Creative Soundblaster X-Fi 5.1 USB

Jake Carroll sets his testing gear to stun and takes no prisoners.

Something that has always been missing in the mobile computing market is serious sound. The Creative Soundblaster X-Fi 5.1 USB aims to provide a market-filler, addressing:

A 5.1 channel surround decoder solution.
Sonic enhancement of lossy audio with Creative’s Crystalizer technology.

This month, we test the Creative Soundblaster 5.1 X-Fi USB, comparing the Crystalizer output with a non-processed signal on 128Kbps encoded MP3 audio. In theory, the Crystalizer technology should even out some of the inconsistencies in highly compressed audio, making it more pleasing to the human ear.

Our test system this month consisted of a MacBook Pro running Windows Vista Ultimate Edition Service Pack 1. We hooked up a set of Sennheiser HD457 headphones as well as the usual collection of speakers from Altec Lansing (U-621s) and Logitech (z-5500s).



The slider in Figure 1 allows the user to affect the signal processing to a lesser or greater extent. In practicality, we found this to make the 128Kbps audio sound louder, with accentuated high and low frequencies, or the opposite if the function was turned off. As to whether or not it improves the quality of the audio itself, the best we can say is that the function ‘fills out’ the potentially cut frequencies. This isn’t so much intelligent psycho-acoustic engineering taking place, but some primitive graphic equalisation. There doesn’t appear to be an adaptive algorithm used here.

Not satisfied with our own ears’ appraisal (and moreover, looking for some hard numbers to see what impact the post processing technology has on the signal!), we employed Right Mark’s Audio Analyser engine to benchmark the quality of the audio internally, with the Crystalizer turned on and turned off. Figure 2 shows a comparison.



The Crystalizer essentially destabilises the frequency response from the nominal form, making it deviate +/- 3Hz away from the control signal (in green). In applying the Crystalizer technology, we are gaining frequency at one point, but removing it or decreasing it at the other end of the scale. At a very scientific level, this is a sub-optimal approach to fixing compressed audio. As we mentioned previously, a psycho-acoustic approach using an adaptive algorithm, rather than EQ’ing would seem more appropriate here.

We decided to check if the act of applying the Crystalizer technology actually distorted or cleaned the sound. We did this by measuring the intermodulation distortion quotient (talk nerdy to me, baby! –ed) of the sample audio with and without the Crystalizer.

Unfortunately, it appears that adding the Crystalizer technology into the mix only served to create more intermodulation distortion. This appeared to be consistent with 24 and 32bit playback.



Regardless, the Soundblaster X-Fi USB device delivers EAX 5.0 to the laptop/portable world effectively, with all the definition and driver compatibility that the internal PCI/PCI-E solution offers. We tried a few of the regulars out, such as Battlefield 1942 and Assassins’ Creed. The EAX 5.0 HD options were all available with full acceleration. Curiously, the use of the USB external processor seemed more reliable in terms of install and detection than its PCI/PCI-E relatives.

Finally, a word of caution for home studio and digital music creators. ASIO driver modes don’t seem to work, and on top of this, latency to the external USB device is beyond the acceptable realm for use in applications such as Sonar, Cubase SX or Nuendo.

If you need a 5.1 surround solution that is capable of 24bit output, but don’t necessarily need or care about audiophile quality sampling and fidelity, this might be the device for you.