My last design

[Conta]

Hello,
I'm new member (63y old ) and wrote to this forum first time. I represent on your review my last design. Description and photos on my page:
Tube preamp http://audio.ring.lt/pre/pre_en.htm
Power amp http://audio.ring.lt/pw36/pw36_e.htm

[SY]

Good, solid, classic designs with some nice twists. Impressive packaging!

Welcome to the forum- you'll find lots of tube-heads of our generation here. And wine geeks, too (at least one: me).

[Salas]

Very nice, original spirited design, and execution. You obviously know tubes. Are you an electronics military or civil expert?

[Yvesm]

Just can say:
Oh ! ! !

[Conta]

Thanks for good responses. The tube technics disappears. We do not have lectures at universities in Lithuania about tube technics years 30 (or more). Sadly...

I graduated faculty of radio electronics about 40 years ago. Worked years 5 in a sound recording studio. And then years 20 was employed as photographer. Now my job is IT engineer

[ilimzn]

I have a question, about the 6P36S tube...
Nominally it is said it's an equivalent of the EL500, but the construction is different. I've looked at the little data i have and the specs seem higher than the EL500 - you use it at over 18W of total P+G2 dissipation, EL500 is, spec-wise, good only up to 12W plate dissipation. 6P36S also has a much bigger bulb... Do you have plate curves for the 6P36S in triode, or any other observations on this tube you would care to share?

[Salas]

Guys, watch em and learn... The Eastern Europeans are natural with tube logic. They have a knack for it. They think easier of a straighter straight.

[Conta]

Originally posted by ilimzn
I have a question, about the 6P36S tube...
Nominally it is said it's an equivalent of the EL500, but the construction is different. I've looked at the little data i have and the specs seem higher than the EL500 - you use it at over 18W of total P+G2 dissipation, EL500 is, spec-wise, good only up to 12W plate dissipation. 6P36S also has a much bigger bulb... Do you have plate curves for the 6P36S in triode, or any other observations on this tube you would care to share?

No, 6P36S is close resemblance of EL500 only. Beam tetrode 6P36S is original soviet construction with frame grids and strong as tank With 18-22W dissipation this tube sounds very good. Plate curves in triode connection is there:

http://audio.ring.lt/lempos/tetr.gif

[ilimzn]

Originally posted by Conta

No, 6P36S is close resemblance of EL500 only. Beam tetrode 6P36S is original soviet construction with frame grids and strong as tank With 18-22W dissipation this tube sounds very good. Plate curves in triode connection is there:
http://audio.ring.lt/lempos/tetr.gif

I thought as much - I have a 6P45S here, relabeled as EL509, and compared to it the 'mighty' EL509 looks flimsy. The 6P45S is nearly twice the weight. The 6P36S looks to be constructed along similar guidelines, with frame grids for both G1 and G2. I have ben collecting every data sheet for ex-soviet made tubes for ages, and your tride curves are a brilliant addition, I cannot thank you enough! I will also update my files to show that 6P36S is only similar end not equivalent to EL500.

But now, since i have found someone who knows abut these tubes, I have more questions

There are a number of BPTs of interest that I have very little data about.

The first group would be those that seem to have Euro or US equivalents:
6P7S is said to be equivalent to 6BG6 which is fairly well known to work nice connected as a triode.
6P20S is said to be equivalent to 6CB5, curves are somewhat similar but I have not seen anything about triode mode, considering the relatively low Vg2 maximum.
6P27S is often referred to as an equivalent to the EL34, but even though pentode curves are somewhat similar, this is obviously wrong as the 6P27S is a BPT and the EL34 a true pentode. One look at the 6P27S triode curves tells the tale - they are very similar to those of the 6P3S/6L6. This tbe seems to me to be related to the 6P3S...
6P31S is often relabeled as the euro EL36, but the specs give less anode dissipation. The EL/PL36 is very good in triode (far better than specs would suggest) but I don't know anything about using the 6P31S that way.

The second group of tubes are those that don't seem to have Euro or US equivalents:
6P21S is apparently a directly heated BPT with 18W plate dissipation. Unfortunately, I have found no curves for it. It is possible it is actually a unipotential cathode tied to the center tap of the filament. Looks interesting and the pinout seems to indicate RF service.
6P23P seems to be a smaller version, with 11W plate dissipation. Again, i have nothing more but general data.
6P42S seems very similar to the 6P45S except the drawing I have shows a much smaller base, perhaps noval instead of the 6P45S magnoval? I only have general data and a drawing of the bulb...

The third group are power BPTs that have no top cap and seem to have no Eu or US equivalents as well:
6P34S is a 18W PBT which, from the drawing, I guess has an octal base. It appears to have fairly low maximum voltages for plate and G2 too...
6P39S is a very interesting 10W relatively low voltage but very high Gm pentode (56mA/V!) in a most curious bulb - seems like a noval base with 30mm diameter bulb. Again, I have no more data...
6P41S has the same 30mm bulb, but (I am guessing) magnoval base, it reminds me somewhat of the EL508, but seems to have lower maximum voltages and higher plate dissipation.

Any insight, comment or data on any of these tubes would be highly appreciated, i hope i am not asking for too much. If I am, well, you can just ignore me

Thanks,

ZN

[Conta]

Hi Ilimzn,
6P7S is octal mode of 807 tube. With the lowered level of vacuum for not militar purposes. 6P20S is octal mode of 6P42S. 6P27S was experimental copy of EL34 and very small quantity was made. I never had this tube in my hands. 6P31S is stronger model of 6P13S, it is intended for TV models with 110 degree deflection. I have no data about 6P21S and 6P23P, but you may see something here - (PDF's) and curves in triode connection :

http://audioportal.spb.ru/forums/sho...%F1#post131423

No data for tubes 6P34S and 6P39S, sorry. About tube 6P41S I can say that this tube sounds beautiful. Here you can see spectral analysis of popular tubes, sorry in russian:
http://www.next-power.net/next-tube/...r/spectrRU.pdf