Why do DVD players sound bad on CD playback

[PHEONIX]

Does anybody have a technical reason why a CD played back on a DVD player sounds worse than on CD player, even when the digital out is used.


Regards
Arthur

[mrshow4u]

Does anybody have a technical reason why a CD played back on a DVD player sounds worse than on CD player, even when the digital out is used.

I guess I'm kind of new here. Is this a widely held belief??

[PHEONIX]

Originally posted by mrshow4u


I guess I'm kind of new here. Is this a widely held belief??

Yes, though I dont think it. It's something that a lot of people say but I was curious if anybody had a technical reason to explain it.

Regards
Arthur

[clem_o]

The only reason I can think of is that the digital output of most DVD players tend to be 'inexpensively' made, circuit-wise and component-wise. I have not seen a 'DVD only' player that, for example, sports an output transformer to isolate HF noise from the player from reaching the amp. Such ommissions do have a large effect on the playback quality.

Even multi-format capable players (i.e SACD, DVD-A) tend not to have the transformer, on the basis that these newer formats aren't sent out the SPDIF anyway.

Cheers!

[hifimaker]

Also the wavelengths of the laser diodes used in DVD and CD are different spectrums. The better DVD players have dual diodes, one for each format.

-David

[peufeu]

Simple.

A DVD has most of the circuits found in a CD player, plus a video processor, an embedded microcomputer, etc. All this generates a lot of high frequency noise which is generally not properly dealt with.

Also DVDs generally have one master clock which is at 27 MHz, the standard for video signal generation. Audio clocks at 44.1 and 48 kHz are generated from this by a cheap PLL which adds a suitable amount of jitter.

Finally DVD players are generally optimized for image quality and not audio quality, because they are bought to watch movies.

The transport mechanism has no influence on the sound quality.

[georgehifi]

Originally posted by dw8083
Also the wavelengths of the laser diodes used in DVD and CD are different spectrums. The better DVD players have dual diodes, one for each format.

-David

This is probally the main reason, the Philips DVD-963sa had two lasers one green (650nm for dvd) and one red (750nm for cd) for reading the two different formats, but it was'nt a $50 player here in Aus it sold for $1100.

Cheers George

[v-bro]

But this sa-cd player plays cd's on such a high rotation speed it makes lots of mechanical noise (I've had the player in my house for two weeks to test, since I worked for a hifi shop)...
The "rattling" noises were audible through the music sitting on the couch (all our stock had this problem!)

I quickly went back to my modded onkyo....

I also hated the fragile plastic parts in it, as used in a lot of modern "high quality" equipment.

Though I'm Dutch I never liked philips equipment a lot...

And as high speed writing never worked well, won't high speed reading?

[clem_o]

I'm not sure why a difference in laser diode frequency (and thus spot size/wavelength) should make a significant difference in sound delivery. I have a 1st generation Sony dvd player, that uses dual lasers and optics to track dvd and CD - a pretty pricey unit. The sound on cd is "just as bad" as the other players... :-)

With today's higher level of integration, there's much less parts count to deliver the funtionality required by a DVD player, so it should be much more feasible to do the required isolation to reduce noise - but yes, not many manufacturers really do proper shielding...

Cheers!

[fmak]

Originally posted by PHEONIX
Does anybody have a technical reason why a CD played back on a DVD player sounds worse than on CD player, even when the digital out is used.


Regards
Arthur

This is true only for cheaper DVD players. The high end Pioneers do sound decent.

In cheaper players,the clock is derived from the one used for the video section. There is generally very poor power supplies. The auto shut off feature doesn't even allow proper warm up., etc etc

It is also perhaps assumed by the makers that DVD player users are not interested in HQ audio?