Don't have it. It was really a quick build for a friend.
I only have some notes about the OT that was my first prototype with cathode fb. Rather simple but quite good. 10KHz square waves were perfect, 20KHz square waves still good enough. Response up to about 80KHz.
I have the orignal article but it's too big to up-load here. Send me in pm your e-mail.
I only have some notes about the OT that was my first prototype with cathode fb. Rather simple but quite good. 10KHz square waves were perfect, 20KHz square waves still good enough. Response up to about 80KHz.
I have the orignal article but it's too big to up-load here. Send me in pm your e-mail.
The 115V winding was in Mona Ketje's schematic. She must think you are trying to build something for $100 I guess. 
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The Elliptron is a just a variation on Norman Crowhurst's "Twin Coupled" Amplifier, except using less than the full 50% CFB used there. [using the 40% taps comes out to 28% CFB from 0.4/(1+0.4) ] The "Twin Coupled" was in turn an easy way to build the McIntosh Unity Coupled design.
The Elliptron also has a close resemblance to the Circlotron obviously. The bottom inductor/xfmr in the Elliptron can be either a second identical OT, like used in Crowhurst's "Twin Coupled" design, or it could be just a balancing inductor, with optional secondary.
The advantage here is that the 40% winding sections of most off the shelf UL OT xfmrs are well coupled to the secondary for good UL N Fdbk results. By using both UL sections for both tubes, one effectively doubles the coupling to the secondary (1/2 the leakage L). The primary Z of the OT seen by each tube is effectively doubled as well, so a low Z primary OT can be used, again advantageous. The outer 60% plate windings are driven by the plates only, which look like current sources. So leakage L there (usually rather high in low cost UL xfmrs) is actually inconsequential for coupling to the secondary (other than some extra V headroom for the plates).
Using a 2nd OT or balancing inductor (for the bottom grounded DC cathode feed) with an additional secondary (paralleled secondaries) means you get 4X lower leakage inductance from the CFB sections to the secondary. This is now in Mac performance territory.
The tight coupling from cathode to plate (as in McIntosh or Twin Coupled) is still provided by the cross coupling caps. No need for bifilar windings (never was, even McIntosh gave up on them later, just caps). Besides that, real audio amplifiers run in heavy class AB to match the class A region gm to the initial class B region gm for minimal crossover dist. Class B problems don't exist here. (only the 60% plate sections would have class B issues, but they don't affect the CFB N Fdbk)
In my opinion, Elliptron is THE best design out there. But it's never been built. Its a Circlotron that doesn't require floating B+ supplies. Uses off the shelf low Z OTs. With 28% CFB, and high OT BW too. An Edcor P-P OT can challenge a Mac.
The Crowhurst "Twin Coupled" would nominally perform even better (with a high quality multi interleaved OT). But for the usual low cost OTs around, it puts the poorly coupled 60% sections into the CFB section also, which is not so good. Elliptron hits just the right compromise for the cheaper UL OTs.
.
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The Elliptron is a just a variation on Norman Crowhurst's "Twin Coupled" Amplifier, except using less than the full 50% CFB used there. [using the 40% taps comes out to 28% CFB from 0.4/(1+0.4) ] The "Twin Coupled" was in turn an easy way to build the McIntosh Unity Coupled design.
The Elliptron also has a close resemblance to the Circlotron obviously. The bottom inductor/xfmr in the Elliptron can be either a second identical OT, like used in Crowhurst's "Twin Coupled" design, or it could be just a balancing inductor, with optional secondary.
The advantage here is that the 40% winding sections of most off the shelf UL OT xfmrs are well coupled to the secondary for good UL N Fdbk results. By using both UL sections for both tubes, one effectively doubles the coupling to the secondary (1/2 the leakage L). The primary Z of the OT seen by each tube is effectively doubled as well, so a low Z primary OT can be used, again advantageous. The outer 60% plate windings are driven by the plates only, which look like current sources. So leakage L there (usually rather high in low cost UL xfmrs) is actually inconsequential for coupling to the secondary (other than some extra V headroom for the plates).
Using a 2nd OT or balancing inductor (for the bottom grounded DC cathode feed) with an additional secondary (paralleled secondaries) means you get 4X lower leakage inductance from the CFB sections to the secondary. This is now in Mac performance territory.
The tight coupling from cathode to plate (as in McIntosh or Twin Coupled) is still provided by the cross coupling caps. No need for bifilar windings (never was, even McIntosh gave up on them later, just caps). Besides that, real audio amplifiers run in heavy class AB to match the class A region gm to the initial class B region gm for minimal crossover dist. Class B problems don't exist here. (only the 60% plate sections would have class B issues, but they don't affect the CFB N Fdbk)
In my opinion, Elliptron is THE best design out there. But it's never been built. Its a Circlotron that doesn't require floating B+ supplies. Uses off the shelf low Z OTs. With 28% CFB, and high OT BW too. An Edcor P-P OT can challenge a Mac.
The Crowhurst "Twin Coupled" would nominally perform even better (with a high quality multi interleaved OT). But for the usual low cost OTs around, it puts the poorly coupled 60% sections into the CFB section also, which is not so good. Elliptron hits just the right compromise for the cheaper UL OTs.
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What I get for trying to indulge in all this juicy reading while working. I missed the use of two transformers altogether, sorry about that. Do you have a link to the Crowhurst article? I know I have seen it over the years but sadly did not pay much attention to it then. I'll use it as a springboard to understanding the Elliptron. If as you point out, the effects of leakage inductance are at least minimized then it may become a candidate.
Your statement about the beam tubes being constant current (for a given grid voltage) is of course correct, but I fail to see how that alleviates the effect of leakage inductance at the cross over in Class B. Shed some light? I have already said I'm willing to give up on Class B if it makes sense but don't really want to start with a topology that cannot tolerate it in the presence of leakage inductance. I do like the cross coupling caps, there is the potential path for the leakage inductance energy to flow constructively!
Anyway, just want to learn more about this approach. And I love a challenge (like making stuff work at 200C) so if it's never been done before, let's see it!
Thanks again
Rene
Here are some links for the "Twin Coupled" amplifier design by Norman Crowhurst.
http://www.dissident-audio.com/Yves/1960crowhurst.pdf
page 30:
http://www.americanradiohistory.com/Archive-Radio-Electronics/60s/1960/Radio-Electronics-1960-06.pdf
audioXpress: August 2004, vol.35, No.8 | Hifi Collective
The big issue with any CFB or Unity Coupled design is whether the OT will turn the negative Fdbk into positive Fdbk at some high frequency. This could result from poor coupling between the plate and cathode windings in the OT (for the same tube). This may require some loop gain roll-off with freq. to fix, or a transition to local N Fdbk at some frequency. Probably not the kind of challenge the average DIY builder wants. I don't see much influence on this issue between the Mac bifilar and the cross-coupled caps. The Mac bifilar winding (or the cross-coupled caps) couples the tube plate to the OTHER (cut-off) tube's cathode, not much help for this stability issue unless running class A. Although the winding layout of the OT can certainly put some emphasis on plate to cathode coupling of each tube.
Since the plate is high impedance (like a CCS), it does not see leakage inductance (transparent), only distributed capacitance. The cathode however is low impedance, like a voltage source, so is not much affected by distributed capacitance, only leakage inductance. So...., hopefully the plate transfers current accurately to the load impedance, and the cathode is voltage coupled tightly to the load voltage (both ways). So unless the load is highly reactive or resonant, one would not expect a phase issue to arise between plate and cathode to cause CFB tube instability. This does indicate that the cathode windings should be kept low leakage, while the plate windings should be kept low distributed capacitance ( by OT design).
For class B, the problem is the flyback effect from a winding's leakage inductance when its tube cuts off. Either the bifilar or the cross-coupled caps have the same effect here of dumping the current onto the other conducting tube (solved). One might as well just cap cross-couple and distribute the two wires as additional interleaves in the OT by design. (identical AC on the wire pairs, just a DC difference)
.
http://www.dissident-audio.com/Yves/1960crowhurst.pdf
page 30:
http://www.americanradiohistory.com/Archive-Radio-Electronics/60s/1960/Radio-Electronics-1960-06.pdf
audioXpress: August 2004, vol.35, No.8 | Hifi Collective
The big issue with any CFB or Unity Coupled design is whether the OT will turn the negative Fdbk into positive Fdbk at some high frequency. This could result from poor coupling between the plate and cathode windings in the OT (for the same tube). This may require some loop gain roll-off with freq. to fix, or a transition to local N Fdbk at some frequency. Probably not the kind of challenge the average DIY builder wants. I don't see much influence on this issue between the Mac bifilar and the cross-coupled caps. The Mac bifilar winding (or the cross-coupled caps) couples the tube plate to the OTHER (cut-off) tube's cathode, not much help for this stability issue unless running class A. Although the winding layout of the OT can certainly put some emphasis on plate to cathode coupling of each tube.
Since the plate is high impedance (like a CCS), it does not see leakage inductance (transparent), only distributed capacitance. The cathode however is low impedance, like a voltage source, so is not much affected by distributed capacitance, only leakage inductance. So...., hopefully the plate transfers current accurately to the load impedance, and the cathode is voltage coupled tightly to the load voltage (both ways). So unless the load is highly reactive or resonant, one would not expect a phase issue to arise between plate and cathode to cause CFB tube instability. This does indicate that the cathode windings should be kept low leakage, while the plate windings should be kept low distributed capacitance ( by OT design).
For class B, the problem is the flyback effect from a winding's leakage inductance when its tube cuts off. Either the bifilar or the cross-coupled caps have the same effect here of dumping the current onto the other conducting tube (solved). One might as well just cap cross-couple and distribute the two wires as additional interleaves in the OT by design. (identical AC on the wire pairs, just a DC difference)
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Thanks, Smoking-Amp. I'm going to wait until I have quality time to digest all the above. I do have a couple of initial comments/observations.
The leakage inductance I keep bringing up is mostly one of the ones you address in your post. That is, inter primary leakage. (No topology we have discussed so far can ignore primary to secondary leakage inductance, that always needs to be addressed or else.)
Now, an inductance carrying a current acts itself as a constant current source. If the driver stops pushing a current through the inductor, the inductor itself will want to keep on pushing that same current. Of course, this means the higher the resistance of this discharge path, the higher the resulting voltage impulse.
Again, I'm confessing that this needs a lot of quality analysis time but at first glance, how is the cutting off of one of the tubes, just because it is a beam tetrode with constant current characteristics while it is conducting, but cutoff is cutoff in any device, helping to minimize the spike induced by the leakage inductance? In power circuits, running at a constant frequency, there are numerous means of keeping things in check, but of course no such luck here.
Maybe I'm confusing the leakage inductances and you are covering both primary-primary and primary-secondary issues?
Probably so, as the different comments regarding "dumping" (I use that term a lot in my work, like it) and needing Class A.
Anyway, well thought out and lots of food for thought there, give me a couple of days.
Rene
The leakage inductance I keep bringing up is mostly one of the ones you address in your post. That is, inter primary leakage. (No topology we have discussed so far can ignore primary to secondary leakage inductance, that always needs to be addressed or else.)
Now, an inductance carrying a current acts itself as a constant current source. If the driver stops pushing a current through the inductor, the inductor itself will want to keep on pushing that same current. Of course, this means the higher the resistance of this discharge path, the higher the resulting voltage impulse.
Again, I'm confessing that this needs a lot of quality analysis time but at first glance, how is the cutting off of one of the tubes, just because it is a beam tetrode with constant current characteristics while it is conducting, but cutoff is cutoff in any device, helping to minimize the spike induced by the leakage inductance? In power circuits, running at a constant frequency, there are numerous means of keeping things in check, but of course no such luck here.
Maybe I'm confusing the leakage inductances and you are covering both primary-primary and primary-secondary issues?
Probably so, as the different comments regarding "dumping" (I use that term a lot in my work, like it) and needing Class A.
Anyway, well thought out and lots of food for thought there, give me a couple of days.
Rene
The tube that is cutting off causes the problem for the leakage inductance in the associated windings. The residual current wants to go somewhere. One wants to prevent a HF flyback condition. In the Mac design, the 2nd bifilar wire is supposed to share the same leakage L, so can pick up the leakage inductor current and put it into the other, turning on, tube circuit.
The crossed capacitors (without bifilar) simply makes the same connection. Ie, what were bifilar before, are now two separate wires (same place in circuit, no change there) simply connected at their ends by the caps. Effectively paralleling them for AC. So the current is placed into the other now conducting tube circuit. (remember, these two wires always have the same AC operation signal on them, just a DC difference, so no harm in the AC shunting) (there is of course a transfer of the residual current from the cathode winding to the opposite tube plate winding and visa versa (plate 1 to cathode 2), since these are the ones in phase) (same effect in the Mac bifilar)
Either method of coupling (bifilar or crossed C's) does not help the CFB stability issue (N Fdbk phase accuracy) as I mentioned above. That requires (inverted) tight plate to cathode coupling for the -same- tube, which still has to traverse the usual core magnetization path. But winding the CFB parts as low leakage, and the plate winding parts as low distributed capacitance could help. These are (mostly) physically separated wires in the crossed C only Elliptron version, so this could be done in the OT design. The Mac design, using cross caps (no bifilar), could achieve full optimization of cathode and plate winding design (distr. C and leak L) using separated CFB and plate wires.
Note: I miss-counted the CFB (from UL) windings in parallel above (post 103 ) for leakage L reduction (to the secondary). (been a while since I looked at this scheme!) The top xfmr provides single coupling for each CFB section, and using a bottom xfmr with a secondary then doubles the CFB coupling. (not 2X or 4X)
However, the 2X and 4X numbers still hold for UL sections being used by each tube. (half are just in the plate circuit) So overall coupling to the secondary is improved (versus ordinary CT'd OTs). Ie, using more windings in the OT for each tube improves overall coupling to the secondary. The (40% UL) Elliptron uses 70% of the total windings for each tube.
The Mac bifilar design is still using just 50% of the windings for each tube, but this could be brought up to a full 100% if the bifilars were flipped over to cross caps, and the two (previously bifilar) wires were distributed into the interleave design of the OT.
The Circlotron is using 100% windings obviously. But requiring two floating B+ supplies with some additional parasitic capacitance to ground. Split bobbin power xfmrs would help for the Circlotron.
.
The crossed capacitors (without bifilar) simply makes the same connection. Ie, what were bifilar before, are now two separate wires (same place in circuit, no change there) simply connected at their ends by the caps. Effectively paralleling them for AC. So the current is placed into the other now conducting tube circuit. (remember, these two wires always have the same AC operation signal on them, just a DC difference, so no harm in the AC shunting) (there is of course a transfer of the residual current from the cathode winding to the opposite tube plate winding and visa versa (plate 1 to cathode 2), since these are the ones in phase) (same effect in the Mac bifilar)
Either method of coupling (bifilar or crossed C's) does not help the CFB stability issue (N Fdbk phase accuracy) as I mentioned above. That requires (inverted) tight plate to cathode coupling for the -same- tube, which still has to traverse the usual core magnetization path. But winding the CFB parts as low leakage, and the plate winding parts as low distributed capacitance could help. These are (mostly) physically separated wires in the crossed C only Elliptron version, so this could be done in the OT design. The Mac design, using cross caps (no bifilar), could achieve full optimization of cathode and plate winding design (distr. C and leak L) using separated CFB and plate wires.
Note: I miss-counted the CFB (from UL) windings in parallel above (post 103 ) for leakage L reduction (to the secondary). (been a while since I looked at this scheme!) The top xfmr provides single coupling for each CFB section, and using a bottom xfmr with a secondary then doubles the CFB coupling. (not 2X or 4X)
However, the 2X and 4X numbers still hold for UL sections being used by each tube. (half are just in the plate circuit) So overall coupling to the secondary is improved (versus ordinary CT'd OTs). Ie, using more windings in the OT for each tube improves overall coupling to the secondary. The (40% UL) Elliptron uses 70% of the total windings for each tube.
The Mac bifilar design is still using just 50% of the windings for each tube, but this could be brought up to a full 100% if the bifilars were flipped over to cross caps, and the two (previously bifilar) wires were distributed into the interleave design of the OT.
The Circlotron is using 100% windings obviously. But requiring two floating B+ supplies with some additional parasitic capacitance to ground. Split bobbin power xfmrs would help for the Circlotron.
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Yes, exactly. To restate what I had said in my post just before yours, there is energy, residual as you said because the winding in question was imperfectly coupled to the winding with the load, and the inductance will act as a discharging constant current source. If there is either nowhere for this energy to go, or the path is of high resistance, one will get a high voltage spike. Not quite the same as a flyback effect where energy is deliberately stored in the core structure during a "pump" cycle, then dumped during power switch off time to the load via the secondary winding. There, mutual coupling primary to secondary is not important, but coupling of either winding to the core structure is very, very important. If imperfect, then all the ills of leakage inductance will show up.
The only power transformer where leakage inductance is welcomed is the ferroresonant type, where energy is stored in a deliberate series inductance and resonated and then returned to the secondary to produce a constant voltage. They are fun to design, both line frequency and high frequency.
Nevertheless, your well taken point is that this uncoupled energy is going to cause spikes and notches and trouble in general, unless it is well coupled to a controlled and low impedance. The cross coupling caps seem at first glance as the ticket.
I'll have to defer analyzing the rest of your comments until I have time. Overall, thie Elliptron approach sounds like an intelligent attempt to minimize the effects of primary to primary leakage inductance, as the P-S approach does.
Thanks!
The Elliptron version (of "Twin Coupled") was mainly an attempt to optimize for the low cost OTs that were readily available off the shelf. A practical high performance scheme. It does get one thinking about what is going on (subtly) in all these related schemes. (Elliptron seemed like a well fitting descriptive name at the time, versus Circlotron. However there is some registered product out there called Elliptron, nothing to do with audio though. I think it's an exercise machine.)
I would guess that optimized Mac, Circlotron or SEPP, all could hold the performance titles, if every wrinkle is ironed out for each. Elliptron gets you 90% of the way there for 15% of the cost and effort however. A nice improvement would be to put the balancing inductor (for the DC cathode feeds) onto the same OT core, but then it is going to be a custom design. Way easier still than bifilar though.
SEPP should also get one to the high performance level for cheap, mainly a psychological barrier to overcome I think: Asymmetry with a capital A (Mona Ketje will probably offer to burn the 1st one built! )
Humorous to see all the attempts over the years to clone the Mac OTs, usually grinding to a halt over the bifilar part (after talking with an OT winder) and exact # turns and interleaves. (Mac kept changing the design too.) When it is so much easier to make something better or at least equivalent. Circlotron has 1/2 the turns to wind and no bifilar. SEPP with a single winding is also at 1/2 the turns, and no floating power supplies even. The cloners all want to just copy the Mac front end though.
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I would guess that optimized Mac, Circlotron or SEPP, all could hold the performance titles, if every wrinkle is ironed out for each. Elliptron gets you 90% of the way there for 15% of the cost and effort however. A nice improvement would be to put the balancing inductor (for the DC cathode feeds) onto the same OT core, but then it is going to be a custom design. Way easier still than bifilar though.
SEPP should also get one to the high performance level for cheap, mainly a psychological barrier to overcome I think: Asymmetry with a capital A (Mona Ketje will probably offer to burn the 1st one built!
) Humorous to see all the attempts over the years to clone the Mac OTs, usually grinding to a halt over the bifilar part (after talking with an OT winder) and exact # turns and interleaves. (Mac kept changing the design too.) When it is so much easier to make something better or at least equivalent. Circlotron has 1/2 the turns to wind and no bifilar. SEPP with a single winding is also at 1/2 the turns, and no floating power supplies even. The cloners all want to just copy the Mac front end though.
.
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Hey, I know of at least one guy who came up with something different!
I think it was right after I bought the expensive UC Plitron transformers for my amplifier that I really studied out the Circlotron circuit and kind of kicked myself for not going that route. It's a pretty cool circuit.
There is also a variant of the Ciclotron that it is said to be even better. Same AC path as the Ciclotron but a bit different form the point of view of DC analysis. Apparently the idea was published 2 years before Electrovoice by its Japanese inventor:
Super triode connection FX 7044 CSPP
Super triode connection FX 7044 CSPP
Regarding CFB instability I haven't seen any with my amp. I usually also test the amp with purely capacitive load and several RC combinations. Typical values I use are 10nF, 100nF and 1 uF.
Typical good loudspeakers for tube amps only have sensible phase rotation at the woofer resonance, however the argument is rather high too and so it is unlikely that it will be anything different from class A or "light" class AB (i.e. device switching off for very short time) at least for the kind of operative conditions I use.
Typical good loudspeakers for tube amps only have sensible phase rotation at the woofer resonance, however the argument is rather high too and so it is unlikely that it will be anything different from class A or "light" class AB (i.e. device switching off for very short time) at least for the kind of operative conditions I use.
Howdy, Y'all:
I see some of you were busy with ruminations. Cool!
After doing some doodling, reading (thanks for all the links and comments), thinking and conversating, I have decided to go ahead with the P-S/SEPP. While there are challenges, there are promises too.
Lots of little and not so little details to work out for sure. Among them, but certainly not limited to them, there is the drive (I am convinced not nearly as big a dragon as some think), the biasing especially of the "upper" tube, consideration of any kind of UL and/or CFB scheme (I have a non tap solution for the UL but a CFB would likely require a transformer tap which is a bit of a minus in keeping the transformer clean), the use of Schade, overall feedback, and of course, all the phase margin, gain margin, bandpass, etc, etc, calculations. When it's all done, I will include at least in table form the transformer design.
I think I will keep interest going by working on publishing the power supply first, been there and done that so it's more of a documentation effort and hopefully will go fairly fast.
Cheers to all!
Rene
I see some of you were busy with ruminations. Cool!
After doing some doodling, reading (thanks for all the links and comments), thinking and conversating, I have decided to go ahead with the P-S/SEPP. While there are challenges, there are promises too.
Lots of little and not so little details to work out for sure. Among them, but certainly not limited to them, there is the drive (I am convinced not nearly as big a dragon as some think), the biasing especially of the "upper" tube, consideration of any kind of UL and/or CFB scheme (I have a non tap solution for the UL but a CFB would likely require a transformer tap which is a bit of a minus in keeping the transformer clean), the use of Schade, overall feedback, and of course, all the phase margin, gain margin, bandpass, etc, etc, calculations. When it's all done, I will include at least in table form the transformer design.
I think I will keep interest going by working on publishing the power supply first, been there and done that so it's more of a documentation effort and hopefully will go fairly fast.
Cheers to all!
Rene
Rene,
I'm not sure what your design philosophy is and if it is okay with using SS active loads and followers or not, but I thought I would share some work I did a while back with CCS-loaded pentodes and plate-grid feedback. It may or may not have some relevance here since you may need to develop some big swings with good linearity, depending on what type of drive structure you settle on. For large linear voltage swings, this is the best approach I have seen so far.
http://www.diyaudio.com/forums/tubes-valves/288372-idea-driver-cf-output-stage-2.html#post4889889
-Heath
I'm not sure what your design philosophy is and if it is okay with using SS active loads and followers or not, but I thought I would share some work I did a while back with CCS-loaded pentodes and plate-grid feedback. It may or may not have some relevance here since you may need to develop some big swings with good linearity, depending on what type of drive structure you settle on. For large linear voltage swings, this is the best approach I have seen so far.
http://www.diyaudio.com/forums/tubes-valves/288372-idea-driver-cf-output-stage-2.html#post4889889
-Heath
Outstanding results, Heath!
For the P-S, the actual AC swing required will not be as demanding as for a Unity type. The driver for the stage with the apparent cathode load is in fact driving that tube as a common cathode. The driver is applying its output between the cathode and the G1 of the output tube. The cathode voltage is changing of course, but that is easily handled by returning the plate load resistor of the driver to the plate of the other tube, while returning the plate load resistor of the opposite driver to B+.
But if I were doing something along the lines of what George (Tubelab) likes to do and drive the G2, I'd certainly look at using your setup followed by a MOSFET for current gain.
I'm sure you are satisfied with your achievement, really high swings and remarkably low distortion. Cool!
45, thanks for the offer, I will keep it in mind. Right now, the tube make up is projected to consist of (per channel) 2 each 6JV8 and 2 each either 6DK5, 6HD5 or 6HJ5. The triode sections of the JV8 as input, full differential amplifier/phase splitter, the pentodes as differential drivers. Likely I'll use Schade feedback and maybe, maybe, a synthetic version of a little bit of UL drive.
Thanks!
Rene
For the P-S, the actual AC swing required will not be as demanding as for a Unity type. The driver for the stage with the apparent cathode load is in fact driving that tube as a common cathode. The driver is applying its output between the cathode and the G1 of the output tube. The cathode voltage is changing of course, but that is easily handled by returning the plate load resistor of the driver to the plate of the other tube, while returning the plate load resistor of the opposite driver to B+.
But if I were doing something along the lines of what George (Tubelab) likes to do and drive the G2, I'd certainly look at using your setup followed by a MOSFET for current gain.
I'm sure you are satisfied with your achievement, really high swings and remarkably low distortion. Cool!
45, thanks for the offer, I will keep it in mind. Right now, the tube make up is projected to consist of (per channel) 2 each 6JV8 and 2 each either 6DK5, 6HD5 or 6HJ5. The triode sections of the JV8 as input, full differential amplifier/phase splitter, the pentodes as differential drivers. Likely I'll use Schade feedback and maybe, maybe, a synthetic version of a little bit of UL drive.
Thanks!
Rene
Question for y'all who have been following and contributing. I am a few days away from publishing at least a rudimentary version of the power supply with its linear, high conduction angle regulator. I think it will be of interest. I've done this sort of thing before when needing very low noise (to pass some MIL and FCC specs) while providing higher efficiency than a conventional linear can.
I'm thinking it should be included in this thread because it is part of the amplifier, but I'm also thinking it may be of interest to others who are not following or interested in this thread's specific topic.
Opinions?
I'm thinking it should be included in this thread because it is part of the amplifier, but I'm also thinking it may be of interest to others who are not following or interested in this thread's specific topic.
Opinions?
- Status
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