Yamaha @PET RP-U100 personal receiver Shannon Dickson Comments

Sidebar 3: the Yamaha @PET RP-U100 & other spatializers

Paralleling Yamaha's introduction of this new class of PC receiver and spurred on by the rapid growth of the MP3 phenomenon, major players from the virtual 3D world, including Spatializer Inc., SRS Labs, and QSound, have joined the fray with "stereo-enhancing" plug-ins for popular MP3 software players. Spatializer and SRS now offer competing plug-ins for the popular Winamp media player, StreamFX and Wow-Thing, respectively. Spatializer also has a version of StreamFX for the Xing media player, and SRS claims their Wow-Thing will soon be compatible with products other than Winamp. Instead of focusing on MP3-specific players, QSound has so far tailored their IQ plug-in for streaming audio via separate versions for the Real Player G2 and Windows Media Player; thus, their product wasn't directly comparable to the StreamFX and Wow-Thing for this Follow-Up.

I used my custom-built computer system to audition the Yamaha RP-U100 and the software plug-ins. It includes an Asus P3B-F motherboard, 550MHz Pentium III, 256MB of SDRAM, IBM 22GB-7200RPM hard drive, 3DLabs Oxygen VX1 graphics card, LynxONE 24-bit/96kHz pro soundcard (for recording and measurement work), 48x CD-ROM drive, B&W's gorgeous new shielded LM-1 Leisure Monitors, and the Windows 2000 Professional Release Candidate 2 operating system.

Of the RP-U100's six venue options, including Church, Movie, and Game, I found the Jazz, Hall, and Live algorithms best suited to most music, which is what JA found. But only after adjusting such parameters as initial delay, reverb level, virtual room size, surround-channel delay, liveness, and overall applied effects could I create a believable 3D space around my chair without distracting colorations. Don't worry about fine-tuning for each song—just find a setting you prefer for a given recording style and type of music.

Yamaha also includes a Virtual Dolby Digital option, optimized for nearfield two-channel playback of Dolby-encoded material such as DVD movies; it worked well. I found less effective an HP3D surround effects filter for headphones. And, for some tunes, I still preferred the unprocessed direct path through the Yamaha.

The software plug-ins associated with the Winamp or Xing media players use small GUI control panels to vary the degree of spatial and timbral processing applied to MP3, WMA, or WAV files. These algorithms are fully compatible with the Yamaha receiver, so long as you turn off Yamaha's onboard DSP functions and use the algorithms simply as extra options for computer-based MP3 playback.

The StreamFX and Wow-Thing algorithms are quite flexible in their parameter settings. Each includes an amalgam of its company's popular tools for stereo enhancement and spatial envelopment, combined with their proprietary bass-boosting systems: ViBE from Spatializer, TruBass from SRS. The idea behind these bass techniques is to fool the nonlinear ear-brain system into sensing phantom low-frequency fundamentals (which small speakers can't actually produce) by selectively boosting higher-frequency harmonics, which generate intermodulation distortion effects in the ear canal, which in turn are interpreted by the brain as the missing low-bass fundamentals—all resulting in an impression of deeper, richer bass. But make no mistake: These techniques are no substitute for moving real air with a full-range, low-distortion bass system. They do, however, serve their intended application reasonably well.

Caveats and opinions: To evaluate the success of these spatial-expansion algorithms in providing a more rewarding PC-based music experience, I first used the excellent Music-Match 4.2 all-in-one software media player/recorder to encode several CD test tracks to the highest currently available MP3 rate of 320 kilobits per second. Songs included Patricia Barber's version of "Ode to Billy Joe" (Café Blue, Premonition PREM-737-2), and "Chan Chan," from the Buena Vista Social Club (World Circuit/Nonesuch 79478-2).

Encoding MP3 at 320kb/s preserves much better timbre and fine detail, and fewer artifacts, than the more typical 128kb/s rate; the only penalty is the need for more data storage. My comparisons of these MP3 tracks through the various DSP options of the Yamaha RP-U100, and through the alternate software plug-ins via the receiver's direct unprocessed path, resulted in the following observations and caveats.

While the fine-tuned Jazz and Hall algorithms of the Yamaha presented the fewest artifacts and the most natural tonal, spatial, and dynamic renditions of these songs overall, it took considerable initial effort to dial in all the interrelated parameters.

Both the StreamFX and Wow-Thing plug-ins opened up the constricted soundstage endemic to closely spaced PC monitors, while conveying decent imaging and a real sensation of envelopment. However, both of these plug-ins reduce gain by different degrees relative to each other and to the unprocessed sound, to allow greater post-processing headroom for the EQ and spatial effects. Unfortunately, this made direct comparisons between the two, and with the direct sound, very difficult. The Winamp version of StreamFX was quieter than the Wow-Thing; a reasonably accurate evaluation required subjective gain leveling with Winamp's built-in preamp control.

Even so, after adjusting both algorithms to their "best" settings in my system, I found that the StreamFX produced a slightly more cohesive soundstage perspective and a more natural timbre, particularly in the upper midrange, than did the Wow-Thing. The Wow-Thing seemed to emphasize upper-midrange transients more than did the StreamFX, making it sound more exciting initially—an effect readily apparent when I listened to the finger-snaps on "Ode to Billy Joe" and the colorful percussion instruments on "Chan Chan." The Wow-Thing's TruBass had a better range of adjustment than did StreamFX's ViBE bass-enhancement feature, which was too easy to overload, thus making the bass sound less articulate. Interestingly, I found that the version of StreamFX for the Xing player sounded more dynamic and clean than its counterpart for the Winamp. It also had a graphics EQ module in place of the ViBE option. Either the Xing API is superior to Winamp's engine, or perhaps Spatializer just did a better job with their Xing algorithm. Keep in mind that your mileage may vary based on your setup and tastes.

Finally, don't compare the PC audio experience to that from your high-end stereo system—these are two very different contexts. Still, in each case what you're trying to do is create a believable illusion. Judge the success of the Yamaha RP-U100, the software plug-ins, or the combination of the two, based on their ability to enhance your enjoyment of nearfield computer-audio reproduction. On that score, I'm confident you'll find the improved spatial quality presented by these products an encouraging step in the right direction.—Shannon Dickson