MiniDSP DDRC-24 Resampling. Good or Bad?

[macauley86]

I'm thinking of buying a MiniDSP DDRC-24 to use it as a DAC/DSP/Dirac for my system (Mac + Audiolab 8300A + Polk LSiM703).

According to an email I got from MiniDSP, the DDRC-24 resamples 44.1 KHz (all my CD rips) and all other sample rates to its native 48 kHz sample rate.

Is this something to be worried about? Is the resampling going to introduce audible jitter and/or other problems?

 

[beefkabob]

It's conceivable you would notice it, but it's highly unlikely.

 

[ElNino]

Properly implemented asynchronous rate conversion (ASRC) actually helps filter out jitter. The ASRC operates according to its own master clock, and small timing variations in the incoming digital stream actually feed into the math.

Virtually all home theatre receivers from the last two decades use ASRC internally, like the DDRC-24, because operating DSP at a constant rate, clocked by an internal clock, has a lot of implementation advantages.

The only downside of ASRC is that you don't have control over digital filters; you basically get whatever digital filter is being used in the ASRC. This is almost always a conventional sharp linear phase filter (though some ASRCs offer slow roll-off, and Anagram's ASRC was offered with three options). This will make no difference to you if you're used to listening with standard filters. Also, some ASRC implementations don't have sufficient digital headroom to avoid inter-sample clipping on loudly-mastered material. If this is a concern to you, you can lower the source volume by about 3dB, which avoids this in most cases.

 

[oivavoi]

Resampling/sample rate conversion is actually the one domain where digital devices may still sound audibly different, at least according to B&O's Geoff Martin, who tends to know what he's talking about. He wrote several illuminating blog posts on this some time back. @March Audio has previously documented that the minidsp 2x4 HD created artifacts during SRC: https://audiosciencereview.com/forum/index.php?threads/measurements-of-minidsp-2x4hd.2459/page-2
SRC can be done flawlessly, but it isn't done flawlessly in this implementation.

Is it audible? Probably not under normal circumstances. But not perfect at all.

 

[ElNino]

@March Audio has previously documented that the minidsp 2x4 HD created artifacts during SRC: https://audiosciencereview.com/forum/index.php?threads/measurements-of-minidsp-2x4hd.2459/page-2
SRC can be done flawlessly, but it isn't done flawlessly in this implementation.

Those resampling artifacts are -130 dB down. Without ABX testing, I'm very skeptical that those are audible.

 

[daftcombo]

Totally useless if you expect upsampling to be a good thing.
Could be bad if badly done but probably not audible.

 

[oivavoi]

Those resampling artifacts are -130 dB down. Without ABX testing, I'm very skeptical that those are audible.

Valid point. 130 db down obviously can't be heard. My expectation is also that it's inaudible. The more general point though is whether these measurements may be an indication that other things may happen with resampling with complex musical signals that can he heard.

EDIT Here's Geoff Martin going through the issues btw: https://www.tonmeister.ca/wordpress/2018/03/18/typical-errors-in-digital-audio-part-6-aliasing/

 

[ElNino]

EDIT Here's Geoff Martin going through the issues btw: https://www.tonmeister.ca/wordpress/2018/03/18/typical-errors-in-digital-audio-part-6-aliasing/

That article is virtually impossible to parse. He doesn't identify what systems he's showing output from, the bit depth results don't make sense and aren't explained, and he makes a weird comment that "Those “strange noises” – the blobs – are probably artefacts caused by a lossy codec similar to MP3." There's no "codec" involved with ASRC.

 

[oivavoi]

That article is virtually impossible to parse. He doesn't identify what systems he's showing output from, the bit depth results don't make sense and aren't explained, and he makes a weird comment that "Those “strange noises” – the blobs – are probably artefacts caused by a lossy codec similar to MP3." There's no "codec" involved with ASRC.

Yeah, he writes convoluted prose. I generally need to read his stuff two or three times, but then I find that I've learnt a lot. Here's more from him on SRC: https://www.tonmeister.ca/wordpress/2018/08/30/jitter-part-8-3-sampling-rate-conversion/

 

[ofrappier]

https://www.audiosciencereview.com/.../minidsp-ddrc-24-resampling-good-or-bad.9674/