First off, I’m ashamed to admit that I had this little gem in my possession for about 2 years before I finally got the chance to put it through its paces.
After all, it’s just a s/pdif output device for a Raspberry Pi, right? I mean, it’s just s/pdif, how good could it be?
It turns out it can be pretty damned good! But I’m getting ahead of myself.. Let’s start at the beginning.
The DigiOne is a HAT compatible with most if not all RPis and supported by most if not all audio distributions. It is intended to be plugged-in directly on top of the RPi, with no need for an isolator HAT. Plus, it is designed to be powered by the RPi via the GPIO header, so no need (or provision) for an external power source.
The DigiOne utilizes a WM8805 to convert the RPi’s I2S signal into s/pdif. The WM8805 is run in master mode, so as to minimize jitter due to the RPi’s problematic I2S clocking scheme. The WM8805 is clocked by the same oscillators that are used to reclock the s/pdif signal.
The WM8805’s s/pdif output goes through an Si8641 150MHz galvanic isolator and is passed to the “clean” side of the board.
There the signal is reclocked by a high quality flip-flop clocked by high quality NDK oscillators (housed inside a metal box, used for shielding against EMI/RFI). There exist two oscillators, one for the 44.1K family and one for the 48K family of sampling rates. The output of the oscillators is put through NB3L553s for buffering and isolation.
The entire isolated part of the board is powered by a DC-to-DC converter that offers galvanic isolation. Following this converter there exist a large number of LDO regulators and filter components. An LT3042 regulator is used to power one of the most critical parts of the circuit: the flip-flops that do the final reclocking.
So, very solid engineering all around. But how well does it sound?
The answer is, surprisingly well for the money.
My RPi stack included an RPi 3 with the DigiOne, powered by Salas’ new L-Adapter power supply and running Archphile. The music was coming from my NAS. No audiophile ethernet switches were employed. 😛
Pitted against that I had my Logitech Squeezebox Touch running the EDO plugin for up to 192K s/pdif from its coax output and my relatively pricey Pioneer DV-LX50 Universal Player (using its coax s/pdif output).
The music used was Dire Straits’ SACD album (having selected its CD (and not SACD) layer) which was also accurately ripped to my NAS.
Output from the s/pdif transports went into an AK4118-based s/pdif receiver of my own design which in turn feeds my dual mono AK4493 DAC. The DAC’s output goes through a Salas DCG3 preamp into my Hypex amp.
First up was the Pioneer. It had been a while since I had listened to it through its s/pdif output so I was in for a bit of a shock. Its output sounded coarse, strained, tiring. For a moment I thought that it was due to the SACD’s mastering (the CD layers of SACDs are rumored to be mastered intentionally bad so as to give the impression that the SACD layers sound even better than they actually do), but that changed when I switched to the Squeezebox. Things got noticeably better, actually listenable. Not exactly close to what I had been accustomed to using the Squeezebox’s USB port, but closer.
Then I switched to the DigiOne. Wow! All of the “coldness” of the music was gone, the stage gained depth and width, the music became more detailed and lifelike. This was definitely a step up.
I would dare say that this s/pdif setup came in fact close in SQ to my USB setup. This was a very pleasant surprise.
Now I need to do some A-B testing between the DigiOne and the USB output of the RPi. So to-be-continued..
Not much free time these days so updates have been slow.. but I have a lot of interesting stuff cooking in the back burner.
One of them is an audio grade RPi.
Essentially it will be a Compute Module 3 on a mainboard loaded with ultra low noise linear power supplies and some necessary peripherals.
The idea came to me quite some time ago but it wasn’t until last November that I decided to actually go ahead with it.
The proof-of-concept PCBs for the mainboard were done by December.
It appears that even the PoC board, with average quality power supplies, has a cleaner I2S output compared to a standard RPi3 powered by an equivalent linear power supply:
Audio grade Pi:
The next part was the PoC board for the USB Hub & Ethernet controller. That took a bit more time and a 4-layer PCB with numerous 0402 sized components but it too ended up just fine (with the exception of a bad RJ45 footprint..).
So now I have a fully functioning set of boards with average quality power supplies that already performs better than my Squeezebox Touch as a USB transport.
Next step is to design a single board integrating all of the components plus ultra high quality power supplies.
The new DAC features improved clocking (making use of the new “audio grade” “SDA” oscillators from NDK), improved powering scheme (including the addition of a USB type C port for dedicated external power as well as a new layout), and improved filtering capacitors in the output stage.
In order to do a fair comparison, I had to keep all external parameters the same. That meant using two identical Raspberry Pi 3 boards, running the same distribution (Archphile), with same settings, powered from separate but identical power supplies, using the same audio cables, into 2 inputs of my preamp.
Both of the DACs had run for several hours (or even days..) as a “burn-in period”.
Power was delivered through a couple of identical custom-made USB power-only cables and data came in from a file server located several rooms away, through a single ethernet switch.
Control was through Archphile’s ympd web-based MPD client.
I sync’ed the playback of the RPis as best as I could and I set about switching between the two DACs by selecting either one or the other input in my preamp. The volume needed no adjustment – the two DACs output the same signal amplitude (not measured but fairly certain..).
I used a small number of test tracks, representative of both high quality recordings as well as contemporary pop music.
After some considerate going back and forth, I came to a conclusion. The new Boss 1.2 is a definitive improvement on the original Boss. The differences are not night-and-day, but they are there.
The 1.2 manages to have better bass extension, without sacrificing control. It also does a better job of placing the instruments in space, while also managing to sound more realistic – the vocals sound more real, the acoustic guitar sounds more like an actual guitar, and so on.
All of these “symptoms” are classic signs of less jitter being present in the system. So Allo.com’s choice of new audio-grade oscillators and the changes they made to the power supplies have paid off.
Good job keeping the title of “best VFM DAC HAT”. 🙂
Pretty much everyone agrees on this one, still, it took me a while to get on the bandwagon. Probably because I am not using an RPi as my main transport..
In order to test this I needed a proper linear power supply, capable of outputting at least one “real” amp at 5V. It would also have to be as low noise as possible. After some searching I ended up picking the TPS7A4501 for the job. Since its output voltage is adjustable, it would also come in handy for various projects. So I designed a PCB that would do a proper job of “hosting” the regulators along with the necessary rectification and filtering stages and had a bunch of them made.
I also ordered a proper custom-made toroidal transformer, one that would have 5 secondary windings, each of them outputting 6VAC at 1.5A and one sixth winding outputting 3V at 2A. The end game would be to replace all of the RPi’s on-board switching regulators with linear ones.
But for starters I’d just power the RPi with 5V via its USB port. Here are a couple of RPi 3s being powered by my linear supplies. This setup would be used to compare the Allo.com original Boss with its new “v1.2” version. More on that in another post.
Power draw on the linear power supply was measured to be at about 500mA @ 5V.
My “reference” 5V SMPS is this one:
It’s an old but beefy switching mode power supply from an old HP tablet. It’s specc’ed at 5.3V @ 2A.
In order to be as impartial as possible, I took the setup to a friend’s house and had him and a couple of other friends audition the RPi powered either from the SMPS or by my linear power supply.
In both cases, the RPi was running Archphile and was connected to my upgraded-with-ES9028Pro-and-Mercury-Buffalo III DAC via USB.
The difference between the two power supplies was immediately obvious. It was like with the SMPS we had an at-best mediocre source – DAC combination, while with the linear power supply the setup became “proper”, it sounded “in-place” among my friend’s high performing system. The sound stage became better defined, the detail level went up, overall the presentation was more realistic. In other words, it was like the jitter of the system went down, but perhaps the noise levels in the system also decreased.
In other words, IMHO no serious audiophile should be powering his RPi by a run-of-the-mill 5V SMPS, even if he is using it as “just a USB transport”.
Back in September Allo.com had sent me their Piano 2.1 DAC along with their Kali reclocker, but I didn’t have any other DAC HATs to compare it to and it wouldn’t be fair to it to compare it to my Soekris or my Buffalo III DACs. This changed this week, when they sent me their new Boss DAC and by happy coincidence I also had the chance to spend a few days with the Mamboberry LS DAC+.
It was showdown time.
But before I get to the interesting stuff, a few words about the technology used in RPi DAC HATs.
An RPi DAC HAT is fed audio using what is called an I2S protocol. I2S was designed for transferring audio between ICs located on the same PCB, but audiophiles have somewhat stretched its capabilities by using it to transfer audio data between PCBs and some times even between stereo components. It is considered the best, most accurate way to transfer audio data, provided that the I2S signals are properly generated. The RPi has a well-known and documented problem generating proper I2S signals. The problem has remained the same, even though the RPi is now at its 4th generation.
Right now, there exist two ways to deal with this problem:
1) Use some kind of FIFO buffer and reclocker in order to regenerate the I2S signals. Examples of such FIFO reclockers are Ian’s FIFO and allo.com’s Kali. The RPi is configured to output a standard I2S signal and then it’s the job of the FIFO buffer to “fix-up” this signal. The resulting I2S signal is of very high quality, since the FIFO buffers utilize very high quality oscillators and power supplies.
2) Run the DAC in what is called Master Mode. Let’s talk a little more about that.
There are two modes of operation for I2S compatible chips. In case of DAC chips:
Slave mode: The DAC receives all of the I2S signals (BCLK, LRCK and DATA) from the RPi. It is susceptible to jitter since the RPi’s I2S output is problematic.
Master mode: The DAC uses its on-board oscillators to generate the BCLK and LRCK signals, it then sends these signals back to the RPi which uses them to clock its DATA output. This way the RPi does not need to use its own clock, which is problematic for audio use. The end result is an I2S signal of reasonable quality.
Note that not all DAC chips can operate in either of the two modes. Most widespread is the Slave mode, in fact practically all DAC chips support it. The Master mode is supported by a small percentage of DAC chips, like the PCM5xxx series by Texas Instruments or the new ESS DACs (like the ES9038Pro). Well known DAC chips that do not support Master mode include the older ESS chips (ES9018, ES9018K2M, ES9023, etc) and the Asahi Kasei DACs (AK4490, AK4495, AK4497, etc.).
With that out of the way, lets see our contestants.
The Mamboberry LS DAC+ is a moderately priced (54.90€) ES9023 based DAC designed to run in slave mode to the RPi. It is considered one of the better sounding HAT DACs out there.
It has an on-board high quality oscillator (by Fox) running at 50MHz (this essentially means that the 9023 is running at asynchronous mode, that is it is resampling all incoming PCM signals), very good quality LDO regulators and passive components.
It may be powered either through the RPi or by an external (preferably linear) power supply. Officially the ES9023 supports sampling rates up to 192KHz but unofficially it goes up to 384KHz / 32bit. It doesn’t really require special software support on the RPi, you just set it for “generic I2S output”.
The Allo.com BOSS DAC is a somewhat pricier (~70€) master mode DAC.
It is based on the PCM5122 DAC, powered by a top-quality LT3042 LDO regulator utilizing DC filtering by very high quality capacitors (including a 330.000uF supercapacitor!).
Clocking is done by a pair of NDK extremely low jitter and low phase noise oscillators (45.1584 & 49.1520 MHz), powered by their dedicated LDO regulator. Their output is buffered by an NB3L553 clock fanout buffer IC which further reduces the jitter.
Sampling rates up to 384KHz / 32bits are officially supported. It’s powered through the RPi, but it has an “Optional 5V battery power in connector” for future use. I suspect that this connector can also be used to power the Boss, but a certain resistor will need to be removed to isolate this power from the RPi. This DAC needs a special driver, since it needs to set the RPi in slave mode and also communicate with it via I2C to set operating parameters and utilize the PCM5122’s hardware volume control. When the DAC is receiving data from the RPi, the indicator “LED1” lights up.
The Allo.com Piano 2.1 Hi-Fi DAC is another moderately priced (~55€) slave mode DAC, based on PCM5142 DACs. Notice the plural.
On board this HAT we have two DAC chips that output a total of 4 channels. Each of the DAC chips also contains a DSP core, capable of doing equalization, filtering or other functions. These DSPs can be configured using TI’s PurePath software, but that is not a trivial task. The distributions that include built-in support for the Piano 2.1 come with a pre-built set of filters, capable of essentially configuring the DAC in 2.1 mode so that it can be used with one or two subwoofers. The analog sections of the DAC chips are powered by two top-quality LT3042 LDO regulators.
There exists no on-board oscillator, since the DACs are running in slave mode. Sampling rates up to 384KHz / 32bits are officially supported. Power is supplied by the RPi. As you can imagine, this DAC also needs a special driver, since it needs to set up the filters in each of the DAC chips plus to utilize the PCM5142s’ hardware volume controls.
A word about audio distributions
There are many audio-oriented distributions available, such as Archphile, RoonAudio, Moode and Volumio. In order to do a fair comparison, I opted to use the same distribution for all tests. The logical choice was Volumio, since it includes proper support for all of our DAC HATs.
Volumio is very easy to install and is very responsive in my RPi3. No complaints whatsoever.
The idea was to test the DACs in their default operating mode, that is with no mods and no exotic power supplies. When testing without Kali, the RPi3 & DAC were powered by a 5V 2A SMPS I had lying around from an old tablet. It’s a pretty high quality unit, made by HP. Still, at the end of the day it’s just a wall-wart SMPS.
When testing with Kali, I powered the RPi3 with the same SMPS plus I used an 7805-based linear power supply for the Kali & DAC (jumper on Kali was removed to isolate its power from the RPi’s). Again, nothing exotic. Just a relatively low power (1A max) linear power supply.
After I had an initial listen to all of the DACs in pretty much every possible combination, like “plain DAC” or “DAC with Kali” (where applicable of course) and drawn my conclusions, I thought I would take the system “on tour” to a couple of my friends and their superior sound systems. By doing this I was getting a second and third opinion. So, friend#1’s system is a full-blown MBL installation costing upwards of six figures. His main DAC & transport’s cost is in the 20K range. Friend#2’s system is a more DIY affair, consisting of big (and I mean BIG) Magnepan speakers, diy solid state power amp (several hundred watts per channel, many of them in class A, it makes a lot more than a ding in his power bill), diy preamp, Sony XA50ES modified CD player plus (on loan from me) a Soekris DAM1021 DAC.
At friend#1’s, we used an SPL meter to equalize the volume levels between all of the DACs. We listened to 3 specific tracks. At friend#2’s, we also listened to the same 2 or 3 tracks on all of the DAC combinations but didn’t take much care of level matching. The observations of my two friends were practically the same, so I won’t distinguish between them.
We started with just the RPi with Mamboberry LS. The sound was OK, not nearly what you would call “hi-end”, but considering the DAC’s cost it was more than satisfactory.
We then moved on to the RPi with the Boss. The improvement in audio quality was more than apparent. The soundstage became better defined, the instruments more clear, the bass just.. more, but in a good way.
Next up was the Mamboberry aided by Kali. Kali did more than just fix up the I2S signal – it also provided clean power to the Mamboberry. Now the Mamboberry began to show its teeth. This combination gave a more clear result than the Boss DAC, like the music became even more life-like. The bass did not have the same authority, but overall the combination Mamboberry & Kali definitely sounded superior to the Boss.
Finally, we teamed the Piano 2.1 to the Kali. The Piano was configured in stereo mode, since there were no subwoofers present. This combination gave the best overall result, giving a more “analog”, musical result. Its sound was the most smooth of all of the combinations, while at the same time it was the most life-like. You could say that it was the least fatiguing of the bunch.
After we were done comparing the HAT DACs, we thought we should listen to our “proper” DACs, just to put things into perspective. To no surprise, both my friend#1’s DAC and my Soekris properly cleaned the floor with the HAT DACs and it’s a good thing that they did – otherwise we would have felt pretty dumb having wasted so much money on so-called “proper” DACs while we could have got the same result with these DAC HATs. Phew.
So, the end result is not really surprising. The more money you spend, the better sound you will get. No giant killers here. But regarding value-for-money, I think that the Boss DAC claims the prize.
We’ve heard all that hi-end mumbo-jumbo before, right?
Problem is, this time the gadget actually works. I didn’t believe it either until yesterday, when I was invited to a friend’s house. Also invited were a couple of friends and this little guy:
It was accompanied by its designer, Vasilis of Ideon Audio. Mind you, this is the same Vasilis that is behind the Mamboberry DACs.
I’ve known Vasilis for the better part of 10 years now. We have exchanged some pretty sharp remarks over the years, in regards to our shared hobby, but this time I must admit that he’s really on to something.
The 3R contains a TI chip with a low jitter clock and a bunch of LDOs. It is powered by an SMPS wall-wart (rumor has it that it works even better powered by a linear power supply).
What happens is that the 3R is detected by the PC as a USB device which essentially passes-through the DAC that it is connected to. It works like a USB hub – it’s an active device but it needs no drivers.
It works its magic by regenerating the USB signal using its own low jitter clock and low noise LDO regulators.
The end result is that the DAC manages to literally extract more detail from the music stream, be it from a PC or a Mac based transfort. It doesn’t matter what your DAC is – it will make a positive difference. We tested it with a Buffalo III dac (Amanero as receiver with no isolation) and with an Aune S16 (XMOS receiver, isolation, and FPGA doing FIFO and reclocking). In all cases, introducing the 3R into the chain made for better bass definition, more resolution, and better sound stage.
This is some upsetting stuff. This made me feel the same way I felt a few weeks back when I was auditioning Salas’ system and I could hear audible differences when we changed Foobar’s buffer length from 400ms to 1000ms. This shouldn’t happen, but it does.
I don’t know.. Perhaps this is a sign that I should switch to another hobby.
In conclusion, here is a picture of Darth Vader on the 3R:
If you have a half-decent USB dac and you’re serious about audio reproduction (a.k.a. you’ve already invested in a good sound system) you should get one. Not Darth Vader, the 3R.
In Part 1 we installed Armbian on our Orange Pi One (or Lite) and set it up on our local network. At this point, all our work can be done on any PC that is on our network, via SSH connection (putty etc.).
Enabling I2S output
First order of business is enabling the Pi’s I2S output. To do that, we need to edit what is called a FEX file. This FEX file (script.fex) is essentially a hardware configuration file for the Pi. For example, if we wanted to enable or disable a serial port at the hardware level, we would edit this FEX file.
The problem is, this FEX file exists in binary form in our file system so in order to edit it, we need to convert it to a text file. To do that we use the bin2fex command.
So, step by step:
Log into Pi as root and type:
bin2fex script.bin script.fex
Nano is a relatively user friendly editor for Linux, I use it for all my text editing.
Look for twi1. Change it to this:
Then look for pcm0. Change it to this:
Once we are done editing the file, we hit Ctrl-X and choose to save the file before exiting.
Then we need to convert the .fex file back to .bin. We type:
fex2bin script.fex script.bin
and we reboot.
We confirm that we have a new sound device called snddaudio by typing in aplay –l :
Network Share configuration
Now that our I2S output is enabled, we need to give our Pi access to our music. I prefer to store my music in a Synology NAS so I need to configure a network mount on the Pi.
We start by creating a mount point for our share. That can be any empty folder. I choose to mount my shares in mnt/nas-samba. Let’s create that:
Then we install the package cifs-utils:
apt-get install cifs-utils
Now we get to the actual mounting of the share:
For my setup, I add this line: //192.168.0.32/Music /mnt/nas-samba cifs username=,password=,ro,iocharset=utf8,nolock,noauto,x-systemd.automount,x-systemd.device-timeout=10,sec=ntlm,rsize=8048,wsize=8096
This tells our Pi to mount the share //192.168.0.32/Music to the folder that we created above using the credentials that I have supplied. You will need to customize this command to your own network environment.
After a reboot we go to our mount point and have a look inside:
To confirm that the share has been mounted we can use the df -h command, as can be seen above.
This will take a while, since MPD has a bunch of dependencies that will also be downloaded and installed.
Once the installation is finished, we will need to configure it. To do that, we edit mpd.conf:
We need to do three things:
1) Set our music directory to /mnt/nas-samba:
2) Change network binding to “any”:
3) Change the “audio” setting to select our I2S audio output:
We put in this:
name "I2S DAC"
# mixer_device "default" # optional
# mixer_control "PCM" # optional
# mixer_index "0" # optional
This configuration creates an ALSA device called “I2S DAC” that utilizes the Pi’s I2S output. It up-samples all files to 32bits (don’t worry, it doesn’t deteriorate the SQ in any way. It just pads with zeroes when necessary) in order to make this setup compatible with my Buffalo III. Also, it enables software volume control. You can disable it by commenting out the relevant line.
Once we are done, we save the file and quit nano. We then restart MPD to apply the changes:
systemctl restart mpd
MPD Clients Installation
Once MPD is installed, we will need a “human friendly” way of interfacing with it.
In other words, we will need to install what is called a “client”. There exist all kinds of clients, from command line based ones, to web-based environments, to apps for smartphones and tablets. In my setup I install two clients, a command-line based one (mainly for testing purposes) and a web-based one for more general use.
To install the classic command line client “mpc” we enter:
apt-get install mpc
That should take almost no time.
Now that we have at least a basic client installed, is a good time to check that MPD is actually working. To do that, I usually do this:
mpc add http://netradio.live24.gr/886radio
What these commands do is:
1) Add my favorite internet radio station to MPD’s playlist
2) Start playback
3) Check that playback has indeed started.
If it all went well, you should see something like this:
If you have already connected an I2S DAC, you should be hearing music. This means that your MPD is functioning, so the hard part is done.
If by chance you’re looking for the Orange Pi One / Lite’s I2S pinout, you’re in luck. Here it is:
At this point you have a choice to make. You can either install an app on your smartphone or tablet and get things done that way, or you can install a web-based “rich” client. I like rich clients, so after a brief internet search I came across RompR.
The people behind RompR have written a pretty comprehensive installation guide. All of the necessary info is there, for all platforms. But, since this post has to do specifically with the Orange Pi, I’ll give you a customized version of the installation guide. This should take you about 10 minutes. Let’s start.
First we’ll download and install all of the necessary packages:
They are single board computers (SBCs) much like the Raspberry Pi, but they will set you back just over 10€ plus shipping. That is just insane value.
They offer a quad core ARM Cortex A7 processor running at 1.2GHz, 512MBs of DDR3 RAM, an Ethernet port (One) or WiFi (Lite), a couple of USB ports, an HDMI port, etc.
They run Linux (of course..) or Android.
I needed an inexpensive way to listen to internet radio while I was in my kitchen. I already had a low end system set up, consisting of a couple of bookshelf speakers, a power amp and a Squeezebox Classic, but I had to move the Squeezebox to another room so I needed something to take its place. The Orange Pi One plus an inexpensive I2S DAC would fit the bill very nicely.
The idea was to load a stable Linux distribution onto the One and set-up MPD to work with my el-cheapo I2S DAC.
The steps that I am about to describe took me about a day to figure out and needless to say, I learned a lot in the process.
Let’s start with the basics.
You will need an Orange Pi board, a proper power supply (USB power will not work – I suggest that you buy a bundle of Orange Pi + Power Supply from aliexpress), a 4GB (or bigger) Micro SD card and an I2S compatible DAC that does not require a MCLK signal (like an ES9023-based one with an on-board oscillator). For the initial setup you will also need a monitor with an HDMI (or DVI with an adapter) input plus a USB keyboard. If you are a bit more hardcore, instead of using a monitor & keyboard, you can just use the Pi’s serial port with a serial to USB module and putty.
The first step is getting our hands on a Linux distribution that will be a good fit to our application. You might notice that there exist a number of official One distributions: http://www.orangepi.org/downloadresources/ The Lite is not so lucky.
The general consensus is that most of them have issues. The best choice appears to be the Armbian distribution:
Armbian is based on Debian and is very similar to Raspbian (also based on Debian), so if you’ve used Raspbian on a Raspberry Pi you will feel right at home.
For our application we are going to go with the Jessie Server image. We need to put this image file on a Micro SD card. I use Rufus.
We insert the SD card in the Orange Pi, we connect our monitor, keyboard, ethernet and power the thing up.
After about 15-20 seconds, the green power-on LED will start flashing and soon after you will see the initial login screen:
The default credentials are root/1234.
You need to change the default password to one of your liking. Following that, your Pi will request that you create a new user account:
Once you’ve done that, you will be asked whether you would like to change your Pi’s resolution to match your screen’s:
In my case, my lab’s monitor has a 1920×1200 resolution, so I chose to go with the highest supported resolution, so I typed:
h3disp -m 10
One reboot to go and we will be done with the initial setup.
At this point I should point out that I routinely log in to my Orange Pis as root. I can see some of you cringing but I don’t care. Security is way low on my list of concerns when it comes to my SBCs that I use for music playback. If you use a normal user (and not root) on your SBC, all you have to do is prefix the commands that I use with the command “sudo”.
So now, if you have a Pi One and it is connected to your network, it should have acquired an IP from your DHCP server. If you have a Pi Lite, you will need to do some extra work to get it to connect to your WiFi network.
To configure the Lite’s WiFi adapter you need to edit the interfaces file:
If you would like your Pi to get an IP automatically from a DHCP server, you do this:
Again, replace your_ssid and your_password with your actual SSID and password. Note that it doesn’t matter if you are using WPA or WPA2, the script is the same.
When you are done, save the file (Ctrl-X and then Yes a couple of times) and reboot your Lite.
When the system comes back up log in and check if you are connected to your access point by typing:
You should see something like this:
1: lo: mtu 16436 qdisc noqueue state UNKNOWN group default
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: tunl0: mtu 1480 qdisc noop state DOWN group default
link/ipip 0.0.0.0 brd 0.0.0.0
3: wlan0: mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 00:e0:4c:99:f8:3b brd ff:ff:ff:ff:ff:ff
inet 192.168.0.200/24 brd 192.168.0.255 scope global wlan0
inet6 fe80::2e0:4cff:fe99:f83b/64 scope link
valid_lft forever preferred_lft forever
You should see that your wlan0 interface now has an IP.
Congrats, your Lite now has network access. This means that you can put away the monitor & keyboard that you used to configure your Lite and continue on your desktop / laptop by logging in through SSH (using Putty or any other SSH compatible terminal program).
Logging in from Putty, we come to this prompt:
Next, we have to do a full update & upgrade of our installed packages:
The update part should go pretty fast, but the upgrade part will take some time, depending largely on your SD card’s performance.
This concludes Part 1 (a.k.a. “the boring part”). Part 2 will include enabling the Orange Pi’s I2S output and setting up MPD.
Back in August an interesting thread was started on diyaudio.com.
It described a FIFO buffer and reclocker, aimed at SBCs and more specifically the RPi.
Its name was Kali.
The FIFO board would be able to “fix up” the RPi’s problematic I2S output so as to improve the sound quality of the used DAC.
As the discussion progressed, more interesting details came to light.
Kali was basically an FPGA design with on-board RAM, high quality clocks and flip-flops. It would buffer the DATA stream in RAM (about 0.7 seconds of audio) and it would then reclock it using flip-flops outside of the FPGA. The clocks used for the reclocking would be high quality NDK units sporting extremely low phase noise.
It would be powered by a 5V/3A power supply and would supply filtered power to the RPi (or not, selectable by a jumper) as well to the DAC that would sit on top of Kali.
It would have a claimed 3ps of jitter, which is an impressive feat for any I2S source.
It would provide a high quality MCLK output from a U.FL jack underneath the board.
The board’s general availability was scheduled for the end of August, and its price would be in the neighbourhood of $70.
At around mid August cdsgames offered to give away a number of units to diyaudio members for testing. I took him up on his offer and he was kind enough to send me one (along with a Piano 2.1 DAC board, but that’s for another post).
Fast forward to mid-September, when I received a package from India. In it was Kali and Piano 2.1 (more about that in another post).
On the left side of the board we can see the DC IN jacks (barrel and pin header), plus a couple of inductors that help with filtering the power lines. On the top left there is a jumper that controls whether Kali will supply power to the RPi or not. The Kali lists as minimum requirement a 5V/3A power supply. However, Kali itself will consume only about 100mA. The rest of the power is intended for the RPi and the DAC board. Note that Kali is designed so that it powers the RPi and not the other way around.
To the right we have the two NDK clocks, one for each one of the two “families” of sampling rates.
The Kali comes in two versions. One with clocks at 22/24MHz, capable of supporting sampling rates up to 192KHz, and one with 44/48MHz clocks, going up to 384KHz.
Note that there are two footprints available for the clocks so that a curious (and somewhat experienced) DIYer can also try out clocks with different footprints, like for example Crystek units. If you choose to go that way, keep in mind that you will also need to change 2 capacitors from 0.01uF to 0.1uF.
At the top of the board we have the usual 2×20 header that reproduces the RPi’s GPIO pins. There is one notable exception – Kali does not supply 3.3V at the relevant pin, so if your DAC needs to take 3.3V from that pin it will not work (more on that later).
Note that even though Kali has a JTAG header, the manufacturer currently does not support firmware upgrades. That’s understandable.. JTAG is not for consumer use and the manufacturer has to protect his IP..
At the lower end of the board we have an array of LEDs indicating the sampling rate of the incoming signal, along with the status of the buffer (Empty / Full / Lock) and the selected oscillator.
At the bottom of the board there is a U.FL socket that outputs Kali’s MCLK.
So, we have an RPi, we have Kali, now what we need is a DAC. Kali will put a few restrictions on your DAC choices. Your DAC will have to run as “slave” to the RPi, that is it will have to take its BCLK from the RPi and not the other way around. Examples of such DACs include for example virtually all of the DACs based on ES9023 chips. DACs that are designed to run as masters (in order to battle the RPi’s legendary jitter problem), such as the Hifiberry Dac+ Pro & Digi+ will not work, at least not without some extra work.
Plus, like I mentioned earlier, Kali does not supply 3.3V on its top 40-pin header, so if your DAC requires that voltage you’ll need to find a way to supply it externally.
Straying a bit from the DAC HATs, Kali will have no problem feeding pretty much any DAC that accepts standard I2S, like for example a TPA Buffalo DAC.
As a matter of fact, in my system Kali did a remarkable job of improving my RPi’s I2S output. The difference was obvious immediately. My RPi went from being a “net streamer quality” source to giving my Amanero a run for its money. Remarkable.
I am not talking about differences in bass or treble or tonality. It is like Kali manages to extract more music content from the data files. It revealed details that were there but were not audible. The music became more “real”. Imagine going from SD TV to HDTV. And that with the same 44.1K/16bit source material.
This improvement is not apparent only on expensive gear either. My first tests were done on my workbench with my RPi feeding an $8 9023-based DAC and listening through my headphones.
Even with this setup, Kali made a significant improvement to the sound. The $8 DAC went from sounding like an $8 DAC to performing at least decently. It was an obvious improvement.
So I can not imagine a scenario in which the Kali will not make an audible improvement to the sound.
Note that the first batch of Kalis (the ones that were sent to reviewers and a small number of units that were actually sold) had a bug that caused 16bit audio to have its channels reversed (and some more weird stuff happening with their I2S output resulting in somewhat degraded sound quality), but according to allo.com all effected units have been exchanged with fixed ones plus the ones that are shipping now to customers come with a fixed version of the firmware.
Even if for some reason you come by an affected unit, all you have to do is tell your RPi to output 32bit audio. That will fix everything.
I’d like to thank Ioan (cdsgames at diyaudio.com) for sending me the remarkable Kali. It will for sure become a permanent part of my audio chain.