Article on Philips prototype digital amp

[Kjeldsen]

A few years ago (2-4) I read a very interesting article in a hi-fi magazine. It was one or two authors that visited an engineer from Philips. He had developed a digital amplifier (prototype), which worked with 8 different digital amplifiers in parallel per channel. It was fed directly with a DSD signal from a SACD machine. Is there anyone out there that can remember what magazine it's from?

[EDUM]

There was an article in the German HiFi magazine "Stereoplay" in june 2002 (nr 6) . In this Testspecial "Die neuen Digitalamps-das Aus fuer unsere verstaerker" the Philips PPDSD system was discussed.

In that Philips kitchen a lot of beatiful things are cooking. Unfortunately most of it never gets to the market.
(I heard Philips electrostatic speakers driven by an optical isolated high voltage transistor amplifier!)

Ward

[Kjeldsen]

Quick reply I must say

Now I remember, unfortunately I have thrown all og my hifi magazines away last time i moved, so I don't have that issue anymore. If you (or others) could scan the article and attached it here (I don´t now if that is legal?), I would be a happy man.

Brian

[Jaka Racman]

Hi,

Some information is also here: http://www.classd.org/oem_products/p...hilips_dsl.htm and also authors own opinion about it http://audioholics.com/techtips/audi...mplifiers.html.

It really makes you wonder what is behind that 16 transistor UCD amplifier.

Best regards,

Jaka Racman

[Kjeldsen]

This is a very fast answering forum. Very good links.

Brian

[EDUM]

Hello Kjeldsen,

I am sorry I can not help you on short notice with a scan, but may be your local libray has it in their magazine area.

Ward

[lieven]

seems something cooked with two tl3842 (or similar)a couple of mosfets (2sk2645 or similar) and a ?control circuit?

basic setup is the simpliest switching supply you can think of.



have article yet? if not I'll mail it. BTW search for Bruno Putzeys on internet, you'll find it.

just try this one:
http://www.semiconductors.philips.co.../TDA8924_1.pdf

[lieven]

it's a DGC : digital gainclone

use it straight or inversed, hehehe

[lieven]

Bad for Nelson's Alcoa stock....

tda892X not for sale yet, only samples available

[deandob]

Is anyone planning on trying the TDA8924?

Is it the UCD amplifier discussed on the classd.org site that got such a good wrap? Specs look reasonable (comparable to the competition) and the implementation looks to be easy. The UCD amp on classd.org mentions a zero feedback system with feedback (??) taken after the loop filter, but looking at the TDA8924 specs there is no feedback path after the filter so I guess its not the UDC design.

The other interesting thing about this chip is that it mentions high power supply ripple rejection, yet most class D implementations have very low or no (eg. Equibit) supply rejection.

Regards,
Dean