[James Tanner]

Hi All,

My spies in the field are reporting that there is some concern from a number of quarters that the HDMI digital connections (transmission)  are not sounding as good as previous traditional digital USB, AES, COAX and Optical type connections.

Any feedback?

james

[alexone]

hmmm, maybe when the sp3 is ready then we will find the answer. i mean that way it is 'easy' to find out how all these different connectors sound in a Bryston set up.
but given my experiences with my Pioneer receiver i used to listen to (hdmi, i-link, coax, optical) i always felt that the i-link sounded indeed better than all the other digital connectors. the clou on that i-link thing was the QPDS (Quarz Precision Drive System or something like that). Pioneer's technology to eliminate jitter.

btw: i-link was invented by Sony, wasn't it?

 al.

[Gary Listen]

Hi All,

My spies in the field are reporting that there is some concern from a number of quarters that the HDMI digital connections (transmission)  are not sounding as good as previous traditional digital USB, AES, COAX and Optical type connections.

Any feedback?

james

Hi James,

Although I have no personal experience with the digital transmission of audio signals over the HDMI interface, I too have read on many occasions that the HDMI interface is inferior to other digital connections. However, I was encouraged recently by a review I read by Robert Harley on hi-res multichannel audio gear from Sony in The Absolute Sound. In his review he stated:

"This was my first opportunity to compare the sound of digital audio transmitted over HDMI with the same bitstream carried over a coaxial interface. I connected a digital coaxial cable from the BDP-S2000ES (a Sony Blu-ray disc player) to the STR-DA5300ES (a Sony AV receiver), and simply switched between the inputs with familiar CDs as the source. (HDMI 1.3 will also carry two-channel PCM data). High-end equipment designers who had experimented with HDMI reported to me that the interface introduces audible degradation. In fact, an engineer from Arcam told me that the company doesn't implement the audio aspects of HDMI because the sonic degradation is unacceptable. After listening for myself, I can see why. The HDMI connection sounded thinner, brighter, and harder, and had a strange, almost "phasey" character in the midrange. I noticed this only with two-channel material in direct comparison with the coax interface. When listening to Dolby TrueHD or DTS-HD Master Audio through HDMI, I didn't hear these sonic shortcomings."

Mr. Harley states that he did not hear any sonic shortcomings while listening to Dolby TrueHD or DTS-HD Master Audio through HDMI. However, those bitstreams cannot be carried over a coaxial interface. Thus, he would not have been able to make similar comparisons. Maybe the superiority of the hi-res formats overshadows the inferiority of the HDMI interface to make the ultimate sound superior to what is otherwise available. I've got to think there has to be a better interface for hi-res audio.

Gary

[James Tanner]

Hi Gary,

Thanks for the input.

I have been doing some investigating myself due to the SP3 of course and so far here is what I have come up with.

HDMI was developed and optimized as a video transmission medium and audio performance was not the focus of the initial HDMI specifications. Audio was added later to the 'empty' spaces left over in the bit-stream from sending out video.
 
So the way in which the processor handles the audio bit-stream is critical when designing high quality processors using HDMI interfaces. Jitter issues in the audio bit-stream in HDMI transmissions can be dealt with in a number of different ways from doing 'nothing' (maybe inexpensive receiver's, portable players etc.?) to offering high quality 're-sampling and re-clocking' to quality 'oscillators and sample rate converters' etc. on the input.

james

[MOZ]

i think jitter is much more active with PCM sent thru HDMI (2ch CD or HD audio decoded inside the player)... than with "zipped" bitstreams (TrueHD, DTS-HD aso). Am I not right ?