HD-XE1 og støj?

Hej jake51 - så vidt jeg kan forstå, er der noget mere støj ved XE1. Det må der jo være efter som det bliver omtalt. Omvendt har jeg været i stue med begge modeller på én gang, og synes nu ikke det var så slemt med XE1. Måske har det også noget med smag og behag at gøre.

Så på den led (støj) vil jeg nu ikke være så bekymret, og bare ønske dig tillykke med købet, og held og lykke med salget 

Er der en grund til ikke altid at vælge HDMI til overførsel af såvel billede som lyd? Er der en fordel i at nøjes med video signalet og bruge optisk/coaxkabel til lyden?

Læser man denne anmeldelse af XE1'eren  (XA2), står der om lyden:

HD DVD uses as its base standard the Dolby Digital Plus audio format. DD+ requires too much bandwidth (and copy protection) for its full bitstream to be transmitted over a legacy Optical or Coaxial S/PDIF connection. The first generation HD DVD players accommodated this by decoding the DD+ internally and then transcoding it to 1509 kb/s DTS 5.1. The result was a downgrade from the original DD+ but sounded every bit as good as full bit-rate DTS on DVD ever did, which is quite nice indeed. Unfortunately, this strategy left viewers with older Dolby-only audio receivers out in the cold.

The HD-XA2 takes a slightly different tack. Instead of transcoding to DTS, it converts the signal to Dolby Digital 5.1 at that format's maximum bit rate of 640 kb/s. This is arguably inferior to the DTS method (Dolby advocates would disagree), but ensures greater backwards compatibility.

To get the most out of Dolby Digital Plus or the lossless Dolby TrueHD formats that HD DVD offers, owners should ideally use either the HDMI or multi-channel analog audio outputs. In both cases, the player itself decodes the codec as a first step. From there, the audio can be transmitted in uncompressed PCM format over HDMI to an audio receiver for digital-to-analog conversion, or it can be converted internally and output over the analog connections. The HD-XA2 has the same highly regarded Analog Devices SHARC DACs as the previous HD-A1 and HD-XA1 models, so there shouldn't be any quality concerns when using the analog outputs.

Anmeldelsen nævner også noget om en fejl ved XE1'erens analoge udgange:

At least that's the theory. In practice, I ran into some trouble. My audio receiver doesn't have HDMI, so I opted to use the 5.1 analog connections. I adjusted the player's speaker levels and distances to the same settings that worked quite well for me on the HD-A1. Things sounded pretty good until I hit any movie scene requiring bass. Essentially, there was hardly any LFE activity at all. When the building collapsed in 'World Trade Center,' it did so with barely a rattle. That didn't seem right. I switched over to the DD 5.1 downconversion over the player's S/PDIF output and replayed the scene. The bass slammed me in the chest as I'd expected it should. Clearly something was wrong. Next I went back to the HD-A1, using its analog outputs, and again I got that deep bass rumble.

At that point I broke out my sound level meter and began taking some measurements. Test tones measured normally on the 'Avia' calibration DVD over both analog and S/PDIF. I also put in some known bassy movies on Standard-Def DVD and had no shortage of expected gut-thumping rumble. Regular Dolby Digital and DTS on DVD don't seem to be affected, but LFE output from the HD-XA2's analog connection is clearly too low on both DD+ and Dolby TrueHD from HD DVD discs.

The HD-A1 had required a 10 dB bass boost at my receiver, as do most multi-channel analog sources. I expected that, but the HD-XA2's LFE is much lower still, to the point of being practically nonexistent. I found a particularly good example to test this at Chapter 2 on the HD DVD edition of 'The Wicker Man' (lousy movie, unfortunately). Nicolas Cage has some dialogue that makes a good reference point to take a non-bassy sound level measurement for volume matching purposes (the clearest line is "I've got it, honey"). Following this line, a truck passes by on the road that should have a good rumble of bass. Then shortly afterwards there's a huge crash that should again obviously provide a clean LFE hit, followed by some fire effects with more rumble.

Using S/PDIF, I set my volume so that Cage's line of dialogue hits exactly 70 dB. Then when I switched to analog, I adjusted the volume to make sure the same line hit that precise point (which required me to turn the volume up). Doing so, I found that the three events (truck passing, truck crash, and fire) had significantly more bass over S/PDIF and almost none at all over analog, even with the 10 dB bass boost at the receiver. Not only was this measurable on the sound level meter, but I have a tactile transducer (bass shaker) attached to my chair that's connected to my receiver's subwoofer output. So I can literally feel any difference in bass (and only bass - the shaker is connected only to the subwoofer output). The transducer gave my chair a good jostle with S/PDIF, but hardly moved with analog.

I tested the HD-A1 using the same methodology, and found both its S/PDIF and analog results were comparable to the HD-XA2's S/PDIF (again, with the disclaimer that my receiver requires a 10 dB bass boost on analog). The only odd man out is the XA2's analog, which has basically no bass at all.

I tried every conceivable option in the XA2's setup menu that might possibly have some impact on this: large speakers, small speakers, different crossover frequencies, subwoofer Use or Don't Use, Dynamic Range Control on or off or auto. In the channel volumes menu, I set the subwoofer for the 0 dB max and pulled every other channel down to the -12 dB minimum. I tested and measured and retested and remeasured that scene a few dozen times. I found small variances with different settings, but nothing really fixed the lack of bass, which is problematic using either the DD+ or TrueHD track on the 'Wicker Man' disc. Yet on the HD-A1 there's plenty of bass using the analog outputs (subwoofer 0 dB, front channels -1 dB are my calibrated settings for that player).

Bass levels on the player-generated test tones and on standard DVD playback are perfectly normal. It is only on HD DVD movies where this happens. I tried to be as thorough as possible in my evaluation, to the point of doing all of my tests on both available HD-XA2s, and found each identical. I've heard reports that the same problem is present when using HDMI to transmit the audio, but unfortunately I wasn't able to check that myself.

As if that weren't enough, I found that audio lip sync is off over the analog connection on many HD DVDs as well. It appears that not enough of an audio delay is present to match up with the player's video processing. It's not terrible but it can be distracting. As with the video stutter issue, feedback on both of these audio problems was provided directly to Toshiba. Hopefully they can get to the bottom of it and fix the problems with future firmware upgrades.

Redigeret af Swearengen - 08-Marts-2007 kl. 17:28