Sound quality limitations of Raspberry Pi + I2S DACs

skypickle · December 30, 2016, 9:27pm

thank you for posting that image but I do not completely understand what the hardware underlies each graph
RPi I2S + ES9023 DAC
BBB I2S + ESS9023
USB-I2S-2+ ESS9023
USB-I2S-1+ESS9023

and what is the difference between USB-I2S-2+ ESS9023 and USB-I2S-1+ESS9023?

allo · December 30, 2016, 10:29pm

None…they share the same databus

santanacorreia · January 1, 2017, 4:31pm

mictester:

We’re talking £25 devices here guys - they will never match a £10k Linn streamer, but for the small investment it’ll sound much much better than a USB DAC and make you smile knowing that you can spend the remainder of the £10k on content, nice wine and holidays.

You’re partially right - with a reasonable DAC (not necessarily a laboratory-quality one) and I²S connection, it’s indistinguishable fron a £10k Linn with most source material! Anyone who tells you anything else is just deluded (and desperately trying to justify his squandered £9,950!). The limiting issues are the housing of the DAC - it should be screened to prevent the analogue end of it picking up noise - and the power supply - don’t dream of using any kind of SMPSU for your DAC!

Just for fun, I recently A - B blind tested a Raspberry Pi / 9023 DAC (homebrew) against a £4k streamer (I won’t embarrass the manufacturer) and no audiophile, record producer, engineer or musician who tried the test could tell one from the other. This conclusively proves two things:

The manufacturers of high-end, high-priced hi-fi are full of BS and they’re just selling a “brand name” rather than anything particularly clever or well-made

The Raspberry Pi is a wonderful little device (if a little under-powered in these days of 4GHz processors)!

Hi mictester,

What do you mean exactly by homebrew?

DilanRoster · January 11, 2017, 11:03am

I think these limitations can make sound worse, nevertheless, thanks for sharing!

alpuy · January 18, 2017, 2:41pm

I saw that there were problems with the jitter and the 24 bits that can be solved with an external USB DAC.

Will i have any problem if i use a rpi shield with an optical output and connect it to the optical input of an integrated amplifier (Marantz 6005)? Does the jitter/24 bits problem still occur or as it is all digital, there is no problem?

Thanks

sangchodecuba · February 12, 2017, 9:54pm

Well for me any Raspberry Pi I2S DAC sound the same! so I just want to go for a cheap option for the Zero as I want to build a bunch of internet Radio on the cheap.
I’ve seen this one on on amazon UK 9£ (with tax and shipment) with shipment is it any good? or any cheaper options?

http://www.raspiaudio.com
https://www.amazon.co.uk/Audio-shield-for-Raspberry-PI/dp/B00MDW602K?SubscriptionId=0ENGV10E9K9QDNSJ5C82&tag=&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B00MDW602K

thanks

volumio · February 12, 2017, 10:00pm

1- The PI indeed can output 24-bit sound via I2S
2- Yes, I2S is a jitter-prone interface. That’s why Reclockers such as the Kali are so effective in improving sound quality on Rasperry PI.

santanacorreia · February 13, 2017, 1:08pm

Aren t there DACs for the Pi that include a reclocker?

volumio · February 13, 2017, 2:36pm

No, I2S DACs normally include a clock (which can be of different quality).
Allo is about to release a new DAC that will include a really good clock (a little less precise than Kali, but they are nuances).
Reclockers are meant to be separate devices

sangchodecuba · February 16, 2017, 5:34am

An update, I received yeserday the yellow RaspiAudio dac http://www.raspiaudio.com for my Raspberry Pi Zero, it arrived via Amazon in a small minimalist zip bag.
it is working well, sound is loud and clear (I tested with a flac file), easy install and cheap (I paid 9£ with tax and shipment).
I guess there are more complex Dac out there but if you need cheap and small I can recommand it.

ThorstoneS · February 24, 2020, 9:03am

Hi,

Apologies for reviving an old thread, but this seems to be the most appropriate thread for my questions.

I am currently running a Pi 2B with the IQAudio Pi-DigiAmp+ HAT driving a pair of DALI Spektor 2s.

I am very happy with the sound so far, but am just upgrading this system (Allo BOSS + Volt).

After a bit of research into the jitter matter can I assume that:

The RPi is limited by the clock quality and the speed (19.2MHz).
The clock speed can be converted to 48kHz via integer division and thus 48kHz should only depend on the quality of the clock.
For 44.1kHz the nearest integer division will give 41.138kHz, which is 0.087% faster than 44.1kHz and thus each cycle is 19ns too short.

Based on that I assume that

a) Playback of 44.1kHz will be 0.087% faster than normal (i.e. about 3 seconds per hour)

b) Jitter is still only dependent on the quality of the clock (19ns jitter would be terrible, so I assume that a) applies).

and finally:

c) Both of these issues should be resolved with the Boss DAC?

Am I missing something? Since the slave DACs don’t seem to have a PLL/clock I assume that they will simply accept the 44.138kHz as 44.1kHz and convert to analogue based on that clock?

Thanks for the help.
T

Charly · February 25, 2020, 12:12am

You are right about limitations of i2S master on RPI, It is not the best I2S master, but not the worst either.Tough if you use boards that are I2S masters and use RPI as slave you can get very good sound that is limited only used clocks, DAC and it’s added components. Of course you will be limited by maximum supported clock and formats supported by driver. I made for myself some DAC’s (based on PCM1792 and ES9028 piggybacked on WM8804) that use this approach and I am very happy with them. In this configuration I can use HIFIBerry Digi+ Pro driver and not worry about Linux stuff. I Like this approach much more opposite to reclockers or SRC’s.

skikirkwood · February 25, 2020, 2:31am

ThorstoneS:

michelangelo:

1- The PI indeed can output 24-bit sound via I2S
2- Yes, I2S is a jitter-prone interface. That’s why Reclockers such as the Kali are so effective in improving sound quality on Rasperry PI.

Hi,

Apologies for reviving an old thread, but this seems to be the most appropriate thread for my questions.

I am currently running a Pi 2B with the IQAudio Pi-DigiAmp+ HAT driving a pair of DALI Spektor 2s.

I am very happy with the sound so far, but am just upgrading this system (Allo BOSS + Volt).

After a bit of research into the jitter matter can I assume that:

The RPi is limited by the clock quality and the speed (19.2MHz).

The clock speed can be converted to 48kHz via integer division and thus 48kHz should only depend on the quality of the clock.

For 44.1kHz the nearest integer division will give 41.138kHz, which is 0.087% faster than 44.1kHz and thus each cycle is 19ns too short.

Based on that I assume that

a) Playback of 44.1kHz will be 0.087% faster than normal (i.e. about 3 seconds per hour)

b) Jitter is still only dependent on the quality of the clock (19ns jitter would be terrible, so I assume that a) applies).

and finally:

c) Both of these issues should be resolved with the Boss DAC?

Am I missing something? Since the slave DACs don’t seem to have a PLL/clock I assume that they will simply accept the 44.138kHz as 44.1kHz and convert to analogue based on that clock?

Thanks for the help.
T

An old post by Archimago from several years ago, but even then jitter wasn’t an issue wih popular I2S DAC’s on Raspberry Pis:

archimago.blogspot.com/2016/10/m … berry.html

I have an Allo Boss on one of my Pi’s and the sound is great.

Charly · February 25, 2020, 7:39am

Allo Boss is also A solution that uses its own clocks and is I2S master - so no RPi clock problems there. PCM5122 chip that it uses is good enough in most cases, it needs very few external components that simplifies design. Hifiberry dac+ pro uses similar design.

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