I have received a fairly enormous selection of Raspberry Pi audio cards from four suppliers (Pimoroni, IQaudIO, HiFiBerry and JustBoom).
It’s a bewildering array of DACs and AMPs, which allow you to turn your Pi into a HiFi system capable of playing sound files up to 32-bit 384 kHz, in theory. In reality 24-bit audio is about the highest quality you can buy and it’s questionable whether human ears can resolve any higher anyway.
Anyway – I’m not planning to turn into a raving audiophile (anyone seen my gold speaker leads?) so here’s the stuff I have been sent. You can click the image for a larger (1500px) version if you want a closer look.
Today, We Look at DACs
But today’s focus is on the three standard DAC (Digital to Analog Converter) boards. It’s mostly a video review, but there will be some other explanations, facts and photos after the video…
To begin with, I decided to compare the three Hat format DACs…
- IQaudIO PiDAC+
- JustBoom DAC Hat
- HiFiBerry DAC+ Standard
I quickly discovered that all three are based around the same chip – the Texas Instruments PCM5122 “Burr Brown 112/106-dB Audio Stereo DAC With 32-bit, 384-kHz PCM Interface”. “PCM512x can essentially drive up to 10 products in parallel (LCD TV, DVDR, AV receivers, and so forth).” So it’s clearly a very capable chip. A single chip costs about £5 from RS, but obviously buying at scale for manufacture brings that down a bit. Either way, you can be sure that’s the most expensive component on the board.
Appearance & Layout
IQaudIO PiDAC+ is black and gold – I can’t fault that, since it’s what I use for my RasPiO range. There’s very few tracks on the underside of the board – the ones that are there are very short. It’s almost 100% ground plane, which is good design practice for an audio board. The layout also makes good use of symmetry. It’s quite a full board with a lot of componentry to place. It has 73 components (excluding connectors).
Both IQaudIO PiDAC+ and JustBoom DAC Hat have adhered strictly to the HAT specification by including camera and DSI screen slots. That probably made things a bit harder in terms of placement and routing. I can’t blame HiFiBerry at all for omitting the slots. It gives you more space to play with.
JustBoom DAC Hat is a funky red colour, which matches the name. It has 60 components excluding connectors. The layout is the other way round from the PiDAC+ with respect to connectors. The two boards both use the same headphone amp chip. Particularly innovative on this DAC is the use of spring connectors instead of headers for connecting the amplifier board (J1 as shown in the video). This enables the board stack to take up less volume, which is a nice design feature.
HiFiBerry DAC+ Standard is a conventional green (default) PCB colour and has a lot less componentry (27) on it than the other two. This is partly due to the absence of the headphone amp circuit seen on the other two boards. But also there’s no interconnect for an amplifer because there isn’t an amplifier to go with it. The underside is almost 100% ground plane as well, with just 5 short tracks visble.
All three boards sounded fantastic listening (with headphones) to Haydn Trumpet Concerto in Bb played by Tine Helseth.
Starting with a fully updated/upgraded version of the latest Raspbian, this is how long it took to follow the intructions provided by the suppliers and get a sound out of the board on mplayer (including mplayer install)…
IQaudIO PiDAC+ 13 minutes 33 seconds
JustBoom DAC Hat about 13-14 minutes if you discount the time it took to get help
HiFiBerry DAC+ about 13-14 minutes if you discount the time I lost misreading the instructions.
Overall User Experience
Within a couple of minutes I found the IQAudio documentation
There’s an explanation of each board in their line-up and installation instructions. They also offer several pre-configured SD card images. I preferred to use vanilla Raspbian, so followed the instructions from a fully updated upgraded (25 Nov) clean installation of the latest Raspbian version (September 2016).
It took me 13 minutes 33 seconds to get a sound out of it. A few minutes of that was mplayer installation. :)
The sound quality is absolutely superb. There is just the teeniest trace of a ‘click’ at the start and finish of playing a track in mplayer in the command line.
I listened to Haydn’s Trumpet Concerto in E flat, played by Tine Thing Helseth. I was planning only to listen to movement 1, but I enjoyed it so much, I listened to all three.
It was a lovely experience with good instructions and everything worked exactly as it should. Very satisfying with no frustrations.
Justboom DAC Hat
It took me a few minutes to find that there weren’t yet any software configuration instructions. There are going to be guides, but they are not yet done. Happily there isn’t much config to do. Quite soon it should be completely plug and play due to the Hat EEPROM “doing its thing”, but I still had to comment out one line in config.txt to disable the default onboard sound of the Pi.
I did get quick attention and support through twitter DMs on a Saturday evening, which mitigated the frustration somewhat. Had it not been for that, the setup time would have been similar to the IQaudIO PiDAC+.
The Justboom DAC Hat is almost plug and play, and it’s likely that it soon will be completely plug and play, which is Aaron’s goal.
HiFiBerry DAC+ Standard
First off I had to find, purchase and solder on a headphone socket before I could do my comparative test with the headphones. HiFiBerry do, however, offer a variant with headphone socket instead of RCA phono. This delayed me getting started, but was not a difficult thing.
I followed the instructions here but had no luck with my soldered on headphone jack. So I tried using the phono connectors with a pre-amp of my own (Art-tech USB dual pre) with also no joy. At 26:43 in I decided to have a break. Frustration mounting.
Then I took another look at the instructions and realised that I had made a mistake and installed the wrong dtoverlay. But you can easily understand how and why I did…
I was looking for DAC+ and saw it in the first entry. But anyway – I’m not going to count that against them in time. If I had managed to negotiate through the instructions correctly, it would have been about 13 minutes time to first sound output – pretty much the same as the others.
The sound quality was excellent and the lack of a headphone amp didn’t seem to adversely affect anything.
The IQaudIO PiDAC+ has the best documentation by a country mile. Following that gave me a completely easy, trouble-free experience. (It also helped teach me a few things which were useful using the other cards.)
The JustBoom DAC Hat is slightly more plug and play. The EEPROM gets the dtoverlay loaded up without the need for a config.txt line addition. Once it’s fully plug-and-play it’ll be excellent. They still have a long way to go with documentation though.
The HiFiBerry DAC+ is the cheapest board by far. It has a lot less components on but it sounded really good to me anyway. If you’re price-sensitive it may be the one for you.
So there you go. I’ll cover amps in another part and Pi Zero DACs in another part. Both of those will probably be after Christmas.