6H2311 E8 tubes ??


I pulled the original tubes out of my Sonic Frontiers Line One pre-amp today and the very faint print on them looks like 6H2311 with E8 below it.

I never heard of that number - am I misreading ? 
randy-11
Parts ConneXion carries Sonic Frontiers.  I'd suggest getting in touch with Chris there.  He should know.
It may be a 6h23N with weak lettering, that is a 6922 substitute.  
could it be 6H23P-EB?

the lettering looks a bit like this:
http://www.thetubestore.com/Tubes/6922-E88CC-Tube-Types/6H23n-EB-6922

wierd looking "P if so - but maybe that's the Russian way

could it be 6H23P-EB?
Yes, it could. The 6H23 is an exact replacement for the 6DJ8/6922/7308 family of tubes.

You have lots of choices for replacement tubes.

http://www.upscaleaudio.com/vacuum-tubes/preamp-tubes/6922-6dj8-7308-pcc88/

Here's a good read about tubes and the SF Line 1 Preamp:

https://forum.audiogon.com/discussions/nos-tubes-for-sonic-frontiers-line-1
The P in the tube types referenced above is often used as an English keyboard equivalent for the 17th letter of the Cyrillic alphabet which looks a lot like the "pi" symbol.  or like an inverted letter U.  If it was a bit smudged, it could easily look like 6H2311. I'm quite sure that's what you have, a 6dj8/6922/ECC88 equivalent.
Thx all!