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Article on Philips prototype digital amp
Article on Philips prototype digital amp
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Old 19th December 2003, 12:21 PM   #21
EDUM is offline EDUM  Netherlands
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Location: Almere
Hello Hercules,

I am no longer working for Philips, But I might be able to help you.

The 930 product was certainly a nice product. A lot of the usual speaker/cabinet/cross-over design issues were "ironed" out digitally. The amplifier however was analog.

Regarding your DCC player the best is to try first:

General Office Address

Philips Electronics Hong Kong Ltd.
28/F, Hopewell Center
17 Kennedy Road, Wanchai
Hong Kong
Phone: +852 2821 5888

Customer Service Information

Consumer Electronics
Phone: +852 2619 9663 (Customer Service Center)
Operating hours: 8:30am - 5:30pm (Mon - Fri)
Daily except Saturday, Sunday and public holidays
Email inquiry: pceinfo.hk@philips.com

The service obligation time is normaly 7 years after production stop. I guess it will not that difficult to get a service documentation for that product. Getting very specific (mechanical) parts migth be difficult.


The vast number of parameters involved in human hearing make imperfect designs certain.
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Old 19th December 2003, 03:22 PM   #22
Hercules is offline Hercules  Hong Kong
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Location: Hong Kong
Dear Ward:

Actually I send the DCC to Philips Hong Kong for service after 1 1/2 year of Philips no longer sell DCC. they said the MR head is bad and no longer have stock... so I'm looking for any chance for fixing out of Hong Kong, especially in Holland!!

anyway, thanks for your help and your information!!! the DSS system is very interesting to me!!
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Old 7th January 2004, 08:09 AM   #23
deandob is offline deandob  Australia
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Default TDA8924 - subwoofer amp


Did you receive your samples from Philips? If so, how does this chip sound?

I'd like to use the TDA in bridged mode for a subwoofer amplifier (bridged mode does 240W in a small package, low component count, smaller heatsink and power supply needed).

The Philips site says that samples are available but it is not clear how to order samples (I'll pay for the chips but no distributor has them in stock yet).

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Old 7th January 2004, 07:52 PM   #24
Pjotr is offline Pjotr
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Default Re: Anyone trying the philips Class D implementation

Originally posted by deandob

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.

That is true. If you look at the data sheet of the TDA8929T modulator-only chip you will see how the modulator works. It uses feedback from the power pulse output. This is the same thing as Tripath does, although the Tripath modulator works somewhat different.

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Old 8th January 2004, 10:51 AM   #25
JohnW is offline JohnW  Czech Republic
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Location: Discovery Bay, Prague, Paris...
There seems to be some confusion here. From what I understand the Philips “UCD” is based upon a Hysteresis Controller, i.e. no fixed Carrier (Clock) just like the first SMPS designs – where as the TDA8924 is based on more conventional Class D technology, i.e. fixed Clock frequency.

If you Email me I will send you a paper which appears very similar to what Philips are calling “UCD”

Sorry I cannot “Post it” as it’s about 250KB
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Old 8th January 2004, 02:00 PM   #26
kuribo is offline kuribo
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I would like to receive the article-how do I email you?

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Old 19th January 2004, 12:37 PM   #27
phase_accurate is offline phase_accurate
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Location: Switzerland
Default Philips patents

Since this one is neat and simple I guess it is the UCD:


And this one I assume is the PP-A and PP-DSD:



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Old 19th January 2004, 05:40 PM   #28
IVX is offline IVX  Russian Federation
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Hi Charles,
IMHO yes it will be UcD if added two last tricks :-)
BTW, I today listened it on tda8938@1Mhz! (up to 3Mhz!),
but output power about 20w (+/-15v used)..What can i say?
It fine for me, however i not cool listener..and no audible different vs 350khz.
Best regards Ivan.
Best regards,
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Old 20th January 2004, 08:37 AM   #29
Jaka Racman is offline Jaka Racman  Slovenia
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Join Date: Dec 2002
Location: Slovenia

maybe Mr. Putzeys waited a little to long with patent application. There are some who came to this idea independently, most notably Subwo1. Look at these pictures, first one is from Mr Putzeys patent and the second one is from US 6,489,841. It is nowadays hard to find something totally new in area of switching amplifiers. But luckily we DIYers can do something regardless of patents and combine best ideas.
So I found out a way to combine two UCD amplifies into full bridge and synchronize them in counter phase to achieve ripple cancellation. This was inspired by Nielsen Karsten (Bang&Olufsen) patent application WO 03/055060. It is still in simulation phase, but it looks promising.

Best regards,

Jaka Racman
Attached Images
File Type: gif ucd.gif (13.9 KB, 712 views)
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Old 20th January 2004, 08:38 AM   #30
Jaka Racman is offline Jaka Racman  Slovenia
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Second picture
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File Type: gif ucd1.gif (13.0 KB, 781 views)
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