What he said. I respectfully disagree but it's not my forum so do as you see fit.
Merry Christmas.
So wait, I'm confused here. You posted a complete copyrighted article and are confused as to why it got removed? If that is okay what is to stop me from posting MJ's Valve Amplifiers or other copyrighted works like mp3s of my favorite songs. Audio Express lawyers would be on firm legal ground suing for damages if Diyaudio allowed these kinds of postings.
Whether the circuits are patentable or not is not the issue. Why don't you re-draw the schematic (that way it will be yours), post it, and we can discuss it. You can also quote small portions of the article (fair use) for use in discussions. But you can't just scan the whole article and post it.
Whether the circuits are patentable or not is not the issue. Why don't you re-draw the schematic (that way it will be yours), post it, and we can discuss it. You can also quote small portions of the article (fair use) for use in discussions. But you can't just scan the whole article and post it.
Thx you for your helpful suggestions and I will try to get to those as in general if it stops the strife on that level alone it makes sense.
Although I must say that it is apparent to me that most in objection here have never read the case law, nor have they ever been involved in such a case. The stages of responsibility for such infringements are long studied and deliberated and I suggest they be reviewed before more open ended, non-specific, not the same type of issue, comments are made.
Or we can do the least ridiculous thing and just let it die here.
Great amp anyone needs help with it let me know.
Precisely. I'm not so worried that AX will sue us (though in theory they could) or whomever illegally posted a copy of their copyrighted article (ditto), but posting their intellectual property is immoral as well as a civil infraction. The forum has rules about these things and ignorance of basic IP law is no excuse.
You're correct, if one redraws the schematic, it is absolutely OK to post- it's now your drawing.
Redrawn Schematic
Here's something similar I drew and simulated in PSPICE. It works.
It shows the feedback scheme used by Orr by simply bringing the output of amp to one of the inputs of an LTP, which then feeds another LTP used as a driver for a totem pole output.
I replaced the negative 450V supply and tail resistors with current sources using LM317s configured as such and the amp simulates extremely well.
Nothing new here folks. Bringing the feedback into one of the grids of the tubes in the first LTP was a good idea, but other than that it's a cookbook design. It looks like a good design, but it's nothing new. IMHO the SRPP voltage gain stages I used are superior to the common cathode stages used by Orr, but that's up for debate.
I'll post the schematic with the constant current sources when I get a chance. This circuit with a -450V LTP tail voltage is impractical but the high voltage helped simuate a CCS until I found a working model of the LM317.
Here's something similar I drew and simulated in PSPICE. It works.
It shows the feedback scheme used by Orr by simply bringing the output of amp to one of the inputs of an LTP, which then feeds another LTP used as a driver for a totem pole output.
I replaced the negative 450V supply and tail resistors with current sources using LM317s configured as such and the amp simulates extremely well.
Nothing new here folks. Bringing the feedback into one of the grids of the tubes in the first LTP was a good idea, but other than that it's a cookbook design. It looks like a good design, but it's nothing new. IMHO the SRPP voltage gain stages I used are superior to the common cathode stages used by Orr, but that's up for debate.
I'll post the schematic with the constant current sources when I get a chance. This circuit with a -450V LTP tail voltage is impractical but the high voltage helped simuate a CCS until I found a working model of the LM317.
An externally hosted image should be here but it was not working when we last tested it.
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I've literally spent 30-40 hours prototyping a wide variety of circlotron drivers and the best I've been able to come up with using PSPICE is about 100 watts per channel into 8 ohms using 150 volt power supplies and as many 6AS7 (6H13C) tubes as you want to string together.
This would actually be easier to do if the tubes could handle higher plate voltages and had higher plate resistances. With feedback the output impedance of this design is extremely low, but the voltage is limited in part by the supply voltages, at least it seems so based on my simulations.
It's very difficult to drive 12 parallel grids, and worse when each has its own adjustable bias resistors.
There's a circuit that I know works, but I can't find the component values and the image is too blurred to read. I'll post it later in hopes someone knows where a legible copy might be obtained. I've managed to squeeze up to 250 watts per channel out of the simulation by manipulating component values, but doing so would reduce the bandwidth, and increasing the bandwidth would reduce the max power.
BTW, the totem pole amp simulates very nicely. I see no instability and the power output is well over 200 watts using 12 tubes into 8 ohms with a wide bandwidth. The only thing that isn't ideal is the asymetric output waveform. How this translates sonically I can't even speculate.
This would actually be easier to do if the tubes could handle higher plate voltages and had higher plate resistances. With feedback the output impedance of this design is extremely low, but the voltage is limited in part by the supply voltages, at least it seems so based on my simulations.
It's very difficult to drive 12 parallel grids, and worse when each has its own adjustable bias resistors.
There's a circuit that I know works, but I can't find the component values and the image is too blurred to read. I'll post it later in hopes someone knows where a legible copy might be obtained. I've managed to squeeze up to 250 watts per channel out of the simulation by manipulating component values, but doing so would reduce the bandwidth, and increasing the bandwidth would reduce the max power.
BTW, the totem pole amp simulates very nicely. I see no instability and the power output is well over 200 watts using 12 tubes into 8 ohms with a wide bandwidth. The only thing that isn't ideal is the asymetric output waveform. How this translates sonically I can't even speculate.
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I've built 12- tube circlotron amps that made 120 watts, and 140 watt amps with 14 power tubes (28 sections). I even built up an amplifier with 84 sections (42 power tubes/channel) and it made over 500 watts. I don't know how much power it made beyond that, as using the 10:1 probe and the highest input setting on the 'scope, the waveform went off the screen. B+ was similar, actually slightly lower than you are using. So I am thinking that there is a bug in your sim that does not show up on the totem pole sims.
I suspect you're right. What I would like to do is design (or find a design) and construct a circlotron with about 150 watts RMS into 8 ohms with a very low output impedance.
I poked around and found the patent and basic circuit of the Rosenblit Transcendent Audio OTL. It's a totem pole. I'm thinking there's got to be a reason that most OTLs are totem pole, but I'm not certain yet what it is.
The first is the amp schematic and the second is the power supply. This is a totem pole with a different feedback scheme than I've seen before. Time for a new PSPICE model.
The entire patent and a (convoluted) description of the operation can be found at:
United States Patent: 5604461
I poked around and found the patent and basic circuit of the Rosenblit Transcendent Audio OTL. It's a totem pole. I'm thinking there's got to be a reason that most OTLs are totem pole, but I'm not certain yet what it is.
The first is the amp schematic and the second is the power supply. This is a totem pole with a different feedback scheme than I've seen before. Time for a new PSPICE model.
The entire patent and a (convoluted) description of the operation can be found at:
United States Patent: 5604461
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This is the one I am mocking up now. I will build the glen orr amp in full since it has proven to be a very nice sound otl and I will finalize that shortly at which time I will post a few photo's here.
One thing I must add is the NOS NIB 6080's or 6AS7's that are out there are 50% of the time trash so be careful on that. You pay above $12 each for them and half the time they are NG where as you buy the Russian version for $5 a pop in bulk and they are good 80% of the time and the seller will resend to cover the bad ones. Go with the Russians they are better.
I'm using the Russian 6H13C and I bought a lot of extras to cull out the bad or severely out of spec tubes.
After reading the patent the only thing I see unique about this design that may not be found in the prior art is the positive feedback from the output to the driver that feeds the output tubes that have their cathodes tied to the output (the top output tubes).
The discussion of the prior art and the unsuccessful attempts by others to create good OTL amps is questionable IMHO. That's not to say this amp isn't innovative, but there were a lot more designs than the single design using a regulator as a negative feedback device to a triode phase splitter than the author describes.
The DC coupling is impressive, and the feedback scheme to supposedly balance the levels AND the impedance of the output tubes is impressive.
I'm just saying the author gives the impression that nobody before 1997 ever built an OTL that could sound anywhere close to a transformer output amp until he designed this OTL.
The author patented positive feedback from the output of a totem pole to the top driver. That's all I see. It takes 10 pages and 4 drawings to demonstrate that???
Here's the prior art. This is how all OTLs were designed prior to 1997 according to the author:
After reading the patent the only thing I see unique about this design that may not be found in the prior art is the positive feedback from the output to the driver that feeds the output tubes that have their cathodes tied to the output (the top output tubes).
The discussion of the prior art and the unsuccessful attempts by others to create good OTL amps is questionable IMHO. That's not to say this amp isn't innovative, but there were a lot more designs than the single design using a regulator as a negative feedback device to a triode phase splitter than the author describes.
The DC coupling is impressive, and the feedback scheme to supposedly balance the levels AND the impedance of the output tubes is impressive.
I'm just saying the author gives the impression that nobody before 1997 ever built an OTL that could sound anywhere close to a transformer output amp until he designed this OTL.
The author patented positive feedback from the output of a totem pole to the top driver. That's all I see. It takes 10 pages and 4 drawings to demonstrate that???
Here's the prior art. This is how all OTLs were designed prior to 1997 according to the author:
An externally hosted image should be here but it was not working when we last tested it.
I'm looking forward to your build and the results.
This was published by RCA in 1954, 43 years before Rosenblitz's description of the prior art above and was the basis for Glen Orr's design, only Orr didn't attempt to make the claim that nobody had ever created a good OTL before Rosenblit did in his misrepresentation of the prior art.
Prior art a "floating regulator" my @ss. I have to conclude the patent office is run by morons.
This was published by RCA in 1954, 43 years before Rosenblitz's description of the prior art above and was the basis for Glen Orr's design, only Orr didn't attempt to make the claim that nobody had ever created a good OTL before Rosenblit did in his misrepresentation of the prior art.
Prior art a "floating regulator" my @ss. I have to conclude the patent office is run by morons.
An externally hosted image should be here but it was not working when we last tested it.
Cecil Hall is responsible for the basic Circlotron circuit, patented in 1954. It was an OTL. The 'Wiggins Circlotron' was a variant. As OTLs go, the concept was in mothballs until the late 1970s, when Atma-Sphere picked up the torch and created a variant.
But there was a lot of activity in the totem-pole arena. Japan was a sort of hotbed for them in the 70s and 80s. It seems to me that Lux and Technics both produced OTLs (not for export) during that time. Neither of them were Futtermans and neither of them had that floating circuit either.
I had some email exchange with Rosenblit shortly after his patent was issued. It was mostly a matter of correction at the time, as he was claiming to have the first OTL patent since Futterman, and my communication was to set the record straight as that claim goes to Atma-Sphere (so far as I know- I could be in the dark as much as Rosenblit was).
I'm looking for a circuit that would allow me to use 6AS7 equivalents (6H13C) in a circlotron topology that would yield about 200 watts per channel. I have as many tubes as I need - that's not an issue for me.
If you had to build just one OTL at 200 watts (into 8 ohms), what would it be and may I ask where did you get the schematic?
Not a big fan of BR frankly. Ralph's stuff though is very good, and he's been at it for a very long time.
His site is here: Atma-Sphere Music Systems, Inc. Dragging high end audio (kicking and screaming) into the future!
His site is here: Atma-Sphere Music Systems, Inc. Dragging high end audio (kicking and screaming) into the future!
+1. Ralph's stuff was very innovative and strikes me as the best way to do OTL.
WHAT???
WHY???
Obviously they are shown for educational value. Please let us not start trying to edit ourselves for the sake of making the world safe. We all need to be our own keepers of our safety. After all we are only as safe as we make ourselves, and this means knowing and having access to knowledge of presently "correct" and formerly practiced SOA.
Beside I'll bet there a many of us who routinely restore or work on old "unsafe" radios and test equipment... we even routinely survive! ;-)
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