S.e. class A as in theory max of 50% of efficency, for every type of tubes.
With triode in not possible to go over 25%, for tetrodes/pentode some percentage more with a reasonble THD
Walter
With triode in not possible to go over 25%, for tetrodes/pentode some percentage more with a reasonble THD
Walter
Alot of dreaming going on here and no designing. The usual process is to start with a defined end result, then find out how to get there. Without actual bench testing, how can you know what to expect?
Actually, it is 25% theoretical maximum, when operated into a resistive load. Because of non-linearity at the maximum voltage potentials of the tubes, the practical efficiency is more like 10% to 20% depending upon the exact circuit components. But that is all more dreaming. What are the tests that show a class A triode tube circuit is far superior to any other type of class A circuit?
RA
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No, theory says 50% (max) of efficency.
Practically, with resonable THD you can reach the 25%.
Each linear triode( 2A3 and 300B, just to say some of them) is much more superior to other type of tube, included the pentode/tetrode connected as triode in a class A circuit, this is simple demonstrated.
You can get better efficency if you use UL on pentode/tetro, of course.
Other the linearity a rule is played from a low Rp so it helps to get a good OT trafo more than other tubes.
This heps also with a complex load, not only resistive
Walter
Practically, with resonable THD you can reach the 25%.
Each linear triode( 2A3 and 300B, just to say some of them) is much more superior to other type of tube, included the pentode/tetrode connected as triode in a class A circuit, this is simple demonstrated.
You can get better efficency if you use UL on pentode/tetro, of course.
Other the linearity a rule is played from a low Rp so it helps to get a good OT trafo more than other tubes.
This heps also with a complex load, not only resistive
Walter
I achieved 10W output with 20W anode dissipation in my CatSkin SET project, using a triode-strapped 6P36S and 12dB negative feedback. Operating point is 200V, 100mA, -25V on G1, running in class A2 with 1K load and grid drive peaking at +16V. It sounds quite fine.
to Binary:
do you know the % of THD at 10 watts?
When you drive positive the grid you are going inside a non linear field; the driver need to give current so you are a risk of great THD mainly odd; with feedback, in this case you may have an increment of distortion
Walter
do you know the % of THD at 10 watts?
When you drive positive the grid you are going inside a non linear field; the driver need to give current so you are a risk of great THD mainly odd; with feedback, in this case you may have an increment of distortion
Walter
to Binary
but the 6P36S has 12 watt of max dissipation on anode!
something strange. it is the right name of tubes?
Walter
but the 6P36S has 12 watt of max dissipation on anode!
something strange. it is the right name of tubes?
Walter
Speaking of switches...
If you switch on and listen one of my pentode amps you would never want any triode. ;-)
If you switch on and listen one of my pentode amps you would never want any triode. ;-)
Yes, in crowded compartment constantly generating sweep pulses during several years 24/7, in a TV where failure of any of many tubed decreases MTBF dramatically...
You can certainly approach 50% efficiency with a triode. My 811 SET amps run the 811's right at 40W PD and make 18.9 watts at 10% THD (a bit over 15W at 5%). That's a hell of a lot more than 25%. This isn't really relevant to what the OP is interested in though.
For an 807 in a single ended amp, I would wire it up as a pentode and you should be able to get 10-ish watts without too much trouble. You'll need a fair amount of feedback to tame the nasties, but the results should be pleasing. This will let you use a bit more voltage on the plate than the SG would like to see and the efficiency will be a bit higher.
For an 807 in a single ended amp, I would wire it up as a pentode and you should be able to get 10-ish watts without too much trouble. You'll need a fair amount of feedback to tame the nasties, but the results should be pleasing. This will let you use a bit more voltage on the plate than the SG would like to see and the efficiency will be a bit higher.
If this are true PM a link and more info.
My FR driver are 94db 8 ohms bass reflex, mains 220V.
Thanks
We already suggested him pentode with local feedback, but he continues collecting theoretical musings... I would in his shoes breadboard it already 10 times...
As I said before I not a builder or tech, but I will try discuss it when I have a builder.
Sorry! I thought you want to DIY an amp because you want better quality than you can buy from China...
No problem, Iam looking a inexpensive tube to SE were I can get 8w or more, I wish to came to a builder w/my preferences defined to no long delay.
I can build just about whatever you want that runs at under 1000V, I just wouldn't be super happy about shipping it to you.
Thanks for inform me I appreciated. Maybe I may prefer a builder located in Russia, maybe not I not sure, as the customs from my country are not friendly w/packages caming from US, duties range from 100 to 130%, not mention any fine.
In fact the customs charge what they want, one time I had 3 Russian packages seized in customs for 14 months, they are not nice people, the customs are a dept from the federal police.
Sorry this out of topic, now cameback to 1625 tube amp.
Years ago I played some test with 811A and 572 (few nos and, at that time, also from Svetlana that sold different versions of both)
Aren't a good tubes for Hifi, much better the 300B or 845 (not for me, too dangerous 🙂 ).
And in every case to get a right performance the efficency is 25%.
The % of THD can tell us something interesting but not exactly what happen.
With 10% if we look on FFT it easy to see lot of harmonics mainly if we drive the power tube in A2.
Also for pentode, non comparision with the performances of, p.e., 300B that is much better , in my opinion.
There is also a great differences also because you don't need feedback ( local or global ) to have a good performances.
Of course the driver must be fine.
Walter
Aren't a good tubes for Hifi, much better the 300B or 845 (not for me, too dangerous 🙂 ).
And in every case to get a right performance the efficency is 25%.
The % of THD can tell us something interesting but not exactly what happen.
With 10% if we look on FFT it easy to see lot of harmonics mainly if we drive the power tube in A2.
Also for pentode, non comparision with the performances of, p.e., 300B that is much better , in my opinion.
There is also a great differences also because you don't need feedback ( local or global ) to have a good performances.
Of course the driver must be fine.
Walter
Years ago I played some test with 811A and 572 (few nos and, at that time, also from Svetlana that sold different versions of both)
Aren't a good tubes for Hifi, much better the 300B or 845 (not for me, too dangerous 🙂 ).
And in every case to get a right performance the efficency is 25%.
The % of THD can tell us something interesting but not exactly what happen.
With 10% if we look on FFT it easy to see lot of harmonics mainly if we drive the power tube in A2.
Also for pentode, non comparision with the performances of, p.e., 300B that is much better , in my opinion.
There is also a great differences also because you don't need feedback ( local or global ) to have a good performances.
Of course the driver must be fine.
Walter
Aren't a good tubes for Hifi, much better the 300B or 845 (not for me, too dangerous 🙂 ).
And in every case to get a right performance the efficency is 25%.
The % of THD can tell us something interesting but not exactly what happen.
With 10% if we look on FFT it easy to see lot of harmonics mainly if we drive the power tube in A2.
Also for pentode, non comparision with the performances of, p.e., 300B that is much better , in my opinion.
There is also a great differences also because you don't need feedback ( local or global ) to have a good performances.
Of course the driver must be fine.
Walter
As the 807 and any other beam power tube contains five electrodes, it's true designation is power pentode. In 1935 British enigneers invented the principle of beam deflection plates (the Harris valve) and sold their invention to RCA. The latter company deliberately decided to call their new 6L6 beam power valve a beam tetrode, in order to avoid paying license fees to the European Philips company, which held the patents on the pentode at that time.
Best regards!
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