Audio Asylum Thread Printer
Get a view of an entire thread on one page
|For Sale Ads|
In Reply to: RE: Chord up-samples? posted by dave789 on June 15, 2017 at 15:17:40
Having spent quite some (great) time with the "cicsmemoryplayer" aka cMP2 project, I was recently drawn in on the unusual way Chord D/A conversion is handled. Some statements/interviews from their owner, their head of engineering and some other postings.
All of it seemed very similar to how cPlay (player software @cMP2) calculates an upsampling with indefinite filter algorithms (sinc- & FIR filters). Difference being that cPlay uses the CPUs cache memory to upsample and Chord is doing this with a FPGA chip.
So yes - Chord DACs definitely uses upsampling.
Hysolid // Mytek Brooklyn // Spectron Musician III // Analysis Audio Omega
In consumer magazine terms, over-sampling means integer times sample rate conversion only; up-sampling means possibly non-integer times sample rate conversion ("asysnchronous" sample rate conversion, ARC) such as 44.1k to 192k.
Do you happen to know whether Chord uses "asysnchronous" sample rate conversion?
> > In consumer magazine terms, over-sampling means integer times sample rate conversion only; up-sampling means possibly non-integer times sample rate conversion ("asysnchronous" sample rate conversion, ARC) such as 44.1k to 192k. < <
The correct technical term is "interpolation". "Upsampling" was generally adopted in video circles, while "oversampling" was generally adopted in audio circles - until the late '90s when dCS found that inserting their professional sample-rate-converter box between the source and DAC (already with built-in "oversampling") changed the sound of the system. They then referred to this as "upsampling", as the only sources of the day were 44.1kHz and it would convert that "up" to either 48, 88.2, 96, 176.4, or 192kHz. Ever since there has been no accepted definition of the terms. The technically correct ones I think you are looking for are "synchronous interpolation" and "asynchronous interpolation".
And to finally answer your question, I am unsure as to what Chord does. Their designer Rob Watts posts a lot at the Head-Fi forums and has explained much of their technology there. I have a vague recollection of him discussing the final delta-sigma modulators in their FPGA system (after all interpolation was performed), but cannot recall if it was done a single frequency master clock or if they had a separate master clock for each of the two sample-rate "families". I'm pretty sure that looking over there (and possibly posting) will provide the answer to your question. Hope this helps.
As always, strictly my personal opinion and not necessarily those of my employer or of Rob Watts.
Post a Message!
This post is made possible by the generous support of people like you and our sponsors: