Avoiding intersample clipping on digital vs analog volume controlled DACs

[flaviowolff]

Hello,
I've read a bit about intersample clipping and I understand that one may avoid it by reducing the software playback volume, normalizing the volume on the player or reducing overall windows volume control (when available).

Two questions come to mind:
1) In the case of a DAC with digital volume control, is the clipping avoidable by adjusting it's own volume, like when adjusting a MiniDSP's output master volume? (In the case of the MiniDSP, there is also an input gain adjustment available. Adjusting that instead of the output seems to make more sense, but I'm not sure).

2) In the case of DACs with analog volume control, like the Dragonfly Black, is it right to assume that any hardware volume adjustment is helpless to avoid intersample clipping, since it occurs in the digital domain? IIRC, the windows volume adjustment operates communicates with the DFB's analog volume control, so it's not digital volume control. If that's the case, software adjustment would be mandatory.

Thank you!

 

[L5730]

In reverse order:

2) A hardware volume knob controlling analogue output level would do absolutely nothing for ISPs as they are a digital thing.
Hardware volume knobs controlling an electronic circuit which adjusts the output level is the same as above.

1) See how the DAC chip handles it's digital audio data. There are often papers that can be read, even if not all of the info is around.
I'd prefer to just feed a lower digital signal (at 24 or 32 bit depth) from software to the DAC driver. Yes, you lose some SNR but really, it's moot for the most part.
If there are hardware controls over the digital input signal, then you just really need to see how they are implemented.

This might be interesting to you:
https://www.audiosciencereview.com/forum/index.php?threads/intersample-over-test.3730/

 

[solderdude]

As L5730 mentioned.

The only way to avoid intersample overs on DAC's that do not have headroom left (some actually do have some headroom) is to lower the digital volume. I suggest about -6dB as most DAC's perform optimally there and there won't be many intersample overs that exceed +6dB.
The dragonfly does not have headroom above 0dB.

 

[pos]

(...) like when adjusting a MiniDSP's output master volume? (In the case of the MiniDSP, there is also an input gain adjustment available. Adjusting that instead of the output seems to make more sense, but I'm not sure).

As you mention the miniDSP, be aware that intersample overs will also happen with ASRC processes which takes place before the input volume stage of such devices. In that situation it is better to lower the volume right a the source, and make sure you output it with the highest available bitdepth.

As a complement, aside from DACs and ASRCs, overs can also happen with EQ and filters, even if none of them exceed 0dB, because of phase alterations that change the way the spectral content sums in the time domain.

IMHO applying volume control at the source is the way to go with modern high SNR DACs.

 

[flaviowolff]

As you mention the miniDSP, be aware that intersample overs will also happen with ASRC processes which takes place before the input volume stage of such devices. In that situation it is better to lower the volume right a the source, and make sure you output it with the highest available bitdepth.

As a complement, aside from DACs and ASRCs, overs can also happen with EQ and filters, even if none of them exceed 0dB, because of phase alterations that change the way the spectral content sums in the time domain.

IMHO applying volume control at the source is the way to go with modern high SNR DACs.

I see. It can get complicated in a case such as the Chromecast audio, in which you can only control the output volume (digital volume control), not the source volume, AFAIK. Tidal and Spotify won't enable volume normaliser when using the CCA. The only option coming to mind is using Roon's CCA integration.

 

[bennetng]

To avoid digital clipping, digital volume control should be used as early as possible, i.e. within the playback software.

Digital volume controls can behave differently even within the digital domain. The link L5370 mentioned has two kinds of clipping tests.

This test is for intersample clipping:
https://www.audiosciencereview.com/...ation-audible-intersample-clipping-test.2231/

This test is for fixed point data conversion induced clipping:
https://www.audiosciencereview.com/...ftware-volume-control.5922/page-2#post-172865

Make sure you can pass these two tests before sending audio data to the outside world.

That said, external hardware volume controls, digital or not, can still be used as master volume control for convenience and safety.

 

[yodog]

So to volume control at the source (my bluesound node 2i) or at a later point in time (at my topping e30 DAC being fed via digital rca from the bluesound)?


which will give better sound quality? And would adding a passive analog preamp have any benefits in this setup?