Hi,

I just purchased a quad of JJ 7591s and was very disappointed to find
that the pins on the tubes are much skinnier than NOS, so they don't
make a secure connection in the socket. To me, this is unsatisfactory,
and in all my research on these tubes I saw nothing mentioned about
the smaller pin diameter; in fact all reports were that this tube is
Plug and Play. To me it is not Plug and Play if you have to modify
the sockets, and if, in the process of modification, you break a
contact or two, the inexpensive cost of the tube is negated by the
time, cost, and aggrivation it will take to replace the socket(s).

When I called to return the tubes, the person I spoke to knew about the
descrepency in the pin size and brushed it off like it wasn't a big
deal. She said that tubes had smaller pins because they were made in
Slovokia. So this begs the question: Do all JJ octal based tubes have a
smaller pin diameter than they're really supposed to, or are the
smaller pins only on the 7591s? No matter what the answer is, don't you
think its a shame that a tube firm will spend its time, money and
resources to create an electrically identical tube, then make it not
quite right by putting what are, essentially, out-of-spec pins on it?
To me, this inattention to that detail makes me want to ask "Why
bother."

I applaud JJ's and Sovtek's effort in making a good 7591, I really do.
But what is the obstacle in making them right?

Cheers.

Malcolm Fuller said:


I just purchased a quad of JJ 7591s and was very disappointed to find
that the pins on the tubes are much skinnier than NOS, so they don't
make a secure connection in the socket.


I recently bought a quad of JJ 7591s for a friend's Mac 230 amp, had
no problems whatsoever with them.
I also used many JJ KT88s, EL34 and the like in the past and never
encountered any base-related troubles.

What ampo did you try them in?

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

On 2005-06-10 16:31:39 -0400, Sander deWaal said:

Malcolm Fuller said:


I just purchased a quad of JJ 7591s and was very disappointed to find
that the pins on the tubes are much skinnier than NOS, so they don't
make a secure connection in the socket.

I recently bought a quad of JJ 7591s for a friend's Mac 230 amp, had
no problems whatsoever with them.
I also used many JJ KT88s, EL34 and the like in the past and never
encountered any base-related troubles.

What ampo did you try them in?

I tried them in a Scott 299c and a Fisher 500B, both with the same
results. American made tubes fit these sockets with the snug
resistance you would expect and you can wiggle the tubes in the sockets
without producing crackling audio, but the JJs danced around
loose-goosie in the same sockets, so much so that they'd lose
connection.

My Scott is still running on its original, Scott branded, Sylvanias, so
it's not as if its sockets have seen a million tube swaps. I've owned
this amp since 1998 and only swapped the tubes to burn in a quad of GE
I found. The Fisher belongs to my dad, but I think it had its OEM
tubes, too, until about a year ago.

Thanks for the response.

"Malcolm Fuller" wrote in message
news:1118431919.713ae8e7b3738b53c3619ce2c136e1e7@t eranews...
Hi,

I just purchased a quad of JJ 7591s and was very disappointed to find
that the pins on the tubes are much skinnier than NOS, so they don't make
a secure connection in the socket. To me, this is unsatisfactory, and in
all my research on these tubes I saw nothing mentioned about the smaller
pin diameter; in fact all reports were that this tube is Plug and Play.
To me it is not Plug and Play if you have to modify the sockets, and if,
in the process of modification, you break a contact or two, the
inexpensive cost of the tube is negated by the time, cost, and aggrivation
it will take to replace the socket(s).

When I called to return the tubes, the person I spoke to knew about the
descrepency in the pin size and brushed it off like it wasn't a big deal.
She said that tubes had smaller pins because they were made in Slovokia.
So this begs the question: Do all JJ octal based tubes have a smaller pin
diameter than they're really supposed to, or are the smaller pins only on
the 7591s? No matter what the answer is, don't you think its a shame that
a tube firm will spend its time, money and resources to create an
electrically identical tube, then make it not quite right by putting what
are, essentially, out-of-spec pins on it? To me, this inattention to that
detail makes me want to ask "Why bother."

I applaud JJ's and Sovtek's effort in making a good 7591, I really do.
But what is the obstacle in making them right?

Cheers.


Do you feel that the tubes act like 7591's? The EH ones shoo' do not. They
don't even fit in the space in many audiofool amps (huge bulbs).
Re-tensioning tube sockets should be fairly trivial, and a good practice
when re-tubing any amp.
-dim

On 2005-06-10 21:04:42 -0400, "shiva" said:


Do you feel that the tubes act like 7591's? The EH ones shoo' do not.
They don't even fit in the space in many audiofool amps (huge bulbs).
Re-tensioning tube sockets should be fairly trivial, and a good
practice when re-tubing any amp.
-dim

Dim,

I really can't make an educated guess on whether or not the JJs acted
like 7591s or not, because they were probably powered in the amp for
less than a minute and a half. All I can tell you is that my American
built tubes fit very snugly in the same sockets and won't come out
witthout a fight. This is why I opted not to retention the sockets; it
just seemed that if something did happen to render the JJs as not good,
then I would probably have to pry the contacts back out to accomodate
my old tubes. The thin metal that makes up the contacts in a socket
won't take much of that, I don't tthink.

Thanks for the response.

Malcolm Fuller wrote:

Hi,

I just purchased a quad of JJ 7591s and was very disappointed to find
that the pins on the tubes are much skinnier than NOS, so they don't
make a secure connection in the socket. To me, this is unsatisfactory,
and in all my research on these tubes I saw nothing mentioned about
the smaller pin diameter; in fact all reports were that this tube is
Plug and Play. To me it is not Plug and Play if you have to modify
the sockets, and if, in the process of modification, you break a
contact or two, the inexpensive cost of the tube is negated by the
time, cost, and aggrivation it will take to replace the socket(s).

When I called to return the tubes, the person I spoke to knew about the
descrepency in the pin size and brushed it off like it wasn't a big
deal. She said that tubes had smaller pins because they were made in
Slovokia. So this begs the question: Do all JJ octal based tubes have a
smaller pin diameter than they're really supposed to, or are the
smaller pins only on the 7591s? No matter what the answer is, don't you
think its a shame that a tube firm will spend its time, money and
resources to create an electrically identical tube, then make it not
quite right by putting what are, essentially, out-of-spec pins on it?
To me, this inattention to that detail makes me want to ask "Why
bother."

I applaud JJ's and Sovtek's effort in making a good 7591, I really do.
But what is the obstacle in making them right?

Cheers.

I'm currently processing a batch of 100 JJ 7591-S.

I don't see any problem with pin size. They're all
fairly normal, aside from the occasional pin which
has too much (or sloppy) solder on it. However,
*oversize* pins have often been a problem on the
JJ E34-L. My number one customer (a boutique
guitar amp builder) switched from the JJ E34-L
to the SED EL34 around a year ago because
the oversize JJ pins were damaging his new
sockets, which were pretty tight to begin with.
The last batch of 200 JJ E34-Ls I had needed
to have many of the pin bottoms chamfered with
a conical HS steel rotary file bit (chucked into
a Dremel) so that the sharp bottom edges of the
oversize pins wouldn't catch on the socket contacts
during insertion. Maybe Ned can comment on this,
since he sells the same ones.

Lord Valve
Glass Hustler

On 2005-06-11 02:19:35 -0400, Lord Valve said:
I'm currently processing a batch of 100 JJ 7591-S.

I don't see any problem with pin size. They're all
fairly normal, aside from the occasional pin which
has too much (or sloppy) solder on it. However,
*oversize* pins have often been a problem on the
JJ E34-L. My number one customer (a boutique
guitar amp builder) switched from the JJ E34-L
to the SED EL34 around a year ago because
the oversize JJ pins were damaging his new
sockets, which were pretty tight to begin with.
The last batch of 200 JJ E34-Ls I had needed
to have many of the pin bottoms chamfered with
a conical HS steel rotary file bit (chucked into
a Dremel) so that the sharp bottom edges of the
oversize pins wouldn't catch on the socket contacts
during insertion. Maybe Ned can comment on this,
since he sells the same ones.

Lord Valve
Glass Hustler

Hmmm, interesting. Have you compared the 7591 S pin widths to NOS, can
you? Do you think that some off spec pins got by inspection, if they
even inspect? The fact that the E34L pins are too long tells me that
they're not paying attention to detail. Octal bases are standardized
and pin size is the elemental part of a tube.

Thanks.

On Sat, 11 Jun 2005 13:50:02 +0000, Malcolm Fuller wrote:


Hmmm, interesting. Have you compared the 7591 S pin widths to NOS, can
you? Do you think that some off spec pins got by inspection, if they even
inspect? The fact that the E34L pins are too long tells me that they're
not paying attention to detail. Octal bases are standardized and pin size
is the elemental part of a tube.

Thanks.

Do you have a micrometer to measure the pin width?
What is it?

Given the age of the the equipment you are installing the
tubes in, and they likely have the usual spring-brass
contact sockets, after years of use the socket pins are probably
spread out to where they won't contact socket pins that are within
normal mechanical tolerances, especially negatively. Ever think
about some new sockets? They're cheaper than tubes but more
difficult to install.

A few years ago, you couldn't buy *any* new 7591's at all, and
decent amps were selling for cheap money because getting 7591's
for a reasonable price was impossible and converting to another
tube was a huge pain in the arse. Now, there's two places making
new, usable, decent 7591 and, guess what, there's folks whining
in public that they suck because (in your case) THE PINS DON'T
FIT SOCKETS IN FIFTY YEAR OLD AMPS! Do you have any idea how
silly this sounds to people who've been maintaining amps
with 7591's all along?

If I were you, I'd be buying new sockets and sending a thank-you
note to Jan Jurco for actually bothering to make 7591. It's
amazing, given the limited market for 7591, that they, or anyone,
wants to make them, but on top of that, some folks
actually want to engage in craven nitpicking, or question
their quality control, based on the PIN SIZE.


--
Ned Carlson Triode Electronics Chicago,IL USA
www.triodeelectronics.com

Hello,

I too have a fisher 500c running JJ7591, all works ok for me.
They exactly fit into the sockets...

I also bought gz34 and kt88, and i can say that they are almost
'perfect'. The sound is very good.

It is not because you have a bad batch that JJ produces ****. For me it
is good value for the money (as some other brands).


Luc D.

On 2005-06-16 04:00:02 -0400, "Ned Carlson" said:

A few years ago, you couldn't buy *any* new 7591's at all, and
decent amps were selling for cheap money because getting 7591's
for a reasonable price was impossible and converting to another
tube was a huge pain in the arse. Now, there's two places making new,
usable, decent 7591 and, guess what, there's folks whining in public
that they suck because (in your case) THE PINS DON'T FIT SOCKETS IN
FIFTY YEAR OLD AMPS! Do you have any idea how silly this sounds to
people who've been maintaining amps with 7591's all along?

If I were you, I'd be buying new sockets and sending a thank-you
note to Jan Jurco for actually bothering to make 7591. It's amazing,
given the limited market for 7591, that they, or anyone,
wants to make them, but on top of that, some folks actually want to
engage in craven nitpicking, or question
their quality control, based on the PIN SIZE.

The octal base was first introduced in 1935, on RCA's metal based
tubes, and since then, the octal base has been standardized, including
(GASP!) pin size. This standardization, along with most every other
tube specification, has been followed by all tube manufactures who have
sold to the North American market - including those in countries such
as England, Germany, Holland, China, and Japan.

In July 1920 the tube manufactures of this country, at the behest of
the government, came to an agreement to manufacture vacuum tubes in a
standardized way. This standardization included (GASP!) pin sizes.
Before this agreement, manufacturers were coming out with tubes that
were just a little bit different than the tubes of competing
manufacturers to avoid patent infringement.

A lot of the time, what would be changed was pin size. This was
eventually seen as not good because, for one reason, radio
manufacturers had to decide which tube maker they wanted to follow,
and, moreover, which pin size to go with; a decision that would
alienate other tube brands. Relaxing the patents on tube designs
ensured that each tube manufacturer had a fair shake in the
marketplace, and gave consumers the choice of where to get tubes.

As part of this agreement, it was agreed that tubes types would have to
meet exactly the specifications of the original manufacturer -
including electrical properties, basing type (including (GASP!) pin
size), and envelope size. If a tube didn't meet the specifications of
the type it was trying to copy, then it couldn't be considered as that
type.

Let' s use the 7591 and the 6GM5 as an example. These tube types are
electrically identical and can be used in the same circuits, but they
have different type numbers. Why? Because they have different pin-outs,
different bases, and different sized envelopes.

If we used Ned's logic of being happy because Sovtek and JJ have come
out with an electrically identical - but not in most every other way -
tube to the 7591, then what's stopping these companies from saying that
their versions of the 7591 is also a 6GM5?

Using Ned's reasoning, if they did decide to do this, then the people
who have amps that use 6GM5s would have to be ecstatic that JJ and
Sovtek have found it in their hearts to call their tube a 6GM5, and
those people should just roll over and modify their amp because the JJ
and Sovtek tube offering is better than nothing.

For somebody who has taken care of vintage amps all along (my father
has been a tech for 48 years. I am 33, and for my 33 years my house has
never been without a tube amplifier. And for the majority of that
time, that's been because I was the owner of such an amp!), I find that
argument preposterous. I also find it a slap in the face to the
manufacturers who are striving to build their tubes to the original
specifications.

But we should just roll over and be happy because JJ and Sovtek have
come out with their "almost 7591s", and have provided them so
inexpensively. In 1973, a new 7591A used to cost $3.75. That was cheap,
even back then. But when you bought one, from any brand, you knew that
it was going to fit the socket without tightening (GASP!) the contacts.

In fact, in replacing tubes in any of my antique radios and amplifiers,
I've never needed to tighten up a tube socket, octal or otherwise. And
in returning my American 7591s to my amp after trying the JJs, there
wasn't any need to tighten the sockets. Why was this? Maybe it's
because the sockets were fine to begin with. I didn't need a micrometer
to know that the pins on the JJ tube was of a smaller diameter. Seeing
all four JJs wiggle around in the same sockets were it takes a
considerable amount of pressure to seat an American tube tells me all I
need to know. Maybe JJ should invest in a micrometer.

And I don't want to hear about the assertion that the differences
between a NOS 7591 and a new "almost 7591s" are there because the
"almost 7591s" were made in foreign countries. If Mullard used the same
standards on its legendary EL34 that JJ and Solvtek uses on their 7591,
would it still be legendary? I doubt it. Also, I recently purchased a
Chinese made 6v6 for my EH Scott SLR-12B and that tube fit perfectly
with having to futz with the socket contacts (it looks like a 6v6,
too). Also, I've bought Sovtek octals before and never had to tighten
sockets to get them to fit.

If I am "craven nitpicking" it's only because I have 85 years of tube
making precedence to back me up. I wrote my original posting not to
say that the JJ or Sovtek tubes sucked, as you, Ned, say I did. My
original intention was to see if the problem I had was an isolated
incident - you know, a batch of out-of-spec pins could've gotten by, I
understand that - or if all JJ tubes had skinnier pins. I didn't know
so I thought I'd ask. It's OK to ask, isn't it? I also stated in that
post that I appreciated JJ's and Sovtek's efforts of making a 7591, but
also wondered why they couldn't just do it right if they were going to
go though all the effort. That's a fair pondering, isn't it?

On 2005-06-16 17:39:21 -0400, said:

It is not because you have a bad batch that JJ produces ****. For me it
is good value for the money (as some other brands).


Luc D.

Why are people putting words in my mouth? I didn't say that JJ produces
****, sucked, or anything that even resembles that nature. I just
wanted to know if all pins on their tubes are smaller, that's it. I
have no right in saying that JJ produces ****,, because I really don't
have that much experience with JJ as a brand.. That's why I started
this thread, to ask about the pins, not to create slander. I did ponder
why would a firm put its time, money, and effort into tooling up for a
particular tube type, only to get the pin size wrong, but that
question, and my whole message, was clearly based on my, albeit
limited, experience. I was hoping that the overwhelming response would
prove me wrong.

Instead I got two messages that people have had no problems with the JJ
7591s, which is great and I am glad that they can work for people, a
message, in this thread, that the pins on E34L JJ will blow out sockets
- including brand new ones - if they're not filed down before
installation, another message, in an email, that said that the JJ 6v6s
also have too fat of pins (this guy was probably afraid to post his
message in the thread because he didn't want to get the "how dare
you question that" attitude), and a diatribe that said that I should
just be happy that JJ and Sovtek are producing something close to a
7591 and not question what's wrong with them. Would people still have
this attitude if these tubes were drawing to much current and taking
out power transformers? I doubt it. But, the way this thread is turning
out, I'm beginning to wonder.

Hello Malcom,

Don't worry, we try to help you. ;-)
You have had 2 guys happy with JJ, and one that is complaining about
the size of the pin. And one that advices you to change the sockets.

The fact is that i have the same amplifier you have. And for me it
works, i use it daily.
So why you don't try to change your 7591 tubes ? Have you asked JJ
about this problem ? Maybe you simply have a bad batch.

Keep us informed of the results of your investigations.

BR,
Luc D.

On 2005-06-17 18:40:30 -0400, said:

Hello Malcom,

Don't worry, we try to help you. ;-)
You have had 2 guys happy with JJ, and one that is complaining about
the size of the pin. And one that advices you to change the sockets.

The fact is that i have the same amplifier you have. And for me it
works, i use it daily.

I use my amp daily, too. I wasn't buying the JJ tubes to fix the amp,
I just wanted to hear what they sounded like. The current tubes in the
amp are the original tubes that came with the amp, and they, knock on
wood, show no signs of stopping. I also was fortunate enough to get my
hands on a matched quad of NOS GE coin based 7591As. All 8 of these
tubes go into my sockets with the same amount of resistance as you
would expect out of a good socket, so I really don't expect that I'd
gain enough to make the JJs a snug home.

So why you don't try to change your 7591 tubes ? Have you asked JJ
about this problem ? Maybe you simply have a bad batch.

Well, if you're asking what i think you're asking, I have tried other
American 7591 in my amp, namely the above stated GEs. I haven't asked
JJ about the problem because I don't know how to contact them
directly. But when I asked the people where I bought the tubes from and
they said that all JJ tube pins were smaller because they were made in
Slovakia. Thinking that that answer was suspicious, that was when I
posted my original message.


Keep us informed of the results of your investigations.

BR,
Luc D.

Thank you for your kind and understanding response.

Cheers.

JJ ELECTRONIC - Slovak republic
A. Hlinku 4
02201 Cadca
Slovak republic
tel: +421/41/4335369
fax: +421/41/4335370



web site : http://www.jj-electronic.sk/

They also have a subsidiary in Canada.

I hope this helps.

Luc .D

Malcolm Fuller wrote:

But we should just roll over and be happy because JJ and Sovtek have
come out with their "almost 7591s", and have provided them so
inexpensively. In 1973, a new 7591A used to cost $3.75. That was cheap,
even back then. But when you bought one, from any brand, you knew that
it was going to fit the socket without tightening (GASP!) the contacts.

Pls excuse a belated reply:

In your lengthy & intricately constructed polemic, you ignore the
concurrent major issue that the new JJ is structurally a very different
tube from the NOS that is very robustly made, has a different internal
structure than NOS & is still under preliminary eval by a number of
smart people. AFAIK we do not yet know whether the JJ may or may not
be so superior in other ways as to nearly moot any significant pin
issue that it may or may not present to most demanding users. It would
seem more fair and far wiser to withhold any categorical critcism or
assessment until we have more of the whole picture - and particularly
in context of its low price. My own and incomplete assessment is to
date leaning toward this tube being such a great value that many of us
wouldn't care much if it had the wrong base, let alone pin tolerance
vagarities.

It's also a touch humorous that in all of your focus upon a possible
minor downside, you didn't attack the fact of its significantly taller
height, too. But I pray not to provide further fodder for seekers of
discontent. :-)

On 2005-06-23 14:40:26 -0400, said:

JJ ELECTRONIC - Slovak republic
A. Hlinku 4
02201 Cadca
Slovak republic
tel: +421/41/4335369
fax: +421/41/4335370



web site : http://www.jj-electronic.sk/

They also have a subsidiary in Canada.

I hope this helps.

Luc .D

thank you, Sir!

said:

It's also a touch humorous that in all of your focus upon a possible
minor downside, you didn't attack the fact of its significantly taller
height, too. But I pray not to provide further fodder for seekers of
discontent. :-)


The EH is taller, the JJ is not.
It fits a Mac 230 with wooden cabinet just like the original, one of
my major reasons for selecting this particular tube.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

On 2005-06-23 21:33:39 -0400, said:

Malcolm Fuller wrote:

But we should just roll over and be happy because JJ and Sovtek have
come out with their "almost 7591s", and have provided them so
inexpensively. In 1973, a new 7591A used to cost $3.75. That was cheap,
even back then. But when you bought one, from any brand, you knew that
it was going to fit the socket without tightening (GASP!) the contacts.

Pls excuse a belated reply:

In your lengthy & intricately constructed polemic, you ignore the
concurrent major issue that the new JJ is structurally a very different
tube from the NOS that is very robustly made, has a different internal
structure than NOS & is still under preliminary eval by a number of
smart people. AFAIK we do not yet know whether the JJ may or may not
be so superior in other ways as to nearly moot any significant pin
issue that it may or may not present to most demanding users. It would
seem more fair and far wiser to withhold any categorical critcism or
assessment until we have more of the whole picture - and particularly
in context of its low price. My own and incomplete assessment is to
date leaning toward this tube being such a great value that many of us
wouldn't care much if it had the wrong base, let alone pin tolerance
vagarities.

It's also a touch humorous that in all of your focus upon a possible
minor downside, you didn't attack the fact of its significantly taller
height, too. But I pray not to provide further fodder for seekers of
discontent. :-)

You seem to set aside in your opinion, though, that since the JJ tube
is constructed differently in regard to it's envelope, as well as
internal features, to make it more robust, it, technically, according
to 85 years of tube making standards, is not a real 7591. Before I had
this 299C, I had a old Stromberg Carlson console stereo, which uses
7408s for its output. A 7408 is, for all intense purposes, a more
robust 6v6 developed by GE. But because the workings of the 7408 tube
differs from that of a 6v6, it had to be assigned a different type
number. That's how things worked in the heyday of a vacuum tube.

Is this splitting the atom? Maybe so. And in this day and age, I'm
really not trying to beat JJ up for making a more robust tube that
might not be the same as an original, Westinghouse built 7591. On the
contrary, I hope it's the best tube out there. I bought my quads based
on the reports that they were more robust and sonically superior, but,
most importantly, I bought them because, even though they are taller
and fatter, they fit my amp. For a more robust tube, a little deviation
in envelope size can be tolerated.

But a deviation in pin size? C'mon. As I pointed out in my earlier
posting, the octal based tube was first used in 1935. How many millions
of octal based tubes been made since then? And, as I asked before, why
would a tube firm, like JJ, go through the motions of making what could
be a great tube only to get the most elemental, and least technical,
part of the tube, it's pins, wrong? The pin diameter of an octal tube
has absolutely nothing to do with the internals of a tube; the leads
coming out of the glass envelope are soldered to the ends of the pins
that are a part of the Bakelite base. Pins of an octal are not reliant
on tube design, but are reliant on a separate base design - a design
that has been around for 70 years. To get that wrong is careless.

Of course, this assumes that JJ chose the wrong pin size on purpose,
which is not known, and moreover, it's not known that I had a bad
batch. This is why I started this thread originally, to find out
what's really that answer. It wasn't to malign JJ, or to bad mouth
tubes of which I only have, at most, 90 seconds of experience with.

What gave me the true discontent was the posting of which you quoted
my response. To think that we should be expected change our nice,
original, vintage tube gear - potentially lessoning it's value - just
because a tube firm has come out with an inexpensive, but way
out-of-spec in most ways, tube is preposterous. It is a slap in the
face to tube companies who can find ways of making more robust versions
of vintage tubes, but also makes sure that those tubes look, and plug
in, like the originals. As I said, a little out of spec in terms of
overall envelope size is acceptable. Gear modification to get a tube to
fit shouldn't be.

Thanks

Sander deWaal wrote:
said:

It's also a touch humorous that in all of your focus upon a possible
minor downside, you didn't attack the fact of its significantly taller
height, too. But I pray not to provide further fodder for seekers of
discontent. :-)


The EH is taller, the JJ is not.
It fits a Mac 230 with wooden cabinet just like the original, one of
my major reasons for selecting this particular tube.

I'm happy it's worked for you, but it seems you haven't seen an NOS
7591A - the JJ is over 3/4" taller. Compared to my RCA the internal
structure is mounted a bit higher in the envelope (which I feel is a
good thing), and the dome of its envelope makes it considerably taller
than the RCA GT shape. The NOS tube is equal in size to an NOS 6V6GT.

Malcolm Fuller wrote:

You seem to set aside in your opinion, though, that since the JJ tube
is constructed differently in regard to it's envelope, as well as
internal features, to make it more robust, it, technically, according
to 85 years of tube making standards, is not a real 7591.

I couldn't be happier about that since what makes a "real
Anytube is to a fair extent up for grabs within the liits of its basic
electrical & connective capabilites, and to some extent always has
been. Not everyone is solely interested in a tube for "vintage" gear -
some of us are more interested in building new things that are better
for our needs, and anything that delivers basic 7591A electrical
performance & pinout while adding robustness holds promise to be
superior, not equal to, its predecessor in demanding gear.

I feel you have somewhat misunderstood or at best mischaracterized
"specs" in particular relation to NOS tubes. NOS could & did vary all
over the place, to the extent that it is hard or maybe impossible to
state categorically that any type of consumer tube was "closer to its
specs" than most current production examples. From a uniformity
standpoint, it is often the reverse. To put it another way, what you
express about "specs" amounts to be accurately approximate. As I've
noted elsewhere recently, there was & is nearly no such thing as a tube
which is "on spec", except by statistical accident.

On 2005-06-25 19:23:36 -0400, said:

I feel you have somewhat misunderstood or at best mischaracterized
"specs" in particular relation to NOS tubes. NOS could & did vary all
over the place, to the extent that it is hard or maybe impossible to
state categorically that any type of consumer tube was "closer to its
specs" than most current production examples. From a uniformity
standpoint, it is often the reverse. To put it another way, what you
express about "specs" amounts to be accurately approximate. As I've
noted elsewhere recently, there was & is nearly no such thing as a tube
which is "on spec", except by statistical accident.

If this is true, why did tube manufacturers go through the time, money
and effort to publish tube manuals to give all the related specs to a
vacuum tube type if, according to you, there was nearly no such thing
as an "on spec" vacuum tube? Yes there are slight electrical variations
between tubes, but they had to be within tolerances or they'd be
rejected.

The way you make it sound, we were in a crap shoot when it came to
buying a tube. We were not. Anyway my true concern is with the physical
aspects of the tube. it is possible to mechanically standardize
something without having "statistical accidents" on our side. Using
your logic, we could've never gotten through the industrial revolution
because we couldn't have built anything exactly the same twice. The
tires on our cars would all be different sizes, and we'd be lucky if
they were all round. We'd never know how long a foot is because we
couldn't build two rulers that were exactly the same size; and that's
only if were got the first one right.

Come on, give me a break! A bulb size is a bulb size, a pin's gauge is
always going to be the same size. A 7591 only had one bulb size, and
all octal tubes had one, uniform pin size. Sovtek and JJ came out with
their 7591s because their saw a market of vintage amplifier owners who
craved the tube, not because they wanted hobbyists to build amps around
them.

Malcolm Fuller wrote:
On 2005-06-25 19:23:36 -0400, said:

I feel you have somewhat misunderstood or at best mischaracterized
"specs" in particular relation to NOS tubes. NOS could & did vary all
over the place, to the extent that it is hard or maybe impossible to
state categorically that any type of consumer tube was "closer to its
specs" than most current production examples. From a uniformity
standpoint, it is often the reverse. To put it another way, what you
express about "specs" amounts to be accurately approximate. As I've
noted elsewhere recently, there was & is nearly no such thing as a tube
which is "on spec", except by statistical accident.

If this is true, why did tube manufacturers go through the time, money
and effort to publish tube manuals to give all the related specs to a
vacuum tube type if, according to you, there was nearly no such thing
as an "on spec" vacuum tube? Yes there are slight electrical variations
between tubes, but they had to be within tolerances or they'd be
rejected.

The way you make it sound, we were in a crap shoot when it came to
buying a tube. We were not. Anyway my true concern is with the physical
aspects of the tube. it is possible to mechanically standardize
something without having "statistical accidents" on our side. Using
your logic, we could've never gotten through the industrial revolution
because we couldn't have built anything exactly the same twice. The
tires on our cars would all be different sizes, and we'd be lucky if
they were all round. We'd never know how long a foot is because we
couldn't build two rulers that were exactly the same size; and that's
only if were got the first one right.

Come on, give me a break! A bulb size is a bulb size, a pin's gauge is
always going to be the same size. A 7591 only had one bulb size, and
all octal tubes had one, uniform pin size. Sovtek and JJ came out with
their 7591s because their saw a market of vintage amplifier owners who
craved the tube, not because they wanted hobbyists to build amps around
them.

You know, some folks are just unhappy people no matter what you give
'em, and will find a way to misalign reality to suit their unhappiness
no matter what you tell 'em. I give up. :-)

Malcolm Fuller wrote:

But a deviation in pin size? C'mon. As I pointed out in my earlier
posting, the octal based tube was first used in 1935. How many millions
of octal based tubes been made since then? And, as I asked before, why
would a tube firm, like JJ, go through the motions of making what could
be a great tube only to get the most elemental, and least technical,
part of the tube, it's pins, wrong? The pin diameter of an octal tube
has absolutely nothing to do with the internals of a tube; the leads
coming out of the glass envelope are soldered to the ends of the pins
that are a part of the Bakelite base. Pins of an octal are not reliant
on tube design, but are reliant on a separate base design - a design
that has been around for 70 years. To get that wrong is careless.

Of course, this assumes that JJ chose the wrong pin size on purpose,
which is not known, and moreover, it's not known that I had a bad batch.
This is why I started this thread originally, to find out what's really
that answer. It wasn't to malign JJ, or to bad mouth tubes of which I
only have, at most, 90 seconds of experience with.

In the fifties and later - Octal pins DID get smaller, and tapered. GE
refers to this in the literature for TV repair folks - Their "service
designed" line had tapered pins to make the job of changing tubes more
convenient.

Folks that used 6SN7s in NON-ATT Phone systems complained, and had
special batches made with non-tapered pins.

Get out a micrometer and see if the pins are significantly smaller than
on a GE "service designed" 12SN7GTA...

On 2005-06-26 08:07:42 -0400, said:

You know, some folks are just unhappy people no matter what you give
'em, and will find a way to misalign reality to suit their unhappiness
no matter what you tell 'em. I give up. :-)

Isn't it a reality that pin size, bulb size, in fact, anything
physical, can be, or has been, made to a uniform size and therefore,
can be, or has been, made a standard? If not, am I living in a
parallel universe because everything I've leaned seems to be wrong..

On 2005-06-26 09:21:36 -0400, Charles MacDonald said:

Malcolm Fuller wrote:

But a deviation in pin size? C'mon. As I pointed out in my earlier
posting, the octal based tube was first used in 1935. How many millions
of octal based tubes been made since then? And, as I asked before, why
would a tube firm, like JJ, go through the motions of making what could
be a great tube only to get the most elemental, and least technical,
part of the tube, it's pins, wrong? The pin diameter of an octal tube
has absolutely nothing to do with the internals of a tube; the leads
coming out of the glass envelope are soldered to the ends of the pins
that are a part of the Bakelite base. Pins of an octal are not reliant
on tube design, but are reliant on a separate base design - a design
that has been around for 70 years. To get that wrong is careless.

Of course, this assumes that JJ chose the wrong pin size on purpose,
which is not known, and moreover, it's not known that I had a bad
batch. This is why I started this thread originally, to find out
what's really that answer. It wasn't to malign JJ, or to bad mouth
tubes of which I only have, at most, 90 seconds of experience with.

In the fifties and later - Octal pins DID get smaller, and tapered. GE
refers to this in the literature for TV repair folks - Their "service
designed" line had tapered pins to make the job of changing tubes more
convenient.

Folks that used 6SN7s in NON-ATT Phone systems complained, and had
special batches made with non-tapered pins.

Get out a micrometer and see if the pins are significantly smaller than
on a GE "service designed" 12SN7GTA...

That maybe so. But the 7591 would've been developed after this overall
change. This also tells me another thing of significance, and that was
that people were allowed to complain and those complaints were heard
and satisfied. Why is it that when people have legitimate complaints in
this day and age their told to stop whining? In the thread, I was
essentially told that Sovtek and JJ made their 7591s not for vintage
amp owners such as I,, but for hobbyists, or companies, to build amps
around them. If that were true, why did they designate the tube as a
7591. They know where the market is. It's funny to me to see that
people would rather come up with excuses why a company had to get a
product wrong rather than demanding they get it right. We live in a
consumer driven world, but we're giving up all our power. That's not
right.

But getting back to the pins. GE was known for doing other funky things
with octal bases; in the 70's they developed the "coin based" octal. I
do not have a micrometer, nor do I have a "service designed" 12SN7GTA.
However, I do have a quad of "coin based" 7591s and they fit my sockets
just as snugly as the OEM tubes. Can I assume that these coin based
pins have the size and taper size you did describe?

Thank you for your response.

Malcolm