 might be under 100 EUR. These are the mysteries of the tube world. Both tubes are excellent in my opinion and should be placed somewhere on the same price level.
And for the ones who appreciate pictures, here's a new one:
But my latest changes have not provided only benefits. When I switched the interconnects and made some arrangements with the rest of the cables to provide a better orientation and comfort, I start to listen and make an assessment to the Clearway and observe that the left channel is somehow muffled, but to a very small extent. I said "OK, maybe this recording has a problem". But hours were passing and I was still observing this problem and it was becoming annoying. I was convinced that the Clearway left channel cable has a problem. So I started to switch cables and the problem was still there. I said that maybe Elise has a problem on one of the channels. I remembered that I switched some tubes before changing cables and maybe the auto-bias mechanism was doing something wrong. So I start to switch power tubes and driver tubes without any positive result.
Anyway, I reached the point when I decided to try the headphones to a different amp just to eliminate them from the equation. So I turned on, after almost 3 years, my audio-gd NFB11. And the problem was there. Now everything was clear to me: the T1.2 headphones have a problem. OK, but how I fixed it? It was so simple that I am ashamed it took me so long to find it. It seems there was an imperfect contact on the left jack of the cable which was connected to the left driver. Even if everything looked fine, something was not properly working there.
So, in conclusion, this problem is fixed now and leads me to the conclusion that every interconnect, socket and additional stuff is only adding another layer of possible problems. I was very happy when Beyerdynamic changed the cables on T1.2 with some interchangeable ones and thought that this will make much easier the maintenance and cable rolling, but in the end I used only the stock Cardas Clear Light one and look that I had a problem instead of a benefit from it. Who knows, maybe in the future I'll try a Moon Audio Silver Dragon. And another conclusion was that before we search for the perfect tubes and make very critical and analytical assessments, we need to be sure that the rest of the line and cables are properly connected and filtered. I wonder how many such problems are caused by these intermediary jacks. I just observed now something that I have forgotten: the stock T1.2 cable provided a 3.5mm jack and a converter to 6.3mm. So another possible... point of failure? I guess in the end I'll reach
@hypnos1 conclusion and solder everything...
If I can find a benefit from all this effort, that one is: after 3 years I listened to my SS amp and remembered why I decided to go with a tube amp. But who knows, the Devil on the left shoulder tells me Violectric V281 might change my opinion. Let's hope the Angel on the right one will keep me from spending more money.
PS. I know that my latest posts are somehow off topic, but still Elise is a part of them. I'll try to stick on tube rolling which is the purpose of this thread but I would say that these observations about the environmental effects on our amp are also of interest. What I would advise before going to spend hundreds or thousand of EUR on tubes and amps: ensure you have the proper cables, grounding, filtering of the AC source and everything in place. Otherwise you'll reach my position of learning after 2 years that a connection jack on your headphone can make you loose many hours of your short life. And of course, try first 7236 with proper cables before other more expensive power tubes.