GC SuperSymmetry

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
The one and only
Joined 2001
Paid Member
For those who didn't find "Monolithic SuperSymmetry" interesting
enough, I present a concept schematic which uses power chips
such as the LM3875 or 3886 (or anything else, for that matter).
 

Attachments

  • gc ss 1.png
    gc ss 1.png
    4.1 KB · Views: 22,667
Nelson Pass said:
For those who didn't find "Monolithic SuperSymmetry" interesting
enough, I present a concept schematic which uses power chips
such as the LM3875 or 3886 (or anything else, for that matter).


Is this an offshoot of looking into lowcost solutions to audio equipment? I have been wondering what topology is used in the FirstWatt amplifier.

George
 
The one and only
Joined 2001
Paid Member
Netlist said:
Nice to see another variant of simplicity to play with. :cool:
As stated, supersymmetry works best with simple circuits.
Is the complexity of such an LM38xx not an issue?
/Hugo

Setting the gain around each Chip Amp via the - input loop
allows quite a bit of adjustment in this regard. The Chip
Amps are of course enclosed in the loop formed by the diff
pair, and so their distortions will tend to be nulled, reducing the
overall effect toward the performance of the diff pair itself.

I hope you guys appreciate that I used Bipolar transistors
just for the occasion. ;)
 
Mr Pass,

You never run out of ideas, don't you.
There are 2 feedback loops, one is around each differential transistor (set by 2 resistors) and the other one is around (-) input of the GC (also set by 2 resistors).
What is the good proportion of gain between these 2 feedback system?. Usually the one around GC is bigger. But by how much (compared to the one in the differential) is the best?

Also in this kind of system, every GC will see only half the impedance of the speaker. If the speaker is 8ohm, each will see 4ohm. But if the speaker is 4ohm, each will see 2ohm. GC chips cannot stand this low impedance. Is there any current boosting method so that this power amp can work with 4ohm speakers?
 
Interesting design. While some of the SuSy design have problem with absolute DC offset, in this design, there is no R at all at differential to ground.
The only ground reference can be found in GC input/output. Is this the one who sets the 0 point of the whole system?
Also no "magic resistors" needed from each outputs to CCS of differential?
 
Mr Pass, altho I respect you for your dedication and continuous pursuit of quality in audio field along the great source of brilliant ideas you brought I feel somehow that what you did until now in the amp arena was to pursue the quality alone.
I think the time has come in one way or another to pursue both the quality and efficiency. I don't know if the GC or discrete is the way to go, I don't know if it could be achieved following the current amps path(which looks like bigger, heavier...) at all.
Anyway, the fact remains that you are not the only one delivering great class A amps(even if you are the best, you are not by a great margin). You would be the best and impose yourself if you would find the way that leads toward efficient amps.
There is no question in my post, so I am not expecting you to reply regarding this matter, but please, please at least give it a thought.
 
grataku said:
roibm,
it's simple physics really, it takes more energy to do more, it takes more energy to produce better sound.


more energy to do more with the meaning more power or more production or similar, yes, I agree. it requires always more energy to produce 2 units than to produce one(unless the production has a minimum quantity of over one, in which case to produce one is more expensive, if only one is required/needed).
more energy for quality? I will never agree upon this. It comes down to how intelligent/good a design is. the history has proved this long ago at global level.
 
Roibm,

While suggestions are being made, allow me to make one to you. I work in the Alternative Energy Technologies group of Powertech Labs, the research subsidiary of the Canadian electric utility BC Hydro, so I am directly involved in this issue. My suggestion is that you need to find better reading material and learn to think for yourself.

While factual information is presented on "Life After the Oil Crash" in support of the authors views, the information presented is only a small fraction of the real picture. Further, the author of that website (and book) steadfastly ignores all factual information that in any way contradicts his views. The scenarios he discuss' are extremely unlikely worst case scenarios that will only occur if every alterantive energy effort fails, and have been published to capture the imaginations of the uninformed.

While I applaud and support your efforts to encourage environmentally friendly and responsible actions, please recognize that by promoting such alarmist reactionary material is actually harmful to the very cause you are supporting. I strongly encourage you to read as many viewpoints as you can on this subject and hope you will discover a more balanced and productive approach.

P.S. Your message posted in this thread is considered "threadjacking", which is a no-no. The proper way would have been to start a new thread in this forum on the subject.
 
metalman said:
P.S. Your message posted in this thread is considered "threadjacking", which is a no-no. The proper way would have been to start a new thread in this forum on the subject.
Metalman, I do thank you for your reply.
I recon it is somehow threadjacking, but it also has a link to GC which consumes very very few watts at idle and during operation at normal levels.
If the mods find my post abusive, please cut it to a new thread, or move it to texas if it is generally unwelcommed.

As about the website, the author and his almost unknown book... it is the worst scenario, I agree, but I really fail to see a reliable alternative energy source at the moment. As you are working on the field of alternative energy, you sure know about this better than I do, but please don't post about it here. Beside the global resources left might be ballooned too(see Shell case). The post I made was meant for Mr. Pass only and was really not about oil or whatever similar. It was about amps, quality AND efficiency(not quality alone). Better said, quality of a class A but without class A.
 
A shot in the dark.

Well, since noobody else (read better) is taking the bait, here is my first kick at the can.

I believe I have set the voltage gain of the differential pair of bipolar transistors to 1 (at this point just to keep things simple, and assuming the hfe of the bipolars is 200), and the gain of the opamps to 20 (linear not dB). I believe I have chosen the values of R7 and R8 to reduce the size of the feedback signal to the right level to generate an equal distortion on the opposite half of the circuit, but I am having trouble wrapping my head around this. It seems to me that by setting the feedback from the opamps to the differential pair to match the noise in amplitude and phase on both sides I am also feeding the signal back to the inputs out of phase but equal in amplitude, which ultimately means no output signal.

Am I even slightly on track or have I just made an idiot of myself? :fim:
 

Attachments

  • susy gainclone tja r1.gif
    susy gainclone tja r1.gif
    16.8 KB · Views: 9,397
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.