Mike Lewis wrote:
Hello,

Has anyone here ever used the 6DZ7 tube in a design? It seems like it
would be a good choice for a push-pull output stage having two pentodes
in the same envelope. The price is quite good too. Was it introduced
close to the start of the decline of vacuum tubes and therefore was not
incorporated into many consumer products, or is there something
undesireable about it?

Thanks.

Mike L.

I've wondered about that too. It was not yet listed in RC-24 (1965), and
by RC-27 (1970) it was already shuttled to the "back of the book" for
replacement use only.

The specs show it capable of a respectable output power in Class AB1,
but at a low B+ voltage, as would be expected in line-operated designs.
However, its filament voltage/ current doesn't lend itself very well to
such designs. (A variant that used the same heater power at the 0.15A
current used in series-string radios would have had to be 64 volts, i.e.
64DZ7).

I haven't seen any distortion specs (or even curves), but I'd suspect,
given the low plate voltage for which it was designed, that it would be
nothing to write home about.

I almost get the sense that this was an abandoned experiment, perhaps a
foray into higher-powered audio for television sets -- which never took
hold and was dropped.

Any other theories, opinions, or perhaps even facts about this odd tube?

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects: http://dogstar.dantimax.dk |
+--------------------------------------------+

Behold, John Byrns scribbled:



Yes, I had a couple, but sold them. I don't think it would work very
well at low voltage, it's just two 6BQ5s in an octal bulb with common
screen and cathode leads. Not good for UL or triode connection in a
push pull amp.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

Give it a whirl for a computer multimedia setup or headphone amp.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*

On Thu, 17 Jul 2003 21:46:03 +0000, John Byrns wrote:

Yes, I had a couple, but sold them. I don't think it would work very well
at low voltage, it's just two 6BQ5s in an octal bulb with common screen
and cathode leads. Not good for UL or triode connection in a push pull
amp.


Regards,

John Byrns

There wouldn't be any problem with using 6DZ7 as ultralinear or
triode connection, any more than there would be using EL84
in the same application.

I think the main reasons that 6DZ7 didn't take off were the late
introduction date (1961), lack of power vs tubes like 7591, and
that GE probably couldn't make a single 6DZ7 that was cheaper than
2 imported EL84's.
That, and by 1961,EL84 was a fairly well established type
in the market.

"Fred Nachbaur" schreef in bericht
...


Mike Lewis wrote:
Hello,

Has anyone here ever used the 6DZ7 tube in a design? It seems like it
would be a good choice for a push-pull output stage having two pentodes
in the same envelope. The price is quite good too. Was it introduced
close to the start of the decline of vacuum tubes and therefore was not
incorporated into many consumer products, or is there something
undesireable about it?

Thanks.

Mike L.

I've wondered about that too. It was not yet listed in RC-24 (1965), and
by RC-27 (1970) it was already shuttled to the "back of the book" for
replacement use only.

My MK tubes handbook, 13th edition 1968, does list the tube.
Also application data for AB1-PP is given.
Unnecessary to copy that as data in the link below is exactly identical.
Looks like GE data sheet date is 04-1959, but I'm not sure.
BTW, I guess it's obvious that paper-release date does not mean the
corresponding device is release that date. OTOH if a device is released,
there must be a paper-release too. But how to find the earliest paper
released? I don't have a clue. Any electro-archeologists in the group?


The specs show it capable of a respectable output power in Class AB1,
but at a low B+ voltage, as would be expected in line-operated designs.
However, its filament voltage/ current doesn't lend itself very well to
such designs. (A variant that used the same heater power at the 0.15A
current used in series-string radios would have had to be 64 volts, i.e.
64DZ7).

Does your book explicitly list 6DZ7 for (110ac) line-operated designs?
Typical operation values in the GE data sheet are at 250V plate.
So I guess it's useable for line operation, but not intended.
Also, as you said, filament V/I suggests tranny operation.


I haven't seen any distortion specs (or even curves), but I'd suspect,
given the low plate voltage for which it was designed, that it would be
nothing to write home about.

Data sheet, including distortion curves, at :
http://www.mif.pg.gda.pl/homepages/f...093/6/6DZ7.pdf


I almost get the sense that this was an abandoned experiment, perhaps a
foray into higher-powered audio for television sets -- which never took
hold and was dropped.

Maybe another abandoned experiment?
http://www.mif.pg.gda.pl/homepages/f...24/e/ELL80.pdf
Non interconnected g2's make PP-UL possible.


Any other theories, opinions, or perhaps even facts about this odd tube?

A 1960 GE publication about 6DZ7 among others:
http://www.triodeel.com/ham1.gif
http://www.triodeel.com/ham2.gif
Would be interesting to hook up 2x 6DZ7 in PP-UL.
Given Ra-a ~4.5K for 2x 6DZ7 penthode PP, how does one calculate optimum
Ra-a for PP-UL?


Seal your lips, prevent the 6DZ7 frenzy at the Bay!


Cheers,
Fred

Rgds, Jan.


--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects: http://dogstar.dantimax.dk |
+--------------------------------------------+

JKoning wrote:
snip
Maybe another abandoned experiment?
http://www.mif.pg.gda.pl/homepages/f...24/e/ELL80.pdf
Non interconnected g2's make PP-UL possible.

FWIW the ELL80 (aka 6HU8) was the output tube of choice for the
Magnatone model 422 guitar amp... ...not cheap today.

Cheers,
-Robert
QTS
http://www.Braught.com

In article , "Ned Carlson"
wrote:

On Thu, 17 Jul 2003 21:46:03 +0000, John Byrns wrote:

Yes, I had a couple, but sold them. I don't think it would work very well
at low voltage, it's just two 6BQ5s in an octal bulb with common screen
and cathode leads. Not good for UL or triode connection in a push pull
amp.


Regards,

John Byrns

There wouldn't be any problem with using 6DZ7 as ultralinear or
triode connection, any more than there would be using EL84
in the same application.

Could you explain how you are going to do this with the screens of the two
sections tied together? No fair using two tubes in push pull parallel.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

Ned Carlson wrote:
On Thu, 17 Jul 2003 21:46:03 +0000, John Byrns wrote:


Yes, I had a couple, but sold them. I don't think it would work very well
at low voltage, it's just two 6BQ5s in an octal bulb with common screen
and cathode leads. Not good for UL or triode connection in a push pull
amp.


Regards,

John Byrns


There wouldn't be any problem with using 6DZ7 as ultralinear or
triode connection, any more than there would be using EL84
in the same application.

The fly in the ointment is that the screens are internally tied
together, so UL or triode operation would only be possible if two
separate tubes were used, each with its two sections paralleled,
defeating the purpose of having a single bulb for a PP amp.

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

JKoning wrote:
"Fred Nachbaur" schreef in bericht
...

[...]

The specs show it capable of a respectable output power in Class AB1,
but at a low B+ voltage, as would be expected in line-operated designs.
However, its filament voltage/ current doesn't lend itself very well to
such designs. (A variant that used the same heater power at the 0.15A
current used in series-string radios would have had to be 64 volts, i.e.
64DZ7).


Does your book explicitly list 6DZ7 for (110ac) line-operated designs?
Typical operation values in the GE data sheet are at 250V plate.
So I guess it's useable for line operation, but not intended.
Also, as you said, filament V/I suggests tranny operation.

No, my comments were based on the figured given in the (hopelessly
abbreviated) "typical characteristics" in the single-line listing at the
back of the book. But looking again with a magnifying glass, I see that
I'd misread them. The recommended values are 400/300 volts B+, for -11v
fixed bias and 120 ohm cathode bias respectively, screen 250 volts for
both. Total plate current 100/80 mA.

I haven't seen any distortion specs (or even curves), but I'd suspect,
given the low plate voltage for which it was designed, that it would be
nothing to write home about.


Data sheet, including distortion curves, at :
http://www.mif.pg.gda.pl/homepages/f...093/6/6DZ7.pdf

Of course! Good old Frank... Thanks!

I almost get the sense that this was an abandoned experiment, perhaps a
foray into higher-powered audio for television sets -- which never took
hold and was dropped.


Maybe another abandoned experiment?
http://www.mif.pg.gda.pl/homepages/f...24/e/ELL80.pdf
Non interconnected g2's make PP-UL possible.

That does look interesting. Wonder how many of them are out there? They
seem to go for about $10 on ebay ($20 per pair).

Seems there's an American equivalent also, 6HU8.

Any other theories, opinions, or perhaps even facts about this odd tube?


A 1960 GE publication about 6DZ7 among others:
http://www.triodeel.com/ham1.gif
http://www.triodeel.com/ham2.gif
Would be interesting to hook up 2x 6DZ7 in PP-UL.
Given Ra-a ~4.5K for 2x 6DZ7 penthode PP, how does one calculate optimum
Ra-a for PP-UL?

I've never seen or heard of a rigorous treatment, or way of calculating
optimum Ra-a. I've personally just gone by recommendation of the
transformer manufacturer (Hammond), and have noted that the values are
comparable to normal pentode operation, perhaps 10-25% lower.

Seal your lips, prevent the 6DZ7 frenzy at the Bay!

Haha, yes indeed! Interestingly, a search shows none listed at this
time, or in recent completed auctions.

Cheers
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

Robert McLean wrote:
Fred Nachbaur wrote in message t...

Mike Lewis wrote:

Hello,

Has anyone here ever used the 6DZ7 tube in a design? It seems like it
would be a good choice for a push-pull output stage having two pentodes
in the same envelope. The price is quite good too. Was it introduced
close to the start of the decline of vacuum tubes and therefore was not
incorporated into many consumer products, or is there something
undesireable about it?

Thanks.

Mike L.

I've wondered about that too. It was not yet listed in RC-24 (1965), and
by RC-27 (1970) it was already shuttled to the "back of the book" for
replacement use only.

The specs show it capable of a respectable output power in Class AB1,
but at a low B+ voltage, as would be expected in line-operated designs.
However, its filament voltage/ current doesn't lend itself very well to
such designs. (A variant that used the same heater power at the 0.15A
current used in series-string radios would have had to be 64 volts, i.e.
64DZ7).

I haven't seen any distortion specs (or even curves), but I'd suspect,
given the low plate voltage for which it was designed, that it would be
nothing to write home about.

I almost get the sense that this was an abandoned experiment, perhaps a
foray into higher-powered audio for television sets -- which never took
hold and was dropped.

Any other theories, opinions, or perhaps even facts about this odd tube?

Cheers,
Fred



Hello :
It is odd that it is not in RC-24, since it is in RC-23. The
description starts out "Glass octal type used as power amplifier tube
in high-fidelity audio equipment. " etc. It gives a suggested
push-pull circuit data at 400V plate, 250V screen, -11V fixed bias, 40
mA no signal current giving 18 Watts output at 2.5% distortion. For
cathode bias it suggests 300V, 250V, 120 ohm cathode resistor for 66mA
current, resulting in 12 watts at 3.5% distortion.

Oops again, mea culpa. Since it's not in the main body of the RC-24 (not
even a "see chart at end of section" redirection), I wrongly assumed
that there was no entry for it. Indeed there is, at the end of the book
(same listing as in subsequent editions).

Seems to be about halfway between a pair of 6V6 and a pair of 6L6 in
capability, if such a comparison makes any sense.

Robert McLean

Yes, or as others have pointed out, rather like a pair of 6BQ6/EL84's.

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

I had a stromberg carlson stereo power amplifier that used a couple of
these.. Driver stage was a 7199 per channel.. Used a hefty power
transformer, produced about 20Wrms out per channel and sounded quite nice
actually.. I have never seen another, seemed like an ideal amp for a
smaller system.. Nicely put together, high quality parts. Sold it
unfortunately ages ago, did not recognize its rarity at the time - and I
have never seen another.

Kevin

"Fred Nachbaur" wrote in message
...


JKoning wrote:
"Fred Nachbaur" schreef in bericht
...

[...]

The specs show it capable of a respectable output power in Class AB1,
but at a low B+ voltage, as would be expected in line-operated designs.
However, its filament voltage/ current doesn't lend itself very well to
such designs. (A variant that used the same heater power at the 0.15A
current used in series-string radios would have had to be 64 volts, i.e.
64DZ7).


Does your book explicitly list 6DZ7 for (110ac) line-operated designs?
Typical operation values in the GE data sheet are at 250V plate.
So I guess it's useable for line operation, but not intended.
Also, as you said, filament V/I suggests tranny operation.

No, my comments were based on the figured given in the (hopelessly
abbreviated) "typical characteristics" in the single-line listing at the
back of the book. But looking again with a magnifying glass, I see that
I'd misread them. The recommended values are 400/300 volts B+, for -11v
fixed bias and 120 ohm cathode bias respectively, screen 250 volts for
both. Total plate current 100/80 mA.

I haven't seen any distortion specs (or even curves), but I'd suspect,
given the low plate voltage for which it was designed, that it would be
nothing to write home about.


Data sheet, including distortion curves, at :
http://www.mif.pg.gda.pl/homepages/f...093/6/6DZ7.pdf

Of course! Good old Frank... Thanks!

I almost get the sense that this was an abandoned experiment, perhaps a
foray into higher-powered audio for television sets -- which never took
hold and was dropped.


Maybe another abandoned experiment?
http://www.mif.pg.gda.pl/homepages/f...24/e/ELL80.pdf
Non interconnected g2's make PP-UL possible.

That does look interesting. Wonder how many of them are out there? They
seem to go for about $10 on ebay ($20 per pair).

Seems there's an American equivalent also, 6HU8.

Any other theories, opinions, or perhaps even facts about this odd tube?


A 1960 GE publication about 6DZ7 among others:
http://www.triodeel.com/ham1.gif
http://www.triodeel.com/ham2.gif
Would be interesting to hook up 2x 6DZ7 in PP-UL.
Given Ra-a ~4.5K for 2x 6DZ7 penthode PP, how does one calculate
optimum
Ra-a for PP-UL?

I've never seen or heard of a rigorous treatment, or way of calculating
optimum Ra-a. I've personally just gone by recommendation of the
transformer manufacturer (Hammond), and have noted that the values are
comparable to normal pentode operation, perhaps 10-25% lower.

Seal your lips, prevent the 6DZ7 frenzy at the Bay!

Haha, yes indeed! Interestingly, a search shows none listed at this
time, or in recent completed auctions.

Cheers
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+



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