Ultimate Audio Playback => Chatter and forum related stuff => Topic started by: fralippo on July 02, 2019, 11:43:37 am

Title: Digital attenuator
Post by: fralippo on July 02, 2019, 11:43:37 am
I don't use any digital attenuation in my system, although I know that the one used in XXHe is very good, I wonder if it'd be a good idea for the upcoming V2.11 to consider the option to disable it (not only blocking it to zero, but fully bypassing the code).

Maybe most users aren't interested in that and anyway, for the highest possible SQ, that should be carefully avoided.

What do you think?

Title: Re: Digital attenuator
Post by: PeterSt on July 04, 2019, 06:43:17 pm
No votes to be seen anywhere...  :(
But not such a good idea either. The preamp - or any analog attenuation means is still the most detrimental to good SQ. So it would not be a wise thing to leave it out, or to have another parameter/setting for that matter.  :)


Title: Re: Digital attenuator
Post by: numlog on July 04, 2019, 09:09:47 pm
On a similar note I have digital 32 bit attenuator in my DAC (its common now), to me this seems quite transparent. I have tried setting it to 0 and using XXHE for attenuator but I dont think is really bypassing the DAC attenuator and XXHE seems more transparent at 0dB than the DAC, so kind of stuck with that.

That isnt much to design a whole feature around but felt it was worth mentioning

Title: Re: Digital attenuator
Post by: numlog on July 04, 2019, 09:48:58 pm
After posting that I thought about hows it been nearly a year since comparing XXHE attenuator to the DAC attenuator. An innumerable amount has changed and improved since so I had to recheck that... it took a few tracks to notice that XXHE does seem like it does better job attenuating with DAC set to -0.
 XXHE seems warmer and softer in how it influences the sound but remains more transparent, the DAC attenuator imparts a nasty sharpness and hollowness onto the sound.

Title: Re: Digital attenuator
Post by: PeterSt on July 07, 2019, 09:52:54 am
Allow me to take the opportunity to elaborate a bit on that ...

XXHighEnd's volume is "lossless" which means that no rounding takes place anywhere and that from an attenuated "file" the original can be recreated (hence the term Lossless). This is by guarantee / inherently so.

A DAC with digital attenuation under its hood, for 99% sure has to make use of a means which is highly detrimental to the "bit perfect"ness of the audio stream let alone it would be close to lossless which every normal means of attenuattion in software is. Thus, e.g. the Windows volume would be close to lossless which in the end is not lossless at all. And this means "inconsistency" in the rendering, Our brain recognizes that things are not right and the music is perceived as less good and unnatural.

Back to the in-DAC digital attenuation - unless the volume is controlled by in-chip voltage reference (which virtually is non-existent although is exists in some D/A chips (not said that the design uses it), this is so poor that a differential (balanced) setup is not even allowed because of the high THD implied (harder to explain but envision that plus and minus voltage of the signal can differ 0.5 dB in not-linear fashion, that creating the (huge) THD per (L/R) channel. 
Besides this, when single ended (like RCA) there is always the 0.5 difference per (L/R) channel, and that varying throughout the music. And oh, since the 0.5 dB is the accuracy of the chips doing this, it may coincidentally add up to 1dB (or 0dB).

XXHighEnd has just the one and only means to attenuate digitally in a justified fashion. It is also the only software doing it like this and it includes digital gain as well, if the headroom for it is present.


Title: Re: Digital attenuator
Post by: numlog on July 09, 2019, 05:48:07 pm
I had some notion that the recent DAC chips could do this ''bit perfect'' control like XXHE internally, but not a single article mentions the word ''lossless'' when describing the DAC volume control, if thats not a good enough hint.