LOL, you too Bonsai, thanks for starting this thread....
after all this is a DIY board, not a typical chatroom...😀
after all this is a DIY board, not a typical chatroom...😀
Yes , mr. marsh threw me the "bones" ...
I thank him for that. I never even thought of current feedback ...
entrenched in my VFA prison 😀.
What is cool , some of the CFA tech has augmented my VFA tech ..
sort of a cruel "feedback loop" in my mind..
But , better amps on both sides of the fence are the result. 🙂
pS -my goal for the standard DIYA amp is the 2000$ OEM/audiophile setup.
OS
I thank him for that. I never even thought of current feedback ...
entrenched in my VFA prison 😀.
What is cool , some of the CFA tech has augmented my VFA tech ..
sort of a cruel "feedback loop" in my mind..
But , better amps on both sides of the fence are the result. 🙂
pS -my goal for the standard DIYA amp is the 2000$ OEM/audiophile setup.
OS
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😎🙂 to all.
I'm off to P.Vallarta, Mexico and then to Bangkok, Thailand and then to Kathmandu, Nepal and then to....
Party hardy. Make me a high power CMA. OK?
-Richard Marsh
I'm off to P.Vallarta, Mexico and then to Bangkok, Thailand and then to Kathmandu, Nepal and then to....
Party hardy. Make me a high power CMA. OK? -Richard Marsh
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😎🙂 to all.
I'm off to P.Vallarta, Mexico and then to Bangkok, Thailand and then to Kathmandu, Nepal and then to....
-Richard Marsh
So when are you getting back?
😎🙂 to all.
I'm off to P.Vallarta, Mexico and then to Bangkok, Thailand and then to Kathmandu, Nepal and then to....
-Richard Marsh
We will be "A drippin' " with 1/2KW CFA's (with 5ppm) by the time you return.
I will make sure of that ... 😀
Enjoy
... OSOK !
Maybe this summer - as that side of the planet has the Monsoon rains.
Last time it started flooding everywhere in Thailand and I got out on the last airplane before the airport flooded. Before that, I missed being wiped out in the great Tsunami... two days after I left my hotel on the coast, it and everyone was destroyed. So, returning time is never a sure thing.
-Richard
Maybe this summer - as that side of the planet has the Monsoon rains.
Last time it started flooding everywhere in Thailand and I got out on the last airplane before the airport flooded. Before that, I missed being wiped out in the great Tsunami... two days after I left my hotel on the coast, it and everyone was destroyed. So, returning time is never a sure thing.
-Richard
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We will be "A drippin' " with 1/2KW CFA's (with 5ppm) by the time you return.
I will make sure of that ... 😀
Enjoy
Oh my gosh! But while you're at it, EC feedback is inherently more fun.
Well, I just stopped by to pour some more gasoline on that fire.
I actually don't have any idea what this means, but Kean and Elvee know. They've been publishing brand new EC stuff and it really works well. Quite lively, and clear, you know. And it could be exploited. . .
And you never measured the GainWire as you promised!
Have a good time, I spent one week in Porta Vallarta when I worked in Mexico. The sea is with big waves all the time, not good for swimming, come to Croatia if you like calm and crystal clear sea.
BR Damir
I agree with Richard (I think). This topic has pretty well run its course, except for petty squabbling about definitions and such. The inherent simplicity and slew rate advantage of the CFA has been diluted by excessive complication and added features, like balanced input. The schematics that I put up should have shown this to you.
Attachments
Well it's not really new. Forr posted a very yellowed french article showing something almost identical to the Kuartlotron.
Believe it or not, it is difficult to find a place in these amps where known error cancellation schemes can actually be used. The Kuartlotron-type cancellation could be used for the input stage of a VFA or CFA but the input stage is rarely a dominant source of distortion, so it wouldn't do much good, except in the case of VFAs, to increase loop gain.
Power amp topology has improved so much that often only the output stage is a dominant source of distortion. But it is very difficult to apply cancellation to an output stage because:
1: Power transistors are operating far outside their intrinsic region of operation, so cancellation is more difficult.
2: Power transistor characteristics may vary too much to apply clone-cancellation (cancelling multiple clone devices with the measurement of a master device).
3: Effective schemes may require 2 to 3 times more parts, which would give greater service elsewhere.
4: Thermals are difficult to control and cannot be cancelled.
Bonsai knows of a correction scheme (AFEC?) using an opamp that seems pretty simple and effective , but it doesn't seem to be very popular.
😎🙂 to all.
I'm off to P.Vallarta, Mexico and then to Bangkok, Thailand and then to Kathmandu, Nepal and then to....
-Richard Marsh
Safe Travels Mr. Marsh
🙂
BenchMark power amp.... uses feedforward correction in the OPS.
patents are 8004355, 8421531.
100W/8 per channel.
Bridgeable (340W).
Clipping indicators.
3 switchable gain levels [to help keep from clipping].
SMPS.
Looks like an old Hafler amp chassis in appearance.
$3000.
Take a look at their distortion specs on thier web site. They only quote for 1KHz (?) as <-118dB THD at any level below clipping.
I think you guys have done as well (?) Dont know if it is CMA or not.
www.highresolutionplayback.com
THx-RNMarsh
patents are 8004355, 8421531.
100W/8 per channel.
Bridgeable (340W).
Clipping indicators.
3 switchable gain levels [to help keep from clipping].
SMPS.
Looks like an old Hafler amp chassis in appearance.
$3000.
Take a look at their distortion specs on thier web site. They only quote for 1KHz (?) as <-118dB THD at any level below clipping.
I think you guys have done as well (?) Dont know if it is CMA or not.
www.highresolutionplayback.com
THx-RNMarsh
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Done as well ?? Ha.. -120 is normal at 2-300W ??
Got other ones that will do 50ppm at 1Kw. 😛
AND at THD20 , as well ...
OS
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its hard seeing the novelty in the THX patent claims - the 1979 JAES Vanderkooy, Lipshitz Feedforward Error Correction in Power Amplifiers paper expresses the combining impedances/balance equations as abstract Z terms - clearly allowing interpretation as R and C, and networks of the same as well as the more common Walker/Quad L,R output combining part types
nor as mentioned does 1 ppm 1 kHz thd spec impress any competent high feedback amp designer
nor as mentioned does 1 ppm 1 kHz thd spec impress any competent high feedback amp designer
Now we're working so hard to overcome distortion and switching elements with an origin primarily in the OPS.
I keep wondering why we keep using an input-stage to error-correct an output-stage, would it not be more clever develop an independent gain of 1 OPS that can be run form a single high(ish) impedance node..??
I keep wondering why we keep using an input-stage to error-correct an output-stage, would it not be more clever develop an independent gain of 1 OPS that can be run form a single high(ish) impedance node..??
+1.
This would be the route to zero or low feedback power amplifier.
IME, low or zero loop feedback can sound very good/friendly indeed.
Dan.
Benchmark Media Systems, Inc. - The New AHB2 - I don't buy it. Exactly the same 1KHz distortions in stereo and bridged mono, that's physically impossible. Only makes sense if you compare the 4ohm stereo with 8ohm bridged, and even then, that's very hard to believe.
The whole dynamic range discussion, and the requirement for the power amp to have the same dynamic range as the digital source, is also nonsense.
Just another marketing driven technobabble, good to impress those with deep pockets and shallow brains.
The whole dynamic range discussion, and the requirement for the power amp to have the same dynamic range as the digital source, is also nonsense.
Just another marketing driven technobabble, good to impress those with deep pockets and shallow brains.