Review and Measurements of Allo Katana and ApplePi Raspberry Pi DACs

[audiobill]

Sorry I was typing on the phone so too brief.

Roon can access networked DACs using either Apple Airplay or Roon's own protocol called RAAT. Volumio which came pre-installed on the Pi that was included on Katana only supports Airplay. Using that, I had no problem playing music using Roon to Volumio and Katana. The issue here was that for measurement purposes I need to have a bit-perfect, 24-bit audio pipeline which airplay does NOT support.

Other Pi OS packages do support RAAT. I just have not had good luck installing them and getting them to work.

They also mentioned DietPi.

 

[Krunok]

Can someone in the USA send Amir a memory card with one of these pre installed on it, it seems his PC must have some special Bill Gates Linux patch on it .

No need for that. Volumio can act as a Roon bridge, all you have to do is type a few commands via CLI and you're done. I sent @amirm list of commands needed to do it yesterday, but no reply. Probably patch blocked it.

 

[Jimster480]

Hello everyone

first a big thx to Amir . I am a fan since he tested the uRendu and seen the extent that some manufacturers go to shade clear test results.

We decided to be diffrent , instead of hiding and arguing , we want the test to speak for themselves. We want to embrace the comunity and be open.

This is our Katana. Above are Amir test results (and we have the same readings)

Now some of you ask about our changes to Katana (Katana 1.2). Look at the above results , roll off is a bit higher than normal and the 88Khz noise...it was audible in one of our test setup.So we changed the filtering...and now roll off is much deeper and the 88Khz is gone. (we removed the R in front of the RC low pass filter)

Please note that jitter (for us) is one of the most important qualities in a DAC

Since we had some time in our hands we also looked at power rails and we decreased the noise on the dual rails feeding the opamp (from 2.7mV to 900uV). One thing we are observing is that THD+N decreased further (Katana 1.2) to (unweighted) from -111 varying to -112.2 (still more testing is required before we make this claim)

So please be patient but we think that our DAC can compete with the best of the best.

So then do you plan to send in the new version to Amir for testing again?

This DAC that was sent to Amir already does very well!

 

[johan]

hi, thank you for your great product, it looks really amazing. I only have two questions, 1, is there any reason why the dynamic range from this test is a little bit lower? 2,why not directly adding the xlr output? It would probably only add 5 bucks while we do not need to solder by ourselves.

I think that DNR of Katana is actually better when comparing apples to apples . You see, DNR depends on output level and Katana has a lower output level . I think that at same level our DNR is better.

XLR connector is too big for the board and we decided against it. Sorry about that.

 

[johan]

So then do you plan to send in the new version to Amir for testing again?

This DAC that was sent to Amir already does very well!

Very soon (10 days)if Amir has the time. Still specs are almost same..not a major change

 

[johan]

Does one perform significantly better than the other?

Nope Katana vs Katana 1.2 measurements are almost same (slight advantage to Katana 1.2 on THD+N)

 

[miero]

@johan On allo web there is a new Isolator model mentioned. Would be on Katana 1.2 a galvanic isolation of I2S & I2C links between DAC and RPi+uC?

 

[Krunok]

Sorry I was typing on the phone so too brief.

Roon can access networked DACs using either Apple Airplay or Roon's own protocol called RAAT. Volumio which came pre-installed on the Pi that was included on Katana only supports Airplay. Using that, I had no problem playing music using Roon to Volumio and Katana. The issue here was that for measurement purposes I need to have a bit-perfect, 24-bit audio pipeline which airplay does NOT support.

Other Pi OS packages do support RAAT. I just have not had good luck installing them and getting them to work.

If you couldn't make Volumio work with Roon you could have use Volumios own bit perfect player that can be accessed via its web interface instead of Airplay.

Btw, these are the commands that install Roon support on Volumio:

sudo apt-get update
sudo apt-get upgrade

sudo apt-get install bzip2

cd /opt
curl -O http://download.roonlabs.com/builds/roonbridge-installer-linuxarmv7hf.sh 4
chmod +x roonbridge-installer-linuxarmv7hf.sh
sudo ./roonbridge-installer-linuxarmv7hf.sh
rm roonbridge-installer-linuxarmv7hf.sh

 

[johan]

@johan On allo web there is a new Isolator model mentioned. Would be on Katana 1.2 a galvanic isolation of I2S & I2C links between DAC and RPi+uC?

Yes thats correct. RPI will be galvanically isolated from Katana stack (i2s i2c). Great efforts were put into DC/DC convertor to be as quiet as possible (using RC snubbers across all switching elements , 4 in total) and using common mode chokes to remove all emi.

Bu using an isolator you have an inherent delay (14ns if I remember correctly) through the barrier and max sample rate will be 32/192Khz

 

[Soniclife]

Here are the IMD test results at 6 pints...

I've heard of beer goggles, but beer analysers are new to me. Always good to be breaking new ground.

 

[johan]

The right solution is a very straightforward. Use external clock(s) to generate I2S bitclock and left-right clock and configure RPi in a slave I2S mode. If you add also a galvanic isolation between RPi and DAC+clocks you will get a perfect solution with an immunity to a jitter and EMI.

Yeap Miero you are absolutley right .( Are you the famous Miero with the BBB driver? ). Katana is a master dac (and RPI is a slave). No one is using the ess dac ic in this configuration even though its the best. (mainly because they have to make it compatible with every inputs).
We tested the THD+N using the isolator but we cannot see a meaningful improvement in the numbers .

 

[helloworld]

I think that DNR of Katana is actually better when comparing apples to apples . You see, DNR depends on output level and Katana has a lower output level . I think that at same level our DNR is better.

XLR connector is too big for the board and we decided against it. Sorry about that.

btw，in the manual, you recommend using 5V3A psu， Can I use 5V2.5A?
Also, @amirm ，is it possible that you measure the THD+N and dynamic perfomance with the xlr connector soldered on the board? I am hoping to see a better performance. Thanks.

 

[johan]

Katana needs about 1.1A at 5V

RPI power depends on model but a 2.5A can be used

XLR output measures slightly worst. You dont have the spave for XLR connectors you will need connectors that are panel mounted.

 

[miero]

Yeap Miero you are absolutley right .( Are you the famous Miero with the BBB driver? ). Katana is a master dac (and RPI is a slave). No one is using the ess dac ic in this configuration even though its the best. (mainly because they have to make it compatible with every inputs).
We tested the THD+N using the isolator but we cannot see a meaningful improvement in the numbers .

Yes, I was doing on the BBB's Botic driver.

Isolation will be more usefull in the real world than on a test bench. For example connect RPi to a TV that is electrical appliance class I (HDMI shield connected to electrical earth/ground) or which is connected to a cable television. And on the other side a single ended outputs of DAC that area also connected to the earth (via amplifier). Yes, it depends on a scenario. Without HDMI connected it is much better. Have you tried to measure it while RPi is connected via Wifi and doing some data transfers?

 

[johan]

Hi Miero

thats an interesting point and I agree that real world test scenarios are more suitable to isolator.

We will take some measurements sometimes next week .

 

[orchardaudio]

For comparison purposes, I ordered the ApplePi DAC which started as a kickstarter by now Orchard Audio. I purchased it through Amazon at $200 plus $5 shipping. Alas, that is an incomplete solution to get this DAC going. If you look at this picture you see that it requires stand-offs and an extra long "stacking header" to mate with the Pi:

The amazon listing and my website both link to clear install instructions as well as stating that the header and standoffs are not included.
The install instructions can be found here:
https://drive.google.com/file/d/1b6Y6fvdK50TgxC3CAdWk2_2lO_vVovy9/view

Interestingly ApplePi does a bit better:

That is well shy of advertised 128 dB however.

Can you please let me know what instrument you are using to perform the measurements? I have verified the 128dB of SNR (A-Weighted) with both an Audio Precision APx515 and ATS-2. Also the 128dB would be for the balanced output, the RCA output will be 125dB.

Here is 24-bit silince A-Weighted (Mini-XLR Ouput 5Vrms is 0dB):

Here is SNR A-Weighted

 

[miero]

@orchardaudio ... @amirm writes "above measurements as always have no weighting" ... can you repeat your measurements without weighting? But it requires to use the same sampling frequency 44100Hz as amirm used, because without weighting those values will not be comparable.

Also I don't think that you measure the same thing as amirm. Notice "Dynamic range - AES17" under his graph.

This measurement was first defined in a standard in Section 9.3 of AES17, under the heading “noise in the presence of signal.” A similar measurement called “dynamic range” is mentioned in IEC61606.

Source: https://www.ap.com/technical-library/more-about-signal-to-noise-ratio-and-dynamic-range/

 

[bennetng]

Here are the IMD test results at 6 pints from -50 dBFS to 0 dBFS in 10 dB increments. The dashed line is the much higher resolution output of Topping DX7s created over USB from my computer. The red is also Topping but now driven by those few steps using Volumio. It kind of, sort of shows the "hump."

Katana and ApplePi show better results across the board and without that hump.

View attachment 14947

The data is pretty coarse though. I would need to add more steps to be definitive.

As it is, it points to something specific to ESS DAC and how Topping buffers its output.

Boy, manual testing is so time consuming!

It seems that the hump at -30dB is gone but there's another hump at -10dB? Would like to see more detailed measurements.

 

[orchardaudio]

@orchardaudio ... @amirm writes "above measurements as always have no weighting" ... can you repeat your measurements without weighting? But it requires to use the same sampling frequency 44100Hz as amirm used, because without weighting those values will not be comparable.

Also I don't think that you measure the same thing as amirm. Notice "Dynamic range - AES17" under his graph.

Source: https://www.ap.com/technical-library/more-about-signal-to-noise-ratio-and-dynamic-range/

@miero Dynamic Range and SNR is not quite the same thing. At this time I cannot repeat the measurement without A-Weighting because I do not have the equipment any more.

 

[orchardaudio]

Let's look at jitter and noise (at 48 kHz):

Here, Katana (in red) is textbook perfect other than a tiny 4 kHz jitter component below -140 dB.

ApplePi on the other hand (in blue) has a lot of spurious noise and jitter sources. Broadening of the "skirt" around our main 12 kHz tone indicates low frequency random jitter (could be a clock issue or noise from the Pi). The higher frequency peaks are likely different timers and clocks running around in the Pi, bleeding into the DAC. Fortunately all of this is either very low in amplitude or masked so not an audible concern. But when you pay $200 for a DAC, you like to see such mistakes avoided.

With the ApplePi Volume-Clocker this jitter should be completely eliminated.