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.

Is my power supply good enough? 

Terrible drama then, desperation, no certainesses, no peace. Then he will start to browse and google compulsively, ask in forums, call his mom, loose hairs etc etc.

Well, at this point, there is only one thing you can do. Get a better one. So, for those of you in these miserable condition, here’s a tip on how to choose wisely a good power supply for Raspberry Pi.

Let’s introduce what are we talking about

Why Power supply is so important? Trivially speaking, we can say that our fancy audio\electronic gizmos work with electricity. And, the better and the most stable electricity we can give to them, the better they will work. This comes to an extreme importance in Audio, but can be true also for all kind of electrical equipment.  Let’s see why:
Most circuits works with DC. DC is direct current, which is:

used to refer to power systems that use only one polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current.For example, the voltage across a DC voltage source is constant as is the current through a DC current source. The DC solution of an electric circuit is the solution where all voltages and currents are constant. It can be shown that any stationary voltage or current waveform can be decomposed into a sum of a DC component and a zero-mean time-varying component; the DC component is defined to be the expected value, or the average value of the voltage or current over all time.

 

http://en.wikipedia.org/wiki/Direct_current

 

Usually, direct current is obtained by rectifying AC (Alternated current), which flows by our wall socket. A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
This is the first quality sensible step that our electrons are faced to do. In these process, it could happen that some residuals of the AC’s typical voltage oscillations will remain in the DC stream, producing some kind of “fluctuation” from our desired voltage.
This phenomenon is called ripple:

The most common meaning of ripple in electrical science is the small unwanted residual periodic variation of the direct current (dc) output of a power supply which has been derived from analternating current (ac) source. This ripple is due to incomplete suppression of the alternating waveform within the power supply.

This could be better described with picture below:

As you can see, by simply rectifiying AC (first scenario) we will end with lot of oscillations in voltage, this will result in poor performance (in audio domains). As for our Raspberry Pi, a power supply with high ripple will result in malfunctions, sd card corruptions etc etc.
In the second picture, we’ll see how a filter applied to our power supply can dramatically reduce ripple. This more stable voltage will result in a HUGE improvement in audio applications, and for our raspberry Pi will mean better working conditions.
Those of you who already know about this matter could find this explanation extremely reductive and simple. I know it is, but I’m trying to keep things simple.

So, what power supply should I choose? There are 2  main categories:

Linear power supplies

These are the type we discussed earlier, as you can see the first component (from left side) is a power trasformer, this transform the voltage from our wall socket to a desired one (let’s say 24 volts), passing this step the current is still alternated.
Then it passes trough some diodes (1,2,3,4), their function is to rectify current and make it dc. Passing this step our DC is very dirty, and that’s why there will be some filtering capacitors (C) to smooth it out and reduce ripple. This is a very simple schematic, but should give you the idea. Usually, where a given voltage with very low ripple is needed you’ll use also a voltage regulator. This component will reduce the imput voltage to a given one, and provide very low ripple output. Capacitors are often used to further smooth the output voltage, and their quality is hugely responsible of subsequent psu quality.
The main disadvantage of these kind of power supply is their efficiency. Lot of energy got wasted in this process (as heat, for example) and they usually drain lot more current than they put out.

Then, we’ll find

Switching power supply

A switched-mode power supply (switching-mode power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a source, like mains power, to a load, such as a personal computer, while converting voltage and current characteristics. An SMPS is usually employed to efficiently provide a regulated output voltage, typically at a level different from the input voltage.

Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions (which minimizes wasted energy). Ideally, a switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time.

So as you can understand, switching power supplies achieve the same result by turning on and off repeatedly (thousands of times per second) the electrical stream, resulting in better efficiency (no rectification, no voltage transformation, no voltage regulation). The main disadvantage are in terms of quality. Switching power supply usually have higher ripple than linear power supplies.

So now the choice is between quality and efficiency. Since our raspberry Pi will draw as much as 700 mA (current) at 5 ± 0,25 volts      (voltage) we should choose a psu which can output at least 1 amp (extra 300mA for connected devices such as DACs or usb keys), whith a voltage between 4,75 and 5,25 volts. Any different value from these will (and I mean, it will) result in SD Card corruption, especially if you decided to overclock your PI.
By choosing a linear power supply for Raspberry Pi, like

, you’re sure gettin highest quality power supply, but this will result in lot of enery wasted and a higher electricity bill (of course, relatively speaking) (please also mind that you should change the DC jack in favour of a microUSB plug). By the other hand a switched mode power supply for Raspberry Pi like this (or

if you’re on the other side of the Atlantic)  will  be an energy saving savy choice but quality wise, is the worst scenario you can get.

And after telling you all of this, I’ll let you cry in tears and desperately wating to know what to do by saying goodbye !

Next , will come a comparison of multiple power supply for Raspberry Pi, and a project of a custom power supply which will hopefully satisfy both quality and efficiency!

L'articolo Power Supply for Raspberry Pi, what you should know about sembra essere il primo su RaspyFi.