It isn't the bits, it's the hardware


I have been completely vindicated!

Well, at least there is an AES paper that leaves the door open to my observations. As some of you who follow me, and some of you follow me far too closely, I’ve said for a while that the performance of DAC’s over the last ~15 years has gotten remarkably better, specifically, Redbook or CD playback is a lot better than it was in the past, so much so that high resolution music and playback no longer makes the economic sense that it used to.

My belief about why high resolution music sounded better has now completely been altered. I used to believe we needed the data. Over the past couple of decades my thinking has radically and forever been altered. Now I believe WE don’t need the data, the DACs needed it. That is, the problem was not that we needed 30 kHz performance. The problem was always that the DAC chips themselves performed differently at different resolutions. Here is at least some proof supporting this possibility.

Stereophile published a link to a meta analysis of high resolution playback, and while they propose a number of issues and solutions, two things stood out to me, the section on hardware improvement, and the new filters (which is, in my mind, the same topic):



4.2
The question of whether hardware performance factors,possibly unidentified, as a function of sample rate selectively contribute to greater transparency at higher resolutions cannot be entirely eliminated.

Numerous advances of the last 15 years in the design of hardware and processing improve quality at all resolutions. A few, of many, examples: improvements to the modulators used in data conversion affecting timing jitter,bit depths (for headroom), dither availability, noise shaping and noise floors; improved asynchronous sample rate conversion (which involves separate clocks and conversion of rates that are not integer multiples); and improved digital interfaces and networks that isolate computer noise from sensitive DAC clocks, enabling better workstation monitoring as well as computer-based players. Converters currently list dynamic ranges up to∼122 dB (A/D) and 126–130 dB(D/A), which can benefit 24b signals.

Now if I hear "DAC X performs so much better with 192/24 signals!" I don't get excited. I think the DAC is flawed.
erik_squires
In this limited industry somewhat exclusively does upsample mean resample by async sample rate converter (and it was pretty much a made-up term), which most people know, but what they don’t know is that the underlying technology which is pretty much exclusively some form of synchronous oversampling in the form of fractional delay filters, which provides an underlying shift upwards in the spectra from the original sample rate, coupled with a time compensated curve-fit which provides for the final sample rate and provides the jitter attenuation (something not needed with async streaming sources of course). So when claiming advantage of upsampling to a higher frequency, is it the inherent oversampling, the jitter reduction, or the pick of final sample rate, or some combination of?


As Cleeds pointed out, you can’t make a generalization to all cases based on one example.

That Benchmark found that "performance" based on data sheet and some simple performance metrics was better at 24/96 than 24/192 is not at all surprising. At lower speeds, you have less contribution to the output from the switching CMOS switches, less dynamic power (and less glitch energy) contributing to a quieter environment, and even simply more time to settle to the final value. Perhaps in Benchmark’s specific case, decoupling the output frequency from the input also removed sources of synchronous noise. Of course, they are running in 2x mode anyway, so technically the DAC is running close to 192KHz internally, so what exactly does that 96KHz even mean in their argument ... not to mention that it then runs into a much higher rate sigma-delta modulator. Does their product match the data, or does the data match the product ?


However, the items they cited w.r.t the data sheets and their tests, are not guarantees of excellent perceived sonic performance which would trade off high sample rate, system noise, with analog filtering. The article is also 10 years old, so what was best 10 years ago, may have shifted up 2x or more in terms of what was best.

I don’t think you have well made your point, simply because tests have been done with 24/96 native, and 24/96 down-sampled mathematically to 16/44.1 and then upsampled to 24/96 so that the playback path was identical, all that was changed was the information rate.
Now that this thread has gone off the rails, I'd like add on my thought on spinning disks.  If the data was not fully retrieveable, would a DVD work?  Video signals I belive are more critical than audio signals in that we would see errors from the disk, possibly similar to the Compression, micro and macro blocking, banding and posterization seen on streaming video/cable tv.  
No one is saying a DVD or CD won’t work. What I’m saying is the way the system was designed DVDs and CDs and Blu Ray appear to be working 100% but are actually working less than 100%. How much less less than 100% depends on many factors. Its not as if there are “data dropouts” that are audible or visible. It’s more subtle. It’s a subtle degradation of the sound or picture. It’s not the disc per se but how the disc is read. The disc has all the data, the system can’t read/interpret it accurately or completely. Think of it like an 8 cylinder car running on 7 cylinders. It will still run OK.
... if only we had things like dynamometers, or error rate detectors so we would not have to guess if these were issues or not.