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Review and Measurements of HifiBerry DAC+ Pro XLR

amirm

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#1
This is a review and detailed measurements of the HifiBerry DAC+ Pro XLR. It was kindly purchased by a member and drop shipped to me. It costs USD $59.90 which is quite cheap for balanced output. I think the cheapest stand-alone DAC with XLR output that I have tested was US $150 (Massdrop Grace SDAC Balanced). Even including the cost of the Raspberry Pi, you are less than $100 here and you get streaming functionality to boot.

Here is what it looks like:

HIFIBERRY DAC+ PRO XLR Audio review.jpg

The giant XLR connectors dwarf the rest of the board. They are sturdy though and had no trouble supporting the weight of my XLR cables although the rest of the unit as you can imagine, is quite unstable. You would need to weigh it down somehow to keep it from following the XLR cable to the ground or wherever it goes. :)

The Pro designation in the name means that it has dual clock oscillators instead of using the poor quality clock that the Pi generates (they are the two rectangular parts near center right). XLR means exactly that. Instead of the RCA jacks in regular HifiBerry DAC+ Pro which I just reviewed, you get balanced XLR outputs. This is nice because it sharply reduces the possibility of nasty ground loops which are hard to deal with it when they bite you.

The heart of the device is the TI PCM5242 DAC chip with balanced outputs. Its rated distortion and noise is 94 dB (SINAD). Let's see if the actual implementation gets there.

DAC Audio Measurements
Here is our dashboard view:
HIFIBERRY DAC+ PRO XLR Audio Measurements.png


Output voltage of 4.2 volts is slightly higher than nominal value of 4 volts we like to see which is fine. Alas, total SINAD (signal over noise and distortion) falls short of TI spec of 94 dB. But maybe TI means distortion alone in which case, we are there with third harmonic peeking its head to that level in the FFT graph above.

The measured SINAD places the XLR version just behind the RCA version:

Best Audio Dacs Measured and Reviewed 2019.png


That is not a significant factor though. Compared to Grace SDAC, we have a shortfall of 5 to 6 dB.

Jitter performance is good and similar to RCA version:
HIFIBERRY DAC+ PRO XLR Jitter Audio Measurements.png


Multitone performance is again similar but perhaps a hair worse:
HIFIBERRY DAC+ PRO XLR Multitone Audio Measurements.png


Filter response is identical:
HIFIBERRY DAC+ PRO XLR White Noise Filter Response Audio Measurements.png


Conclusions
The HifiBerry DAC+ Pro XLR has performance that is essentially identical to RCA version of it. You pay $20 more which to me is a reasonable insurance to pay against ground loops. Sadly the inclusion of XLR doesn't bring better fidelity.

Overall, based on low cost of the solution I am going to recommend the HififBerry DAC+ Pro XLR even though I wished it had better measured performance.

------------
As always, questions, comments, recommendations, etc. are welcome.

Have to do a bunch of system upgrades and that is costing money. So appreciate any donations toward that using:

https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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#2
That lower stopband attenuation initially looked to me like overload at internal digital path. Quite a few DAC chips has suffers from that, when it's being fed by high level white noise. Sometimes just small attenuation of test signal by 2-3 dB will significantly improve attenuation of its reconstruction filter. Similarly such lack of internal headroom is indicated by clipped overshoots of reconstructed square wave at DAC output, especially with minimum phase filters.

But in this case, the measured response apparently corresponds to TI chip datasheet figures.
http://www.ti.com/lit/ds/symlink/pcm5121.pdf (p. 9) So DAC performs exactly as initialized.
However it also supports longer FIR filter with higher latency and steepness, rated to 100dB of SB attenuation. Chip at this HAT is in software mode and initialized as via I2C bus from RPi by respective Linux kernel module.
Just quickly looking to few relevant pieces of code..
https://github.com/raspberrypi/linu...486cc335224882/sound/soc/codecs/pcm512x.h#L62 (register is there)
https://github.com/raspberrypi/linux/blob/rpi-4.19.y/sound/soc/bcm/hifiberry_dacplus.c#L145 (we can add modification to init there)

So for anyone bit geeky and interested, it could be quite easy to mod by adding of line to setup respective register values and recompile the module.

I had RCA version of the HAT, but gave it as a gift to my ex GF as part of the "Spotify Box", so can't really try to do that ATM. Getting that box back for playing would definitely involve some unrelated talking ;)

Anyway, thanks Amir for the measurements.

Michal
 

Joachim Herbert

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#3
Now this might be a challenge for @IVX. A high performance shield for the raspberry pi. While there are offerings they seem to be based on lowend chips. Just imagine a competently designed board based on one of the newer ess chips plus custom housing. Plus spdif out, just in case. Streamer of my dreams.
 

somebodyelse

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#4
Now this might be a challenge for @IVX. A high performance shield for the raspberry pi. While there are offerings they seem to be based on lowend chips. Just imagine a competently designed board based on one of the newer ess chips plus custom housing. Plus spdif out, just in case. Streamer of my dreams.
The Katana and ApplePi are still in the top quarter of all DACs tested. I don't think they have the SPDIF output though.
 
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#6
@amirm How did you power the DAC during the test? Through the PI or directly to the DAC?
I have experienced differences in the sound depending on where I connect, and with what power supply (Cheap noisy 5V power vs a "more expensive" IFI iPower supply) .
 
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#8
I can understand you @Joachim Herbert . I also like ICs better. There are really good measuring devices on ASR, that just use one or two Operational Amp IC per output.

And another thing, what I don't like from their website Allos website:
Katana gives you the choice between 2 stages:
"Pure THD+N":
At -112.9 Thd+n 1Khz A weighted, this stage will satisfy those that want no distortion in music. Board sounds very good.
"Sound quality" stage: 100.5 Thd+n a weighted 1Khz, this board has been optimized for sound quality. While sacrificing some thd+n numbers we found the subjective experience to be, in a word, closer to analog sound.
"Sound quality stage" smells like...

But they show the THD+N and with Pure stage it is a really good DAC for a RPi, as measurements on ASR show.
 
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amirm

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#9
@amirm How did you power the DAC during the test? Through the PI or directly to the DAC?
I have experienced differences in the sound depending on where I connect, and with what power supply (Cheap noisy 5V power vs a "more expensive" IFI iPower supply) .
Through Pi. Since measurements match chip company data with lab supplies it should not make a difference.
 

somebodyelse

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#10
But in this case, the measured response apparently corresponds to TI chip datasheet figures.
http://www.ti.com/lit/ds/symlink/pcm5121.pdf (p. 9) So DAC performs exactly as initialized.
However it also supports longer FIR filter with higher latency and steepness, rated to 100dB of SB attenuation. Chip at this HAT is in software mode and initialized as via I2C bus from RPi by respective Linux kernel module.
Just quickly looking to few relevant pieces of code..
https://github.com/raspberrypi/linux/blob/7ee8d72eeb56b85aaad25f368b48https://github.com/raspberrypi/linux/blob/7ee8d72eeb56b85aaad25f368b486cc335224882/sound/soc/codecs/pcm512x.c6cc335224882/sound/soc/codecs/pcm512x.h#L62 (register is there)
https://github.com/raspberrypi/linux/blob/rpi-4.19.y/sound/soc/bcm/hifiberry_dacplus.c#L145 (we can add modification to init there)
It may already be exposed - it looks like there are controls defined for most of the adjustable things in the base pcm512x driver, so unless it's overridden elsewhere (mixer quirk for hifiberry?) you can probably already change it at runtime.
https://github.com/raspberrypi/linu...86cc335224882/sound/soc/codecs/pcm512x.c#L463
 

Jimster480

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#11
I don't see the purpose in this product considering the poor performance... I guess if you are just driving speakers with it for outside this can work fine? Otherwise Its not competitive in any manner when you can spend a bit more for so much better performance.
 
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#12
I don't see the purpose in this product considering the poor performance... I guess if you are just driving speakers with it for outside this can work fine? Otherwise Its not competitive in any manner when you can spend a bit more for so much better performance.
It's one of very few Raspberry Pi HAT DACs with XLR output, so it's kind of unique.
 

Xulonn

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#14
Heat - even lower heat over time - reduces the lifespan of electronic components. Enclosing electronics in plastic - an insulator - when heat-dispersing metal options are available doesn't make sense to me. So when I recently purchased an RPi3+ and HiFiBerry DAC+ for showing weekly movies at our little local community theater, I ordered the steel case. (The HiFiBerry replaced a Wetek Hub Android box re-flashed to run boot to LibreElec/Kodi, but it only had one USB port and no audio out (no internal DAC) which required the addition of an outboard HDMI "audio extractor" box.

The HiFiBerry / Raspberry Pi3+ combo with the steel case is one of the best kits I have ever assembled - well designed, well made, and everything fit perfectly. The OSMC OS was easy to install and worked perfectly the first time it booted. After playing a 2-hour movie with video to the projector via HDMI and audio to the sound mixer board/amp, the RPi3+/HiFiBerry unit is barely warm.

The HiFiBerry / RPi3+ has 4 USB ports, and HDMI out which goes to an Optoma projector for our rear-projection screen in a 100 seat community theater. With the HiFiBerry DAC, we get reasonably high-quality audio output. Simple pro audio systems like ours use mostly 1/4" (6.3mm) connectors for speakers and RCA connectors and/or 3.5mm jacks for audio input to the little mixer. The theater's 2.1 channel speaker system consists of a pair of stand-mounted Electrovoice PA monitors with a BIG subwoofer on one side.

I run OSMC on the Raspberry Pi, and it has a much simpler and more elegant minimalist-style interface than the default Kodi interface, which is perfect for my needs. I show movies in 1080p with 2-channel audio, and have not tested the unit with 4K video or multi-channel audio - but I would not expect this simple, basic HTPC box to do well for that level of playback.

For our donation-supported theater and very limited budget, this system works perfectly. For A/V presentations in the theater that are part of our "Tuesday Morning Market" at the center, mics and laptops are used. But for movies, the Raspberry Pi / OSMC box and me using a wireless keyboard to manage the screening while sitting in a front-row seat near the side of the theater where the electronics are located is a perfect setup.

bcp.jpg
 
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