Outstanding!
Congratulations Atmasphere!
I noticed today that Ralph Karsten (whom regular and even occasional participants in this forum will of course recognize as the designer and proprietor of Atma-Sphere Music Systems, as well as a uniquely valuable contributor to the forum) was granted United States patent number 10,469,042 on November 5, 2019. It covers an audio amplification technique he had indicated here that he has been developing, which in simple terms appears to me to basically be a clever combination of an analog-to-pulse train converter (as used in traditional class D amplifiers for example, among other audio-related applications), with an output stage employing circlotron topology (analogous to the topology used in his OTL power amplifiers, but utilizing solid state devices).
Congratulations Ralph!!
Best regards,
--Al
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I’m curious though, not being well versed in the entire history of switching amps, what parts are new here? The balanced outputs?Hi Erik, What is new is defined by the 20 very precisely worded claims stated in the "Claims" section of the patent (which are on the last two pages of the document I linked to). Also, keep in mind that even if a design is comprised entirely of parts, sub-sections, or other elements none of which are new it may still be very patentable, as long as those elements are combined in a manner that meets the basic patentability requirements of being new, useful, and non-obvious to one reasonably skilled in the particular art. Best regards, -- Al |
@erik_squires FYI, patents are also presented at uspto.gov in an alternative format in which the claims section is identified more explicitly, and is placed near the beginning. I chose the other format for the link I provided in my initial post, though, because with this alternative format it can be more difficult to find the figures/drawings. In the immortal words of Roseanne Roseannadanna, it’s always something :-) Best regards, -- Al |
Ralph has a uniquely thorough appreciation and understanding of "what matters to the ear". My mentor Earl Geddes (with Lydia Lee) had a pair of peer-reviewed papers on distortion perception published in the Journal of the Audio Engineering Society. Their findings backed up everything Ralph had been telling me. In fact after writing the papers Earl remarked to me, "now I understand why you and your friends like tube amps". I think we are extremely fortunate Ralph has chosen to pour himself into designing a switching amplifier that actually works with the characteristics of human hearing instead of against them. We may be about to see switching amps that do not have the traditional drawbacks of switching amps. Right now I’m really glad I’m a speaker designer instead of an amp designer, because I would hate to compete against what’s coming. Duke yeah, I’m also an Atma-Sphere dealer |
You guys know that I've been a speaker builder for many years. Through my struggles in the amp forums here, the past couple of years, I have built modified and repaired several amps to improve my knowledge. My studies on circlotron started with Jim Bongiorno and the old Sumo Nine. I have a highly modified Nine which is very good. Then looked at how circlotron worked in tubes and how it was modified to work OTL. So, If I understand what Al has written, Ralph has created a symmetrical bridged class D tube amplifier.... Of course, I'm guessing, but I'd love to hear more. Can Ralph or Al expand on this? Very interesting indeed. |
@timlub Hi Tim, Thanks for the mention, but of course my knowledge of the design is limited to what is said in the patent. And the Abstract at the beginning, supplemented by the figures (especially the first three) seem to me to present a good concise overview. Regarding your mention of tubes, the figures depict a circlotron output stage that is FET-based, and I suspect that is what Ralph has been developing. I note, though, that the second of the 20 claims broadens the scope of the patent such that it also encompasses tubes as well bipolar transistors when used in a similar configuration. Best regards, -- Al |
So, If I understand what Al has written, Ralph has created a symmetrical bridged class D tube amplifier.... Of course, I’m guessing, but I’d love to hear more.@timlub The tube part isn’t right, but otherwise, yes. Essentially the invention is a Circlotron class D amplifier. Prior to this the prior art was either half-bridge or full-bridge; the former needing two output devices which are arranged in a ’totem-pole’ configuration (and is a fairly simple circuit), the latter being two half bridge circuits driven in opposition. Now there is a third means, the Circlotron, which has more in common with a half bridge circuit except for two important changes: its symmetrical and the output devices are not directly in series with each other. Its the latter bit that is the most interesting, as this essentially reduces shoot-through currents which allows for a circuit with less dead time. In a nutshell its a method of reducing distortion in a class D design. |
I expect it will have no issues driving Alexias! :-) Congratulations. atmasphere7,779 posts11-25-2019 11:43amSo, If I understand what Al has written, Ralph has created a symmetrical bridged class D tube amplifier.... Of course, I’m guessing, but I’d love to hear more.@timlub The tube part isn’t right, but otherwise, yes. Essentially the invention is a Circlotron class D amplifier. Prior to this the prior art was either half-bridge or full-bridge; the former needing two output devices which are arranged in a ’totem-pole’ configuration (and is a fairly simple circuit), the latter being two half bridge circuits driven in opposition. Now there is a third means, the Circlotron, which has more in common with a half bridge circuit except for two important changes: its symmetrical and the output devices are not directly in series with each other. Its the latter bit that is the most interesting, as this essentially reduces shoot-through currents which allows for a circuit with less dead time. In a nutshell its a method of reducing distortion in a class D design. |
I wonder. TACT made an amplifier that was essentially a power DAC. It took a digital signal and converted it to a PWM at I believe it was 9 mHz This was converted to analog in the output stage. Volume was controlled by raising and lowering the voltage to the output stage with all the digital remaining a 0 dB, the highest resolution. It was a great sounding amp. I wonder if this is what Ralph has in mind. Since he now has the patent I wonder if he would care to elucidate? Earth to Ralph, you out there? Mike |
The first rule of avoiding patent challenges is to say as little as possible about the invention after the patent issues. So I won't ask any questions, because if I were Ralph, I wouldn't say anything the patent doesn't say. But I do wish to offer my congratulations to Ralph. It will be quite interesting to see how products based on this invention perform. I could not be happier (perhaps ignorance is bliss) with my M-60s. I'd be at a loss to imagine how they could be improved upon with respect to sound. Not saying the M-60s are the worlds best sounding amps, just saying that my 3.3s with the current tube complement have not been bettered by anything I personally have heard at any price. Now if the new technology closely approached the sound of my 3.3s, had better stability into low impedance loads, and produced less heat, I'd be willing to take a hard look. Duke observed that Ralph has a special gift for understanding what is important to the ear. I agree based on my experience with the M-60s and also based on his astute contributions to this forum. So I'm expecting that any product that comes out of his shop is going to sing sweetly. I'll be following any new product releases. |
Drat, Ralph beat me to the patent office! With my vast technical knowledge of electronics I have absolutely no idea what any of this is talking about. But I do want to congratulate you Ralph, know it will be successful and must say that I will be more than a little interested in following the roll-out. |
I could not be happier (perhaps ignorance is bliss) with my M-60s. I'd be at a loss to imagine how they could be improved upon with respect to sound. Not saying the M-60s are the worlds best sounding amps, just saying that my 3.3s with the current tube complement have not been bettered by anything I personally have heard at any price.This is all about the way the loudspeaker and amplifier work together. Some speakers don't like a lot of damping and then our OTLs play them nicely. Other loudspeakers simply can't be driven well by any tube amp without feedback; that's what the class D is for. In both cases the idea is to minimize higher ordered harmonic production and IMD to prevent harshness. Someday maybe there will be a 'universal amplifier' but IMO that's still a ways off. Thanks for all your comments :) Have a Happy Thanksgiving! |
Hi Ralph: My congratulations on winning the patent! Just out of curiosity, at least for now, a question... For starters I am basically very low-tech in my understanding of your work. But I am curious if your new amps would be usable for my Linkwitz LX521.4 open baffle speakers? In case you don't know these speakers, the LX521.4 system involves two monitors with 5 drivers each. To drive them I now use two very nice sounding Parasound A51 5-way multi-channel amps. Would it be cost-effective to make a multi-channel amp, say 5-channel, or would that just multiply the cost by 5 (or perhaps 2.5 if the starting point for the comparison is a stereo amp)? Also is your design energy efficient, in the way that Class D is supposed to be? Thank you |
+100 @twoleftears |
Just reading this revived thread. Makes me miss AL.... @atmasphere Ralph, you guys were a good team of sorts. Al always had your back and really had my back too. Miss my friend. |