Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

Jon

Jon Yaeger wrote:
Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

Jon

Supposedly from what little I know the recipies for the materials used
in NOS tubes are better and last longer with more consistency. I can't
use JJ or GT or Sovtek. A GE or RCA or Sylvania just makes me so happy
everytime they light up.

"Jon Yaeger" wrote in message
...
Almost any Sovtek 9 pin miniature tube that I've tested and that has been
in
service for a few years is bad (e.g. 6922, 12AX7).

Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to
be
safe . . .

Anyone have a similar or contrary experience?

Jon
JON:
I was looking at ebay months ago and someone was selling cartons of sovtek
X7s. He said they had not been factory tested. So, the factory lets the
bad ones out. No telling where they end up.

I suspect that many, or all, major manuf. through the tube era sold off
their seconds. Probably many of the NOS tubes at AES tube sales, etc. are
the cartons of seconds that have been sitting for decades.

One thing about JAN tubes, they are usually cheaper and they are put through
higher QC standards.

Also, there may be a growing counterfeit tube industry. The pointed sovetk
pins are probably akin to that part of the world. I have some IEC(formerly
Mullard's budget line) 6GH8s that have these pointed pins and they say W.
Germany on them. Something doesn' t make sense.

Sovtek guitar amp OEM tubes seem to burn a long time, but I got some Sovtek
12AX7WBs from either Parts express or MCM and some of them have very weak
transconductance. The low priced stuff may not be properly screened.

Mark

Jon Yaeger wrote:

Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

In what way?
Poor emission, ie, low gm, high noise, what?



Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

Jon

I have had no problems with Sovteks.

But then most amps i supplied had NOS input tubes and only the power tubes were
sovtek.

CJ use 6H30 in their 140w models.
but if you ask them or ARC how long the tubes last you may not
get a straight answer.

Patrick Turner.

in article , Patrick Turner at
wrote on 5/9/05 10:41 PM:



Jon Yaeger wrote:

Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

In what way?
Poor emission, ie, low gm, high noise, what?


***** low emission


Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

Jon

I have had no problems with Sovteks.

But then most amps i supplied had NOS input tubes and only the power tubes
were
sovtek.

CJ use 6H30 in their 140w models.
but if you ask them or ARC how long the tubes last you may not
get a straight answer.

Patrick Turner.

Mark wrote:
I have some IEC(formerly Mullard's budget line) 6GH8s that have these
pointed pins and they say W. Germany on them. Something doesn' t make
sense.
------
IEC was International Electronics Corperation or Company (I forget).
They are now ICC, International Components etc...
They bought rights to use Mullard name in USA. There are real Mullards
that they sold and whatever else they felt like putting the name on.
GE's, Japanese, East Euro, etc...
Google "Ned" +mullard +iec and get a clearer understanding of how it
went.
Hi Ned ;-)

And I do know how to spell corporation most on most days ;-)

On Mon, 09 May 2005 13:53:27 -0400, Jon Yaeger
wrote:

Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

I've no comment on current production, but mid-1990's "USSR" EL84's
will blacken internally immediately and then run forever. And that
era's 6SN7 and 6SL7 equivalents are perfectly fine. I prefer them to
Tungsol's, RCA's and almost anything except maybe early Sylvania's.
Just a very personal opinion, of course, and of no real value.

6922's are variable; buy some from Jim or Ned; get the best they
offer; life's short; don't dick around.

Chris Hornbeck

Chris Hornbeck wrote:

On Mon, 09 May 2005 13:53:27 -0400, Jon Yaeger
wrote:

Almost any Sovtek 9 pin miniature tube that I've tested and that has been in
service for a few years is bad (e.g. 6922, 12AX7).

Jim McShane says that current Sovtek production doesn't have this problem.
I'm not entirely convinced. Makes me want to stick with NOS stuff just to be
safe . . .

Anyone have a similar or contrary experience?

I've no comment on current production, but mid-1990's "USSR" EL84's
will blacken internally immediately and then run forever.

I had one failure of a sovtek EL84 a year ago.
But that was a rare failure.
But what is the muddy blackening that is seen in EL84 tubes, both sovtek and
NOS?

Patrick Turner.

And that
era's 6SN7 and 6SL7 equivalents are perfectly fine. I prefer them to
Tungsol's, RCA's and almost anything except maybe early Sylvania's.
Just a very personal opinion, of course, and of no real value.

6922's are variable; buy some from Jim or Ned; get the best they
offer; life's short; don't dick around.

Chris Hornbeck

Hi Jon,

I have half a dozen Sovtek 6922 running in a pre for
almost a decade by now with daily usage and heater switch
on/off. Maybe 3/4 year ago I measured them for emission
and transconductance and, within small tolerances, they
perform exactly like a pair of unused spares from the
same time / batch.

For the used ones with surely more than 10000 op hours
on their back I would have expected emission to be
lower than with the spares, but not so.

This might not be representative, of course.

I also have some Reflektor plant 6H8C/6SN7 and 6H9C/6SL7
which probably are approaching an 10000h op time by now, too.
Comparing them to spares from probably the same batch, only
the worn 6H8C show a little bit less emission than the
unused spares. But even when dropping the heater voltage by
10% to 5,7V, the worn ones still test "good" emission-wise
on my tube testers.

Besides that, I don't have other Russian tubes with considerable
operation time on their backs.

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

in article , Tom Schlangen at
wrote on 5/10/05 8:45 AM:

Hi Jon,

I have half a dozen Sovtek 6922 running in a pre for
almost a decade by now with daily usage and heater switch
on/off. Maybe 3/4 year ago I measured them for emission
and transconductance and, within small tolerances, they
perform exactly like a pair of unused spares from the
same time / batch.

For the used ones with surely more than 10000 op hours
on their back I would have expected emission to be
lower than with the spares, but not so.

This might not be representative, of course.

I also have some Reflektor plant 6H8C/6SN7 and 6H9C/6SL7
which probably are approaching an 10000h op time by now, too.
Comparing them to spares from probably the same batch, only
the worn 6H8C show a little bit less emission than the
unused spares. But even when dropping the heater voltage by
10% to 5,7V, the worn ones still test "good" emission-wise
on my tube testers.

Besides that, I don't have other Russian tubes with considerable
operation time on their backs.
Tom


Tom,

Thank you and the others who responded.

Interesting . . . My experience has been totally different from yours. I
can only wonder why.

Jon

On Tue, 10 May 2005 09:29:44 GMT, Patrick Turner
wrote:

I had one failure of a sovtek EL84 a year ago.
But that was a rare failure.
But what is the muddy blackening that is seen in EL84 tubes, both sovtek and
NOS?

Sorry, I don't know. Always assumed that it came from the hot bits,
on the theory that anything from the plates would be drawn to the
cathode by their charge.

Mullards are famous for being muddy brand spanking new. I hope
some metalurgist will see this and shine some light.

Chris Hornbeck

Hi Chris,

Mullards are famous for being muddy brand spanking new.

Yes, many Mullards show dark colored getter mirrors. AFAIK
this is caused just by the getter materials mix they used
and nothing to worry about.

Tom

--
this is my favourite sig, since there is no reference to
Kibo, Discordianism or The Church of the Subgenius in it.

On Wed, 11 May 2005 11:00:46 +0200, Tom Schlangen
wrote:

Mullards are famous for being muddy brand spanking new.

Yes, many Mullards show dark colored getter mirrors. AFAIK
this is caused just by the getter materials mix they used
and nothing to worry about.

Yeah, but I was thinking more of brown spots near the plate holes.
Reliable folks have said it's because the valves were run at
the factory, for testing possibly. But Mullards get almost
as smokey during their life as Sovteks. Well, not really...

Chris Hornbeck