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Test Results

Like many other sound cards, the Auzen X-Fi Bravura doesn’t have an ADC of a high enough quality to measure the characteristics of its own outputs. Therefore for this review I employed a professional audio interface E-MU 1820 for that purpose. I would have gladly used it in my earlier tests if Auzen’s CA20K2-based X-Fi Forte and HomeTheater didn't conflict with it. Based on a different audio controller, the Bravura is perfectly compatible with the E-MU 1820 as well as with the Creative Xtreme Audio, Auzen Prelude and ASUS Xonar D2. To my surprise, these sound cards were all quite content working together under Windows 7 x64. The Prelude was the only one to occasionally conflict with the E-MU 1820 over ASIO, but this didn't prevent me from measuring its characteristics as well.

Another innovation in this review is a test of impulse response during which the tested sound card is made to reproduce a square wave with a sampling rate of 44.1 kHz. The result is recorded at maximum resolution the E-MU 1820 supports, namely 192 kHz/24 bit, which helps reveal any ringing at the wave fronts.

Finally, I measured the quality of cancellation of the byproducts of digital-to-analog conversion: ultrasound noise and aliasing noise. To perform this test I reproduced a sliding pure tone on the tested sound card, i.e. a sinusoid wave with a frequency of 20 Hz to 22 kHz.

Let’s first check out the results of traditional tests in Rightmark Audio Analyzer Pro 6.2.3. For the results to be as accurate as possible, I disabled all effects in the sound card's settings and selected a sampling rate in the Windows control panel to match the reproduced signal (44.1 or 48 kHz).

The results above suggest that the Auzen Bravura’s integrated ADC is greatly inferior to the professional audio interface in every parameter, yet the playback quality of 44.1kHz signal is even worse due to high noise. However, both measurements via the E-MU 1820 show excellent noise results at 44.1 kHz. Why?

The fact is, just when I began my tests with the E-MU 1820, the Auzen Bravura suddenly began to reproduce such signal with high quality when the device’s sampling rate was set at something other than 44.1 kHz in the control panel. The results were excellent when the sound was reproduced via DirectSound, but there were too much noise with WASAPI. My luck ended as suddenly as it had come. After some events, the most likely of which was the installation of the ASIO4ALL driver, the frequency automation that allowed reproducing audio of any quality without distortions just stopped to work. Below you can see two graphs that illustrate how great is the difference between the card's operation modes and outputs as well as between the Bravura's line input in comparison with the E-MU 1820.


Auzen Bravura Frequency


Auzen Bravura intermodulation distortions

As you can see, the Bravura’s headphone output delivers excellent results that surpass the capabilities of the E-MU 1820’s ADC, let alone the Bravura’s own line input. The line output distortions, on the contrary, are high and can be easily spotted even if measured via the card's own line input. The distortions provoked by the nonmatching sampling rates of the reproduced audio and the audio device setting in Windows 7 are just awful. Interestingly, when the sound card's headphone output is set at 96 and, especially, at 192 kHz, the distortions are not so conspicuous whereas the stereo panorama acquires more depth and the voices and instruments get a specific crystal-like clarity that some users may even like.

Anyway, sound cards with the Creative CA0110 chip generally deliver their best sound quality when the highest sampling rate is set in the Windows control panel. Users of such devices may want to learn the simple procedure of measuring with RMAA available at the official website in order to make sure that their sound card works properly. When measuring the parameters of an Auzen Bravura, you should keep it in mind that the maximum signal level is 3 volts on each of the card's outputs whereas the allowable input level is only 2 volts for some reason. Auzentech engineers didn’t follow the conventional level of 2 volts before, but they used to reset the sensitivity of the line input accordingly.

Taking advantage of the unexpected complaisance of the E-MU 1820 which agreed to work with all of the sound cards and was free from the ground loop problem which might worsen the measured characteristics, I could carry out some previously undoable measurements with my Auzen X-Fi Prelude 7.1. Its own line input didn’t provide the required quality and its results were not very high when measured via a Creative X-Fi Elite Pro or ASUS Xonar D2.

The Auzen Bravura isn’t bad in terms of headphone output quality, but the line output distortions are worse than with the other tested cards, including the Auzen Forte/HomeTheater that employ very similar components. I hope this is not a flaw in the circuit design but a manufacturing defect although neither gives the manufacturer any credit.

The Bravura’s headphone output surpasses the three other tested cards but in my ASUS Xonar D2 review I could see that sound card deliver higher results in terms of noise and distortions when tested via its own line input. Thus, the similar results of the three tested sound cards are due to their interaction with the E-MU 1820's inputs.


Frequency response of the four sound cards

Comparing the frequency response of the sound cards, we can note the odd hump in the Auzen Prelude’s graph and the waviness of the Creative PCIe XtremeAudio’s one. The latter can be explained by the documented feature of the digital filter of the AK4359 converter whereas the Prelude’s behavior is not so easy to comprehend. I will discuss it shortly. Here, I can note that the Auzen Prelude has an early decline in the low frequencies that the other sound cards do not have. I hadn’t noticed this before with this card, but it is the oldest among the samples I tested, so I suppose this must be the consequence of a loss of capacitance by the blocking electrolytic capacitors due to aging. Interestingly, the ASUS Xonar D2 and the Creative PCIe Xtreme Audio do not have capacitors in their line outputs and have a similar frequency response in the area of low frequencies. The Auzen Bravura's headphone output features the highest uniformity in high frequencies.


Intermodulation distortions of the four sound cards

The graphs showing correlation between distortions and frequency indicate a lack of anomalies that might be provoked by resampling when the sound card's settings do not match the reproduced audio material. Thus, the mystery of the accidentally discovered “magic” mode of the Auzen Bravura remains unclear. If it is software resampling, its quality is just amazing. The smooth rise in distortions at higher frequencies is due to the insufficiently high quality of the E-MU 1820’s inputs which limit the results of the Auzen Bravura. The Auzen Prelude is the closest to the Bravura’s performance despite being inferior to the other two cards in terms of noise which affects this test.

Now let’s take a look at the harmonics of all the four cards:


Bravura Headphones Out


Bravura Line Out


Prelude


Xonar D2


PCIe Xtreme Audio

Despite the different circuit design and converters, the distortions on the Bravura’s two outputs are very similar but their level on the line output is many times that of the headphone output. Interestingly, such a high level of distortions is barely noticeable when listening to music. It is also interesting that the improvements in sound quality over time, which are quite perceptible to the ear, only resulted in a tiny improvement in the distortions level which might as well be due to a thermal drift of parameters or measurement inaccuracies.

The Creative PCIe Xtreme Audio, on the contrary, is a nice surprise. Being the cheapest product in this review, it proved to be the best in terms of the high harmonics, being only inferior to the Auzen Bravura in the second harmonic level and to the ASUS Xonar D2 in the third harmonic level. No wonder that it was quite competitive against the more expensive and renowned opponents in my subjective tests.

 
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