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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th November 2008, 01:12 PM   #11
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It has to convert back to analog at some point. I can't hear digital.
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Old 8th November 2008, 03:40 PM   #12
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Its okay o go from digital to analog....

But its not okay to go from digital to analog to digital to analog to digital to analog to digital to analog to digital to analog.

It just seems that class D has been stuck a bit among us diy guys, without moving on to the next level....

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Old 8th November 2008, 04:44 PM   #13
BWRX is offline BWRX  United States
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Quote:
Originally posted by oon_the_kid
It just seems that class D has been stuck a bit among us diy guys, without moving on to the next level....
Why does it seem to be stuck? What's the next level?
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Old 8th November 2008, 05:16 PM   #14
bwaslo is offline bwaslo  United States
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Oon -

You do know that Class-D amplifiers, in general, are analog amplifiers, not digital, right?. Sorry if this is obvious, just making sure because many people equate "Class D" with quantized "digital" and it just isn't so. Some class D amp circuits might be fitted with D/A stages at the input or even within a feedback loop, but the output stage (and power amplification) of Class D is entirely analog.

Instead of controlling current flow into a load, to form a voltage power signal (at least, as well as linearity and turn-on points of the controlling devices permits), class D controls switch timing (entirely continuous, not quantized) which forms the voltage power signal. Class D performance is independent of the linearity of the output devices (but has some dependence on how well switching timing is controlled). It's just a different analog to the signal, timing rather than current.

Like digital circuits, output stages in class D switch between two states. But a digital circuit switches only at certain time points, while Class D switches in continuous time.

Sorry again if I'm saying what you already know. Maybe this will prevent others from misinterpreting.
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Old 8th November 2008, 06:48 PM   #15
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Quote:
Originally posted by BWRX


Why does it seem to be stuck? What's the next level?
Forum is freezed by TRIPATH CHIPS
No one, thinks out of the box, except few left.
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Old 8th November 2008, 07:24 PM   #16
BWRX is offline BWRX  United States
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The Tripath based amps are a great way to get into the hobby and start learning about class d. The fact that they're reasonably cheap and sound good is a nice bonus!

There are plenty of schematics and designs out there to move onto the "next level" if one so desires. Not many have the time, desire, tools, etc. to do so.
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Old 8th November 2008, 09:08 PM   #17
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Quote:
Originally posted by Workhorse


...
No one, thinks out of the box, except few left.

Quote:
Originally posted by BWRX
...There are plenty of schematics and designs out there to move onto the "next level" if one so desires. ...

Case in point. But for the forest there were no trees.

Workhorse, get yourself up to speed:

Class D Design Issues
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Old 9th November 2008, 03:19 AM   #18
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Bwaslo,

Yes, I am aware of the operations of the class D amp. However, in a normal sound system, the signal is converted from SPDIF/I2S to current in a DAC, which in turn goes through an I-V stage for final conversion to voltage. This in turn goes through a VR for volume control and another circiut for pre-amp(sometimes). This in turn is fed into the input of the Tripath chip which has an inverting amp to bias it to before the final conversion to PWM in the DSP. This is a rather long winded of achieving the right PWM duty cycle. It should be possible to figure out the right PWM duty cycle without having to go through the analogue path from the SPDIF/I2S by usage of a DSP. Volume control could be implemented there too.

I think that would reduce the degradation of the signal a long way....

Oon
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Old 9th November 2008, 03:30 AM   #19
Pano is offline Pano  United States
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Quote:
Originally posted by Workhorse
Forum is freezed by TRIPATH CHIPS
No one, thinks out of the box, except few left.
Huh??

Dude, have you actually been reading this forum?
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Old 9th November 2008, 06:06 AM   #20
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Quote:
Originally posted by panomaniac


Huh??

Dude, have you actually been reading this forum?

I think yes, but i found T-amps attract many guys except me.
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