So, these ones could be the right USB DAC for your Raspberry Pi

Budget Conscious

Hifimediy Sabre USB DAC 2

This is a dac closely resembling Nwavguy’s ODAC. You should however not expect the same build quality and attention to details. But this has an advantage over it’s famous competitor: it can eventually be fed with an external psu (external PSU will improve dramatically audio quality, not relying on Pi’s polluted DC, and releaving you from buying a good psu for the pi itself). Furthermore it can output Spdif signal via coax, you can use it as a cheap transport. My friends at Tforum report that it’s capable of driving low-impedance headphones, altough a custom headphones amp is commonly suggested.

PROS:
-Cheap                                                                                       NO LONGER AVAILABLE ON EBAY
-Can directly drive headphones
-Spdif Out

Bang for the buck

Schiit Modi DAC

This is the latest dac from the guys from Schiit. For less than 100 bucks you get an async usb receiver (the highly regarded CM6331A) paired with the legendary AK 4396. For sure a really hard to beat combo for that price. This DAC sounds really really good, and it’s design just increases its appeal. RaspyFi is being developed while listening to this dac. Is this enough for you?

PROS:
-Async Receiver
-Features one of audiophile’s favourite DAC
-Excellent performance/price ratio
-Elegant design                                                               Get it on Schiit’s Store

I also reccommend to read the (italian) review by stereo-head.it , is well worth it!

NwAvGuy’s ODAC

Take it as a statement. This DAC set lots of controversies since the beginning of it’s development by the heretical designer NwAvGuy. The ODAC was designed to prove that engineering a really transparent musical device required a careful trial and error approach, debunking some audiophiles myths. It was built to have outstanding measurable specs. I bought it as soon as it came out, fascinated by the phylosofical meaning it had. You know, I’m quite pragmatic and I don’t like the “esoteric” fuzz most designer use to develop their produtcts. This DAC, when it came out, outperformed most highly regarded dac as of S/N ratio, db range and so on. Just math, only objective evaluations (that’s where the name comes, O stands for objective). Well, I love it. But honesltly I have to admit that nowadays you can have something better in that price range, especially with Diy. I dropped it in favour of my Diy XMOS2 + Sabre Dac

PROS:

-It’s engineering is carefully documented
-Sounds really neutral and detailed               Get it on Epiphany Acoustics or HeadnHifi

If you’re in headphones mood, then you should definetely consider also the Nwavguy’s combo of ODAC + H2.  Again, this device came trough a pedissequal engineering process, aiming to obtain verifiable transparent performances. If you wish to know more about this, well here are your answers. I did not listened to it, but if I should put on an headphone system, this will be my device of choice.

PROS:

-It’s engineering is carefully documented
-A complete USB to Headphone device            Get it on Epiphany Acoustics
-The combo will sound theoretically better than separate devices

XMOS ES9023 Asynchronous DAC Decoder USB to Optical Coaxial 384K 32Bit Weiliang

This device seems really interesting, and not only thanks to the longest name ever seen on Ebay. What you get here is a boxed unit featuring the ESS 9023 DAC (my favourite so far, until I’ll listen to 9018), paired with an XMOS2 receiver. You also get otpical and coaxial S/PDIF out. I cannot imagine something more flexible out there. So, on paper this seems really promising. Please don’t take this as a blind endorsement, I didn’t listen to it so cannot pronounce about it’s sonic qualities. Just saying we have a potential bang for the buck champion.

PROS:
-XMOS2 async receiver
-Features one of audiophile’s favourite DAC
-Already boxed and finished
-Analog JACK, SPDIF out (optical and coaxial)
-Really flexible device
-Can be fed with an external PSU (definetely suggested)

Usb to Spdif

Hiface Two

If you need to get Spdif out out of Raspberry Pi, or any other device relying on USB  just buy it. There’s not much to say on the Hiface Two. It’s a status symbol, the guys at M2Tech did an excellent job. This features an XMOS receiver that will go as high as 24/192. It’ compatible out of the box with RaspyFi and all other Linux distros. Of course it works as well with Pcs and Mac.

PROS:
-Async  USB Transport
-Compatible with RaspyFi out of the box                 Get it on ebay or amazon

XMOS 192kHz high-quality USB to SPDIF

This could be a solid and cheaper alternative to the Hiface II, the module is exactly the same found on my XMOS2 to i2s receiver, which I strongly recommend. With this you get spdif out, in a nice box… Maybe gold could not be your favourite colour, but I mean… This is definetely worth!

PROS:
-Async  USB Transport
-Compatible with RaspyFi out of the box       Get it on 

-Boxed and ready to play
-Cheaper than an Hiface Two

Diy

DAC SABRE 9023 + XMOS2

I may be biased. But guys, this is definetely the best combo you can have for the 100 euros pricetag. This DAC is well known, and its sound is recognized to be one of the best nowadays. This guys makes excellent products and this DAC is a masterpiece. It’s so tiny but it features a ultra low noise regulator and the semiconductors are carefully selected. In few words, it sounds amazingly good. I DEFINETELY suggest you to visit it’s store, if you’re a diyer looking for hi quality stuff, this is the place
I paired with an USB XMOS2 receiver. This features a full thesycon windows driver, and it’s compatible of course with Linux (RaspyFi as well). This can go as high as 384khrz!!! If you wish to feed it with a custom PSU, instead of USB’s DC, you can. You can also change some resistor to match your dac’s impedance… What do you want more? I sugest also to visit it’s store…

I’ll cover the building of this DAC, you can find my preliminary thoughts here

PROS:
-Sounds amazing, for less than 100 euros
-Highly customizable
-GET IT!
Buy on ebay:

UPDATE

As an alternative, you can also try this DAC

I received mine few days ago, so haven’t tried it yet. So I cannot say anything on this DAC, only that is compatible with the i2s transport listed above

DAC Mini AK4396

If you want to try a diy AK4396, which is an highly regarded piece of silicon, just go with this DAC. It has an high reputation on DiyAudio and amongst other audiophiles circles. Furthermore, you can decide where to push its performance. A respected user of Tforum and DiyAudio published a BOM that will raise its performance a lot. You can find all info here.
If you wish, you can also connect it directly via i2s to the  XMOS2 USB TO I2S following this guide .

PROS:

-A custom solution, in every aspect                  Get it on ebay

UPDATE :

I’m currently building another step up of my Reference DAC. It sits on a completely different level from the ones you have seen before on RaspyFi, in terms of performance, build complexity and pricetag. But on paper, it seems that I’m gonna end up with something truly impressive. It will feature :

• The top end ESS SABRE 9018, in a 7.1 configuration (yeah, I really meant 7.1)
• XMOS2 USB Input via i2s
• Optical and coaxial input
• Both balanced and unbalanced analog out
• Separate and improved clock

The Recipe is :

• A custom 4x8vac 1A PSU custom built from Audiophonics.fr

So, on paper, this DAC could be an ending point for every audiophile around. But its building is something really challenging, so please start this adventure only if you are an experienced DIYer. I’m going to document the building of this DAC in a future article, since it really deserves a careful and comprehensive explanation. I looked out for months to find the best recipe for me, this is what I ended up with. So again, if you want something really over the top this is what you’re looking for, mind that it’s gonna need quite some time and expertise to be built.

Medium Price DACS

(Please note: I don’t own any of these DACS, but if I would spend some more to have one, I’ll have one of these)

Audioquest DragonFly

This is one of the most interesting DAC available today, an async USB DAC as compact and as good sounding is difficult to find, you’ll read about the only contender later on…
I suggest you to read this article by John Atkinson, which can describe this DAC way more better I could ever do.

PROS:
-Confortable with it’s tiny dimensions
-Excellent measurable performances
-Can directly drive Headphones

Get it on ebay or Amazon

Musical Fidelity V-DAC II

I’ve dreamt a lot about owning this DAC. If you need to be flexible, for example using a cd player with coax output, a blu ray with a optical output and RaspyFi with USB input, this could be your DAC. The USB receiver is not the best one available (Ok let’s say that people is not so enthusiast about it), but you can always use a Hiface Two to improve USB performance.
So, if you need lot of flexibility and a good sounding DAC. This is your choice.

PROS:
-Features lot of connections (USB, Coax Spdif, Optical Spdif)
-Regarded as very natural and relaxed
                                                      Get it on ebay or Amazon

Micromega MyDac

A respected diyer regards this DAC as the best you can get under 1000 euros. I must confess that I desire it a lot, and  if everything goes well I’ll buy this in few time (birthday…) . This DAC has all the flexibility you can have with the V-DAC II, but it features an async usb receiver (XMOS) . So you can reasonably espect an higher quality out of it if USB is your source of choice. Plese note that the price tag of the MyDac is higher than the one of the VDAC II. But if you can go that extra mile, go with this. All I know of this DAC comes through reviews, and my friends spoke to me about the MyDac with enthusiastic words. The implementation seems very good on paper. Please note that Micromega has built its reputation through the years with excellent products, especially with cd players. So you should go confortable with this firm.
I want it.

PROS:
-Features lot of connections (USB, Coax Spdif, Optical Spdif)
-XMOS async receiver
-Enthusiastic reviews on web                                           Get it on ebay or Amazon

Hiface DAC

The guys at M2Tech just released this DAC. I consider this as a contender for the Dragonfly DAC. Because of it’s tiny dimentions. On paper this little device has excellent capabilities: 384kHz/32bit, async transfer (based on XMOS as Hiface Two) and can drive medium to high impedance headphones. I don’t know which DAC chip it relies on, but sure we’ll find out when a friend of mine will end his review.
The only concern is that it needs at least 500 mA at 5v to work properly, so no direct connection with the Raspberry Pi. But we can always use an additional psu. See later to find out.

Check also this excellent review (in Italian)

PROS:

-Tiny Dimentions
-XMOS async receiver
-Can directly drive headphones
                                                    Get it on ebay or Amazon

SOMETHING TO IMPROVE YOUR USB DAC 

I found a pretty valid comment from Klinkt Beter (one of the best contributors here on RaspyFi) stating that he could improve his system overall performance connecting his dac to the  iFI iUSB psu:

Here’s what he said:

tried many things:

1. soundlogic XT 5600mAh battery pack with micro usb cable to pi
2. Tentlabs tube heater supply calibrated to 5V direct on the 5V GPIO headers (which claims to have very low noise and is powered by a lineair supply using a real transformer)
3. usb power output of the iFI iUSB power supply using a cheap 1 euro micro usb cable to the pi.

The iFi wins on all levels as it also directly powers your usb dac and ignores the usb power from the pi on the USB outputs, only passes the signal through.

The iUSB has a second USB output which can be used to power the pi, or to use iFI’s special cable that combines two USB host connectors and on the other end one printer style USB connector to have even more power to your dac.

The Tentlabs heater supply has slightly better transients and more bass, but sounds more aggressive to my ears. The iFI is lighter and more spacier, which is what I prefer.

Wiring scheme:

Power output of iFI iUSB -> PI micro usb input
USB output of Pi -> USB input of iFI iUSB
iFI iUSB usb+power output -> dac

Basically, what this device does is replace the crappy usb dc with a stabilized one, they report their psu to achieve a 0,1 uV noise factor, that is (if verified) pretty remarkable. You can find out more at http://www.ifi-audio.com/en/iUSB.html

I want to test it out, I’ll report my results as well.

Any suggestions?

You can also give a look at RaspyFi’s DAC compatbility list

L'articolo The right USB DAC for your Raspberry Pi sembra essere il primo su RaspyFi.

Recipe:

1- A piece of plexiglass, or whatever material you wish to use

2- Some screws and spacers

3- 4 sylicone feets (also rubber is good)

4- Some tools, a dremel is suggested.

I started cutting 2 identical pieces of plexiglass with the dremel, the measure 10 x 7 cm approx. To get the borders pretty smooth I used some glass-paper.  Then I made some holes in the corners, and two smaller holes where the Raspberry mounting holes are:

Now, let’s bond the Pi to the lower part of our case, and attach the screws:

Then, add your rubber feets ( I definetely suggest to use them, in order to make your Pi more stable on your desk\table\floor).

Et voilà, put the screws and the spacers, and you’re done!

This is mine, for comparison some healthy goods and the tiny ODAC. Joyful.

Really nothing special. But it’s easy to do, it’s pretty good looking and allows you to attach every peripheral you wish to the Pi.

DIY strikes again.

L'articolo A simple and good looking case for our Raspberry sembra essere il primo su RaspyFi.

Hey,

I’m experiencing audio stutter while playing movies via the Raspberry Pi to the TV. I used to have the 1080p videos buffering all the time, but I fixed by switching my shares from Samba to NFS, using Hanewin NFS Server. That fixed all the buffering issues and makes the Pi read the shares much, much faster.

http://openelec.tv/forum/134-usage/40394-audio-stuttering

I’m also having problems with RaspyFI, when i comment out the line

format          ”44100:16:2″    # optional

in order to avoi resampling (you remember Audiophilia Hysterica obliges you to think resampling is evil??) I get audio stuttering, especially with flac with samplerate higher than redbook standards . I do really think this is related to an driver issue of the Soc controlling both ethernet and USB.

The main theory circulating on the net states that usb related issues (which can affect wi-fi dongles transfer, keyboard and mouse imputs etc etc) are due to some drivers problems which manifestates themselfs under heavy stress of usb\ethernet pathways, in conjunction and in some cases alone. More precisely there seems that there is some packet loss:

- USB congestion:our devices work in full-speed (USB 1.1 12 Mbit/s) and transmit at max 1 packet of 64 bytes each frame (64 Kb/s). We have analyse the transfer with and USB analyser and ALL packets are correctly transmitted over the wire (no bus reset, no invalid packet, the USB host ack all packet). this mean that the USB Host controller of the raspberry Pi as correctly received and ack the missing USB packet.Our conclusion is that or the libusb or the linux kernel drop some packets and do not raise any error.
We have found a serious issue on the raspberry PI USB stack (or at last the HID USB stack). We produce USB device and have found that we often get missing packet.
We have create an specific firmware illustrate the problem. This debug protocol is very simple the Raspberry will send one packet of 64 bytes, then the device will start a burst of USB transaction. Our USB device work in full speed (USB 1.1) and follow the HID protocol. All packets have the same size (64 bytes). the first uint32_t will contain the current packet number and the second uint32_t will contain the number of packet to send. Each packet is numbered and we stop after burst of 4096 packet of on the first missing packet.

The debug program call libusb-1.0, and will look for one of our device with the debug firmware, then send one USB packet to the device to start the burst. Then we will wait for all packet and check that all packet are send. You can download the source here http://www.yoctopuce.com/tmp/debug_libusb.zip

We have test this code and firmware on many linux platform (i386 and x86_64), and on a ARM based NAS (QNAP TS-219P II). We never get any missing packet. but on the Raspberry PI we always get missing packets. We have check with a USB analyser that the missing packet is correctly sent on the wire (the packet has been correctly acked by the Raspberry PI USB host). It seems that the packet is lost by the Raspberry PI firmware.

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=5249

In addition to this:

The USB driver may not be fixable, the jury is still out on this one. There are three key problems:

1) Documentation on the Broadcom USB controller is proprietary and is not made openly available by the Raspberry Pi Foundation.

2) The USB core for the Broadcom SoC was bought from a 3rd party, and we are told that not even Broadcom has full documentation, nor understands the driver.

3) The Foundation has discovered that the controller and its driver expect realtime response from the ARM core, and if Linux’s non-realtime scheduling doesn’t respond in 1 ms, a split transaction USB event can be dropped. Not surprisingly, this occurs regularly and produces lost mouse clicks, stuck keyboard keys, etc..

That’s a pretty nasty combination of problems, and it means that assuming that it’s fixable may not be a safe prediction. We’ll have to wait and see.

For the time being though, USB and networking (which is implemented over USB) have a large catalogue of issues and incompatibilities. All boards have this inherent problem but YMMV on whether the issues bite you, as it depends on exactly what devices you have connnected and what you’re doing with the board.

In addition to the above faults, the community discovered a PCB track layout error on the board which causes a proportion of the USB chips to overheat owing to an incorrect connection. It doesn’t appear to be critical but wastes power and the heat may shorten board or device lifetime.

Relations are very tense on the forum, and the Foundation has banned people who express their concern about the faults.

http://hardware.slashdot.org/story/12/08/24/2228251/serious-problems-with-usb-and-ethernet-on-the-raspberry-pi

 

So what happens? Under heavy load some of our precious binary vives is lost and never reaches our fancy USB Dac. Setting the resample mode seems to avoid it because of less bandwith is required to stream the audio to the dac, but we don’t want this as we are:

1- Applying some post processing to our audio stream (which, I remember should be evil to us…)
2- Making our hi-res flac library very sad
3- Degrading our listening experience as it is non-bit- perfect (wheter this is perceptible or not, still I don’t know… but we are damn audio purity integralists, aren’t we?)

But, is there a light out of the tunnel? Of course yes, theorethically at least.

As you can find out from that quote:

3) The Foundation has discovered that the controller and its driver expect realtime response from the ARM core, and if Linux’s non-realtime scheduling doesn’t respond in 1 ms, a split transaction USB event can be dropped. Not surprisingly, this occurs regularly and produces lost mouse clicks, stuck keyboard keys, etc..

 

So, if we succeed in compiling a real-time kernel, hopefully out problem will be solved and finally we’ll have bit perfect reproducion. This is already in process, as a superuser from tforumhifi il helping while compiling a custom real-time kernel for RaspyFi, you can follow the iter here on the RaspyFi thread:

http://www.tforumhifi.com/t32285-raspyfi-raspberry-pi-voyage-mpd-progetto-per-un-ottima-sorgente-low-cost

Meanwhile, a possible solution for audio stuttering via usb is made possible by setting the Usb transfer rate to USB 1.1 and setting it in full mode:

We have run some tests today to validate the tentative fixes.

First we have run rpi-update to get the latest fix. Here is my cmdline.txt and the kernel version

CODE: 

root@raspberrypi:/home/pi# more /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
root@raspberrypi:/home/pi# uname -a
Linux raspberrypi 3.2.27+ #160 PREEMPT Mon Sep 17 23:18:42 BST 2012 armv6l GNU/Linux


As expected, Gordon fix does not completely solve the issue of packet loss in this case, but the packet loss seems to happen far less frequently (I have been able to stress the PI for several minutes before I get a missing packet).

Then we have added the dwc_otg.speed=1 parameter to force USB to work only in full speed mode (speed of USB 1.1). This solved the issue. This confirms that the PI has some trouble to handle USB 1.1 devices behind an USB 2.0 hub, but forcing the USB to work in full speed mode completely solves the packet loss for our USB 1.1 devices.

Our working config:

CODE: 

root@raspberrypi:/home/pi# more /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 dwc_otg.speed=
1 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
root@raspberrypi:/home/pi# uname -a
Linux raspberrypi 3.2.27+ 

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=5249&start=200

This is done byadding the dwc_otg.speed=1 parameter to force USB to work only in full speed mode:

sudo nano /boot/cmdline.txt

and adding dwc_otg.speed=1 in the text. ctrl +x, y and reboot

adding the dwc_otg.speed=1 parameter to force USB to work only in full speed mode

Some reported this solution as working, It’s worth trying… I’ll let you know…

Then a final option is this, that prevents kernel panic by setting always free quote of memory and setting the Soc in turbo mode.

Just to report, I had exactly the same error and I solved with:

• vm.min_free_kbytes = 32768 in /etc/sysctl.conf
• smsc95xx.turbo_mode=N in /boot/cmdline.txt

Remember that with turbo mode enabled you are seriously risking to corrupt your SD card…

So, that’s all about USB problems with the PI, I’ll upgrade this post with new informations when they’ll come out.

L'articolo Anatomy of a PI – USB Audio quality and related issues on Pi sembra essere il primo su RaspyFi.

First update:

apt-get update
apt-get updgrade

Y, then Y again

When updating process is over:

reboot

Let’s disable Ipv6, that Raspberry Pi

Just add this line at the end of l file /etc/hosts

::1 localhost.localdomain localhost

Now we can install mpd

apt-get install mpd

Y

On the Pi it usually gives some error messages, we can safely ignore them.

reboot

Le’ts create our playlist folder:

mkdir -p ~/.mpd/playlists

Now let’s edit our mpd.conf file:

nano /etc/mpd.conf
And modify the string:

bind_to_address “localhost”

in

bind_to_address “127.0.0.1″

Ctrl + x ,then Y.

If we want to store our music library on a usb storage:

Let’s see how Debian calls our drive: (formatted in fat32):

fdisk -l

Specifically for me: /dev/sda1

Let’s create the  Music folder and chmod it :

mkdir /media/Music
chmod -R 777 /media/Music
mount /dev/sda1 /media/Music

Modify the fstab file with our partitions :

nano /etc/fstab
just add this line:

/dev/sda1 /media/Music vfat defaults 0 0

Ctrl+x then Y

Let’s check if everything is ok:

mount -a

If we don’t get any error message, we’re ready to go.

reboot

If we want to use a nas as storage (SAMBA)

Install samba client

apt-get install smbclient

Creating  mount directory:

mkdir /mnt/nas
chmod 777 /mnt/nas

Mount the nas

mount -w -t cifs -o username=,password= //192.168.1.nasip/sharename /mnt/nas
If you’ve protected your share with password, insert them. If none password or user has been set, just leave this field empty

Check with:

ls /mnt/nas

If everything is ok, you should see your directories.

Let’s set the automount

nano /etc/fstab

Add this line in the end

//192.168.1.ipnas/sharename /mnt/nas cifs username=,password= 0 0

Check with:

mount -a

If no error appears, again, we’re ready to go

reboot

Ok, last entries in our configuration file:

nano /etc/mpd.conf

Let’s tell mpd where our music is stored:

Usb storage:

music_directory “/media”

Nas storage:
music_directory “/mnt/nas”

If you have a usb dac, let’s tell mpd to use this instead of the shitty analog out:

audio_output {
type “alsa”
name “USB Dac”
device “hw:1,0″ # optional
format “44100:16:2″ # optional
mixer_device “default” # optional
# mixer_control “PCM” # optional
# mixer_index “0″ # optional

These options can be quite different depending how debian calls your dac, but i always used that with different usb dacs and it always worked. You can try by changing in 1,0 instead of 0,1 but this is up to you. As you can see, I din’t changed everything from resampling to buffer size etc etc. This will be done in future tweaking tutorials. Anyway the quality of music reproduction with these settings is pretty awesome, so expect some minor improvements with further tweakings.

Some examples:

If you wish to enable audio buffering (and so ram reading). Uncomment these strings.

#audio_buffer_size “2048″
#buffer_before_play “10%”

If you want to send the audio stream directly to the usb dac, bypassing any software\hardware mixer. Change the string

mixer_device “default”

in

mixer_device “none”

ctrl+ x e Y

reboot

Now You should choose a client in order to control your mpd box. The best available is GMPC for Windows\Linux. Pretty simple and straightforwarding (sometimes it freezes, hope this will get solved) you can find it here. Then you can use Mpdroid or Mpod to control mpd via smartphone. These 2 clients are really good and goodlooking.

Happy music, folks!

L'articolo Ho to install Mpd on an existing Debian installation on Raspberry Pi sembra essere il primo su RaspyFi.

You can find it here

This really comes ready-to-play out of the box. Just copy it on your SD card via Win32diskimager (you can grab it here) and you’re ready to go. Then you only need to connect trough SSH and edit your mpd.conf file.

If you don’t have any SSH client, I strongly suggest to use putty (available here)

you can do it by tiping on your ssh terminal :

User: root
Password: raspi

nano /etc/mpd.conf

It’s configured to find your music on usb or on a nas. If you prefere to read your music on a usb key (or hard disk, but you should use a self-powered hard disk to do so) just modify your file as follows

#music_directory “/mnt/nas”
music_directory “/media/Music”

and then ctrl+ x, then y

Otherwise, store your music on a samba share called Nas and modify as:

music_directory “/mnt/nas”
#music_directory “/media/Music”

and then ctrl+ x, then y.

then reboot

reboot

And you’re ready! Just play your library with your favourite client and enjoy!

Known issues:

-no 512mb support
-flac over 96khrz need to be resampled

L'articolo Raspyfi first alpha release is out! sembra essere il primo su RaspyFi.