Good evening,
to get a nice triode sound you must make sure that the voltage gain of the triode is very close to the maximum possible gain of the triode called µ (micro).
This µ is set by the construction of the valve. It changes a little bit with the plate voltage. This is one importand aspect of the characteristical triode sound. To get the sound you like, try out some triodes.
I can not show you the sound in the forum but measuring the change of µ is possible.
The driver stage is biased to get full µ at low plate voltage. In the triodelington stage I disconnected the speaker to get full µ. Now it is possible to compare two different constructed ECC82. Valve A is modern construction. Its plate construction is similar to the ECC88. The other one valve B is a well known kind of the ECC82. See pic attached. The propagated µ in the databooks is 17.
At low plate voltage the µ of valve A = 17,3 and µ of valve B = 16,7.
At high plate voltage µ of valve A = 17,9 ; µ of valve B =14,9.
The µ of valve A increases a little bit with the plate voltage. At valve B it decreases. The µ change of valve B goes in a different direction and is stronger. Isn’t it interesting?
I don’t want to say which sound I like more. It is yours to try it out! The triodelington amp shown here is constructed to get as much triode sound as possible. Not every triode amp is designed in this aspect.
Kind regards,
Darius
PS: I am not able to upload the updated schematic
.