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Class D Switching Power Amplifiers and Power D/A conversion

Breakthrough DD amplifier?
Breakthrough DD amplifier?
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Old 8th February 2019, 09:36 PM   #11
Windforce85 is offline Windforce85  Poland
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Patent is like 'hey, I am here, please take a look at what I've done, feel free to copy and use it in your area where all rules can be obeyed.' If I patented something I also would like to not show it to everyone. Another issue is that today literally everyone can patent almost everything. Almost wherever you move there is already a patent for something. It leads to development curiosum. If breathing was patented would it be legit to stop you from breathing?

Last edited by Windforce85; 8th February 2019 at 09:45 PM.
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Old 8th February 2019, 09:48 PM   #12
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by FauxFrench View Post
You mention an internal feedback loop. Due to my ignorance regarding "DD" amplifiers I will ask, isn't it so that a numerical amplifier operates on a description of the input that is so (absolutely) precise as the input sampling allows and needs no feedback?
Evidently, motion feedback will require a feedback loop. But without motion feedback and with high precision input sampling, for me to see it is a matter of converting the PCM description into a PWM description and the job is done? Few uses post-filter feedback anyway. Evidently, both a very precise and fast A/D for input sampling and a fast high-resolution DSP for conversion are needed.
In some part of the amplifier the numerical data words have to be converted to analog values - voltage, current, time, able to drive low impedances with lots of watts. Think of class D on steroids. And to make that as linear as possible you probably can't do without feedback. Lots of it.

Jan
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Old 8th February 2019, 09:52 PM   #13
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by Windforce85 View Post
Patent is like 'hey, I am here, please take a look at what I've done, feel free to copy and use it in your area where all rules can be obeyed.' If I patented something I also would like to not show it to everyone. Another issue is that today literally everyone can patent almost everything. Almost wherever you move there is already a patent for something. It leads to development curiosum. If breathing was patented would it be legit to stop you from breathing?
Its a fine line. You don't want to give the competition any ideas, but you also don't want them to discover the thing themselves and the go into direct competition with you.

And of course, eventually the patent fight will be won by the party with the deepest pockets.

Jan
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Old 11th February 2019, 04:22 PM   #14
Oneminde is offline Oneminde
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Quote:
Originally Posted by FauxFrench View Post
The fully numerical amplifier is coming and it is counter to the DIY idea of adaptation.
Would you so kindly explain or send me to a informative page which explain what fully numerical amplifier is ?

Thanks.


- Edit -
If you are talking about class D and PWM etc, then I'm good

Last edited by Oneminde; 11th February 2019 at 04:25 PM.
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Old 11th February 2019, 04:33 PM   #15
jan.didden is offline jan.didden  Europe
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I think he means an amp that accepts digital input instead of analog.

In either case, the PWM/class D stage is always analog of course.

Jan
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Old 11th February 2019, 05:09 PM   #16
Oneminde is offline Oneminde
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Originally Posted by jan.didden View Post
I think he means an amp that accepts digital input instead of analog. In either case, the PWM/class D stage is always analog of course.

Jan
Okay, got it - PCM, Sigma-Delta etc etc. But do we really need digital amplifier these days, that is the question.

My 2 cents regarding the DD amp posted in Quantifying class A quality:

Quote:
I get a hint of a TON of feedback, digital correction etc. Not a fan of that. Sure, the THD+N is looks okay, besides massive spikes at 10kHz and 14-15kHz. On top of things, its more or less a digital amplifier. They might impress with good numbers, but remember, greater than 0.01% in THD (which is already an audiophile grade) has no real benefit since no one can detect it and is therefore only used for bragging, same with S/N in the range of -110-120 dB is absolutely acceptable - sure, the lower it is the better. But digital amplification these day ... mhe, I see no need for that. Pure analog class D with a minimum amount of closed loop or open loop feedback, heck yes. The rule is: Feedback is bad. Same thing with capacitor based DC servo on the output line.. If you know what you are doing, you can achieve outstanding performance without corrupting the signal via intermediate digital modulation.

Often it is not about you as an engineer and with that I mean your knowledge about electronics, but rather development of components and their ability to work closer to a theoretical ideal. The less ideal a component is the more the engineer must compensate and compensation is in reality not a merit of excellence. So, take two engineers: Both achieve the same performance, the difference is amount of components, topology, placement, EMI, IMD figures, efficiency etc - the one who reach stable function with least amount of parts and without compromises is perhaps the better engineer. On the other hand, a complex and heavy amplifier impress more.

Take the Vitus Audio SM-103 monoblock: 150w Class-AB w 1st 100w Class-A. S/N 110 dB and THD+N 0.01% - its not using toroidal core or R-Core or latest SMPS tech, nope, its using an EI laminated core transformer which is probably the worst thing you can use in an audio amplifier and all for the low price of $40 000/pcs ... Jebus.
Not to hack this thread and do carry on debating the DD amp in general, but perhaps you Jan could shed some light on the question I had and reason for creating the thread.

Quantifying class A quality.

- Oneminde
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Old 11th February 2019, 06:15 PM   #17
jan.didden is offline jan.didden  Europe
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Well I have seen measurements of Bruno's earlier feats which were more linear than a good class A amplifier. class A solves some issues elegantly but also has non-linearities of course.
So, much more important than the class of the amp is how competently it is designed. It is all about how little it subtracts or adds to the input signal while amplifying it.
Perfection doesn't exist.

Jan
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Old 11th February 2019, 06:53 PM   #18
Oneminde is offline Oneminde
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Originally Posted by jan.didden View Post
It is all about how little it subtracts or adds to the input signal while amplifying it. Perfection doesn't exist.

Jan
100% agreed. This outrank the class used
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Old 11th February 2019, 07:50 PM   #19
FauxFrench is offline FauxFrench  France
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Quote:
Originally Posted by Oneminde View Post
Would you so kindly explain or send me to a informative page which explain what fully numerical amplifier is ?
Thanks.
- Edit -
If you are talking about class D and PWM etc, then I'm good
Yes, my intention was to limit to amplifiers where signal treatment is fully numerical, except evidently at the very output which today is PWM based but may become streams of charge pulses.
The advantage from a design point of view is that all treatment is through numerical manipulation such that any analog uncertainty is avoided.
You rightfully ask if such amplifiers are really needed and the answer from an audiophile point-of-view may be no. But, you are going to get them anyway because from a production point of view they are economically less risky to handle. Put the circuit together as described in the datasheet and application notes, eventually enter your own firmware and let the robots do all the work. The complexity will be very high but who cares as long as it is successfully captured in a few chips for robot mounting.

Evidently, the music sources will for long remain dominantly acoustic and need sampling. As long as we cannot enter the nerve system directly with electrical stimuli that are perceived as sound we will have to rely on our ears. My guess is that anything in-between these two analog states will in a foreseeable future be handled numerically only for mainstream consumer products.
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Old 11th February 2019, 08:09 PM   #20
Oneminde is offline Oneminde
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Thanks
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