RPi3 Allo BOSS and SoX settings

[hifinet]

Maybe this isn't news to most, but it was for me. Just wanted to share my experiences with MoOde 6.4 and SoX settings. My best sound quality on my system to date.

Hardware: RPi3B+ Allo BOSS v1.2 rev 5 with single Aukey 20000 mAh battery USB-C

Software: MoOde 6.4.0 2019-11-24

Sox resampling 32/384 Very high quality multithreading yes

Prior to this I was using SoX 32/352.8, trying to keep integer operations for 16/44.1. 32/284 makes a big difference, and I think it's because the DAC chip oversampling filter is bypassed. Setting  says "NOTE: Filter is bypassed if sample rate is 384 kHz."

[inthemoode]

Sox resampling 32/384 Very high quality multithreading yes

Prior to this I was using SoX 32/352.8, trying to keep integer operations for 16/44.1. 32/284 makes a big difference, and I think it's because the DAC chip oversampling filter is bypassed. Setting  says "NOTE: Filter is bypassed if sample rate is 384 kHz."

Interesting.  I too was told to keep it at 352.8 kHz.  I am using a Topping D10.  Thinking I might switch it to 384 again.  Where did you see that note about the filter being bypassed?  Doco on your DAC I presume?

[Tim Curtis]

The Oversampling Filter (OSF) bypass option at 384 kHz only applies to audio devices based on Burr Brown PCM5xxx DAC chips for example Allo Boss DAC. The topping device is based on ESS Sabre ES9018K2M DAC chip.

You can read about the OSF bypass specification in the chip data sheet. See Page 21.
http://www.ti.com/lit/ds/symlink/pcm5121.pdf

The question is whether resampling all the music at the host to a fixed rate (384K) is "better" than letting the PCM5xxx chip do its thing with native rates. I suppose that as with all audio tweaks there will be different opinions :-)

-Tim

[hifinet]

The question is whether resampling all the music at the host to a fixed rate (384K) is "better" than letting the PCM5xxx chip do its thing with native rates. I suppose that as with all audio tweaks there will be different opinions :-)

-Tim

In my opinion, the SoX resampling sounds better than the internal TI 5122 resampling. Significantly better. I am posting this to suggest that if you have the 5122 (e.g. HiFiBerry, etc.), give SoX 32/384 a try, and see what you think. I would like to hear your opinions.

I mostly listen to classical. I think choral has been some of the most difficult music to reproduce. SoX 32/384 has really cleaned up the sound of choral.

[inthemoode]

The Oversampling Filter (OSF) bypass option at 384 kHz only applies to audio devices based on Burr Brown PCM5xxx DAC chips for example Allo Boss DAC. The topping device is based on ESS Sabre ES9018K2M DAC chip.

You can read about the OSF bypass specification in the chip data sheet. See Page 21.
http://www.ti.com/lit/ds/symlink/pcm5121.pdf

The question is whether resampling all the music at the host to a fixed rate (384K) is "better" than letting the PCM5xxx chip do its thing with native rates. I suppose that as with all audio tweaks there will be different opinions :-)

-Tim

Thanks for the info.

As for the resampling, I do believe that Sox does it better.  Resampling to 384/32 sounds a LOT better than 44.1/16 fed straight to the Topping D10.  The rpi, especially the rpi 4 ,  seems to have no trouble handing the processing either.   This is a great feature.

[inthemoode]

I mostly listen to classical. I think choral has been some of the most difficult music to reproduce. SoX 32/384 has really cleaned up the sound of choral.

Fully agree.  Many systems fall down trying to reproduce a large choir in full gallop.

[philrandal]

The question is whether resampling all the music at the host to a fixed rate (384K) is "better" than letting the PCM5xxx chip do its thing with native rates. I suppose that as with all audio tweaks there will be different opinions :-)

-Tim

In my opinion, the SoX resampling sounds better than the internal TI 5122 resampling. Significantly better. I am posting this to suggest that if you have the 5122 (e.g. HiFiBerry, etc.), give SoX 32/384 a try, and see what you think. I would like to hear your opinions.

I mostly listen to classical. I think choral has been some of the most difficult music to reproduce. SoX 32/384 has really cleaned up the sound of choral.

I wonder if it sounds better because SoX doesn't suffer from the TI 5122's intersample overload distortion mentioned in the comments here - http://archimago.blogspot.com/2016/10/me...m5122.html

Or maybe not! A later post by Archimago says he uses a 4dB attenuation in Sox to avoid overload distortion:

http://archimago.blogspot.com/2018/01/mu...lters.html

Cheers,

Phil

[hifinet]

Or maybe not!  A later post by Archimago says he uses a 4dB attenuation in Sox to avoid overload distortion:

     Can -4dB attenuation be programmed into SoX in Moode? I would like to try that. I have noticed increased distortion with higher output CDs. For example, BBC CDs are low output, and sound very clean. One troublesome CD is the Classic Records CD of RCA Venice. I would like to drop it by -3dB and see if it cleans up the string sound on that CD. I suppose I could recode the 16/44.1 file with -3dB filter for the few problem CDs I have. Plan to try that.

[Tim Curtis]

MPD does not expose that SoX option. It only has bit depth, sample rate, channels and quality.

If you want to attenuate volume you could try the Parametric EQ. Disable the 4 frequency bands and set Master Gain to -4dB.

[rh2018]

Can Alsamixer card gain be set to persist through bootup by adding a command to a config file or start-up script?

As mentioned in Phil's post, The 4db attenuation when upsampling with SOX is important to minimise overmodulation.

The screen grab is from my Pi4 to HiFiBerry's new USB to I2S interface card and HiFiBerry Digi plus.
So far working very well with SoX set for 32/384 and Alsamixer at -4db as shown. 

Richard

https://www.hifiberry.com/docs/data-shee...et-usbi2s/[url=https://www.hifiberry.com/docs/data-sheets/datasheet-usbi2s/][/url]