I have been sitting on a bunch of 6P1P-EV for years that I paid next to noting for.
Always assumed they were close to a 6AQ5 in capability and so never really found a use for them.
As electrically the 6AQ5 and the 6V6 are pretty close this got me thinking what could these old 6P1P really do.
I made up a chart to compare some basic physical and electrical parameters.
Thought I would share my data in case anyone finds this of interest.
Heater power, a reasonable proxy of the cathodes ability to emit electrons is close in all three, the 6P1P a little better @ 109% of the 6V6.
Maximum anode voltage on the data sheet shows the 6P1P-EV limited to only 250V but the anode data curves extend up to 475V or 118% of the 6V6's 400V on the data sheet.
Does this mean anything? Perhaps as there are many motivations at work when a data sheet is written.
For heat dissipation surface area can be a reasonable proxy for total power dissipation all other factors being the same. I admit I do not know what exact materials the 6V6, 6AQ5 or 6P1P are made of.
I found it interesting that the 6AQ5 anode area is only 71% of a 6V6 and the 6P1P is closer but still smaller at 85% of a 6V6.
The area of the glass bulb affects total power dissipation and here the 6AQ5 is 43% of a 6V6 and the 6P1P is much better at 71% of a 6V6.
All three are rated at 12 watts of anode dissipation but it seems to me perhaps different sized watts were used with the 6AQ5 data sheet and the 6V6 is old school conservative. 😉
S (mA/V) is close for all three with the 6P1P being 119% of a 6V6.
The bias point with 250V screens is virtually the same 44-45mA anode current at -12.5V on g1.
Peak plate current at a=100V is again close, a 6AQ5 @117% of a 6V6 and a 6P1P @99% of a 6V6.
A stand out difference is rated G2 power. The 6AQ5 and the 6V6 both at 2 watts, the 6P1P @1.3 watts or 65% of a 6V6.
Suggests if you want to push a 6P1P it is best to carefully watch the screen voltage and current levels in your design. Limiting the peak screen voltage and current when the anode voltage drops at the bottom of the output waveform is going to be important to keeping a 6P1P from screen death is seems. This suggests a limiting factor for maximum power that can be pushed out of a 6P1P will be screen power levels.
On one hand the 6P1P seems closer in ability to a 6V6 than a 6AQ5 when physical size is looked at.
On the other hand the low 1.3 watts screen rating on the 6P1P does suggest that 6AQ5 power levels maybe all there is before the screen fails.
I would like to hear from anyone with direct experience in pushing 6P1P tubes to levels closer to 6V6 power levels and above 6AQ5 power levels.
Always assumed they were close to a 6AQ5 in capability and so never really found a use for them.
As electrically the 6AQ5 and the 6V6 are pretty close this got me thinking what could these old 6P1P really do.
I made up a chart to compare some basic physical and electrical parameters.
Thought I would share my data in case anyone finds this of interest.
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Heater power, a reasonable proxy of the cathodes ability to emit electrons is close in all three, the 6P1P a little better @ 109% of the 6V6.
Maximum anode voltage on the data sheet shows the 6P1P-EV limited to only 250V but the anode data curves extend up to 475V or 118% of the 6V6's 400V on the data sheet.
Does this mean anything? Perhaps as there are many motivations at work when a data sheet is written.
For heat dissipation surface area can be a reasonable proxy for total power dissipation all other factors being the same. I admit I do not know what exact materials the 6V6, 6AQ5 or 6P1P are made of.
I found it interesting that the 6AQ5 anode area is only 71% of a 6V6 and the 6P1P is closer but still smaller at 85% of a 6V6.
The area of the glass bulb affects total power dissipation and here the 6AQ5 is 43% of a 6V6 and the 6P1P is much better at 71% of a 6V6.
All three are rated at 12 watts of anode dissipation but it seems to me perhaps different sized watts were used with the 6AQ5 data sheet and the 6V6 is old school conservative. 😉
S (mA/V) is close for all three with the 6P1P being 119% of a 6V6.
The bias point with 250V screens is virtually the same 44-45mA anode current at -12.5V on g1.
Peak plate current at a=100V is again close, a 6AQ5 @117% of a 6V6 and a 6P1P @99% of a 6V6.
A stand out difference is rated G2 power. The 6AQ5 and the 6V6 both at 2 watts, the 6P1P @1.3 watts or 65% of a 6V6.
Suggests if you want to push a 6P1P it is best to carefully watch the screen voltage and current levels in your design. Limiting the peak screen voltage and current when the anode voltage drops at the bottom of the output waveform is going to be important to keeping a 6P1P from screen death is seems. This suggests a limiting factor for maximum power that can be pushed out of a 6P1P will be screen power levels.
On one hand the 6P1P seems closer in ability to a 6V6 than a 6AQ5 when physical size is looked at.
On the other hand the low 1.3 watts screen rating on the 6P1P does suggest that 6AQ5 power levels maybe all there is before the screen fails.
I would like to hear from anyone with direct experience in pushing 6P1P tubes to levels closer to 6V6 power levels and above 6AQ5 power levels.
Nearer to 6AQ5.
For what it is worth, I vastly prefer 6V6 or 6P6, despite the low gm.
Perhaps user error, but I never got similar performance from 6P1P (anode volts are more limited , vg2 volt limit doesn't work out so well, in SE triode, as I was using them.
Under those limitations (Va=Vg2=<300V) 6P6S were my preference.
This may not be the same story in PP
Looking at the Soviet datasheets the cutoff anode volt maxima, is what I refer to.
In 6P6S this is Ao of 300V or more, 6P1P is 250V (Ao at 280V if I recall right)
I suspect the other voltages refer to PP operation, but don't take my word as gospel.
For what it is worth, I vastly prefer 6V6 or 6P6, despite the low gm.
Perhaps user error, but I never got similar performance from 6P1P (anode volts are more limited , vg2 volt limit doesn't work out so well, in SE triode, as I was using them.
Under those limitations (Va=Vg2=<300V) 6P6S were my preference.
This may not be the same story in PP
Looking at the Soviet datasheets the cutoff anode volt maxima, is what I refer to.
In 6P6S this is Ao of 300V or more, 6P1P is 250V (Ao at 280V if I recall right)
I suspect the other voltages refer to PP operation, but don't take my word as gospel.
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I agree.
The Russian 6P6S with black glass is a real tank. They take abuses that even the older 6V6GT cannot take. I tried the 6P6 in my 60W EL34 prototype (pentode + cathode feedback). I only reduced the screen grid voltage to about 280V but left the anode voltage at 425V and adjusted the bias to get some 25-30 mA quiscent anode current. They made over 40W output power without visible distortion (on the scope).
That's a good news, I have read often the opposite, 6P6S can't take abuse, maybe for guitar amps with high screen voltage?
Do they "sound good" for you?
I have just finished a balanced amp with 6P6S triode connected, they sound fine to me but no comparison done because I don't have US/EU 6V6 (these little bottles are not cheap..)
Triode connection of 6V6 may not be the best, efficiency is terrible..
Do they "sound good" for you?
I have just finished a balanced amp with 6P6S triode connected, they sound fine to me but no comparison done because I don't have US/EU 6V6 (these little bottles are not cheap..)
Triode connection of 6V6 may not be the best, efficiency is terrible..
The 6P6S can take up to 350V anode voltage, 310V on g2 and 13.2W plate dissipation without any issue. Those are uprated specs respect to the original 6V6.
I would not trust judgments made on guitar amps as these often abuse a little bit too much. I only did a short test but normally can get about 25W out of the 6P6s staying within specs (i.e. 350V plate voltage, 300V on g2 with 8K plate-to-plate). Cannot do that with similar all-glass variants.
If one wants a 6V6 with a bit more juice then the JJ 6V6S is the choice: https://www.jj-electronic.com/en/6v6s
The triode efficiency could get better using the 6P6s at 350V anode voltage but staying at 10-11W dissipation (more like the older 6F6). I think 2.3-2.5W or so should be possible instead of the 1.6-1.7W of the standard 6V6 at 300V. Higher anode voltage is normally the way to get more efficiency.
I would not trust judgments made on guitar amps as these often abuse a little bit too much. I only did a short test but normally can get about 25W out of the 6P6s staying within specs (i.e. 350V plate voltage, 300V on g2 with 8K plate-to-plate). Cannot do that with similar all-glass variants.
If one wants a 6V6 with a bit more juice then the JJ 6V6S is the choice: https://www.jj-electronic.com/en/6v6s
The triode efficiency could get better using the 6P6s at 350V anode voltage but staying at 10-11W dissipation (more like the older 6F6). I think 2.3-2.5W or so should be possible instead of the 1.6-1.7W of the standard 6V6 at 300V. Higher anode voltage is normally the way to get more efficiency.
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45 reply jives eith my limited experience.
I was able to squeeze about 2W with 6P6S in triode, with anode volts at 300-330V, local FB in the output stage (plate to grid of 1st stage, which many wouldn't recommend) - but it worked well with roughly 0.5-1.0% THD, OPT was around 8k.
In this case I was driving them with 6S6B-V subminiature (medium mu) triodes, singleton 6N16B, and these triodes were used because of their very good linearity.
I was able to squeeze about 2W with 6P6S in triode, with anode volts at 300-330V, local FB in the output stage (plate to grid of 1st stage, which many wouldn't recommend) - but it worked well with roughly 0.5-1.0% THD, OPT was around 8k.
In this case I was driving them with 6S6B-V subminiature (medium mu) triodes, singleton 6N16B, and these triodes were used because of their very good linearity.