Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?


Regards,

John Byrns


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

There is the triode/dual diode 6AV6. Just don't use its "detector"
sections. It is a small, nice Septal tube which You can get as NOS RCA or
eq. for a few dollars. Its triode section is almost 100% half of an
ECC83/12AX7. See http://store.yahoo.com/triodeel/6av6.html
As per Your question, well, You just waste 50% of Your tube, but it works.

Ciao

Fabio


"John Byrns" ha scritto nel messaggio
...

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?


Regards,

John Byrns


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

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

Patrick Turner.



Regards,

John Byrns

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

In article , Patrick Turner
wrote:

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7, but I
have never heard of a 12AU7 variation like this.

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.


Regards,

John Byrns


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

Hi John ,

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7

Assuming Patrick is right (and I don't see why not) I would use
system "A" in monoblock "A" and system "B" in monoblock "B" .
If you swap both 12AX7 's after 5 years you'll have fresh tubes again .

Ronald .

John Byrns wrote:
In article , Patrick Turner
wrote:


John Byrns wrote:


Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?


Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7, but I
have never heard of a 12AU7 variation like this.


A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.


The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.


Regards,

John Byrns


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

John,

If heater power is a problem why not use a 6AQ6 which is like a 6AV6
with a 150 mA heater. It may be hard to find now though.

Regards,

Bill Cohn

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.


The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.


There's the 6AQ6. which consumes 150ma at 6.3V for the
heater. It isn't exactly half a 12AX7 though, but looks
to be half a 5751 (mu=70, gm=1200, Rp=58K). Can you
work with that?

John Byrns wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7, but I
have never heard of a 12AU7 variation like this.

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.

Regards,

John Byrns

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

An alternative might be a 6BH6 Triode connected.

See http://frank.pocnet.net/sheets/093/6/6BH6.pdf

for a plot of triode curves. Looks like Triode MU is approx 50.

Cheers, John Stewart

"John Byrns" wrote in message
...
In article , Patrick Turner
wrote:

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half
of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7, but I
have never heard of a 12AU7 variation like this.

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.


Regards,

John Byrns

7C6 JB, Loctal though and \more like a 6SQ7. Has the rump rump mu of 100 but
gm of~1000. 'bout $10- $11 ea. from the usual sources. 150 mA heater. Are
you THAT limited on heater power?
MarkS
tube manual junkie\

John Byrns wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7,

That would be the 20EZ7. But that needs a whole 20 volts, too much I think for
what you have in mind.

Another dual high MU triode with a 150 ma heater & lots of zip is the 17EW8. Part
of the 6BK7, 6BQ7, 6BZ7 family. I've found the 6BQ7 types very good for audio when
properly applied.

JLS

but I
have never heard of a 12AU7 variation like this.

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.

Regards,

John Byrns

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

John Byrns wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

Hi All,

I am need of a single triode similar to half of a 12AX7. Unfortunately
there does not seem to be a tube that contains only as single triode of
the 12AX7 type, in the way that a 6C4 is like half a 12AU7. Would
connecting only half the heater of a 12AX7, and leaving the second half of
the heater dark cause any problems with the tube?

There are no problems using just half a 12AX7.
But why not parallel the halves?

Because the object is to find a tube that consumes half the heater power
of a 12AX7. Maybe I should drop the experimental monoblock idea and go
back to a full stereo version, then the 12AX7 heater would cease to be a
problem. A solution for the monoblock would be if there were 100 mA
heater versions of both the 12AX7 and the 12AU7, I have a vague
remembrance that there is a 100 mA heater variation of the 12AX7, but I
have never heard of a 12AU7 variation like this.

A 6AV6 will have a single 12AX7 half, and have a 7 pin miniature base.
It has two diodes, and was used in countless valve radios.

The 6AV6 consumes the same amount of heater power as a 12AX7, this does
not meet the goal.

Fair enough.
Saving 0.945 watts is important.

Patrick Turner.



Regards,

John Byrns

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

Fair enough.
Saving 0.945 watts is important.

That's what I thought at first , but .......

What if he wants to heat the (first) pre-amp tube with Ic
of his power tubes ??
DC heating for free ;-))

Ronald .

In article , "Ronald"
wrote:

Fair enough.
Saving 0.945 watts is important.

That's what I thought at first , but .......

What if he wants to heat the (first) pre-amp tube with Ic
of his power tubes ??
DC heating for free ;-))

Ronald .

A gold star for Ronald! Not only do I want to heat the (first) "pre-amp"
tube, actually the phase inverter, with DC from the output stage cathodes,
but also the driver tube. There is a total of 200 mA available for the
job, and I would like to hold the voltage drop to 20 volts at the outside.

With a 6211 driver and say a 6AQ6 as the phase inverter, the total voltage
for both tubes in series is 18.9 volts at 150 mA, which is within reason.


Regards,

John Byrns


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

(John Byrns) said:

A gold star for Ronald! Not only do I want to heat the (first) "pre-amp"
tube, actually the phase inverter, with DC from the output stage cathodes,
but also the driver tube. There is a total of 200 mA available for the
job, and I would like to hold the voltage drop to 20 volts at the outside.

With a 6211 driver and say a 6AQ6 as the phase inverter, the total voltage
for both tubes in series is 18.9 volts at 150 mA, which is within reason.


How about an EBC81/ 6BD7?
http://4tubes.com/All-Files/datashee...tml/EBC81.html

--

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

Sander deWaal said:

(John Byrns) said:

A gold star for Ronald! Not only do I want to heat the (first) "pre-amp"
tube, actually the phase inverter, with DC from the output stage cathodes,
but also the driver tube. There is a total of 200 mA available for the
job, and I would like to hold the voltage drop to 20 volts at the outside.

With a 6211 driver and say a 6AQ6 as the phase inverter, the total voltage
for both tubes in series is 18.9 volts at 150 mA, which is within reason.


How about an EBC81/ 6BD7?
http://4tubes.com/All-Files/datashee...tml/EBC81.html


ARGH!
Make that UBC81/ 14G6.
http://tdsl.duncanamps.com/show.php?des=UBC81

--

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

John Byrns wrote:

In article , "Ronald"
wrote:

Fair enough.
Saving 0.945 watts is important.

That's what I thought at first , but .......

What if he wants to heat the (first) pre-amp tube with Ic
of his power tubes ??
DC heating for free ;-))

Ronald .

A gold star for Ronald! Not only do I want to heat the (first) "pre-amp"
tube, actually the phase inverter, with DC from the output stage cathodes,
but also the driver tube. There is a total of 200 mA available for the
job, and I would like to hold the voltage drop to 20 volts at the outside.

With a 6211 driver and say a 6AQ6 as the phase inverter, the total voltage
for both tubes in series is 18.9 volts at 150 mA, which is within reason.

Regards,

John Byrns

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

If you have 20 volts & 200 ma, why not a pair of 20EZ7's? That way you have
two double triodes to work with. JLS