Overview of the DAC U2 HiFiMeDIY – small, yes udalenky




Overview of the DAC U2 HiFiMeDIY – small, yes udalenky

Today I’ll tell you about an incredibly interesting device. It just so happened that the built-in sound card modern laptops obviously can not please the owners of sound. Come to the aid of external DACs typically connect over USB and performing the role of a sound card. Today I’ll tell you about one of the most compact solutions of this kind. Concurrently, it is also the most inexpensive, but it sounds very good. It’s about the DAC from U2 HiFiMeDIY .

The development of modern microelectronics has led to the emergence of really great chips. A striking example can be considered Sabre 9023 DAC from ESS Technologies. Its main advantage is that it requires a minimum “binding” and thus the output gives enough power to listen to headphones without an amplifier. Of course, manufacturers of solutions for music lovers and audiophiles could not ignore it and created a lot of decisions based on it, a couple I even described: ODAC and iFi IDAC . Due to the small size of this chip were also created several miniature DAC, no bigger than a normal USB-stick. One of the most famous – is unreasonably expensive Dragnofly from Audioquest.

Appeared relatively recently, from DAC HiFiMeDIY won a lot of fans, as evidenced serve rank high on Head-Fi (at time of writing – # 4 in reytintse DACs!). Of course, this solution is not for the “audiophile”, such need “company name”, “exclusive manufacturing technology 5-layer board” (even if the device or not) and other delights. But U2 is perfect for those who want to get better sound than the built-in sound card provides his computer, while not spending a lot of money (DAC price $ 57) and place.


What is DAC and why is it needed? I’ve already talked about it in my review HiEnd solutions Yulong DA8 , but just in case again. DAC is connected to your computer and works as an external sound card (or rather half of it focused on playing as audio DACs typically do not contain). Computer transmits an external DAC sound in digital form, and the latter had already translates into analog form. Since even a simple circuit solution DAC 99.999% of cases better than the built-in sound card or laptop computer, and the sound of a single device turns out much better.


Separately, I note that in the range HiFiMeDIY have a few modifications on this chip DACs and in this form factor: standard, for Android, and asynchronous. In the case of DAC for Andorid all more or less clear: it connects via USB OTG devices to the operating system that supports USB Audio protocol, and allows you to listen to music with a quality superior “on-board” solution smartphone. There is also a cheap and simple solution, as well as the DAC with integrated headphone amplifier.

So what is the difference between an ordinary and an asynchronous DAC?

“Normal” converter acts as a digital signal receiver: computer sends bits of information at a given speed, and “not interested”, as they were received by the DAC. In this case, from the DAC requires incredibly accurate frequency coordination with the computer is not always achievable in practice. Mismatch reception and transmission in this case leads to the emergence of “jitter” that degrades the sound quality. Asynchronous DAC works differently: he sends a computer (or other source) requests the next chunk of data and processes them. This mode allows you to avoid any form of disagreement. Therefore, a small overpayment for an asynchronous version of the DAC HiFiMeDIY – quite justified.
Technical characteristics

U2 characteristics published not so much. That’s what I was able to gather.

Supported modes: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz, 16 bit and 24 bit
Input: USB
Outputs: 3.5 mm audio combined with optical
Output level: 2.1 Vrms at a load of 4.7 KΩ, 1 Vrms at a load of 30 Ω
Dynamic range: 112 dB


Appearance U2’s incredibly minimalistic. It fully justifies its name in the sense that the developers have managed small-scale production. U2 have no box, it comes in the usual package of “bumps” polyethylene. The body is a small cuboid, at one end of which is placed a short USB-cable to connect to a computer on the other – 3.5 mm output for audio. This is the same connector optical output jack that allows you to use U2 as converter from USB to optics. In the corner of the device is located LED indicator work.

In general, the design of a simple, no frills, but with the marginal price and compact size quibble here is silly. Especially worth noting that the internal DAC performance at a high level, the soldering quality, the details are not saved (within a budget device, of course).


To listen to the following equipment:

Apple MacBook Pro 15 “early 2011
USB isolator iFi iUSB Power
Decibel as a player
Recording in lossless-formats
Audio-GD NFB-6 as an amplifier
Headphones: Fischer Audio TBA-04, VSonic GR01

ESS Sabre 9023 – almost self-sufficient chip. It does not require complex binding (though not eliminate it if you want the developers), so creating DACs on it – the main thing is not to spoil it. U2 developers succeeded fully. In the role of USB-interface they used SA9023 chip from SAVITECH (despite the coincidence index, this chip has no relation to the DAC chip itself). In the role of the generator is 27-MHz resonator with a chip PLL1705. The design of the DAC scheme is used without coupling capacitors at the output, which is also a beneficial effect on the sound.

Обратная сторона платы U2

Users Windows can use ASIO drivers developed SAVITECH.

The funniest thing in a situation with this device is that it plays better than many much more expensive solutions, and some even bypasses. First of all, thanks to the good in this DAC and the controller, the second – a competent circuit solutions.

“Out of the box” sound U2 detailed, rather cold, but without exerting excess HF. At the sound of a lot of air and light, although the bass also clears well. Sibilance mild background noise depends on the quality of your USB-output (see below about the filter). Volume reserve – sufficient for most headphones are not tight. Well this DAC combined with different amplifiers, due to its “transparency” it almost does not introduce distortion in the sound picture.

To unlock the full potential U2, I sent it back for revision Friend master. In the course of finalizing the DAC has undergone many changes:

tantalum removed from the analog section and replaced by higher-capacity electrolytic
recalculated filter and its components replaced by higher quality, and the amplitude of the output signal slightly reduced for greater detail
sold separately powered chip DAC
Part ceramic capacitors shunted

После модификации

Since this modification could not fit in the original package, for capacitors were cut holes in the lid and pull the entire DAC was shrinking. View was a bit amateurish, but increase the sound quality is more than justifies it.

After modifying sounding player becomes not so pronounced cold-added drive bass that makes the sound more musical DAC. Sound becomes “multifaceted”, an imaginary scene becomes more voluminous, better separation of instruments.

Since U2 is powered by USB, and the small size does not allow to implement a serious supply filter, the sound of the DAC depends on the quality of implementation of the USB bus on your computer. To solve this problem, HiFiMeDIY offer a simple but effective insulator. It is made in the same form factor as the U2, only instead of audio jacks on it is USB-connector. Including it before the DAC (not necessarily them to be U2), you can significantly improve the quality of USB power and improve the sound.

USB изолятор


Very inexpensive device with huge potential. Do not be fooled very simple appearance, for its modest price, this small DAC able to please the owner of a very good sound.
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