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PostPosted: Thu Aug 30, 2007 9:21 pm 
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http://www.pat2pdf.org/patents/pat7221216.pdf


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PostPosted: Sun Sep 02, 2007 12:54 am 
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Sheep
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This one was easy :)

DE10300195 2004-07-22 ALTHOFF JUERGEN (DE)
Quote:
Low frequency class D vacuum tube amplifier has multivibrator that varies clock output pulse duty cycle according to control voltage so pulse time-voltage area difference varies with input signal


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James

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PostPosted: Tue Sep 04, 2007 6:43 pm 
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Hen

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Hmmm, I’m no switching amplifier guru, but combining the Class D operation with a switched supply rail (a la Class G) seems a cool way to gracefully handle high-crest-factor material. Also, the differential feedback path shown in Fig. 10 is nice since it doesn’t assume both sides of the H-bridge are identical.

Cheers,
Casey


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PostPosted: Tue Sep 04, 2007 9:52 pm 
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CaseyWalsh wrote:
Hmmm, I’m no switching amplifier guru, but combining the Class D operation with a switched supply rail (a la Class G) seems a cool way to gracefully handle high-crest-factor material. Also, the differential feedback path shown in Fig. 10 is nice since it doesn’t assume both sides of the H-bridge are identical.

Cheers,
Casey


Hi Casey, good comments.

Multi rails in conjunction with class d isn't novel though, even in power supplies it is only used for extreme power to the likes of which will never be a concern in audio, so why do it here?

At a glance it seems here they're saying it is novel since it is coupled with a hysteretic converter and it keeps the switching frequency from dropping "too low", I call that BS, if the frequency modulation is a concern there are known techniques to have fixed frequency hysteretic convertors which would be far superior than this mess of a frequency modulator. So what's the real purpose of it?

Aside from that supposed "pro", let's talk about a few of the likely cons. Stepped rails provide a boost in efficiency wrt to a less than highly efficient amp like class B, and adds non linearity, which it's apt to doing in class d as well.

Factor in the already high efficiency of class d though, and what do you get for that effort? An extra supply stage, more components/complexity= reduced efficiency, reduced reliability, increased EMI and interractions, which nuforce doesn't have a grasp on at all btw.

The only way I can see it being at all worthwhile is by crying "music power" to give you increased peak power for short duration, and using that to undersize your main supply even further, so it can be built cheaper. It also mentions its use with their supposed "class n", which "supposedly" means a one step conversion from AC to audio. If they ever got that working right the only pro I see is still smaller supplies, with all the same cons mentioned.

This could be their bandaid road to their promised late comming 1000W "class N" thing.

I think this is low quality, pseudo high power, sub woofer for car audio material, that will make your fillings glow in the dark. Be weary of the "amp of the year" reviews and infamous false marketing that's bound to follow.

Let's watch and see what follows.

Cheers,
Chris


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PostPosted: Wed Sep 05, 2007 4:06 pm 
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Benjamin
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The novelty is..........

The patent holder! Someone who really has a clue on EMI control.

Cough, cough........[joke]

Jocko


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PostPosted: Wed Sep 12, 2007 2:09 am 
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Sheep

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Anybody have heard about discount on US patents??? More you can patents stupidity, more you save...I think he forgot some other configuration in his patents....Like no feedback, or add fews more pole to feedback....Or use a transformer for feedback...oh...better, use optocoupler in feedback loop...Maybe it could be good with zener too....With a vacum tube? Or optical fiber? P4 CPU? LOL


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