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Hi-Fi

Audiophonics DAC PCM1794 XMOS: Qobuzism for this elegantly designed device with remarkable sound restitution!

By Barry Moore |

With the DAC PCM1794 XMOS, commercialised by Audiophonics, we are dealing with a device that is not intended to be exhaustive but rather classic in its presentation, its connectivity and its decoding potential. A device that also offers excellent sound performance while remaining easy to use: Qobuzism!

Audiophonics, a company that imports various High-Fidelity devices as well as electronic modules, accessories and components for amateurs of personal production or those who wish to improve their current installation, also distributes a number of other products under their own brand, one of which we have previously tested on Qobuz, the DAC PCM5102, one which also received our prestigious Qobuzism award for sound excellence.

This benchmark will be devoted to another device marketed by Audiophonics under its growing brand. This is a digital-to-analog converter for a domestic hi-fi system, since it not only draws its energy from a main power source, but is also clearly designed for this purpose from an aesthetic perspective.

In essence, the Audiophonics DAC PCM1794 XMOS, which boasts USB, S/PDIF coaxial and optical inputs, benefits from a physical presentation that allows for easy integration with numerous audio installations. There really is excellent sound performance on offer here for more than reasonable prices. There is also a version of this DAC without a USB interface (Audiophonics DAC PCM1794 AK4118).



Appearance

The Audiophonics DAC PCM1794 boasts a sober and elegant presentation, manufactured from sandblasted alluminium with a natural finish.


The two control dials are symmetrically-placed on either side of the central display. The left dial is used to start, whereas the right one is a pulse pattern (forward or backward) for selecting the digital input (USB, S/PDIF coaxial or optical) and offers a choice of two central pressure filters.

The yellow-over-blue display indicates the selected input and the sampling frequency on the upper line, with the selected filter 01 or 02, displaying clearly on the second line.

The connectivity of the device can be summarised by the 3 digital inputs: 1) 2 USB type B for connecting to a computer, or Android smartphone or tablet, 2) S/PDIF coaxial and optical, 3) the analog outputs.

Production

If the exterior of the body of the PCM1794 DAC gives a great impression, this impression is just as good and maybe even better once we look under the hood. We can appreciate the craftsmanship of the different elements of both the housing and the electronic composition.


There is no switching power supply used as a universal power supply, but a good, traditional-styled linear power, it is stable (also by the weight which adds to the perceived value), a more noble choice for purists, and it doesn't generate high frequency pollution.

This DAC is equipped with an R-type transformer core (the best type of transformer, according to some) of 30VA (a comfortable power for DAC) with multiple windings that will provide just as many independent DC voltages. By connecting the orange wire and the white wire, the switch on the facade kicks off the series for the two 110V primaries of the transformer that receives 220V.


We note that the power management part is treated less "luxuriously" than the power supplies for the other parts of the electronics, using only standard rectifier diodes (1N4007 of type 1A, 1000V), the other rectifier diodes are Schottky models, more efficient (5A current and low forward voltage drop, so fewer losses and less heating).

The filtering is carried out by 2200F/25V electrochemical capacitors (no less than eight in number), and manufactured by BCcomponents - a reputed brand in this field.

The regulation of the +5V tension of the electronics control (and display) is entrusted to a classical LM7805 while the + 5V supply of certain chips conversion part is regulated by an adjustable L317 low noise regulator. A rapid response regulator in the form of a Linear Technology LT1963 is responsible for regulating the voltage of + 3.3V required for the digital analog converter chip.

To power the amplifiers of the analog part, a couple of adjustable low noise regulators (LM317 and LM337) are responsible for the regulation of symmetric voltages +/- 15V.

The USB interface calls upon a fait appel à little piqued chip on a connector of the main circuit, the latter being common to the DAC PCM1794 XMOS and DAC PCM1794 AK4118 models, and which also avoids complications caused by the wiring of an under-equipped circuit . Here we use the same base circuit, and it is even very likely that we can evolve the version of the DAC without USB to one with.


This USB card uses a GT1325 XMOS processor compatible with 24-bit PCM signals at up to 192 kHz. On its side we can see the three oscillators necessary for its operation and synchronization with digital audio signals.

In the below visual you can see the receiving S/PDIF signals circuit, a model Asahi Kasei AK4118 also for switching between different digital inputs.


Digital to Analog conversion is provided by a Burr-Brown PCM1794 circuit (24-bit at 192kHz), with a number of differential outgoing signals whose voltage conversion is carried out by the Burr-Brown OPA2604 operational amplifiers, with the exception of outputs and field effect transistors (FET). The signal filter calls on a Texas Instruments LME49720 dual operational amplifier (very low noise and low distortion). These integrated circuits are mounted on a support for possible trials of other models.

Listening

The Audiophonics DAC PCM1794 XMOS offers a particularly refined sound restitution, doing justice to the music. This is especially evident on Beethoven's Concerto for Violin by Vera Beths accompanied by the Tafelmusik ensemble and conducted by Bruno Weil, an interpretation on period instruments whose delicacy and particular colours were found easily with the PCM1794 XMOS DAC, the beauty of the orchestra and the fullness of the soloist are all captured perfectly.

We come back to listen to an often forgotten recording that this DAC brings to lift in a significant way. Vivalid's Vespri per l'Assunzione di Maria Vergine extraordinarily interpreted by the Concerto Italiano conducted by Rinaldo Alessandrini. Again, a lot of finesse and colours restored with art, sharp attacks and a wide sound stage which is shared without interfering instruments, soloists and choirs.

Note that we have chosen the 01 filter with a very good balance with our installation, the return with the filter 02 was pulling slightly upwards and didn't suit us, but who can possibly give a little brightness to a system that needs it.

Beautiful restitution, deep and intense, when listening to the song One from the album x (Deluxe Edition) by Ed Sheeran. We hear not only the artist singing, but also his breathing and the drum rhythm in wonderful detail.

In conclusion, with its implementation and its traditional design - and especially the use of a neat linear power supply - the Audiophonics DAC PCM1794 offers excellent sound performance marked by great refinement. Qobuzism 100% deserved.


Thanks to Audiophonics for providing the DAC PCM1794 XMOS for testing.

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