Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems HD621 jitter levels

Happy New Year!

Quick question: do we have actual numbers for the level of jitter in the HD621? We know that HDMI is generally in the 1000+ps range - I just wondered what Meridian were able to achieve with their dejittering in this box...

There appears to be very little objective info published on any of the current M products. The only stuff I've seen are review measurements from Stereophile and Miller Audio Research.

The results of LPCM HDMI based jitter tests mentioned above appear to vary widely from product to product. Implementation of HDMI Audio Rate Control (ARC) compatible products also appears to reduce the comparative i.e from 8500ps to 205ps level but is limited to compatible devices. Products from Arcam and Classe appear to achieve lower HDMI jitter levels without using ARC but I'm not sure if this is by using asynchronous sample rate converters.

Would be interesting to see some info on M gear from credible third party's rather than just M marketing.

Avii

This ARC thing is not in the HD621, is it?

There are jitter figures in the Stereophile tests for the 808, for example.

AFAIK the HD621 doesn't support ARC.

Unfortunately most implementations of ARC are proprietary i.e. Sony HATS, Pioneer PQLS etc. Both source and sink device need to support a compatible version of ARC.

As per my OP "The only stuff I've seen are review measurements from Stereophile and Miller Audio Research". There is very little info on other products or "versions" of the same model in M's range. Miller Audio Research has some measurements on the G68 and G95. The later was classed as a test fail due to jitter levels.

Avii

I don't know too much about Pioneer's PQLS, but when I looked into Sony's HATS system, it only seemed to work for audio-only data.

Mark S

Not sure what you mean by "audio-only" data using HDMI Audio Rate Control ?

The implementation I've seen in the past apply to LPCM format audio and manufacturers offer versions that support 2 channel or multi-channel. It appears Pioneer also now claim to support this feature on bitstream. From a Pioneer Blu-ray product "Our unique PQLS ensures jitterless transmission of uncompressed 2-channel or multi-channel LPCM, and also bitstream audio over HDMI to compatible Pioneer AV receivers".

There a video outlining PQLS in the bottom left of the page in this link - http://www.pioneer.eu/uk/products/42/98/405/SC-LX85/index.html

I recall talk of Ayre implementing an "open" version of ARC but I'm not sure what sink products would support it if they did.

Avii

I mean audio only (e.g. from an SACD) as opposed to audio with video (e.g. from a Bluray). I suspected that when video data was being carried that there would be too much traffic for the ARC to work. But I see from your Pioneer quote that that is not the case. The only Sony player to feature HATS was a SACD player; the Bluray player in the same range didn't offer HATS.

Mark S

Mark:

Is it possible that HATS was used to dejitter DSD?

Yes, I'm sure HATS was used to dejitter DSD, but also PCM, both of which the Sony 5400 SACD player can ouput over HDMI.

Mark S

Miller Audio Research HDMI measurement of the Sony XE5400ES and Sony sink -

"Unit Serial Number: Sony SCD-XA5400ES & STR-DA5400ES HDMI sequence

SACD Jitter (HATS Off) Fail

Total correlated Jitter (re. -3dBFs into 47kohm) =
8131psec (Left Channel)
8121psec (Right Channel)level"

SACD Jitter (HATS On) PASS

Total correlated Jitter (re. -3dBFs into 47kohm) =
219psec (Left Channel)
207psec (Right Channel)"

Miller Research notwithstanding, I had both Sony SCD and STR 5400 at home. Nice couple, better sound with HATS activated, but not a better CD player than the G08 I had at the time.
Btw there was the rumour Sony put a lot of effort on this SCD as a CD player, but inside I just found very plain components, off the shelf DAC and opamps, all quite ordinary save for a new and particular Sony chip driving the HDMI out (the HATS brain off course). No other Sony player had/has it AFAIK.
I also had the Pioneer system (drive+receiver) but as an audio player (and amp) was behind the Sony pair.

I'm not suggesting Sony and Pio will sound better or worse than any other solution. They are just examples of how ARC can influence jitter performance.

HDMI ARC is similar in principle to how async USB controls the flow. It can help improve aspects of performance but is but one element in the overall solution.