by Sergey Romanov
09/03/2009 | 10:03 AM
Since the announcement of Auzentech’s very first sound card based on the Creative X-Fi audio processor, I could not find an answer to one question: why had Creative given birth to its own market competitor? I was really at a loss trying to find an explanation during the review of the Auzen X-Fi Prelude 7.1 because Creative itself did not offer a similar combination of price and sound quality, not even the very option of encoding into Dolby Digital format. The fact that this feature subsequently appeared in the Sound Blaster X-Fi Titanium series (and became available for Creative’s earlier products as a paid add-on) makes me suspect the Auzen Prelude to have been a kind of a testing ground for polishing the technology off prior to implementing it in mass products under Creative’s own brand. But it is only new products from Auzentech that might clear up the issue.
Announced in mid-June 2008 and scheduled for September, the X-Fi HomeTheater 7.1 model was jointly developed by Auzentech, Creative, Nvidia, Silicon Image and CyberLink as the first Auzen sound card for the PCI Express bus. The development has taken rather too long, however. ASUS has long introduced its Xonar HDAV1.3 with similar functionality. Creative has launched a whole series of PCI Express products, but Auzentech could not offer anything new to its customers.
Since the release of the new sound card was only delayed due to the polishing off of its HDMI functionality, in early December 2008 Auzentech announced one more product that looked like an X-Fi HomeTheater without HDMI-related chips. The analog section of the original card had high component density in order to accommodate those HDMI chips, and without HDMI it proved to be a low-profile device. I dare suppose that it is the reduced height that ensured the release for the Auzen X-Fi Forte 7.1. So far, no product from Auzentech based on the X-Fi processor has ever directly competed with a product from Creative. They are always different in functionality and price category. For example, the X-Fi Prelude 7.1 does not spoil the sales of the X-Fi Elite Pro because the latter comes with an external I/O unit with a headphones amplifier and guitar input. The new X-Fi Forte 7.1 differs from the Creative X-Fi Titanium series with its form-factor and functionality and from the Creative X-Fi XtremeGamer with higher price and PCI Express. So, I guess I’ve come up with a good explanation of the licensing of X-Fi technologies to a third party and now we can proceed to taste more fruits of the collaboration between Creative and Auzentech.
There is a lot of free space in the small black-and-gray box because the kit includes only the bare minimum of things. Besides the card with a replaceable mounting bracket, there is a short braid of cables with analog connectors, an installation disc with brief user guide, an RCA-TOSLINK adapter and optical cable that resembles the one from the Auzen X-Fi Prelude 7.1 kit but is made from translucent plastic.
The card’s main features and capabilities and the system requirements are indicated on the box but nearly all the text is in very small print. The contents of the box are listed on the smaller side panel. Auzen is no good at providing visual information to the user.
Moreover, as you can see, the six connectors of the analog cable only differ with the color of the cambric tape on the wire. They are hard to differentiate in dim lighting. It is far more convenient when the connectors themselves are made from plastic of different colors as it was done with the Audiotrak Prodigy 7.1 LT, for example.
The included installation guide does not describe the card’s connectors, so you have to find the correct way of attaching your system case cable to the card’s 20-pin header.
Although the system case’s audio connector should be HDA-compliant, you can also use a system case with an old-type AC’97 connector if you disable automatic headphone detection in the sound card settings.
There is some confusion about the specs at the manufacturer’s website, but they are accurate in the user manual.
You can learn more about the specs of the employed components and expansion opportunities by reading the summary tables at the Auzentech website. They allow comparing different sound cards easily. The full list of compared cards can be seen in the first table.
After the ASUS Xonar Essence STX, the specifications of the Auzen X-Fi Forte 7.1 inspire no awe in me. The Forte equals the Auzen X-Fi Prelude in the formal quality of the front output because it comes with the same digital-to-analog converter. The Forte is identical to most Creative X-Fi series products and inferior to all ASUS Xonar series ones in the quality of the other outputs and line input. However, a number of technical solutions bring the Auzen X-Fi Forte 7.1 closer to the ASUS Xonar Essence STX as I will explain in the next section.
As opposed to the Auzen X-Fi Prelude 7.1, the software installer allows to select components and offers programs and add-ons that have been previously available to owners of Creative sound cards only. Particularly, these are AutoMode Switcher, Sound Blaster Plugin for Microsoft Media Center, Sound Blaster Vista Control Panel, 3DMIDI Player, WaveStudio and MediaSource. To my utter disappointment, MediaSource does not include DVD Audio Player, so you will have to try and find yourself a DVD player program that will be able to output high-resolution sound through the X-Fi Forte 7.1 without converting it into a lower-quality format. A disappointing thing too is that THX Setup Console, for setting up sound processing depending on the placement of the speaker system, is still unavailable.
The driver takes a lot of time to install and is incompatible with other X-Fi based sound cards. I could not make my X-Fi Forte work along with an X-Fi Prelude, X-Fi Elite Pro or a professional audio interface E-MU 1820. The controls provided by the software do not differ from those of other X-Fi based sound cards, so I can just link you to the Auzen X-Fi Prelude 7.1 review where you can find a detailed description of them. When it comes to setup options, the Auzen X-Fi Forte 7.1 only differs from the previously reviewed card with the selection of recording sources. It does not offer Analog Mix and S/PDIF-in but has an additional microphone input.
Yes, this sound card is capable of recording two microphones (or a microphone and the line input) simultaneously. Some people may find this feature highly useful. Besides, the X-Fi Forte 7.1 is equipped with an additional headphone output with integrated amplifier developed by Auzentech. In the next section I will tell you more about the technical solutions implemented in this sound card.
The Auzen X-Fi Forte 7.1 has a black PCB with a unique velvety coating I have never seen before. Together with the darkened metal of the mounting bracket and the bright green capacitors, this endows the card with an original and attractive appearance that the photograph fails to convey.
Thanks to its reduced height, the sound card can be installed into slim system cases. The Auzen X-Fi Forte 7.1 is designed like the out-of-production Audiotrak Prodigy 7.1 LT which also used to have an integrated headphones amplifier and a braid with 3.5mm analog connectors. Modern low-profile sound cards come either with fewer outputs (like the Audiotrak Prodigy HD2) or with analog inputs and optical output combined (ASUS Xonar D1) or with nonstandard output connectors (Creative X-Fi XtremeAudio) or with all of that (Creative X-Fi XtremeGamer). And if you need a low-profile PCI Express sound card, your choice is limited to two models only: the ASUS Xonar DX and the Auzen X-Fi Forte 7.1 that I am talking about right now.
The card’s heart is the latest audio processor E-MU 20K2 that is used by Creative in its Titanium series sound cards. It is identical to the E-MU 20K1, the basis of all X-Fi family cards, in terms of sound processing, but features an integrated bus controller optimized for PCI Express and supports DDR memory. As opposed to the Auzen X-Fi Prelude 7.1, the card’s 64 megabytes of buffer memory are represented by a single X-RAM chip, which helped save PCB space.
The high component density is not only due to the specific form-factor. It is also due to the unusually broad range of functions. As I mentioned above, the X-Fi Forte 7.1 seems to trace its origin to the not-yet-released X-Fi Home Theater, but a close examination of the comparative tables reveals one important difference between them: the latter card’s four stereo outputs have identical characteristics whereas the front output of the Forte is based on a separate stereophonic DAC from Asahi Kasei and a higher-quality operation amplifier. Of course, a sound card does not have to have high-quality analog outputs if it is mostly meant to deliver sound via a digital interface (HDMI), but a high-quality DAC makes the HDMI-less model more appealing in the customer’s eyes. Moreover, the combination of AK4396 and LM4562 chips (the latter was later renamed into LME49720) was quite successful on the X-Fi Prelude. Still, I’ve got one question: why AK4396 if it is no better than the CS4382 installed on the other outputs in terms of distortions? Auzentech makes use of the AK4396 in their third sound card model in a row, why not make at least a small step forward? I don’t even mean the newest AK4399 which boasts best-in-class specs. The AK4390 would suffice as it is superior to the AK4396 across most of parameters. I can remind you that ASUS offers better DACs even in the less expensive models of their Xonar family.
Instead of a higher-quality DAC, Auzen engineers have fitted as many as two ADCs, one of which is only responsible for the microphone input on the computer case’s front panel. Neither the WM8782 (SNR -100dB, THD -93dB), nor the WM8775 (SNR -102dB, THD -95dB), which is responsible for the line, microphone and auxiliary inputs, boast high specs. Most of Creative X-Fi series cards come with the same converter and the Auzen X-Fi Forte 7.1 does not make use of two out of the eight channels provided by the CS4382 (the front output and the headphone amplifier are equipped with a dedicated AK4396 DAC), which makes me suspect that Auzentech receives a set of chips from Creative that includes an audio processor, system memory, DAC and ADC chips. Using this chip-set, the company has created an original sound card.
To tell the world how unique the Auzen X-Fi Forte 7.1 is, a special document was issued. It was later published in the Tech Notes section of the manufacturer’s website, describing in detail that the sound card is equipped with a high-precision clock generator, carefully calculated analog filters with minimum phase shift, high-quality components, and a number of exclusive technologies such as balanced power generation system, pointing ground design (using the star topology typical of high-end equipment), a composite headphones amplifier, and a microphone amplifier with balanced input. Unfortunately, I could not find any details about the clock generator and the characteristics of the filters whereas the other technical solutions are covered in the Tech Notes section, so I will only dwell upon a few unobvious points here.
One of the most important innovations implemented by Auzentech is the headphones amplifier. Until now, sound cards that allowed to directly connect headphones used to do with the modest capabilities of opamps installed on the appropriate output. When a load with a few dozen Ohms’ impedance is connected to the output of such an opamp, the latter’s linearity usually worsens and there are some other undesirable effects. Reinforcing the output with a buffer based on the same opamps helps reduce the negative consequences of low-Ohm load but does not eliminate them altogether. One possible solution of this problem has been recently examined in our review of the ASUS Xonar Essence STX sound card where a high-speed operation amplifier with current feedback plays the role of a headphone amplifier. For all advantages of such opamps, the TPA6120A2 model was not particularly good at handling a 32Ohm load while the amplifier’s output resistance could not be close to zero even theoretically because of the need for an output resistor to isolate the opamp from the load capacitance. A special buffer, e.g. an LME49600, might be used, but Auzentech engineers went their own way.
The headphone amplifier of the Auzen X-Fi Forte 7.1 is based on a composite design with an NJM4580 amplifier and a buffer based on eight transistors from an obscure maker. A couple of transistors more can be found on the reverse side of the PCB. Amplifiers based on discrete components have been considered a prerogative of expensive external devices and have not been used on sound cards except for the twin products Audiotrak Prodigy 7.1/Terratec Aureon Space whose 4-transistor buffer was Class B and did not ensure high sound quality. Thus, it is the external DAC called Audiotrak DrDAC 2 that seems to be the most similar product to the amplifier of the Auzen X-Fi Forte 7.1 but it is a few times as expensive as this whole sound card.
The purpose of the Balanced Power Generation System is to convert the +12V voltage from the PCI Express bus into bipolar ±10V power. The key feature of this system is in the symmetric filtering of the converters’ ultrasound noise to ensure that the potentials of the positive and negative buses change concordantly. Theoretically, the level of the virtual ground remains the same across a very wide range of frequencies and power noise cannot seep into the sound card’s output signal.
The Pointing Ground Design means two well-known principles. First, the digital and analog grounds are separate. And second, all ground interconnects of all analog section components converge in a single point (the so-called star). The latter principle is most important for power amplifiers because the voltage drops down in PCB interconnects when high currents are flowing in them, and the ground ceases to perform its role of the reference zero potential. The Auzen X-Fi Forte 7.1 comes with a rather serious headphone amplifier that has an output power of 2x100 milliwatts, so this wiring is quite useful.
One more special feature of the sound card is the support for microphones with symmetric signal. A symmetric transfer of weak signals can improve their protection against noise, and such microphones could only have been connected to studio equipment or professional sound interfaces like the E-MU 1820, which are absolutely incomparable to the Auzen X-Fi Forte 7.1 in terms of price. Coupled with the opportunity to record the line and microphone inputs simultaneously, this sound card might be a good tool for a home recording studio, but there is one hitch: the microphone amplifier with symmetric input is installed on the same analog-to-digital converter that services the line input. That is, you still have to choose either one or another when recording. Moreover, the opportunity to connect a stereophonic microphone mentioned in all the manuals proved to be not true. Only monophonic sound can be recorded from both microphone inputs.
Winding up the description of the sound card’s hardware, I want to note the capacitors and resistors which are often undeservedly disregarded as unimportant. For example, in our ASUS Xonar Essence STX review we saw a considerable difference in the measured characteristics of the right and left channels that did not depend on the opamps and the tested output (line or headphone). Therefore, I was glad to learn that the Auzen X-Fi Forte 7.1 uses 1% tolerance resistors. This should ensure that the characteristics of the different channels coincide.
ASUS emphasized the importance of Nichicon’s FG series electrolytic capacitors in achieving the resulting sound quality of the Xonar Essence. Auzentech uses capacitors from Nichicon, too. These are the eight bright-green Nichicon ES series capacitors installed on the analog outputs. The power supply of the analog circuits is filtered with inexpensive general-purpose capacitors of Sam Young’s SHL series. There are also 14 electrolytic SMD capacitors on the PCB, a couple of film capacitors in the front output filter and nine tantalum AVX capacitors in the power circuits of the DAC and ADC. In the next section I will try to tell you how these variegated components affect the sound quality of the card.
Like in all previous reviews, I checked out the audio card’s sound quality with a pair of Grado SR 325i headphones, a C.E.C. HD53R-80 amplifier, and various musical material in WAV and APE formats reproduced through foobar2000 0.9.6 with foo_out_asio 1.2.7 plugin. To minimize any digital processing of sound in the driver, the card was switched to Audio Creation mode with Bit-Matched Playback enabled.
The test computer was configured as follows:
Frankly speaking, when I recognized in early photos of the Auzen X-Fi Forte 7.1 the same digital-to-analog converter and operation amplifier as had been used in the Auzen X-Fi Prelude 7.1, I began to expect these two cards to have identical sound quality. However, there are far more differences between them than similarities. But I’m anticipating.
First off, it proved to be impossible to pit these two cards directly against one another because the driver version 1.1 for the Prelude and version 1.0 for the Forte, published on the same day on the Auzentech website, were incompatible. Depending on what driver was installed last, one or the other card did not work. I tried to force driver installation, with or without replacing older files with newer ones. I even tried to modify the Forte driver, being newer in terms of file versions, by adding Prelude-related strings into the INF file, but all in vain. So, what to do then? I had noticed the ASUS Xonar Essence STX to sound almost like the Auzen X-Fi Prelude 7.1 if its default NJM2114 opamps were replaced with NE5532P opamps. The Auzen Forte is not exactly an opponent to the ASUS Essence because these products are developed with different goals in mind, but they do have a lot in common including a PCI Express bus, a dedicated headphone output with integrated amplifier, and music-oriented capacitors. So if these two cards prove to be similar in sound quality, the Auzen X-Fi Forte 7.1 might be called the winner as offering more capabilities at a lower price!
However, these hopes were shattered as soon as I tried to listen to music, without even comparing the sound to that of other sound cards. The Auzen X-Fi Forte 7.1 was unpleasantly aggressive and I had a headache within half an hour of listening to it in headphones. Its stiff highs jarred on my eardrum and its sharp bass lacked the bottommost frequencies, transforming each drum into a “tum-tum” drone. There was almost no sound stage altogether, which was absolutely unlike the Auzen Prelude! That was even not comparable to anything I had heard before, including the integrated audio of mainboards. The closest example I can think of is the sound of a too-tight guitar string. This initial experience calmed me down somewhat and I took to testing an ASUS Xonar Essence STX in games for the appropriate review. The Auzen Forte was left in the system case to warm up.
I had been rather skeptical about the need for audio equipment to warm up to work properly as I had not been able to see this effect in practice. All sound cards I had tested earlier did their best right out of the box and my initial impressions were no different from later ones, such factors as driver issues and software settings put aside. However, the warming up indeed applies to the Auzen Forte due to two reasons. Its electrolytic capacitors have a very high operating temperature and its sound quality improves over time! The two largest capacitors in the voltage converter (470µF, 16V) are scorching hot at work and the rest of the components, including the blocking capacitors Nichicon MUSE (33µF, 25V) on the analog outputs, are hot, too. I don’t know for sure if this is the reason for the changes in sound, but it is a fact: the stiffness of high frequencies vanished in a few weeks, bass sounds became more detailed, and the aggressiveness turned into good macro dynamics.
In my three previous reviews I referred to the sound of the Auzen Prelude as comfortable, gentle and airy. The card’s exceptional tonal neutrality together with high definition and spatial resolution provoke the presence effect with high-quality binaural recordings but prove to be impotent with full-bodied music. The Prelude is not good with heavy metal and with the fortissimo of brass wind instruments, violins and choruses, as if choking. While a recording is calm, the card reproduces it with superb detail however complex the polyphony might be. But as soon as the power of sound exceeds a certain limit, the recording becomes flaccid and lacking in resolution.
The Auzen Forte proves to be almost completely the opposite. It is good with intensive guitar solos, concert trumpets and other calm-shattering instruments, but is clearly inferior to the sound cards reviewed earlier in micro dynamics. Where the Prelude constructs around the listener the concert hall, studio or scene the composition was performed in, the Forte only defines the most conspicuous landmarks. Where the Essence surprised the listener with its details across the entire frequency range, with the force and liveliness of overtones, the Forte leaves just the basic framework of the musical composition with a poor stereo image and without distinctive tiering. Although not exactly flat, the sound scene is almost devoid of perspective. Reverberations are weak and vocals are not as magic as with the Prelude. Bass sounds are worse, too. High frequencies are not very detailed and are rather unnatural. The attack seems to be somewhat protracted, worsening the naturalism of timbres and clarity, but the Forte can easily compete with any other sound card in terms of dynamics.
If compared directly to the Forte, the Xonar D2 delivers a somewhat clearer sound and much more distinct reproduction of environmental acoustics. It produces a soft and nice sound with distinct smaller details and excellent dynamics. The Xonar D2 is somewhat better than the Forte at building the sound scene in terms of spaciousness and sharpness of images, but may be inferior to the Prelude in the acoustic correctness of those images. For example, the clicking of an oboe’s valves in one recording was perceived as a separate sound source due to the difference in the reflections of sound from the studio walls. The Prelude is also better at reproducing realistic applause, the Xonar D2 and Forte taking second and third places, respectively.
Why do I not compare with the ASUS Xonar Essence STX? As I wrote in an earlier review, this card is potentially better than others but its default opamps are not quite good while my replacements for the I/U stage were deficient in one respect or another. For example, the NJM2114 has a poor control of bass, minor distortions of tonal balance and muddy and loud highs which can be easily heard in recordings of a drum. The NE5532 improves bass sounds, removes the coloring, but does not clean the highs and limits the dynamics. Thus, with every opamp I tested the Essence was inferior to its opponents in some specific parameter but it always delivered a detailed sound, saturated timbres, good spatial resolution and clarity. Could it be the effect of special capacitors? I might have achieved optimal characteristics by buying and testing other opamps and this would have made the Essence even more superior to other sound cards.
Does the Auzen Forte react to opamp replacements? Being unsatisfied with its sound on the first day of my tests, I replaced its LME49720 with AD826 but the difference was negligible. The sound of the AD826 had left an ambiguous impression on me in my tests of the Auzen Prelude, the LM4562 proving a better option.
Having used (i.e. warmed up) the Forte for a month, I made another try and could hear the difference right away. The AD826 makes the smallest details somewhat fuzzy, but creates a good volumetric stereo panorama with a distinct perspective and much better separation of instruments. Vocals and wind instruments are more impressive and bass sounds are more defined. High frequencies are softer and more detailed, but the overall sound acquires a certain melancholy hue I find it difficult to describe.
Next I tried an OPA2132P but not for long because I heard a caricature of music with a toy-like scene and a strong coloring of all frequencies. That was queer because this opamp had done well enough on the Auzen Prelude.
Not hoping for any good outcome, I installed an NE5532P on the card and was surprised once again. This time it was a pleasant surprise. The changes in the sound scene were almost the same as with the AD826.
The older NE5532 could not deliver as high resolution as the newer chip, but was still better than the default LME49720 in some parameters. Frankly speaking, I can’t even explain this by comparing their specs.
And the biggest surprise was when I installed an AD823 which changed the card’s character completely. The lack of micro dynamics and poor echeloning are nonexistent with the AD823! Dynamics is even overemphasized occasionally. The sound scene is drawn very finely (even though not very deep). Environmental acoustics can be heard distinctly. Applause is finally as good as real. String instruments get more realistic, violins being most exciting. The binaural recordings from the Audio STAX – The Space Sound disc were reproduced without a flaw and I was ready to call the AD823 the ideal option for the Auzen Forte but then I quickly realized that most musical albums were irritatingly sharp with this opamp. The tonal balance is shifted into the high-frequency area and the sound is overall too shrill, especially when reproduced via the integrated headphone amplifier. Thus, each of the opamps I tested had some drawbacks and I had to go on looking for an optimal option.
I ordered an LM6172, an opamp with good specs and positive user reports, but it was not quite good, either. One sample of this opamp was as good as the AD826. The LM6172 seems to me to be in between the AD823 and LME49720 in terms of sound quality. It is a little aggressive but good at reproducing vocals. It has rather clean but somewhat too sweet highs, which provoke the feeling of a lack of bass in heavy metal recordings, especially when listening to them via the integrated headphone amplifier. Environmental acoustics are lacking, too, whereas the AD823 reproduced it rather too conspicuously. Yet the more I listened to the Auzen Forte with this opamp, the more I enjoyed the music. It is another case of warming up of electronic components? But this improvement in sound was emerging for a few days and was not related to temperature. By the way, the LM6172 has a wide variance of characteristics (particularly, open-loop gain and common mode rejection ratio), so I recommend you to buy a few samples of this opamp and select the best of them if you want to use an LM6172 with your sound card.
It is the amplifier developed by Auzentech that I can find no fault with. It was better than the Xonar Essence STX’s amplifier with low-impedance headphones (Grado SR 325i) although the Auzen X-Fi Forte 7.1 itself does not sound that good. I could not find an obvious deterioration in sound quality when comparing the Auzen Forte’s integrated amplifier with the C.E.C. HD53R-80 except that the piano was somewhat more realistic on the C.E.C. The integrated amplifier occasionally delivers a better resolution and clearer highs, but it is about the highs that I have some gripes. I guess they are due to the NJM4580 chip employed in the amplifier. The NJM4580 is installed on rear outputs, so its sound can be rather easily learned. Unfortunately, the developer has not provided the option of solder-free replacement for this opamp.
Comparing the rear channels (“Back” and “Side”) with the front output, I could find no substantial difference. Moreover, the front output would often produce a less natural sound with an LME49720 opamp than the rear channels, especially in terms of sound scene depth. As the card was “warming up” and when the opamp was replaced with the AD826, the rear outputs did not seem so attractive, yet offered better micro dynamics and resolution in some recordings. There were some sound defects in the rear outputs such as “graininess” in cymbals, “cardboard” in drums, and suppressed and unexpressive vocals. The same characteristics are typical of the NJM4580 as far as I could examine it with other sound cards, but are not always to be heard. As a result, my preference is divided between the front and rear outputs, which again raises the question whether the dedicated AK4396 DAC is needed on the front output.
I was also curious to check out the professional microphone amplifier of the X-Fi Forte 7.1, so I bought an inexpensive dynamic microphone in addition to my old electret-foil one. To my surprise, the card coped with both microphones well, ensuring a dynamic range of about 60dB on both inputs at a rather high sensitivity. The sensitivity of the front-panel microphone input is half the sensitivity of the professional amplifier whose connector is located at the back panel of the case.
I will not dwell upon the gaming properties of the Auzen X-Fi Forte 7.1 because they are no different from those of any other sound card based on the E-MU 20K audio processor of the first or second version. Everything said on this topic in my previous reviews stays true. I can only add that with the AD823 opamp sound effects and spatial positioning are the most distinct while the background music is not as obtrusive as with the LME49720.
It was a trouble to measure the characteristics of my Auzen X-Fi Forte 7.1 and I did not obtain ideal results anyway. To remind you, RMAA performs its measurements by recording a reproduced signal via a line input of a sound card, and the result is always limited to the capabilities of that input. The specifications of the WM8775 ADC installed on the Auzen Forte suggest that it is impossible to achieve a SNR better than -102 when measuring via the sound card’s own line input. Therefore I am very curious about how the dynamic range of 116dB was achieved for the front output in the measurement results posted in the Tech Notes section of the official Auzentech website.
My attempts to perform the measurement via higher-quality line inputs of other sound cards were not very successful due to a number of reasons. The maximum output signal of the Auzen Forte is 3V, but it proved to be incompatible with professional sound interfaces from E-MU which could digitize such signal and I did not have other brands’ equipment at my disposal. If the sound volume is decreased to the regular level of 2V, you cannot achieve maximum results. Moreover, the results were worsened even more by a high level of noise and interference, obviously due to the power supply of the Auzen Forte’s analog circuitry (the Balanced Power Generation System). The headphone output delivered much more credible results thanks to lower output resistance, so let’s discuss them first.
Below you can see the characteristics of the headphone output as measured through the Auzen X-Fi Forte 7.1’s own line input at different sample rates as well as through the line input of an ASUS Xonar Essence STX.
The results suggest that the noise (and dynamic range) is indeed limited to the Auzen Forte’s ADC, but the harmonic distortions are almost the same irrespective of the sound card. Let’s take a look at the distortion spectrums.
Auzen X-Fi Forte 7.1 headphones Out distortions; measured via X-Fi Forte line-out
Auzen X-Fi Forte 7.1 headphones Out distortions; measured via Xonar STX line-out
When measuring via the Auzen Forte’s line input, we can see a big difference in the harmonics between the left and right channels which is not observed when the measurement is performed via the higher-quality line input. The second harmonic is somewhat higher when measured via the ASUS Xonar STX but the other harmonics are lower. However, these differences may be due to the reduction of the reproduction volume to 2V rather than to the higher quality of the Xonar STX’s ADC. To make the picture complete, I will show you the official diagram for the AK4396 DAC which is responsible for the card’s front output and headphone amplifier.
My measurements of the card’s line outputs produced the following results:
The front output could not outperform the headphone output in terms of measured characteristics despite the latter’s extra amplifier based on an opamp and eight transistors. Moreover, the rear output is almost no different from the front one if measured via the line input of the Xonar STX, i.e. with the volume level reduced by about 3dB. This does not agree with the data published on the Auzentech website.
Now let’s take a look at the distortion spectrums.
Auzen X-Fi Forte 7.1 front Out distortions; measured via Xonar STX line-out
Auzen X-Fi Forte 7.1 rear Out distortions; measured via Xonar STX line-out
The total harmonic distortion being similar, the rear outputs (a CS4382 DAC with a filter based on an NJM4580 opamp) differ from the front output (an AK4396 DAC with an LME49720-based filter) in having a 10dB lower second harmonic and an almost 10dB higher third harmonic. The rear outputs also have a higher level of the dissonant seventh harmonic.
And now let’s move on to the most interesting test. It is the test of the headphone amplifier under load. The measurement method was adjusted to a new recording sound card, which was an ASUS Xonar Essence STX. This card’s line input is designed to record peak to peak signal up to 5.65V, but most headphones are unbearably loud at such a voltage. To perform the test under more real-life conditions, but also to comply with the signal level requirements of RightMark Audio Analyzer, I had used to increase the sensitivity settings in the Creative X-Fi Elite Pro mixer. The ASUS card’s driver does not offer this opportunity, so I just used RMAA’s own ability to increase the volume of the recorded signal within 9dB which had been used to measure at an even lower volume. Thus, the system was calibrated for a volume of -7dB before the test, which agrees with the volume I had used in my two previous sound cards reviews, yet the new results cannot be directly compared with those published earlier. Particularly, the Xonar STX did much better in this test whereas the C.E.C. HD53R-80 did somewhat worse than they had done in my previous test sessions.
I test amplifiers under load using a homemade splitter that connects the amplifier’s output with the headphones and the sound card’s input. To minimize noise, the splitter is made from screened cable, which results in a considerable growth of crosstalk under such load as a pair of Grado SR 325i headphones (32Ohm impedance), so you should only use the Stereo Crosstalk results for comparisons within this test session only. I also tested the C.E.C. amplifier with a different cable connected into the duplicate connector of the right output.
The summary table with the results of three amplifiers indicates that the integrated amplifier of the Auzen Forte ensures the lowest level of harmonic distortions. Moreover, it delivers the best result among all devices we have tested in our labs. The dynamic range is obviously limited by the quality of the Auzen Forte’s own line input and the problem with noise when measured via a different sound card. Anyway, 90dB is quite a good result, too. The only drawback of the Auzen Forte’s amplifier is its non-zero output resistance, which leads to insufficient electric damping of the dynamic heads at low frequencies. This explains the poor results of the intermodulation distortion test in which a high-amplitude 60Hz tone is used.
On the other hand, the ASUS Essence’s integrated amplifier is not any better. It is the C.E.C. that has the lowest output resistance which can be observed in the distortions at low frequencies as well as in the influence of the nonuniformity of headphone impedance on the amplifier’s output voltage.
Amplifiers gain-frequency characteristic under heavy load
The graphs above make it clear that the Essence STX amplifier has a somewhat larger frequency range but the Auzen and C.E.C. amplifiers cannot be blamed as their frequency range at -0.5dB is 15 to 40,000Hz.
Auzen X-Fi Forte 7.1 nonlinear distortions spectrum
The harmonic distortion spectrums of the Auzen amplifier do not differ much when measured via the card’s own line input or via the Xonar Essence STX. The second and third harmonics are no higher than -100dB. The higher-order harmonics fall down quickly, and the most dissonant seventh harmonic is almost completely lost in noise. That’s an excellent result!
Asus Xonar Essence STX nonlinear distortions spectrum
The ASUS amplifier might be called excellent, too, if the second and third harmonics at a load of 32 Ohms were somewhat lower. The higher-order harmonics fall down very quickly here.
C.E.C. HD53R-80 nonlinear distortions spectrum
It is the C.E.C. amplifier that boasts the best linearity. Its fourth harmonic is already hard to see. In fact, the only unpleasant thing is the rather high third harmonic. However, in the previous test of the same amplifier with the same headphones but with a Creative X-Fi Elite Pro and with a different mainboard, the third harmonic was not visible at all in the amplifier’s right channel. So, I am not going to blame the amplifier. It is excellent even with a load of 32 Ohms.
I also measured the card’s line output using its own line input with every opamp and was surprised to see that the measurements were indicative of the difference in quality and character of distortions. It is not big but the measured characteristics of the Auzen Prelude did not depend at all on the opamp employed. It is the AD826 that delivered the lowest THD. The LME49720 and OPA2132 had the highest THD. The others were in between with the same result of 0.0009% but with different shape of distortions. Perhaps this is just a measurement inaccuracy, but the results were repeatable.
Modern digital-to-analog converters, including the AK4396, offer a choice of several oversampling and digital filtering modes. The sharp roll-off mode ensures better damping of high-frequency noise and is the most popular, but the slow roll-off filter handles the signal more carefully, which may result in a more natural sound. Judging by the smooth decline of the output signal amplitude at high frequencies and the sound improvements with the high-speed opamps AD826 and LM6172, the Auzen Forte uses the slow roll-off mode. These modes are selected on the software level with the DAC configuration register, so the setting may change with driver updates, making the card sound more like the Auzen Prelude.
And finally, I have to tell you about a queer bug in the first version of the Auzen Forte driver. It is going to provokes some trouble for people who use the hibernate feature in Windows XP (I did not test the card in Windows Vista). The problem is that the front output and headphone amplifier begin to sound very dull after your computer awakes from hibernation. The rear outputs, serviced by another DAC, are not affected. This reminds de-emphasis, so I guess the AK4396 is not initialized properly and enables de-emphasis on leaving the hibernation state. This is odd because the AK4396 works with the X-Fi chip without any problems on the Auzen Prelude.
The testing of the Auzen X-Fi Forte 7.1 has left an ambiguous impression. First off, it is absolutely not an Auzen X-Fi Prelude 7.1 of a smaller form-factor as you might expect judging by the specifications and employed chips. On the contrary, these two audio cards prove to be completely different! To my greatest surprise, the Auzen Forte shows its best at reproducing full-bodied music with expressive drive (hard rock, heavy metal, symphonic orchestra) that is the only weak spot of the Auzen Prelude, but in all other factors the newer card falls short of the quality standards set by the Auzen Prelude over two years ago, notwithstanding the declared advantages such as the precision clock generator, high-quality passive components and an ingenious power circuit of the analog section. To make it even more complex, the card’s sound quality changes greatly over time. Although these changes make the card sound better, who knows what it is going to sound like after a while?
Featuring a number of unique capabilities for its class, the Auzen Forte implements them in a strange way. For example, the support for studio microphones with balanced connection and the declared opportunity to record both the microphone and the line input simultaneously proved to be incompatible. You can have either a studio microphone or the option of simultaneous recording of the line input and microphone connected to the system case’s front panel. The indubitable advantage of the easy replacement of the front output’s operation amplifier is negated by the inability to replace the headphones opamp. The highest quality of the headphone amplifier is somewhat spoiled by the imperfect quality of the front output this amplifier is connected with on the hardware level. The use of the stereophonic AK4396 DAC together with the eight-channel CS4382 provokes some questions because these amplifiers have the same specified level of distortions. And subjectively I could not find any advantage of the former over the latter.
Who is a potential buyer of this card? Although the Auzen X-Fi Forte 7.1 does not look like an indisputable leader in terms of quality in its price sector ($150 if purchased from the Auzentech website), it might entice you with the numerous advantages over opponents, the most important of which is the top-quality headphones amplifier. Moreover, if your system case connectors comply with the HDA standard, the card enables the appropriate driver mode and turns off the line outputs automatically as soon as you plug your headphones in. Coupled with the full-featured audio processor X-Fi, this makes the Auzen Forte a perfect choice for gamers and a worthy opponent to the Creative X-Fi Titanium Fatal1ty Edition.
As for music reproduction, you can correct it to your own taste by replacing the opamp with one of the adapters offered by Auzentech or with an LM6172.