This might sound weird, and I certainly don't hold the key to all the answers, so my question might make you laugh or not.
Is it possible or even a good idea to phase 4 tubes in such a manner that each one shares a portion of the sine wave? yeah I hear the laughing. No I don't mean 180-180 degrees as a P-P. I mean each side of the push pull contains two tubes, not in parallel,(4 tubes total for amp) but say the first tube goes from 0-45 degrees and again it goes from 90 to 135 degrees. The second tube from 45 to 90 and again from 135 to 180. Or something of that nature. The third and fourth tube do the other half of the cycle.The thought is to push more power from the tube than possible with class A, B etc.
Just thinking one might get twice the power than with 2 tubes in parallel each side. so instead of four 6AQ5's doing 20 watts get 40 watts, for example. Is this just a bad idea and a waste of server space?
Is it possible or even a good idea to phase 4 tubes in such a manner that each one shares a portion of the sine wave? yeah I hear the laughing. No I don't mean 180-180 degrees as a P-P. I mean each side of the push pull contains two tubes, not in parallel,(4 tubes total for amp) but say the first tube goes from 0-45 degrees and again it goes from 90 to 135 degrees. The second tube from 45 to 90 and again from 135 to 180. Or something of that nature. The third and fourth tube do the other half of the cycle.The thought is to push more power from the tube than possible with class A, B etc.
Just thinking one might get twice the power than with 2 tubes in parallel each side. so instead of four 6AQ5's doing 20 watts get 40 watts, for example. Is this just a bad idea and a waste of server space?
ah ;p i see.
would work best with single frequency or square wave signals (simple predictable signals)
and, well, a tube is a tube, average power will be the same, work twice, rest twice so to say.
it makes me think of a system where every 5 seconds another bridge carries the load.
but fun topic
would work best with single frequency or square wave signals (simple predictable signals)
and, well, a tube is a tube, average power will be the same, work twice, rest twice so to say.
it makes me think of a system where every 5 seconds another bridge carries the load.
but fun topic
I think there are a couple of issues. I've never heard of this being tried in audio, but it looks like class C operation. In other words, each tube conducts for less than 1/2 of 360 degrees. The issues I see are 2x crossover distortion, since the output tubes collectively will "cross zero" 4 times per 360. I am also not sure whether this requires something like two p-p transformers or four SE transformers...or how to exactly set this up bias vs. grid voltage wise. This also seems like it would be much more sensitive to the power supply, since you have a couple of big current draws happening suddenly, but they might cancel enough.
It's an interesting question, but I worry that if it worked well that Bogen or some other PA amp manufacturer would have already done this since they'd have been able to effectively double the power and thus the value of their equipment when watts were at a premium. That being said, you'd think the Roman empire would've invented the airplane too.
It's an interesting question, but I worry that if it worked well that Bogen or some other PA amp manufacturer would have already done this since they'd have been able to effectively double the power and thus the value of their equipment when watts were at a premium. That being said, you'd think the Roman empire would've invented the airplane too
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well, what really sets class c apart is that the tube conducts only hard, with little voltage across it (say peak of sine).
but one may need to run it at rf, and use some sort of high power demodulator to listen to it ;p
or equivalently, use a resonant output circuit, for 1 single tone, or listen to square waves.
or, many many ones combined to a wideband output.
a sortof analog wavelet amplifier ;p
but one may need to run it at rf, and use some sort of high power demodulator to listen to it ;p
or equivalently, use a resonant output circuit, for 1 single tone, or listen to square waves.
or, many many ones combined to a wideband output.
a sortof analog wavelet amplifier ;p
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Efficiency comes from keeping the voltage across the tube minimized. Class G or class H do that by using multiple B+ levels for multiple tubes or by tracking B+ levels for one set of tubes (tracking of the audio envelope + some margin). Commonly done for SS amplifiers, could be done for tubes too. Problem with tubes though, is that they require a lot more minimum voltage to operate than SS devices.
Well, one could just cheat:
http://www.diyaudio.com/forums/showthread.php?postid=871030#post871030
This could also be seen as class H (tracking rails) if the tube amp is implemented using pentodes, since the SS amp would effectively be feeding a tracking B+ back thru the output xfmr to the plates. Using triodes though looks more like series connected amplifiers, due to their low plate Z allowing SS bleedthru.
Another way would be to use tubes for the lowest power level of a class G amplifier, and Mosfets for the higher power (and B+) level(s). A similar setup that has been used before has triodes for the 1st level and pentodes for the higher power level. Grid biasing determines when each tier parallels in.
http://www.diyaudio.com/forums/showthread.php?postid=871030#post871030
This could also be seen as class H (tracking rails) if the tube amp is implemented using pentodes, since the SS amp would effectively be feeding a tracking B+ back thru the output xfmr to the plates. Using triodes though looks more like series connected amplifiers, due to their low plate Z allowing SS bleedthru.
Another way would be to use tubes for the lowest power level of a class G amplifier, and Mosfets for the higher power (and B+) level(s). A similar setup that has been used before has triodes for the 1st level and pentodes for the higher power level. Grid biasing determines when each tier parallels in.
multiphase switchmode in/converters are possible and extant, is that what you meant?
where multiple phase shifted bridges feed a common out, to roughly divide the output ripple for a given output capacitance of the filter, by the number of bridges afaik.
your very cpu power feed may have it ;p ridiculous currents btw, say 30 A :O
where multiple phase shifted bridges feed a common out, to roughly divide the output ripple for a given output capacitance of the filter, by the number of bridges afaik.
your very cpu power feed may have it ;p ridiculous currents btw, say 30 A :O
Here's an article from Radio Electronics (1956) that shows "extended class A" - parallel push-pull with class A and class C coming in on peaks.
http://www.audiophool.cjb.net/Misc/RE_5-56.pdf
http://www.audiophool.cjb.net/Misc/RE_5-56.pdf
Heh... Walker patented Current Dumping 20 years after it was published by somebody else.
Approximately at the same time when he patented it I made my class A+C SS amp independently...
Thank you Tom! Unfortunately, I can't click "Thank you" button: they were expired.
For an example, if you can find a copy, this in Tremaine's "Audio Cyclopedia", the combination triode/pentode circuit is shown in Figure 12-130. It is described as "extended Class A". I was searching the forum for "extended Class A" because I am interested in building one of these, and the search led to this thread.
They do that. It's called a distributed amplifier.
Amplifiers are arranged along a pair of transmission lines, so that the input is applied to each amplifier in turn, phase shifted as it goes. Because the capacitance and impedance of each amplifier acts on its own segment of the transmission line, they are able to operate sort of independently, so the output signal is built up as it travels down the line.
At low frequencies, the transmission line reduces to a simple wire, and you have a simple parallel output.
Tim
Amplifiers are arranged along a pair of transmission lines, so that the input is applied to each amplifier in turn, phase shifted as it goes. Because the capacitance and impedance of each amplifier acts on its own segment of the transmission line, they are able to operate sort of independently, so the output signal is built up as it travels down the line.
At low frequencies, the transmission line reduces to a simple wire, and you have a simple parallel output.
Tim
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