[Ian Thompson-Bell]

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian

[mick]

On Thu, 31 Jul 2008 18:43:35 +0100, Ian Thompson-Bell wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?



I would have thought that PCC88s would have been fairly consistant, but
not necessarily. They were designed for use in TV sets, where quantity &
low cost were more essential. That's why they have 300mA heaters - for
series use across the mains. I assume that you gave then the correct
current? It works out at about 7.5V IIRC.


--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net
Filtering everything posted from googlegroups to kill spam.

[Ian Thompson-Bell]

mick wrote:
On Thu, 31 Jul 2008 18:43:35 +0100, Ian Thompson-Bell wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?



I would have thought that PCC88s would have been fairly consistant, but
not necessarily. They were designed for use in TV sets, where quantity &
low cost were more essential. That's why they have 300mA heaters - for
series use across the mains. I assume that you gave then the correct
current? It works out at about 7.5V IIRC.



Yes and no. I have seen many designs where PCC88s are used at the preamp
output and run off 6.3V heaters for extended life. Ferrograph used them
a lot in their top of the range tape recorders and I have one with just
such an output stage.

I ran them from a 6.3V heater winding but as it is rated far higher than
the 0.6A taken by the two PCC88s the actual measured heater voltage in
the test rig is 6.95V.

Cheers

Ian

[Patrick Turner]

Ian Thompson-Bell wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian

Test more samples to get a better idea.

Patrick Turner.

[Ian Thompson-Bell]

Patrick Turner wrote:

Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian

Test more samples to get a better idea.

Patrick Turner.

Unfortunately I have no more samples to test.

Cheers

Ian

[Patrick Turner]

Ian Thompson-Bell wrote:

Patrick Turner wrote:

Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian

Test more samples to get a better idea.

Patrick Turner.

Unfortunately I have no more samples to test.

Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.



Cheers

Ian

[Nick Gorham]

Ian Thompson-Bell wrote:
Patrick Turner wrote:


Ian Thompson-Bell wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian


Test more samples to get a better idea.

Patrick Turner.


Unfortunately I have no more samples to test.

Cheers

Ian

I can't help thinking to be at least sure you have tested the valves in
the correct state, you should feed the PCC's heater from a 300ma CCS

--
Nick

[Ian Thompson-Bell]

Nick Gorham wrote:
Ian Thompson-Bell wrote:
Patrick Turner wrote:


Ian Thompson-Bell wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s
are
skip material.

Thoughts anyone?

Cheers

Ian


Test more samples to get a better idea.

Patrick Turner.


Unfortunately I have no more samples to test.

Cheers

Ian

I can't help thinking to be at least sure you have tested the valves in
the correct state, you should feed the PCC's heater from a 300ma CCS



Sorry, but why would you do that? They are not designed for constant
current supplies are they? Surely, in those days nothing was run from a
constant current supply. Or have I missed something?

Cheers

Ian

[Ian Thompson-Bell]

Patrick Turner wrote:

Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian
Test more samples to get a better idea.

Patrick Turner.
Unfortunately I have no more samples to test.

Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.


Well the 10 Russian samples are all by the same manufacturer and from
the same batch AFAIK so presumably that's a help.

The other thing I find interesting is you often see on the net that a
6N1P is equivalent to an ECC88/6DJ8 when in fact it is a near equivalent
of a 12AT7. I can see why someone wanting to sell a 6N1P would do this
but but there are technical sites that make the same error.

Cheers

Ian

[Nick Gorham]

Ian Thompson-Bell wrote:

Ian


I can't help thinking to be at least sure you have tested the valves
in the correct state, you should feed the PCC's heater from a 300ma CCS



Sorry, but why would you do that? They are not designed for constant
current supplies are they? Surely, in those days nothing was run from a
constant current supply. Or have I missed something?

Cheers

Ian

No, but they are designed to be heated by 300ma, and a CCS seems the
simple way of doing that. Unless you have a bench supply and can adjust
the voltage to give you 300ma through the valve.

They were effectivly used with a constant current supply by being fed
via a large dropper resistor.

--
Nick

[Patrick Turner]

Nick Gorham wrote:

Ian Thompson-Bell wrote:

Ian


I can't help thinking to be at least sure you have tested the valves
in the correct state, you should feed the PCC's heater from a 300ma CCS



Sorry, but why would you do that? They are not designed for constant
current supplies are they? Surely, in those days nothing was run from a
constant current supply. Or have I missed something?

Cheers

Ian

No, but they are designed to be heated by 300ma, and a CCS seems the
simple way of doing that. Unless you have a bench supply and can adjust
the voltage to give you 300ma through the valve.

They were effectivly used with a constant current supply by being fed
via a large dropper resistor.

All tubes have a specified heater voltage and heater current.

If you apply the data specified voltage, you should see the data spec
current.

Alternatively, applying the specified current should give a voltage
across the hot resistance as specified.

If this don't work out then you are left wondering if its best to have
the correct current, but wrong voltage,

or the correct voltage, and wrong current.

Either way one might get a different heater temperature which may affect
emission and tube life.

Patrick Turner



--
Nick

[Patrick Turner]

Ian Thompson-Bell wrote:

Patrick Turner wrote:

Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian
Test more samples to get a better idea.

Patrick Turner.
Unfortunately I have no more samples to test.

Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.


Well the 10 Russian samples are all by the same manufacturer and from
the same batch AFAIK so presumably that's a help.

The other thing I find interesting is you often see on the net that a
6N1P is equivalent to an ECC88/6DJ8 when in fact it is a near equivalent
of a 12AT7. I can see why someone wanting to sell a 6N1P would do this
but but there are technical sites that make the same error.

Cheers

Ian

Take a look at 6N1P at
http://www.mif.pg.gda.pl/homepages/f...112/6/6N1P.pdf

The gm is around 4.5mA/V and µ = about 35, so Ra is about 7.7k,
at about 7 mA.

So the 6N1P is much closer to 6DJ8 than it is to 12AT7, which has a µ =
55, Ra = 15k.

Notice the data has a range of gm values.

The data aknowledges that gm and Ra change a lot with Ia variations, and
that µ is the most constant,
and so it is with 12AT7, and 6DJ8.

As Ia is reduced, gm becomes lower, and because Ra = µ / gm , Ra becomes
higher.

The µ can be read for any value of Ia on the anode curves graph.
It is the Ea change for a given Eg change along horizontal Ia lines.

When you see how to caculate the µ after reading the Ea Eg on horizontal
load lines, ie, constant current lines,
then you see µ is the easiest to read off, and the most constant.
Gm can also be read off seeing the Ia change on a vertical line for any
Ea value
and for a given difference of Eg, say 1 volt.

A straight line tangent drawn against any point on any one of the Ra
curves for Eg values will give the Ra
for that working point. So low Ea/Ia changes will occur with Ra being
what you calculate
from your tangent slope, Ea change / Ia change.

Otherwise, ya hafta measure it all on a sample.

Patrick Turner.

[Ian Thompson-Bell]

Patrick Turner wrote:

Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian
Test more samples to get a better idea.

Patrick Turner.
Unfortunately I have no more samples to test.
Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.

Well the 10 Russian samples are all by the same manufacturer and from
the same batch AFAIK so presumably that's a help.

The other thing I find interesting is you often see on the net that a
6N1P is equivalent to an ECC88/6DJ8 when in fact it is a near equivalent
of a 12AT7. I can see why someone wanting to sell a 6N1P would do this
but but there are technical sites that make the same error.

Cheers

Ian

Take a look at 6N1P at
http://www.mif.pg.gda.pl/homepages/f...112/6/6N1P.pdf

The gm is around 4.5mA/V and µ = about 35, so Ra is about 7.7k,
at about 7 mA.

So the 6N1P is much closer to 6DJ8 than it is to 12AT7, which has a µ =
55, Ra = 15k.


Yeah but, no but, the 6DJ8 has a gm at least twice that of a 6N1P so the
6DJ8 has an ra about half that of a 6N1P. About the only thing they have
in common is mu.

Notice the data has a range of gm values.

The data acknowledges that gm and Ra change a lot with Ia variations, and
that µ is the most constant,
and so it is with 12AT7, and 6DJ8.

As Ia is reduced, gm becomes lower, and because Ra = µ / gm , Ra becomes
higher.

The µ can be read for any value of Ia on the anode curves graph.
It is the Ea change for a given Eg change along horizontal Ia lines.

When you see how to caculate the µ after reading the Ea Eg on horizontal
load lines, ie, constant current lines,
then you see µ is the easiest to read off, and the most constant.
Gm can also be read off seeing the Ia change on a vertical line for any
Ea value
and for a given difference of Eg, say 1 volt.

A straight line tangent drawn against any point on any one of the Ra
curves for Eg values will give the Ra
for that working point. So low Ea/Ia changes will occur with Ra being
what you calculate
from your tangent slope, Ea change / Ia change.

Otherwise, ya hafta measure it all on a sample.


Good stuff Patrick, me ruler and pencil will be workin' overtime.

Cheers

ian

[Ian Thompson-Bell]

Nick Gorham wrote:
Ian Thompson-Bell wrote:

Ian


I can't help thinking to be at least sure you have tested the valves
in the correct state, you should feed the PCC's heater from a 300ma CCS



Sorry, but why would you do that? They are not designed for constant
current supplies are they? Surely, in those days nothing was run from
a constant current supply. Or have I missed something?

Cheers

Ian

No, but they are designed to be heated by 300ma, and a CCS seems the
simple way of doing that. Unless you have a bench supply and can adjust
the voltage to give you 300ma through the valve.


Well the spec says 7V heater supply and mine measures 6.95 which is
close enough. I just measured the current through the pair in my test
rig and they take 0.59 amps - is that close enough?

Cheers

ian
They were effectivly used with a constant current supply by being fed
via a large dropper resistor.

[Nick Gorham]

Ian Thompson-Bell wrote:


No, but they are designed to be heated by 300ma, and a CCS seems the
simple way of doing that. Unless you have a bench supply and can
adjust the voltage to give you 300ma through the valve.


Well the spec says 7V heater supply and mine measures 6.95 which is
close enough. I just measured the current through the pair in my test
rig and they take 0.59 amps - is that close enough?


Probably, but it would be better to have them in series, thats how they
were intended, you don't know from that if the two valves are passing
the same current.

--
Nick

[Ian Thompson-Bell]

flipper wrote:
On Thu, 31 Jul 2008 18:43:35 +0100, Ian Thompson-Bell
wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Ebay ads notwithstanding, the 6N1P is not a 6DJ8 equivalent.

Indeed. Even Wikipedia makes the link:

"The 6N1P has similar ratings to the 6DJ8 and in the past was sometimes
rebranded as such, however differences between the two types (the 6N1P
requires double the filament current and has only one third the S value)
mean they are not directly interchangeable."

I am in the process of putting together a spread sheet comparison of the
B9A double triodes which I'll share when complete.

Cheers

Ian

[Ian Thompson-Bell]

flipper wrote:
On Sat, 02 Aug 2008 14:09:54 +0100, Ian Thompson-Bell
wrote:

flipper wrote:
On Thu, 31 Jul 2008 18:43:35 +0100, Ian Thompson-Bell
wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?
Ebay ads notwithstanding, the 6N1P is not a 6DJ8 equivalent.
Indeed. Even Wikipedia makes the link:

So, what's your point?


I was agreeing with you is all.

"The 6N1P has similar ratings to the 6DJ8 and in the past was sometimes
rebranded as such, however differences between the two types (the 6N1P
requires double the filament current and has only one third the S value)
mean they are not directly interchangeable."

I am in the process of putting together a spread sheet comparison of the
B9A double triodes which I'll share when complete.

Might as well list the Svetlana 6N1P as a separate tube because, IMO,
the Svetlana 6N1P isn't a 6N1P. It's closer to a 6N3P.


The Svetlana 6N1P data sheet claims mu=33, gm=7.5mA/V, ra=4.4K.
Only the 'better' versions of the 6N3P approach that gm value. Most are
in the 4 to 5 region.

Cheers

Ian

[Ian Thompson-Bell]

flipper wrote:
On Sat, 02 Aug 2008 20:45:07 +0100, Ian Thompson-Bell
wrote:

flipper wrote:
On Sat, 02 Aug 2008 14:09:54 +0100, Ian Thompson-Bell
wrote:

flipper wrote:
On Thu, 31 Jul 2008 18:43:35 +0100, Ian Thompson-Bell
wrote:

After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?
Ebay ads notwithstanding, the 6N1P is not a 6DJ8 equivalent.
Indeed. Even Wikipedia makes the link:
So, what's your point?

I was agreeing with you is all.

ok


"The 6N1P has similar ratings to the 6DJ8 and in the past was sometimes
rebranded as such, however differences between the two types (the 6N1P
requires double the filament current and has only one third the S value)
mean they are not directly interchangeable."

I am in the process of putting together a spread sheet comparison of the
B9A double triodes which I'll share when complete.
Might as well list the Svetlana 6N1P as a separate tube because, IMO,
the Svetlana 6N1P isn't a 6N1P. It's closer to a 6N3P.

The Svetlana 6N1P data sheet claims mu=33, gm=7.5mA/V, ra=4.4K.
Only the 'better' versions of the 6N3P approach that gm value. Most are
in the 4 to 5 region.

Sure you're not thinking the 6N1P? My 6N3P datasheets spec 6mA/V as
nominal.


Data sheets for the 6N3P seem a bit variable. One equates it to the 2C51
with a gm of 5.4mA/V, a Russian one I found lists gm a 4.9mA/V, another
equates it to a 6385 with gm=5mA/V, and another lists 3 'types' of 6n1P
with gm varying between 4.8 and 6.8mA/V across the range.

I think you are right that a comparison of the curves is a better
approach than comparing raw mu,gm and ra under (possibly) varying
conditions.

Thing is, I cannot find a data sheet for the 6N3P which includes curves.
Where did you find yours?

Cheers

[Ian Thompson-Bell]

Ian Thompson-Bell wrote:

Thing is, I cannot find a data sheet for the 6N3P which includes curves.
Where did you find yours?

Cheers


Ignore that, I just found one, with curves and gm=6mA/V and in Russian too.

Cheers

Ian

[Patrick Turner]

Ian Thompson-Bell wrote:

Patrick Turner wrote:

Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian
Test more samples to get a better idea.

Patrick Turner.
Unfortunately I have no more samples to test.
Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.

Well the 10 Russian samples are all by the same manufacturer and from
the same batch AFAIK so presumably that's a help.

The other thing I find interesting is you often see on the net that a
6N1P is equivalent to an ECC88/6DJ8 when in fact it is a near equivalent
of a 12AT7. I can see why someone wanting to sell a 6N1P would do this
but but there are technical sites that make the same error.

Cheers

Ian

Take a look at 6N1P at
http://www.mif.pg.gda.pl/homepages/f...112/6/6N1P.pdf

The gm is around 4.5mA/V and µ = about 35, so Ra is about 7.7k,
at about 7 mA.

So the 6N1P is much closer to 6DJ8 than it is to 12AT7, which has a µ =
55, Ra = 15k.


Yeah but, no but, the 6DJ8 has a gm at least twice that of a 6N1P so the
6DJ8 has an ra about half that of a 6N1P. About the only thing they have
in common is mu.

Not so fast me lad, 6DJ8 only has a high gm when you have about 10mA of
Ia.
With Ia at a more commonly used value of 5mA, gm is about halved,
and Ra doubles to about 5k+



Notice the data has a range of gm values.

The data acknowledges that gm and Ra change a lot with Ia variations, and
that µ is the most constant,
and so it is with 12AT7, and 6DJ8.

As Ia is reduced, gm becomes lower, and because Ra = µ / gm , Ra becomes
higher.

The µ can be read for any value of Ia on the anode curves graph.
It is the Ea change for a given Eg change along horizontal Ia lines.

When you see how to caculate the µ after reading the Ea Eg on horizontal
load lines, ie, constant current lines,
then you see µ is the easiest to read off, and the most constant.
Gm can also be read off seeing the Ia change on a vertical line for any
Ea value
and for a given difference of Eg, say 1 volt.

A straight line tangent drawn against any point on any one of the Ra
curves for Eg values will give the Ra
for that working point. So low Ea/Ia changes will occur with Ra being
what you calculate
from your tangent slope, Ea change / Ia change.

Otherwise, ya hafta measure it all on a sample.


Good stuff Patrick, me ruler and pencil will be workin' overtime.

In a preamp, the only important parameters are ones right at the working
Ea & Ia point at idle because
the Vswing is only a few volts either side of this Iq point.

And so it is with output stages in power amps.

If you have a pair of KT88 in PP with say Ea = 500V and IaQ at say 35mA,
gm is much lower than the
11mA/V quoted the tube specs. Ra is a lot higher as well.
So the Rout of the pair of beam tetrodes is determined by the class A
working pont because
99% of what we listen with is around that 35mA point where Ia changes
are quite low.
µ = gm x Ra, so Ra = µ / gm, so as Ia becomes lower, and µ is the most
constant thing,
Ra becomes much higher.

Measuring it is reality of course.

Build the amp.

Set the amp for 4V0 with no load, 1kHz.
Then connect 8 ohms, and measure the new VO.

Rout = V change / Load I change = Vchange / ( Load VO / Load ohms ) =
load ohms x Vchange / Loaded VO.

Ra-a at the small signal swing = OPT turn ratio squared x Rout at sec -
all winding resistances refered to Prim.
Or since most OPT have 10% winding losses, Ra-a = OPT TR squared - 10%.

The Ra-a you get without the global or other types of series voltage NFB
will be much higher
than twice the Ra given for a tube in the data specs.

The same ideas can be applied to work out Rout of any device.

And when NFB is connected.

A good multigrid output tubed power amp should have its high Rout of
many times the speaker Z
reduced to 1ohm or less for an outlet which is an ideal match for 8
ohms.

Triodes such as 300B can get you there without the loop FB.

Patrick Turner.




Cheers

ian

[tubegarden]

Hi RATs!

Fortune has left me with some nice old speakers and a few tube
amplifiers to while away my time until the Big School Bus comes and I
leave this pleasant home.

I only listen to what each tube, or cap, or speaker location, does
when performing Musical reproduction.

Attempting reproduction almost always gets the most involvement
possible.

I like listening, even when the immediately previous bit of technology
was obviously "superior".

I was born by Lake Superior. It is big and occasionally lovely, but
being the biggest freshwater body does not really mean it will always
be the best. Sense and honesty often must change their meanings as
this future unwinds from the old spool

Happy Ears!
Al

[Ian Thompson-Bell]

Patrick Turner wrote:

Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
Patrick Turner wrote:
Ian Thompson-Bell wrote:
After checking out 10 off 6N1P and a pair of PCC88s in my test rig it
seems these tubes are not really as similar as I thought.

All 10 6N1Ps recorded an plate voltage between 140 and 150V and a
cathode voltage between 2.5 and 2.7 volts.

The two PCC88s read from 101 to 125V plate volts and 2.85 to 3.25V
across the cathodes.

OK this is not a definitive test but the 6N1Ps were very consistent and
very close within a tube. The PCC88s seem to be all over the place even
within a tube.

I conluce the Russian 6N1Ps are good and the pair of Miniwatt PCC88s are
skip material.

Thoughts anyone?

Cheers

Ian
Test more samples to get a better idea.

Patrick Turner.
Unfortunately I have no more samples to test.
Our own conclusions about the tubes we use can be in error if we depart
from the basic scientific method
which needs the measuring a large enough number of samples to come to a
conclusion that
is right, and which discovers the variations between samples.

Basically, hobbyists are suck it and see types.
Not all samples of tubes I might have would indicate that all of a type
might be crook.

You could get 10 samples of 12AU7 by different makers, and I could do
the same.
Each of us might conclude different things about the makers and the
tubes.

But most brands of 12AU7 I encounter which are little used, or NOS are
remarkably similar
and usable in the same circuits, and each triode section is close to
each other.

Patrick Turner.

Well the 10 Russian samples are all by the same manufacturer and from
the same batch AFAIK so presumably that's a help.

The other thing I find interesting is you often see on the net that a
6N1P is equivalent to an ECC88/6DJ8 when in fact it is a near equivalent
of a 12AT7. I can see why someone wanting to sell a 6N1P would do this
but but there are technical sites that make the same error.

Cheers

Ian
Take a look at 6N1P at
http://www.mif.pg.gda.pl/homepages/f...112/6/6N1P.pdf

The gm is around 4.5mA/V and µ = about 35, so Ra is about 7.7k,
at about 7 mA.

So the 6N1P is much closer to 6DJ8 than it is to 12AT7, which has a µ =
55, Ra = 15k.

Yeah but, no but, the 6DJ8 has a gm at least twice that of a 6N1P so the
6DJ8 has an ra about half that of a 6N1P. About the only thing they have
in common is mu.

Not so fast me lad, 6DJ8 only has a high gm when you have about 10mA of
Ia.
With Ia at a more commonly used value of 5mA, gm is about halved,
and Ra doubles to about 5k+


Notice the data has a range of gm values.

The data acknowledges that gm and Ra change a lot with Ia variations, and
that µ is the most constant,
and so it is with 12AT7, and 6DJ8.

As Ia is reduced, gm becomes lower, and because Ra = µ / gm , Ra becomes
higher.

The µ can be read for any value of Ia on the anode curves graph.
It is the Ea change for a given Eg change along horizontal Ia lines.

When you see how to caculate the µ after reading the Ea Eg on horizontal
load lines, ie, constant current lines,
then you see µ is the easiest to read off, and the most constant.
Gm can also be read off seeing the Ia change on a vertical line for any
Ea value
and for a given difference of Eg, say 1 volt.

A straight line tangent drawn against any point on any one of the Ra
curves for Eg values will give the Ra
for that working point. So low Ea/Ia changes will occur with Ra being
what you calculate
from your tangent slope, Ea change / Ia change.

Otherwise, ya hafta measure it all on a sample.

Good stuff Patrick, me ruler and pencil will be workin' overtime.

In a preamp, the only important parameters are ones right at the working
Ea & Ia point at idle because
the Vswing is only a few volts either side of this Iq point.


Yes, you are right. I guess that was the 'marketing hype' of the day.

Cheers

Ian

[[email protected]]

On Aug 2, 8:26 pm, flipper wrote:
Might as well list the Svetlana 6N1P as a separate tube because, IMO,
the Svetlana 6N1P isn't a 6N1P. It's closer to a 6N3P.

Is there a Svetlana 6N1P? I have never seen one. The 6N1Ps I have in
Svetlana boxes are actually Voskhod, Kaluga 6N1P-EV tubes. But perhaps
there is a bit of difference between the -EV and the standard version?

Best regards,

Mikkel C. Simonsen

[tubegarden]

On Aug 8, 10:13�pm, wrote:

Is there a Svetlana 6N1P? I have never seen one. The 6N1Ps I have in
Svetlana boxes are actually Voskhod, Kaluga 6N1P-EV tubes. But perhaps
there is a bit of difference between the -EV and the standard version?

Best regards,

Mikkel C. Simonsen



Hi RATs!

Does the place of assembly of the tubes I am listening to make any
difference?

The advertisers are a bit more enthusiastic about the concept than my
little system and frail old ears notice

I hear what I hear. I type what I type. Does anyone wish to guess
which brand keyboard I am using ???

Happy Ears!
Al

[Mikkel C. Simonsen]

tubegarden wrote:

Is there a Svetlana 6N1P? I have never seen one. The 6N1Ps I have in
Svetlana boxes are actually Voskhod, Kaluga 6N1P-EV tubes. But perhaps
there is a bit of difference between the -EV and the standard version?

Does the place of assembly of the tubes I am listening to make any
difference?

No, my point was just that the much discussed "Svetlana" doesn't exist.
The Svetlana's are the same as other 6N1Ps, and sound the same also.

The advertisers are a bit more enthusiastic about the concept than my
little system and frail old ears notice

This is the case here also I think. The Svetlana datasheet was created
by the marketing people (to sell more tubes), and is a work of fiction


Best regards,

Mikkel C. Simonsen

[Andre Jute[_2_]]

On Aug 13, 10:35*pm, "Mikkel C. Simonsen" wrote:
tubegarden wrote:

Is there a Svetlana 6N1P? I have never seen one. The 6N1Ps I have in
Svetlana boxes are actually Voskhod, Kaluga 6N1P-EV tubes. But perhaps
there is a bit of difference between the -EV and the standard version?

Does the place of assembly of the tubes I am listening to make any
difference?

No, my point was just that the much discussed "Svetlana" doesn't exist.
The Svetlana's are the same as other 6N1Ps, and sound the same also.

All of this is true but irrelevant. You might as well says, "Oh, yes,
well, Coca-Cola doesn't really exist. All these independent franchise
holders just put fizzy water in bottles with the word Coke on them."
That too is true but a totally incomplete picture.

Furthermore, being overly pedantic about Svetlana, or sneering at it
as a merely marketing (subgenre branding) operation, misses the main
point of its existence, and the reason to mourn its passing: it
introduced us to tube we would otherwise never even have heard about.
6D22S, for instance, is a stunning HV rectifier.

But there is more to be grateful to Svetlana for. SV572-3 -10 and -30
are actually new tubes with superb sound (when correctly implemented,
an ambience somewhere between a 211 and an 845 -- and who can bestow
higher praise than that?).

Now let praise famous men, even if their intention was only making a
buck (Ecclesiastes).

Andre Jute
Kilovolt thrills

[Patrick Turner]

Andre Jute wrote:

On Aug 13, 10:35 pm, "Mikkel C. Simonsen" wrote:
tubegarden wrote:

Is there a Svetlana 6N1P? I have never seen one. The 6N1Ps I have in
Svetlana boxes are actually Voskhod, Kaluga 6N1P-EV tubes. But perhaps
there is a bit of difference between the -EV and the standard version?

Does the place of assembly of the tubes I am listening to make any
difference?

No, my point was just that the much discussed "Svetlana" doesn't exist.
The Svetlana's are the same as other 6N1Ps, and sound the same also.

All of this is true but irrelevant. You might as well says, "Oh, yes,
well, Coca-Cola doesn't really exist. All these independent franchise
holders just put fizzy water in bottles with the word Coke on them."
That too is true but a totally incomplete picture.

Furthermore, being overly pedantic about Svetlana, or sneering at it
as a merely marketing (subgenre branding) operation, misses the main
point of its existence, and the reason to mourn its passing: it
introduced us to tube we would otherwise never even have heard about.
6D22S, for instance, is a stunning HV rectifier.

But there is more to be grateful to Svetlana for. SV572-3 -10 and -30
are actually new tubes with superb sound (when correctly implemented,
an ambience somewhere between a 211 and an 845 -- and who can bestow
higher praise than that?).

Gee, I must look all that up; could be very handy to know about,
especially when a new KR845 now retails for usd $480.00!

Patrick Turner.

Now let praise famous men, even if their intention was only making a
buck (Ecclesiastes).

Andre Jute
Kilovolt thrills