Smaller than a computer mouse, the Creative Xmod packs some surprising sonic powers inside its sleek white shell. The Xmod is a combination audio interface and enhancer. When you plug it into your computer's USB port, the Xmod becomes an external soundcard, taking over the audio input and output duties and adding a handy volume knob. Pressing the knob even mutes the audio. Flip the Crystalizer switch and the Xmod does some fancy digital signal processing to "restore" the audio information hacked away by lossy compression schemes such as MP3. (Creative enthusiastically describes the result as sounding "better than CDs.") A 3D switch creates a virtual surround effect on headphones or stereo speakers.
A couple of months ago, I got to review an Xmod and I loved it. So when I had to return the review unit, I went out and bought one with my own money. That's when I really started to go wild. In this article, I'll share some of the unexpected ways I've found to pump up digital audio with the Xmod.
The Xmod's enhancement effects are derived from Creative's X-Fi sound cards. Creative's engineers did a lot of modeling and mathematics and figured out how to localize sounds by using the physics of the human ear, the shape of the human head, and advanced digital signal processing. By employing delays, HRTFs, and other signal processing techniques, they turned the two real speakers of a pair of headphones into simulated nine-speaker surround sound.
The results sound impressive. You tell your computer to treat the Xmod as a Dolby Digital 5.1 output device, plug in your headphones, and the audio surrounds you using virtual speakers as the device decodes six-channel AC3 audio streams from your DVD. The rumbles, vrooms, and kabooms fly from left to right, from front to back, and sometimes they travel right through your head. Groovy stuff, even without chemicals.
Of course, Creative isn't the only company to deliver virtualized sound. You can buy the same sort of signal processing from other vendors such as Bose, Dolby, and SRS. The Creative Xmod, though, gives it to you in a compact, affordable device. And it works on both headphones and speakers.
Figure 1: Switches on either side of the Creative Xmod allow you to enable or disable the X-Fi Crystalizer and the X-Fi CMSS-3D effects. The line input is at front left; the headphone output is on the right. Around the back are the USB port and line output.
Think about that for a second. The mathematics of headphone and speaker delivery are quite distinct. When delivering sound to headphones, you deal with two isolated signals. You feed one signal to the left ear, another to the right. You don't have to worry about sounds traveling through your head to get all mixed up on the other side.
Working with speakers is different. Sounds cross from left to right and right to left, because there's no physical barrier between them. So the mathematics gets trickier because you've got to build an ideal listening environment for the person sitting in the middle while the crossed-over sounds have to either strengthen or cancel each other out.
The Xmod provides both kinds of outputs—speakers and headphones—automatically switching effects when you plug into the headphone jack.
But that's not all the Xmod can do. It also offers a feature called the Crystalizer. The Crystalizer restores missing frequencies and dynamic range to compressed sound. This processing produces deeper bass sounds, clearer voices, and an overall better defined signal—or at least it does for clean, well-recorded data. When dealing with noisy source material (such as homemade podcasts), the Crystalizer accentuates the high-frequency noise, making the podcasts really hard to listen to. But for clean sound, the Crystalizer is indeed sparkly.
The threat of enhanced noise is just one reason to be judicious when enabling the Xmod effects. Fortunately, the Creative folk have built two switches into the device (Figure 1). One turns the Crystalizer on or off, the other enables and disables the 3D effects. You can experiment as you listen; there are no delays when changing settings as processing is all done in real time.
Tip: It's rare these days to find a computer without a microphone jack, but they do exist. My ancient 733MHz G4 Macintosh doesn't have one but it does have a USB port. Some underpowered laptops, like certain Dells, can start sputtering their audio when you begin moving the mouse. So it was a nice surprise to discover that I could plug a mic into my Xmod, fire up Skype, and basically treat the little white box as the external mic jack that I've always wanted. In other words, an Xmod can function as a compact, portable audio interface. Although the manual says, "Monitoring of recordings is not available. You can only check your recording afterwards," I've never encountered any problems monitoring my Xmod during Skype chats or for any other microphone or line-in use.
Have you ever wanted to go up to a designer and smack him on the head, Three Stooges-like, for his design blunders? The guy who designed the default effect levels for the Xmod probably deserves one of those smacks and here's why. To change the levels, you need to use a "secret button." As Figure 2 shows, this button is the entire top half of the Xmod. Press it and you'll feel a click.
Figure 2: The upper half of the Xmod acts as a secret settings button, allowing you to set the intensity of each effect rather than just switch the effect on or off.
Here's how it works: normally the large silver knob in the center of the unit adjusts playback volume. Turn it clockwise and you increase your system's volume; go counterclockwise and you decrease it. Click the knob and you toggle Mute. (When sound is muted, the third light from the top of the unit turns red.)
To adjust the intensity of the Crystalizer effect, double-click the secret button. The second and third indicator lights switch off and the blue light that usually indicates whether the Crystalizer is enabled or disabled begins to blink. A fast blink tells you the Crystalizer is cranked up high. A slow blink tells you the effect is diminished. Adjust the knob, turning counterclockwise to decrease the effect or clockwise to increase it. The light changes its blink rate accordingly.
There are no numbers. There are no blinks-per-second codes (at least not as far as I could figure out). It's all subjective. Faster means more Crystalization, slower means less. And if you wait more than about five seconds without touching anything, the entire Xmod exits the settings mode and returns you to normal playback mode.
To adjust the 3D effect, double-click the secret button (the Crystalizer light begins to blink) and then click once more. The blinking indicator moves to the X-Fi CMSS 3D light. Again, adjust the knob counterclockwise (less effect) or clockwise (more effect) and watch the blink rate increase or decrease. To finish your settings, click the secret button one last time or just wait five seconds. The Xmod leaves the setting mode.
It's a half-assed, clunky way to change your settings, but it does allow users to dial back on the Crystalization, which can be distracting at its most intense setting. I prefer to leave the 3D effects full-on all the time.
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If your computer doesn't come with a full-featured Dolby Digital decoder for 5.1-channel sound, you miss out on a lot of the DVD experience. Instead of hearing wrap-around sound, you end up listening to a downmixed 2-channel version instead. Systems that offer Dolby decoding don't necessarily produce multichannel output, and if you don't have five speakers, you'll need a virtualization program to get the surround effect. That's where the Xmod comes in.
First, consider using VLC for your DVD playback. VLC, which runs on most computer platforms, is a free download from http://videolan.org. More important for us, it can use the A52 codec to decode DVD audio into proper 5.1.
By connecting your headphones to your Xmod, your Xmod to your computer, and playing your DVDs back using VLC, you'll be able to hear the virtualized Xmod 3D experience—a striking effect.
Tip: Mac users can download a copy of the A52 codec from this A52Codec development page. Windows users can use this link instead.
The powers of the Creative Xmod aren't limited to the speakers connected to your computer. You can bring your Xmod into the living room and use it to enhance the audio for your TV or stereo. The secret lies in positioning the Xmod between the sound source and the speaker system and powering the Xmod without a computer.
In order to power your Xmod, you'll need an USB power supply that provides the standard five volts but runs off of AC power. You can pick up one for a couple of bucks at many online sites such as DealExtreme, or if you're looking for a higher end product, Apple sells an adapter for about $30. To use the adapter, plug it into the wall and plug your Xmod into its USB port. If you have a powered USB hub on hand, you can use that instead of laying out the cash for an AC adapter.
Audio hookup is easier. Plug the audio output of your sound source into the line-in jack on the bottom left of the Xmod. When the Xmod detects a signal from this jack, it automatically selects it as its audio source. Then you connect the Xmod's line output to the auxiliary input on your stereo. (See Figure 3.)
You can use the Xmod with this setup to restore impact lost in MP3 or AAC compression, or to add virtual-surround sound to your TV reception. Be aware that success of the stereo-based 3D effects depends on positioning the listener in the "sweet spot" in front of and between the two speakers. The effect simply won't work for a large room full of viewers positioned randomly for TV viewing or stereo listening. It's really a one-person effect.
Tip: Although Apple's AirPort Express uses lossless compression to stream music from your computer over WiFi, Stereophile reports that the AirPort's analog output is compromised. You can get around that by using the AirPort Express's digital audio output (assuming your stereo has a digital input). But since you're likely to be playing compressed music to begin with, the Xmod Crystalizer effects won't be wasted.
Figure 3: In the living room, the Xmod can enhance WiFi and TV sound.
If your car stereo provides an audio input jack, you can use an Xmod to enhance playback from your portable media device (iPod, Creative Zen, Zune, etc.) while on the go. To accomplish this, you'll need to pick up a cigarette lighter-to-USB power adapter, such as the one found here for about five bucks. You'll also want to pick up an adapter power splitter and an adapter for your media player. (See Figure 4.)
The splitter allows you to power both your player and your Xmod at the same time. After hooking both items up to their power source, connect the audio output (typically the earjack) from your media player to the input jack of the Xmod, and the speaker output of the Xmod (upper-right corner) to the A/V input of your car stereo. This allows you to process the audio from your player with the Xmod and send the results through your car speakers. As with the living room setup, this system works particularly well with the Crystalizer to enhance the compressed tracks on your portable player.
Figure 4: Use a cigarette lighter splitter to provide power to both your media player and your Xmod.
You can "inflate" the quality of your compressed audio files by playing them back through the Xmod and capturing the results on your PC or Macintosh. For example, the iTunes Store sells audio compressed at 128 kbps. You can use the Crystalizer to enhance the audio and a software program like Audacity or Audio Hijack Pro to capture the results at a higher bitrate. Just connect the Xmod to your computer with the USB cable, play back your music in Windows Media Player or iTunes, and record the system audio to capture the enhanced results. Figure 5 shows the settings I use on the Mac to capture the best possible quality results using this method.
Figure 5: These settings in Audio Hijack Pro ensure that the captured audio is recorded at the highest possible quality.
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Unfortunately, the Xmod doesn't apply its enhancements to your computer's digital audio stream when you use the Xmod's line-in/microphone input. The enhancements show up only at the speaker or headphone audio jacks. This trick uses the Xmod's audio output jack rather than USB. Note that some X-Fi Sound Blaster cards can resample their output internally, which may allow you more flexibility for tricks like this.
If you want to capture audio using the virtual 3D surround sound effects and intend to play back your audio via headphones, you have to be trickier. Disconnect the Xmod from your computer and hook its headphone output into your computer's line input jack. (And no, you can't do this trick on a machine without an input.) Then power the Xmod using an external USB AC adapter (Figure 6) and connect your MP3 player (iPod, Zune, etc.) to the Xmod's input jack.
Set up your recording software to capture audio from the computer's line input, adjust the playback and capture levels as needed, and then capture the audio from the MP3 player as it plays back through the Xmod.
Yes, it's more than a little Rube Goldbergesque in how the job is accomplished, but it allows you to capture your sound complete with headphone-specific virtual surround sound and it sounds terrific when played back through headphones. Be aware that you may pick up noise due to the extra Digital-to-Analog-to-Digital conversion steps.
Tip: If you want to listen to the enhanced audio directly from the MP3 player, skip the computer and stick your earphones directly into the headphone jack on the Xmod.
Figure 6: Use the Xmod to "inflate" your audio and record tracks with built-in virtual surround sound.
The Creative Xmod transforms the listening experience, particularly when watching DVDs with exciting 5.1 Dolby Digital surround sound on your computer. Between the virtual 3D, which you can enjoy either through headphones or speakers, and the quality-enhancing Crystalizer, the Xmod offers a lot of audio bang for relatively few bucks. If you own an Xmod or a similar audio enhancement device, I hope this article will encourage you to play with it in new and creative ways.
Thanks to Jean-Michel Trivi of Creative and Paul Kafasis of Rogue Amoeba for their technical insights.
Erica Sadun has written, co-written, and contributed to almost two dozen books about technology, particularly in the areas of programming, digital video, and digital photography.
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