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hifiberry digi+ digital interpolation filter - nosferatu_cat - 09-27-2018

I've been using a pi 3B+ with a hifiberry digi+ running into an SMSL class D amp for my bedroom system.  Soprano instruments, especially strings, didn't sound right to me.  They definitely sound different from my living room system. Recalling digital filter settings from my Cayin music player, I decided to try  magic.  I fooled around (empirical rules of course) with the digital interpolation filter settings.  The default is FIR interpolation with de-emphasis.  Ringing-less low latency sounds best to me.  The ragged attack on the soprano instruments seems moderated and the sound is similar to my living room system now.  Is this voodoo, or is it a reasonable tweak?  I'm using mostly FLAC files so I wonder about the word "interpolation."


RE: hifiberry digi+ digital interpolation filter - DRONE7 - 09-27-2018

Quote: I fooled around (empirical rules of course) with the digital interpolation filter settings.

These settings....where ?


RE: hifiberry digi+ digital interpolation filter - nosferatu_cat - 09-28-2018

(09-27-2018, 10:17 PM)DRONE7 Wrote:
Quote: I fooled around (empirical rules of course) with the digital interpolation filter settings.

These settings....where ?

On the Audio Configuration menu click on the button labeled "Chip Device Settings."


RE: hifiberry digi+ digital interpolation filter - Tim Curtis - 09-28-2018

There are no Chip Options for Hifiberry Digi+ or Digi+ Pro.

Its only certain DAC's that offer Chip Options.


RE: hifiberry digi+ digital interpolation filter - kit1cat - 09-30-2018

Here's an interesting article on the various filter settings.

http://archimago.blogspot.com/2016/10/measurements-hifiberry-dac-pro-pcm5122.html


RE: hifiberry digi+ digital interpolation filter - nosferatu_cat - 10-06-2018

(09-28-2018, 05:23 PM)Tim Curtis Wrote: There are no Chip Options for Hifiberry Digi+ or Digi+ Pro.

Its only certain DAC's that offer Chip Options.

Thanks.  I suspected it was voodoo.  The odd thing is that the options are available.


RE: hifiberry digi+ digital interpolation filter - nosferatu_cat - 10-06-2018

Yesterday I substituted a Hifiberry Dac+ for the Digi+.  I'm using an SMSL AD18 amp, which has an SPDIF input.  When I went back to the line input the SQ improved.  Since the problem was "birdies" with the SPDIF input I'm wondering if it's digital artifacts.  That means at least 2 potential sources, the Hifiberry board or the DAC in the amp. When I feel ambitious I'll try hooking up the Hifiberry Digi+ setup to my living room receiver to see what it's like.  I liked the convenience of using the SPDIF input because it freed up the only line input.  I guess one solution is spending more money.   Big Grin

BTW, I tried Volumio and Rune (forgive me) with the Digi+.  Volumio sounded marginally better and Rune about the same.  This makes me think that if software is a problem it's not the main one.  Using the board with the line out is a significant improvement over any of the SPDIF setups.  I do prefer MOODE over the other two.  It offers a lot more flexibility and a superior UI.  I'm enough of a command line person so that the setup for a new rev doesn't bother me.


RE: hifiberry digi+ digital interpolation filter - rhizomusicosmos - 10-07-2018

The "birdies" you are hearing may be aliasing in the sub 20kHz (i.e. audible) band. As an experiment, you could try resampling everything with SoX to the maximum sample rate your setup supports and see if that eliminates any artefacts.

The DAC+ Pro I have is more prone to aliasing than other DACs I own but most of the artefacts are above the audible band, though I did hear aliasing on tone sweeps when the tones themselves became inaudible. I have the normal Hifiberry Digi but haven't tested it.

I notice the SMSL AD18 has USB input. Have you tried connecting it to the RPi that way? This would bypass the Hifiberry and you could see if that sounds any better.


RE: hifiberry digi+ digital interpolation filter - rhizomusicosmos - 10-09-2018

(10-06-2018, 04:26 PM)nosferatu_cat Wrote:
(09-28-2018, 05:23 PM)Tim Curtis Wrote: There are no Chip Options for Hifiberry Digi+ or Digi+ Pro.

Its only certain DAC's that offer Chip Options.

Thanks.  I suspected it was voodoo.  The odd thing is that the options are available.

This is odd, as the Digi+ Pro should not have these options because it doesn't use a digital interpolation filter -- it is not a DAC, it is an I2S to SPDIF converter.

Are you sure you're not confusing it with the filter options available for the Hifiberry DAC+?


RE: hifiberry digi+ digital interpolation filter - nosferatu_cat - 10-10-2018

(10-09-2018, 12:40 AM)rhizomusicosmos Wrote:
(10-06-2018, 04:26 PM)No, oddly enough, the options are there and available.  I realize that the help text says that they\re for the  Burr Brown TI chip and Tim confirms that they shouldn't be there.   I've made a few programming mistakes like that, accidentally leaving in a menu option that shouldn't have been available.  The good news is that it has to be harmless.  nosferatu_cat Wrote:
(09-28-2018, 05:23 PM)Tim Curtis Wrote: There are no Chip Options for Hifiberry Digi+ or Digi+ Pro.

Its only certain DAC's that offer Chip Options.

Thanks.  I suspected it was voodoo.  The odd thing is that the options are available.

This is odd, as the Digi+ Pro should not have these options because it doesn't use a digital interpolation filter -- it is not a DAC, it is an I2S to SPDIF converter.

Are you sure you're not confusing it with the filter options available for the Hifiberry DAC+?