[R-390] Foreign tubes 12ax7 (r390/r388)

[Tim Shoppa]

kc0lwn asked:
> This is a technical slightly off topic question. 
> I have an r-388 in addition to my r-390a.
> Does anyone have any experiance with Russian or
> Chinese tubes that will replace the 12ax7.  The US
> made NOS stock tubes are getting to be quite
> expensive.
> Ibeleive the  r390 uses a 12ax7 so I am hoping
> someone has experiance.

Well, my R-390A has no 12AX7's, but my experience
with Eastern European 12AU7's (Tesla, now JJ) was
less than stellar, with intermittent interelement shorts.

Don't get too wrapped up in the astronomical 12AX7 prices...
some are highly desired by the audiophile types and others
are ignored.  I'm sure the ignored kind (even if Chinese
or Russian or E. European) will do fine.  Even though just
looking in the catalogs I'm surprised that used random 12AX7's
seem to sell for more than the new imports.

And the JAN/industrial number (5751) that's somewhat compatible
seems to be pretty expensive too.

Tim.