WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
i fully agree with swapping the Chinese junk to more fine-sounding tubes.
Sorry; i can only speak on the 6SN7. Tube-rolling was EXACTLY the reason why i use this type so often. By simply swapping the 6SN7 "A" to type "B" you can really change the musical presentation without touching the soldering iron. Now that is handy indeed !
The technical data of this tube is very versatile. I found someday a notice that: "the 6SN7 was the tube that the USA made great". Now there are of course always nicer choises but for versatility......
Besided that the 6SN7 is made by a lot of manufactorors and there is a lot to choose from.
I got more than 100 matched 6SN7-pairs here......collecting them for quite some time.
In my set (picture included) you'll find the 6SN7:
- as the input tube of the 833-amp;
- as the main tube of the headphone-amplifier;
- as the output device for the phonostage.
What sound are you look for. Every 6SN7 has of course it's different "sound", but that is obviously very depending on the schematic/components/complete system.
So here are MY remarks, based on MY set.
My advise: get some pairs and start finding what YOU like (which is quite depending of the rest of the chain).
Option: 4 June is at Hoenderloo a "old radio fair". You can bet i'm there. And afterwarts our small audio-club is gathering in Ede at my place to discuss the latest topics, show the goodies from the fair, etc.
You're welcome to join.
I got enough 6SN7's.
Don't know what you mean about substituting ECC types - if you mean 9 pin, then not a good idea - stick to octal, or indeed loctal. Now, if you want some cheap NOS 6SN7 type tubes change the sockets and go loctal with the 7N7. You even have the 7AF7 which is quite cheap and has round plates. Loctal is the cheap way to go with 6SN7 types. Or rewire the octal base, fit a topcap and use VT-99s, that's another nice 6SN7 style tube for not much money. Not a lot of people know that, as Michael Caine would say.....
I have a Chinese "Music Angel" 845SET and my experience is the same as yours.
Pulling the 6N9P first tube (used for SRPP input) and replacing with NOS Sylvania 6SL7 made a significant improvement.
Pulling the 6N8P driver (two sections paralleled in CC stage) and replacing it with NOS Sylvania 6SN7 made a HUGE improvement.
The Sylvania tubes were just what I happened to have on the shelf at the time.