HDMI Audio Jitter Reduction

[Ralf11]

How good is HDMI as an interface (if it is improved by the technology below)?

Oppo info:

The UDP-205 features a high-stability, high-precision HDMI clock and a special HDMI audio jitter reduction circuit. This unique design significantly reduces jitter and eliminates timing errors, allowing you to enjoy your music with increased accuracy when you use the audio-only HDMI output port for connecting the audio signal. PCM and DSD signals rely on the HDMI clock directly, so the HDMI audio jitter reduction circuitry can improve the sound quality of PCM and DSD audio. 

[esldude]

If you haven't seen this page it explains what they are doing.

https://www.oppodigital.co.uk/Understanding-the-HDMI-Audio-Jitter-Reduction-Circuit-OPPO-UDP-205.html

From that page is the following FFT of a jtest signal from the Audio HDMI output

 

 

Here is one with similar scaling I did for an inexpensive HDMI switcher in green, and an old Tact RCS 2.0 unit in blue.

You can see the HDMI switcher has a 10 db or so higher basic noise floor vs the low jitter Oppo HDMI.  And some higher and more numerous jitter related spurs around the central tone vs the low jitter Oppo HDMI.

 

The blue trace however is lower in noise and lower in jitter related sidebands than is the Oppo HDMI.  So while this is an improvement the HDMI output looks to be less than a fantastic result in terms of jitter related sidebands.  Or at least in comparison to a 15 year old piece of audio gear.

[esldude]

Making you wonder a bit more is a measurement by Archimago of the Oppo BDp 105 using the HDMI.

 

 

The right hand graph looks more similar to the old Tact RCS than it does the Oppo graph posted in their own page. 

 

http://archimago.blogspot.com/2017/04/measurements-oppo-bdp-105-rca-xlr-hdmi.html

[mansr]

At a glance, what they're saying is basically true. The audio clock is derived from the video clock, and using a simple ratio makes it easier for the receiver's PLLs to produce a stable frequency. Whether this difference is at all audible is another story.

[Don Hills]

1 hour ago, mansr said:

At a glance, what they're saying is basically true.

...

Whether this difference is at all audible is another story.

 

Note that in the Oppo statement they are careful not to say that you'll hear a difference.

[Ralf11]

True - I'm wondering what interface to use to shoot Redbook rips from my mac mini to the Oppo 205 for playback.

 

Toslink?

HDMI?

USB?

 

 

[esldude]

4 hours ago, Ralf11 said:

True - I'm wondering what interface to use to shoot Redbook rips from my mac mini to the Oppo 205 for playback.

 

Toslink?

HDMI?

USB?

 

 

USB would be lowest jitter.

 

Toslink would prevent any electrical noise travelling across the connection.

 

HDMI...........why, there are no advantages.

 

The Mac Mini doesn't have the best toslink output, so I would go with USB.

[Ralf11]

Thanks.  Maybe there is a galvanic isolator in my future...