Class D and analogue

[Rivendell61]

On the Hypex web site--a new paper by Bruno Putzeys.
http://www.hypex.nl/docs/allamps%20hypex%20layout.pdf
It is from 2006 AES in Paris.

*diyaudio.com/forums/classd is referenced in footnote #5 of the paper.....

Mark

[Snickers-is]

Wery interesting reading.

BTW, I think figure 7 is missing, or is it just my eyes that are missing?

[FastEddy]

" On the Hypex web site--a new paper by Bruno Putzeys.
http://www.hypex.nl/docs/allamps%20hypex%20layout.pdf
It is from 2006 AES in Paris. ..."

After reading the doc, it appears that this Class D amp does not use a specific frequency for switching power to output ... but senses the data rate of the input and "locks on" to some high harmonic, thus passing the gas at a rate (freq.) commensorate with quality ...!!?!!

I gotta get one of these and play with different sources.

[Pano]

Originally posted by Snickers-is
I think figure 7 is missing

You are correct. Figure 7 is missing.

Intersting paper, some of the informatiion has been covered in this forum, some not.

[Snickers-is]

Originally posted by FastEddy
" On the Hypex web site--a new paper by Bruno Putzeys.
http://www.hypex.nl/docs/allamps%20hypex%20layout.pdf
It is from 2006 AES in Paris. ..."

After reading the doc, it appears that this Class D amp does not use a specific frequency for switching power to output ... but senses the data rate of the input and "locks on" to some high harmonic, thus passing the gas at a rate (freq.) commensorate with quality ...!!?!!

I gotta get one of these and play with different sources.

I believe you got the point. The switching frequency depends (almost) on the 180 degree XO point of the output filter, but it is helped out by an RC-link in the feedback (since the secon order filter does not have a defined 180 degree crossing point. This means it is some dependent on the load, but the frequency is relatively well under control.

[Pafi]

but senses the data rate of the input and "locks on" to some high harmonic

Not exactly. Freq depends on PWM modulation index (a little bit, at high modulation), and theoretically on load impedance, but practically most speakers have so high impedance at switching freq, that doesn't effect switching freq significantly (and this effect is constant).