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Class D Switching Power Amplifiers and Power D/A conversion

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Old 5th April 2009, 12:43 AM   #1
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Default How does Class D work?

I understand the basics of the circuit, but I don't understand how the pulses can sound like music, or like the source music anyways.

Links to articles?
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Old 5th April 2009, 05:59 AM   #2
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It works by integrating the short on-off switching of the power so that the human ear just responds to the varying audio inserted into the output signal.
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Old 5th April 2009, 06:41 AM   #3
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"How does Class D work?"

It works very well - thank you

A good explanation here:
http://en.wikipedia.org/wiki/Switching_amplifier

That Low pass output filter is a big discussion. Plenty of threads here.
With the filter the class-d does present to the speaker the same signal that would come out of any amp.
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Old 5th April 2009, 10:47 PM   #4
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Quote:
Originally posted by raintalk

With the filter the class-d does present to the speaker the same signal that would come out of any amp.
You're blowin' my mind, raintalk.
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Old 5th April 2009, 11:49 PM   #5
wwenze is offline wwenze  Singapore
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Quote:
Originally posted by travis


You're blowin' my mind, raintalk.
That's in theory of course, and in theory all amps should sound sound the same.

But we're in reality here.

And that most class-D amps in the market are for cheapo applications (i.e. computer speakers) doesn't help.
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Old 6th April 2009, 03:24 PM   #6
ssanmor is offline ssanmor  Spain
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Hello,
I wrote and published this some time ago. I would add some comments today, but I think it will help you understand the operation of Class-D and what the limitations were/are.

Hope it helps:

http://sound.westhost.com/articles/pwm.htm
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Old 8th April 2009, 02:07 AM   #7
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Quote:
Originally posted by ssanmor
Hello,
I wrote and published this some time ago. I would add some comments today, but I think it will help you understand the operation of Class-D and what the limitations were/are.

Hope it helps:

http://sound.westhost.com/articles/pwm.htm
First thing I read. Great site.

I just didn't get how the filter turns the pulses back into the original signal. I was thinking running those rectangular pulses through a low pass would make rectangular pulses with rounded corners.
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Old 8th April 2009, 03:54 AM   #8
Eva is offline Eva  Spain
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The pulses are generated in a way such that they already contain the audio signal, plus the high frequencies that are attenuated by the filter. That's the trick.
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Old 8th April 2009, 09:03 PM   #9
Pafi is offline Pafi  Hungary
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Quote:
I was thinking running those rectangular pulses through a low pass would make rectangular pulses with rounded corners.
Freq of the pulses (eg. 400 kHz) is much higher than cutoff freq of the filter (eg. 30 kHz), so at the output there is no switching freq left, just audio.
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Old 9th April 2009, 04:17 PM   #10
Gyula is offline Gyula  Hungary
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Quote:
Freq of the pulses (eg. 400 kHz) is much higher than cutoff freq of the filter (eg. 30 kHz), so at the output there is no switching freq left, just audio.
Maybe in an ideal world, it would be true.
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