X-Fi for Music Lovers: Auzentech X-Fi Prelude 7.1 in Detail

Audiophiles do not regard the PC as a serious audio source. Auzentech proves the opposite. Read more about this exciting sound product in our new detailed review.

by Sergey Romanov
12/18/2007 | 09:09 PM

Do you know the word Auzen? I guess not unless you are tracking absolutely all the PC-related news. However, it is the name that should be memorized by every lover of high-quality audio on the PC.

 

Auzentech is a young company specializing in audio cards. Its first press release dated February 2006, the firm is not even two years old yet, but it has already announced a fifth self-developed product and has started selling several interesting devices from third-party developers under its own brand. The newcomer’s activity is worthy of respect considering the audio quality of the company’s latest products. All of them employ superb converters from AKM, replaceable operational amplifiers (opamps), and solid electrolytic capacitors.

Auzentech’s first three products were based on C-Media’s controllers, and the company claims to be the world’s first maker of audio cards with support of Dolby Digital Live and DTS Connect. Perhaps it is so, but this support is implemented by C-Media’s engineers and programmers and available on all cards with the appropriate chip. In April this year there was another piece of hot news: Auzen is preparing a new product based on the Creative X-Fi audio-processor! Until that, Creative Labs had never supplied its technologies to third-party developers, so that was a kind of revolution by itself. Besides, the engineers were set the task of creating a hi-fi product that would combine the newest gaming technologies from Creative with high-quality music playback and advanced audio-editing capabilities.

PCB Design

The goal was achieved by using Asahi Kasei’s AK4396 digital-to-analog converters (previously tested on the Auzentech X-Meridian), solid-state electrolytic capacitors, and combined digital inputs/outputs that allow connecting both coaxial (SPDIF) and optical (TOSLINK) cables by means of included adapters. Besides, the audio card features premium dual-channel operational amplifiers and Asahi Kasei’s best analog-to-digital converter AK5394A that provides a dynamic range of 123dB and a total harmonic distortion of -110dB. The DAC’s parameters are superb as well (120dB and -100dB, respectively) but AKM supplies the better-yet AK4397 as well as the pin-compatible AK4395 that has an improved digital filter. That’s why I don’t quite understand why the AK4396 was selected for all the four stereo outputs especially as the front output is different from the other three.

First of all, the op-amp can be easily replaced – and I caught up at the opportunity during my tests. Second, the output low-frequency filter is based on a new LM4562 opamp which has already earned a reputation for its excellent audio characteristics. The other channels employ no less popular OPA2134 chips. The card’s height proved insufficient to accommodate the DAC and filter of the front channel, so they were moved away from the output connector. This solution can hardly increase the crosstalk and noise very much, yet it is not optimal.

The table below lists the basic parameters of the opamps employed on the audio card. It shows that the chip from National Semiconductor is superior to the Burr–Brown’s chip in every parameter except for the settling time, but that parameter is more important for the ADC’s input filter where the OPA2134 is installed.

 

More about the odd layout of the PCB, the digital-to-analog converter is located very far from the input connectors, almost at the other opposite side of the card. Some of the filtering capacitors recommended by the manufacturer are missing near the converter.

The capacitors that filters converter’s reference voltages have 470µF capacity. Thus, the distortion at frequencies below 80Hz will be higher than the declared level of -110dB.

Hopefully, the filter’s opamps are used in inverting operation. Otherwise, the distortion is going to be higher at the higher frequencies as well.

Comparing Auzentech’s X-Fi Prelude with the top-end product from Creative Technology, you can find quite a lot of things they have in common: the same ADC, four stereo DACs and the same amount of operation amplifiers, two memory chips for X-RAM (one of them is located on the reverse side of the PCB of the SoundBlaster X-Fi Elite Pro).

Apart from the more logical PCB layout and the different set of connectors, the difference boils down to the components used: CS4398 DACs (120dB dynamic range, -107dB THD), NJM2114 operation amplifiers from New Japan Radio Corporation for the output filter of the front output, NJM2068 amplifiers for the other outputs, and some variation of the NE5532 chip from an unknown maker for the ADC filter.

According to the manufacturer specs, these operation amplifiers have a higher distortion than the opamps installed on the Auzen X-Fi Prelude, but it was measured at a tenfold amplification and cannot be compared directly to that of the products from National Semiconductor and Burr-Brown. For reference, the specified distortion of the OPA2134 increases tenfold at such amplification, too. I want to note that the line outputs of both cards lack additional buffers, so the system’s sound may prove to depend on the quality of the cables. The option of plugging your headphones right into the card’s line output is limited, too. The latter comment concerns the Creative card less since the NJM2114 can output much higher current than the LM4562 or the OPA2134.

The main difference between the X-Fi Prelude 7.1 and the X-Fi Elite Pro is about the inputs and outputs. Creative offers one port for digital, line and microphone inputs which are switched by four electromagnetic relays, and three line outputs, two of which have a non-standard 3-pin connector for Creative’s 7.1 speaker systems. The PCB carries an AUX input for a TV-tuner or similar device. The rest of the inputs and outputs are concentrated in an external module attached via a 25-pin 1-meter-long cable.

The external module can be oriented vertically or horizontally. It has two pairs of digital inputs and outputs for coaxial and optical cables, a MIDI input and output, an analog input with RCA connectors, two 1/4” sockets for a microphone, electric guitar and other musical instruments, a digital output for Creative’s speaker systems, and a headphones output with a 1/4” socket and a 3.5mm adapter. The module also offers a control for regulating the volume of the analog outputs, buttons to choose an input and to enable EAX, CMSS 3D and Crystalizer.

Auzentech took a different approach. The user has a full set of standard connectors right on the card: four line outputs, line, microphone and AUX inputs, a digital input and output, and a very useful port that adds a second microphone input and allows connection of the audio ports of standard PC case.

As opposed to the Auzen X-Meridian 7.1 where the headphones output is additionally reinforced with a dual-channel inverting amplifier TPA6111A2, on the Auzen X-Fi Prelude 7.1 it is connected directly to the operation amplifier of the front output filter via 47µF capacitors. The inputs seem to be switched by an ADG412 electronic relay. The card should have acquired broader functionality by means of an X-Tension DIN [URL=http://www.auzentech.com/site/products/x-tension_din.php] module originally developed for the Auzen X-Meridian 7.1 – it provides an additional input for a dynamic or electret microphone (the type is selected with a jumper), SPDIF and MIDI inputs/outputs, and support for Creative’s multi-channel digital speaker systems – but the new audio card proved to be compatible with the MIDI interface and the SPDIF output only.

Installation

There is a lot of free space inside the big and pretty-looking box because the accessories are rather scanty. Besides the audio card, it contains a good optical cable (3m long), a couple of translucent adapters for it, an installation CD and a user manual. No additional software is supplied with the card. The CD only contains the driver for all versions of Windows.

The Auzen X-Fi Prelude 7.1 differs from the Creative X-Fi Elite Pro only with the DACs and the switching of the inputs, so it uses a slightly modified driver from Creative. The installer is greatly simplified: no flash animations, no optional programs, no extra questions. That’s why the installation process is quick and simple. After reading the license agreement, you are offered to choose the initial operation mode and the number of connected speakers.


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The difference in product positioning is clear here. The installer from Creative lists the modes in different order: Game, Entertainment, Audio Creation.


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The driver doesn’t have a digital signature yet, but provokes no problems under Windows XP and Windows Vista 64-bit.

You don’t have to reboot the system after the installation and you are not asked to register, either. An Auzentech Audio Console icon appears in the Control Panel, and the Start menu offers an icon for the Volume Panel which is automatically added into the Startup list.

Unfortunately, the card comes without additional software such as THX Setup Console and Creative MediaSource DVD-Audio Player. The latter program, when installed from the Creative disc, worked with the Auzen X-Fi Prelude normally, but the THN Console couldn’t see the compatible audio card at all.

The Volume Panel icon in the system tray is very handy. If you click it with the left mouse button, the volume control window appears. It also allows to run any Creative’s application installed. A right click on the icon allows changing some basic settings. The application takes no more than 9MB of system RAM.

The rest of the settings can be found in the Audio Console, which is going to be familiar to users of such products as SoundBlaster Live!, Audigy and X-Fi. The only notable difference concerns Dolby: instead of the Decoder tab where you could enable the integrated decoder of multi-channel Dolby Digital and DTS streams, there is a section with quite different contents.

The Auzen X-Fi Prelude can encode all sound (for example, surround sound in games) into Dolby Digital format, saving the user the trouble of laying out heaps of inter-block cables around the apartment. You can only wonder what will happen to signal already in this format (for example, to the sound track of a DVD) since the decoder doesn’t have any more settings. The card doesn’t support such special effects as Dolby Pro Logic IIX, Dolby Virtual Speaker and Dolby Headphone since CMSS-3D technology replaces them all. DTS CONNECT is expected to appear in early 2008. I have no doubt all these technologies will also appear on audio cards from Creative Technology then, too.

A double click on the Volume Panel opens up the console. It is a program for controlling the sound volume, effects and many other features. It is different for every operation mode of the card.


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In the Entertainment mode the console is stylized to look as a hi-fi system, with a volume control occupying almost half the application window and with clumsy timbre controls. The other half of the screen shows a multi-functional display with indicators of current parameters and buttons to evoke the following setup options: speaker configuration, reverberation effects, CMSS-3D, 24-bit Crystalizer, automatic volume adjustment, graphics equalizer, mixer, Dolby encoder, and digital output frequency. Pressing any button removes this row of buttons from the screen. If you want to go over to another settings section, you have to press the Main display button that appears below.


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Considering the sluggish transformation of the display, it is not a great pleasure to use this program, but that’s not the main drawback, however. The bass boost feature and cutoff frequency on Creative X-Fi cards are controlled in the speaker configuration section as well as in the THX setup panel. The latter was not licensed by Auzentech while the console for Windows XP doesn’t have the appropriate button for some reason. The Bass Boost option is available in Windows Vista, though.

The Bass Boost feature is available in the console for the Game mode. Otherwise, the Game mode offers the same functions as Entertainment:


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The driver saves speakers configuration for each of the three operation modes of the card. For three of those configurations (2/2.1/4.1, Headphones, 5.1 or 7.1) the CMSS-3D state is saved while the volume level is memorized independently for the speakers and headphones and does not change when you switch from one operation mode to another. Unfortunately, this handy feature fails in the Audio Creation mode.


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The volume control on the monstrous panel that only fits into the screen at a resolution of 1024x768 or higher remains indifferent to the change of sound volume when you switch from headphones to speakers and back again. Besides, the console doesn’t react if you change the basic frequency of the clock generator with the Settings button in the bottom left corner. The actual frequency will only be displayed when you close and reopen the application.

All sounds reproduced through Windows will be converted to the basic sampling frequency you select in the Settings window. Automatic switching of the frequency is implemented only for ASIO. Upon enabling Dolby Digital Live, the clock generator is switched to a frequency of 48kHz and any attempt to change it leads to a blue screen of death, so be careful. I want to note that the card does not support a sampling frequency of 192kHz at all. The sound is reproduced in 96kHz format even in the Entertainment mode with stereo speakers.

The screenshot below shows the available recording sources. Per-bit recording accuracy can be enabled for digital sources. The option of choosing the file format disappears after your doing so. If you then switch to another source, this option still remains hidden. The signal level is set at zero for every input by default, and it sometimes doesn’t work correctly when you try to increase it. If you find that silence is being recorded in one of the channels, just move the control to zero and then set the desired level again.


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As opposed to the Creative X-Fi Elite Pro, which has a few additional line inputs, all the analog inputs of the Auzen X-Fi Prelude 7.1 are combined under the Analog mix item – you can disable the signal from the Aux and Mic inputs in its additional settings. In the Entertainment and Game mode this is done from the console, but here you have to use Windows’ mixer. You can also adjust the volume of each of the eight reproduction channels there.


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The preferred difference between each channel volumes is maintained when the Master Volume is adjusted. By the way, the maximum volume of the line outputs of the X-Fi Prelude 7.1 is some 8dB above the commonly accepted level of 2V RMS and is as high as 5V, according to the manufacturer.

I cannot but tell you about a curious glitch. When the card was taken out of the system case for photographing, the console changed dramatically: there appeared strange inputs and the Bit-Matched checkbox became available for each recording source.


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The Audio Creation mode allows turning off all processing of the sound outputted by applications. To do so, you should Enable Bit-Matched Playback in the window that opens up after you click the Settings button. This option is also available on the respective tab of the audio console.

I guess the lack of the equalizer, crystalizer and SVM is perfectly made up for by the improved music playback quality I made sure of in following tests.

Acoustic Performance

To measure the quality of equipment objectively, you should disable any possible processing of the signal in the driver, including timbre control, application of special effects, and audio formats conversion. With X-Fi based audio cards this is only possible in the Audio Creation mode if the Bit-Matched Playback option is turned on and the card’s clock corresponds to the sampling frequency of the reproduced signal. The Wave source helps make sure that the original and reproduced signals are identical.


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I performed my measurements at the maximum sampling frequency the cards support at recording, 96kHz. You can click on the summary table for a full report.


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The results are somewhat discouraging: the signal-to-noise ratio and total harmonic distortion do not correspond to the declared 115dB. Compare them to the results of the Creative X-Fi Elite Pro:


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This card has a 10dB advantage in every parameter. However, these measurements were performed over the cards’ own line inputs whose quality is not yet verified. Besides, RightMark Audio Analyzer displays the averaged result for both channels of the card but they differ greatly in the X-Fi Prelude 7.1 as you can see from the THD spectrogram.

It’s clearly not all right with the left channel, the level of second, third and fourth harmonic being 10dB higher than in the right channel. To identify the weak link, the signal from the Auzen X-Fi Prelude was recorded on the line input of the Creative X-Fi Elite Pro which would only live together with the Auzen card in one system after some serious installation effort.


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The ground loops worsen the signal-to-noise ratio for such measurements but the harmonic distortions improve. So, the line input of the Auzen X-Fi Prelude is found guilty, and the nonlinear distortion of its output should be made out among the noise.

The third harmonic is very low, and there are no high-level harmonics at all. The Creative X-Fi Elite Pro is formally superior to the Auzen X-Fi Prelude in terms of total harmonic distortions, but the spectrum shows clearly the fifth and seventh harmonics which have a negative impact on sound quality according to some researchers.

There is no sense in comparing the amount of intermodulation distortions due to the great difference in the noise levels. I can only note that the apprehensions about the high level of crosstalk between the channels come true: the Creative X-Fi Elite Pro is better by 15dB in this parameter at frequencies above 1kHz.

Using the ASIO interface it is possible to send the sound to any of the card’s analog outputs. By the way, there is a strange tone at 12kHz of a mysterious origin when the ASIO is in use.


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The measurements do not show a considerable difference between the Prelude’s outputs, but the front output is better in every parameter except for crosstalk. These are the results you could expect from an audio card with such topology and components. The rear outputs of the Creative X-Fi Elite Pro are, on the contrary, much worse than the front one in terms of distortions.


Click for complete score report

I want to note a strange fact: after a while, perhaps after I had used the card with headphones without an external amplifier, the level of low-frequency noise grew in the right channel.

That was because of the LM4562 amplifier. I replaced it and got rid of that noise. The noise is not audible, the sound remains perfect.

Listening Experience

A high-quality audio section and an acoustically appropriate environment are necessary to compare the sound produced by audio cards of such a high level. I didn’t have such an environment and had to use high-quality headphones instead (Grado SR 325i and Beyerdynamic DT 770 Pro) together with a C.E.C. HD53R-80 amplifier and a Monster Standard Interlink 200 cable.

This class A amplifier has a low harmonic distortion factor (the manufacturer claims it to be 0.009% but my measurements showed 0.019% at 2V on the output) and easily copes with both the low-impedance Grados (32Ohms) and the high-impedance Beyerdynamics (250Ohms). The audio cards’ line outputs work worse with the headphones: the crosstalk grows up considerably, and the frequency response changes greatly at low and high frequencies. Intermodulation distortions get higher, too. Thus, it is not correct to compare the audio cards when connecting the headphones directly to the line output because each of them responds differently to such a load.

Comparing the sound of the Auzen X-Fi Prelude with and without the C.E.C. amplifier, I could note the worsening of the dynamics as well as the precision and dimensions of the scene. The lower the load resistance was, the more evident the amplifier’s advantage grew, also in terms of sound volume – the signal level at the card’s output goes down with a low-resistance load and fluctuates due to the irregularity of impedance relative to frequency. It seems that some of the electrolytic capacitors near the output filters are connected into the signal chain because the same headphones connected to the FP_Audio output (as I wrote at the beginning of the review, this output is connected to the operation amplifier via a 47µF capacitor) sound much louder. Subjectively, the OPA2134 loses detail not so much, so if you have to use headphones without an external amplifier, try connecting them to any of the rear outputs and send the sound to the necessary channels by means of ASIO.

With the C.E.C. amplifier the card sounded fantastically. I couldn’t believe my ears when I heard it first – familiar compositions were so unusual. Scorpions’ Holiday, Gary Moore’s Always There For You, Roger Waters’ Too Much Rope – I always use these compositions for a quick test of sound quality – they all acquired new details and surprised me with natural sounding. I listened through all my collection of test compositions and found nuances, previously unattended to, in every one of them. Interestingly, I had no doubt that each nuance that sounded differently was the correct sound while the audio cards I had listened to before were unable to reproduce it with such mildness and harmony.

The Auzen X-Fi Prelude creates an unbelievably realistic scene, filling it with the deepest bass and natural reverbs with precisely positioned instruments. Minutest details are reproduced in the sound of each instrument. Coupled with the excitingly accurate reproduction of space and distance, this delivers an unforgettable presence effect. The LM4562 was reported to produce a clear uncolored sound, yet I didn’t expect such a outer-space clarity. There are no screens between the listener and the music, and high-quality live recordings provoke an impression that you are indeed in the area where the concert is going on.

The sound from the other line outputs, serviced by the OPA2134 amplifier, is very good, too. The scene and details at mid-frequencies are close to those of the LM4562, but there is no such an impressively voluminous bass. High frequencies sound slightly different, too. Still, I guess this sound is preferable to the sound of the Creative X-Fi Elite Pro. The latter is no worse in terms of details, but produces a bright, somewhat lifeless sound. The Creative card copes much better with headphones attached directly to the line output, though.

The operation amplifier can be replaced without soldering, and I tried to figure out the reason for such a sound of the Auzen X-Fi Prelude by checking it with two operation amplifiers from Texas Instruments I had at hand. The OPA2132P sounded alike to the OPA2134 installed on the rear channels but it seemed somewhat worse at high frequencies and closer to the LM4562 in the deepness of the bass. With a NE5532 the card sounded no better than others – flat, bright and less detailed.

The sound remains clear but loses its precision and spaciousness without the Bit-Matched Playback option or in the Entertainment mode. The Crystalizer effect changes the frequencies somewhat, but kills the scene, so I guess this widely touted technology is only really useful in the Game mode where the sound of music is distorted seriously: it is not a pleasure to listen to music even with such effects as EAX, CMSS-3D, SVM and Crystalizer disabled. The sound is dull and non-dynamic, and becomes just unbearable if you enable CMSS-3D Headphones.

The gaming capabilities of the Auzen X-Fi Prelude 7.1 are the same as those of Creative’s cards with the X-Fi audio-processor, so I don’t want to discuss them at length here. I only want to note that you should enable CMSS-3D for HRTF processing, but the quality of Creative’s 3D sound is greatly overstated in my opinion. In the 2/2.1 Speakers configuration the sound is jerky when the hero is turning around, with the volume suddenly jumping from channel to channel (you can hear the audio stammer in the speaker test where a helicopter’s flyby around the gamer is simulated). In the “CMSS-3D headphones” mode the sounds are muffled, the distance is reproduced incorrectly and the timbre is greatly distorted. The helicopter demo sounds perfect, but I couldn’t hear such positioning in games. Moreover, it is much better to play Crysis with the 2/2.1 setting than with the Headphones.

Conclusion

Auzentech has come up with a highly interesting product that combines extensive gaming capabilities with superb music playback quality. Perhaps today it is the most “musical” sound source for the PC, yet a number of drawbacks limit its possible applications. For example, the lack of a speaker positioning option makes you use the appropriate option of the receiver, which negates the quality of the analog outputs. I also don’t comprehend the purpose of the headphones output without an integrated amplifier. And finally, the card doesn’t suit for recording music as it has too few inputs, lacks a native MIDI interface, and has problems with digitization quality. Thus, the audience for this product is limited to audiophiles who prefer listening music from the PC.

Highs:

Lows:

The second run of mass production began in October. Perhaps it brings about some improvements to the card already. Hopefully, we will get a chnace to check it out soon.