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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th March 2013, 07:51 PM   #111
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For fast rise times the current is supplied by any local decoupling caps, rather than the average current, which is supplied by the PSU proper. This is somewhat redundant for standard analogue audio though (ignoring class D) as most transients are going to be incredibly slow compared to any proper switching events. Providing the PSU is capable of delivering the required current, be it linear or SMPS, it doesn't matter. If it cannot supply the required current the rails will collapse, the PSU might shut down and the amp will clip. If this isn't happening then the PSU is delivering enough current to accurately convey any musical transient.
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Old 8th March 2013, 08:08 PM   #112
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We Men, like the theory because it allows us to speak and speak ...
But in this case it is very easy to see the practical fact.
A toroidal 1kW at 80V with 2x47.000uF has a voltage drop of up to 15-18V repeated under a simple 33-66ms burst @ 1Khz, in a MOSFET amplifier.
below 100Hz, the drop in voltage reaches 20V. thinks with vocals and bass.
I understand that this topic is preferable go around rather than accept it.
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Old 8th March 2013, 08:36 PM   #113
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AP2,
Perhaps someone else with more knowledge of the math can chime in here but that voltage drop sounds extremely high for a regulated power supply. At the same time you are not saying if this is a 20 watt amplifier or a 150 watt amp and that is going to make a world of difference to the voltage drop. Were is Gootee when we need him?
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Old 8th March 2013, 10:36 PM   #114
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Quote:
Originally Posted by xrk971 View Post
AP2,
I don't know where you are getting you info about human hearing. It is well known that the human cochlea has nerves positioned and arranged in a way similar to a mechanical real time spectrum analyzer with various lengths of cilia sensitive to different frequencies, and these cilia are positioned along the length of a fluid channel such that different frequencies excite different portions where the nerves representing various frequency bands are located.
Not quite the story. The cilia are not frequency specific but the location of their (hair-)cells on the basilar membrane is relatively frequency-specific and that endows their signals with a frequency significance. In addition, that significance is only relative as many hair cells are excited to varying degrees even by a single pure tone because the on basilar membrane is dispaced maximally but not exclusively as the travelling wave from a pure tone passes from the base of the cochlea up towards the apex.
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Old 9th March 2013, 07:12 AM   #115
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Quote:
Originally Posted by AP2 View Post
... a voltage drop of up to 15-18V repeated under a simple 33-66ms burst @ 1Khz, in a MOSFET amplifier.
below 100Hz, the drop in voltage reaches 20V. thinks with vocals and bass.
I understand that this topic is preferable go around rather than accept it.
Another reason why class A is preferable.
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Old 9th March 2013, 08:09 AM   #116
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I am glad that someone intervenes, the problem in the forums is always the same. many are full of theory or slogan of the company and do not know the reality. this is my deduction in relation to the various threads and replies I read.
I followed the thread with interest Gootee (I also posted the curves of a ybride module that can perfectly solve the problem of power supply, unfortunately has a high cost of production).
We started from the recognition of a sound to reach the conclusion (in my case). yes if voltage not decrease, changes everything listening especially in D Class.
my previous post, it refers (+ /-80V) to get in 450w mosfet amplifier AB with very soft attak of instrument, instead of original wonderful dry as original.

Just for curiosity,my post on Gootee thread: Power Supply Resevoir Size

regards

Last edited by AP2; 9th March 2013 at 08:35 AM.
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Old 9th March 2013, 08:27 AM   #117
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AP2,
Thank you for the clarification. I just couldn't understand the voltage drop without some context to power output.
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Old 9th March 2013, 08:48 AM   #118
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Just for curiosity,
This is the fast power regulator (30Amp) (one per side need) that produced the behavior shown in the measurement.
This power module (in my opinion excellent), has not been produced.
there are 5 samples only for testing, has developed on ceramic wafer.

Very simple to use eheh!
regards
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Last edited by AP2; 9th March 2013 at 09:02 AM.
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Old 9th March 2013, 08:50 AM   #119
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Originally Posted by Kindhornman View Post
suntechnik,
Some of the worst sounding and distorted sound systems are the single ended tube amplifiers that can barely drive anything but a horn system. So you have to qualify what your requirements are and what you consider accurate sound. I do not consider a tube amplifier that has a 7 watt output as a truly useable device in most application, I do not listen to chamber music at 86db output and call it a day. I am sure with a push pull tube section or a few other high power tube circuits I would be happy but those are so expensive that they become again an esoteric product. It you want or need a higher powered tube amp you will be spending precious resources to get there.
I am apologizing for not answering right away.

I really like Graaf gear (Graaf.it and in USA Atmosphere is following similar approach). For example the upper BW of 13.5II is overkilling 500KHz. Yes human ear cannot hear ultrasound like 500KHz for sure but this is the most natural sounding preamp I've ever owned. True magic. I know that ultrasonic ICs like OPA627 637 are also have good reputation among audiophiles.

While believing in Fourier I am not treating 20-20.000 Hz approach as practical one (wavelets vs Fourier are another can of worms). Class A tends to deliver better BW even in case when printed specs for an amp are limited to 20-20.000Hz. This my explanation why some audiophiles are leaning towards A - the better BW.

Hi Efficiency could be achieved not only by horns but using line arrays as well. McIntosh are making such speakers for example.

Personally I was owning full size Magnepans and Krell FPB monoblock 600 watts of Class A total. Maggies are the best speakers I've heard so far (guy who had owned Maggies but upgraded later to MBL claims that MBL even better but they both finicky in setup and to amplify). Yes back loaded horns are not as accurate. But I've sacrificed Magnepns in favor of Class A amplification.

Yes HiEnd gear is expensive and rare. Speakers price tags & WAF are limited factors in most cases.
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Old 9th March 2013, 09:03 AM   #120
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Hi, If you want to listen to Class D with PRAT and base to die for listen to the Texas Ind range of :
TPA3130D2 15 watts
TPA3118D2 30 watts
TPA3116D2 50 watts
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