Chord QBD76 FIFO buffer curiosity

[msmucr]

Hello to all,

 

this is my first post here and it is driven by my curiosity. :-)

I'd like to ask owners or testers of this DAC to share their experience with its buffer. I'm not into purchase of it, but according to reviews and manufacturer description it has implemented quite unique long buffer. According to reviews it will take approx. 3 sec to start playback, which translates to cca 0,5MB size with CD format PCM audio, on its max. settings.

Usual FIFO length in most designs are about 10ms. For sure FIFO functionality isn't just about its length. If underruns doesn't occur, it is calculated fine.

I'm interested in one thing, how is Chords implementation effective? Did you find, that with long buffer setup, QBD sound quality is less involved by incoming data timing? Like variation between different software players and its settings. Does it help to screen different source quality?

 

Best regards

 

Michal

[Melvin]

Hi Michal .. not an owner of the DAC myself but Chris did a nice thorough review awhile back. I believe he touched on the buffer:

 

Computer Audiophile - Chord Electronics QBD76HD / QBD76HDSD DAC Review

[Quest]

I used to own one.. my short answer is yes - the buffer does help with incoming data and especially bad sources, but if you feed it with a very good source, it can sound even better without buffer.

[msmucr]

Hello,

 

thank you Melvin for link and Quest for reply. I had read that review, but i hadn't descend to second page of its comments for first time. Now i did that and found also your post to it regarding buffer.

It is really interesting, especially your feeling regading better sound with good digital source and disabled buffer... All this just intrigued me from technical standpoint, mainly because of never ending seek for ultimate time decoupling of source and DAC. I've heard (or read) many times from different manufacturers about their final solution for it.. double PLLs, ASRC, JET.. typically crypted under fancy names. But this is for first time, when i've seen so long buffer.

Anyway i hope, that someday companies will be successful with development of some robust mechanism, where source changes and imperfect timing will be pushed to inaudible area even on revealing systems. Dreaming on that.. :-)

 

Have a nice day

 

Michal

[SoNic67]

No PLL, ASRC, JEt can do what a FIFO buffer does in terms of cleaning up the incoming jitter.

However, the FIFO clock and associated circuits must be of very low intrinsic jitter in order to compete with very good sources.

 

For reference, the original CD buffers were 16kB or 32kB (higher end).