How to choose a sound card. (Multimedia PC) (Buyers Guide)
by Richard O. Mann

Let's face it: If you're reading the multimedia section of this magazine, you either have a sound board in your PC or would like to get one. If your sound card is over a year old, you may be considering a new one, to take advantage of the exciting features now becoming avaialble.

Sound is one of the most troublesome aspects of the multimedia PC--the lack of standards means that we're still involved in something like a Beta-versus-VHS battle, only with more than two combatants. To understand the differences among the dozens of sound cards currently on the market, you must work your way through a maze of unpleasantly technical terms.

Even if you understand the terminology, the technology is a moving target, with advances coming every month or two. If you wait to buy a sound card because you hear that something newer and better is coming next month, you'll never enjoy sound on your PC--because there will always something newer, better, and cheaper coming next month.

To choose a sound card, there are some basic technical issues you'll need to understand. Bear with me through the background material, and I'll introduce you to some dynamite new sound cards along with the traditional favorites. (What an industry! Anything popular for a year is "traditional.")

8-Bit Versus 16-Bit Sound

The 8- or 16-bit label on a sound card refers to the number of digital bits the card uses to record a single sound sample. The samples play back in series like frames in a movie (only at a vastly higher rate) to create the desired music, voice, or other sounds. Eight bits provide only 256 possible values per sample, which limits the range and quality of the resulting sound playback. Eight-bit sound is, however, adequate for normal voice applications and provides passable music, such as we've heard from our PC games for years.

The 16-bit boards, however, expand the possible values of a sample to over 65,000, opening new worlds of sound. If you're buying a new board now, insist on 16-bit capability; a year from now you won't be able to buy an 8-bit board.

Sampling Rates

The eye can be fooled into seeing smooth motion with as few as 15 to 20 frames per second (Video for Windows movies generally run at 15 frames per second), but active sound requires considerably faster sequences of sounds. The sampling rate-the number of sound samples played or recorded per second--can range from 4 kHz (1kHz is equal to 1000 cycles per second) to 44 kHz (the rate used in audio CDs) and beyond. Any 16-bit card can record and play back at 11 kHz ("telephone quality"), 22 KHz ("FM radio quality"), and 44 kHz ("audio CD quality"). An 11-kHz sound recording is adequate for voice and many sound effects, but music needs the increased clarity of the higher rates.

Rates come into play not in choosing a card but in managing your sound files. Doubling the sampling effectively doubles the size of the resulting sound file. Recording a Windows-compatible WAV file in 16-bit stereo at 44 kHz takes about 10MB of disk space per minute. You'll rarely use that high a sampling rate except on CD-ROM products. Files created at these rates are too large to be practical.

FM Synthesis Versus Wave-Table Sound

The most common sound technplogy for PCs is FM synthesis, most often supplied by Yamaha OPL2 and OPL3 chips. These chips have a range of standard sounds they can create, or synthesize. When the computer orders the sound card to create a sound, the FM chips kick in to create the electronic sound that comes out of your speakers. Higher-quality boards have enough chips to provide 20 or more voices (individual sounds the card plays simultaneously); standard cards may have only 10 voices.

Wave-table synthesis is the next step up in sound quality. Cards using wave-table technology have digital recordings of actual instruments permanently stored in ROM (Read Only Memory). When the application calls for a grand-piano middle C, the sound card sends exactly that to the speakers. This, of course, happens only when the software is written specifically to call for wave-table sounds.

Some boards, such as the Advanced Gravis UltraSound, let you record your own sounds and selectively substitute them for the sound in the wave table.

Digital Waveform Sound

FM and wave-table synthesis are digital waveform audio. They rely on ADC (Analog to Digital Converter) chips to record and encode sound into digital form and DAC (Digital to Analog Converter) chips to reverse the process on playback. The computer files storing the digital information are quite large, as described above.

Although there's no formal standard for PC sound processing, you'll often see the terms Ad Lib compatible and Sound Blaster compatible used to describe sound boards that use digital waveform audio. The Sound Blaster card, by far the most popular of the first-generation boards, is a de facto standard for most games and educational software. Don't buy a sound card that isn't Ad Lib and Sound Blaster compatible unless you plan to use only Windows programs.

General MIDI--The Next Step Up

To step up to richer, more realistic sound, you'll need General MIDI compatibility. MIDI (Musical Instrument Digital Interface), originally used by musicians and composers with electronic keyboards and other MIDI devices, is gaining popularity as a playback medium for PC sound. General MIDI is an extension of the original MIDI standard.

MIDI is a communications standard that doesn't deal directly with digital waveforms. Instead, MIDI files describe such parameters as note on, note off, pitch change, instrument change, and volume. Because the sounds are stored in ROM and only the performance values are stored in MIDI, that 10MB waveform file we discussed above might take only 35K in MIDI format.

Sound cards boasting MPC compatibility and most second-generation sound cards have built-in MIDI synthesis, a MIDI interface (the Roland MPU-401 is the most common), or both. With some sound cards, you'll need optional equipment to play General MIDI sound. Roland's Sound Canvas ($399-$895), Yamaha's Hello! Music ($449), or Yamaha's TG100 ($449) will give you the full glory of General MIDI when added to your sound card's MIDI interface.

DSP Chips, the Aria Chip Set, and the Future

The newest development in computer sound technology is the DSP (Digital Signal Processor) chip. A DSP chip is specially designed to manipulate realtime digital data, such as sound and video. Programmers can write algorithms for the DSP to achieve effects only dreamed of a few years ago. Further, the DSP can be reprogrammed with software right on your computer, without touching the sound card at all. As newer and better technologies are developed, you won't have to buy a new sound board to get them.

Two manufacturers supplying specialized DSP chips to sound board makers are Sierra Semiconductor and Analog Devices. Sierra's DSP is marketed as the Aria Chip Set, composed of the Aria Synthesizer and the Aria Listener. These chips can provide wave-table synthesis along with Sound Blaster compatibility. DSP hold tremendous potential. The DSP chips in sound boards available today provide wave-table synthesis, additional voices (Aria provides 32 voices), FM synthesis emulation, speech recognition, reverb, three-dimensional sound (including QSound), and multitasking to provide more than one type of sound or effect simultaneously. Note, however, that software must be specifically written for a DSP to access these features.

The future holds additional audio wonders, including much better file compression algorithms to help keep storage demands within reason.

Other Considerations

There's more to buying a sound card than just picking the board with the best specs or lowest price.

CD-ROM drive interface. In a multimedia computer, the sound card usually provides the interface between the computer and the CD-ROM drive. If you buy them together (as in an MPC upgrade kit), the sound card's interface will work with the drive. Nevertheless, it's important to know what kind of interface you're getting.

The SCSI interface is the most commonly used and is emerging as a standard for CD-ROM drives. In the past, Creative Labs' Sound Blaster cards used a proprietary interface that worked with only a few CD-ROM drives. The company still sells this version of its boards but has added a separate Sound Blaster board with multiple CD-ROM interfaces, as well as a board with a standard SCSI-2 interface. A board with a SCSI interface won't limit you when choosing a CD-ROM drive.

Software bundles. Sound boards come with a variety of software packages as part of the basic purchase. Look for waveform editors, speech packages, MIDI sequencers, multimedia authoring software, and similar items. Generally speaking, unless you have a specific need for certain software, the sound card's software bundle isn't likely to be the deciding factor in selecting a card.

Multimedia kits. Buying your sound card as part of a multimedia upgrade kit come with a microphone and an extended software bundle. With the advanced Signal Processor, these cards cost $50 more. Only the MultiCD can use the Wave Blaster upgrade for wave-table synthesis.

Orchid Soundwave 32 (Orchid Technology, 800-7-ORCHID, $299). This new board uses the Analog Devices DSP chip set to provide 16-bit stereo wave-table synthesis, General MIDI support, and backward compatibility to Sound Blaster, Ad Lib, Windows Sound System, Roland MPU-401 MIDI, and Roland MT-32 sound. The DSP chip allows the card to emulate three of these devices simultaneously, letting you have access to the best sound available in any software program you might use. Its CD-ROM interface supports only Orchid, Mitsumi, and Sony drives. It comes with a microphone, speakers, and several multimedia software authoring tools.

Advanced Gravis UltraSound (Advanced Gravis Computer Technology, 800-663-8558, $199). The UltraSound supplies 32-voice wave-table synthesis at an affordable price. It offers compatibility with Sound Blaster and Ad Lib through a TSR driver (a mild disadvantage--TSR are often troublesome with today's complex memory management schemes). Its unique Patch Manager allows you to change the wave-table sound samples to sounds that you generate. It offers a Focal Point 3D sound feature that simulates surround sound.

The CD-ROM interface is an optional add-on board with Sony, LMSI, and Mitsumi drives supported. A SCSI interface should be available by the time you read this. An optional MIDI Connector Box for General MIDI use is also under development. The software bundle includes Power Chords, a guitar-metaphor music program that lets you write and audition guitar chords.

Advanced Gravis UltraSound MAX with 3D (Advanced Gravis Computer, Technology, 800-663-8558, $299.95). The UltraSound MAX board adds 4:1 compression, enhanced 3-D surround sound, and a SCSI interface for CD-ROM drives.

Cardinal Digital Sound Pro 16 (Cardinal Technologies, 717-293-3049, $159). The Digital Sound Pro 16 is based on the Analog Devices DSP chip but doesn't offer wave-table synthesis in its basic card. (Wave-table synthesis requires a $99 plug-in chip). It provides 11-voice stereo FM synthesis and a Sony CD-ROM interface. A SCSI interface comes with the Pro 16 Plus version at $229. It's compatible with Sound Blaster, Ad Lib, Windows Sound System, Compaq Business Audio, and Roland MPU-401 MIDI. The company's promotional materials point out the promise of the software-upgradable DSP chip for compression, voice recognition, and 3-D sound, but these features weren't available at press time.

Diamond Sonic Sound (Diamond Computer Systems, 408-736-2000, $299). Based on the Aria Synthesizer chip, the Diamond Sonic Sound offers 32-voice wave-table synthesis, but the company has chosen not to include the Aria Listener chip for voice recognition in its basic card. (A $129 upgrade provides the Listener chip, voice recognition software, and enhanced General MIDI support.) The Sonic Sound comes with a standard SCSI interface for the CD-ROM drive and the multimedia authoring software.

Logitech Sound-Man 16 (Logitech, 800-889-0043, $199). This basic board uses the Yamaha OPL3 chip to provide 20-voice stereo FM synthesis at all the standard sampling rates with standard compatibilities. Installation is streamlined by making all settings through the software--the board has no jumpers. There's no CD-ROM interface. A $229 Superpack version adds a microphone, speakers, and additional software, including Soft Karaoke.

Roland Audio Producer RAP-10 (Roland, 213-685-5141, $599). For the professionals and audiophiles among us, Roland's RAP-10 sound card provides 28-voice wave-table synthesis using the chip from the Roland Sound Canvas, the MIDI synthesizer that became the model for the General MIDI standard. A custom DSP adds studio-quality reverb and chorus effects to achieve concert-hall realism. We're talking first-class equipment here. Since this is a tool for serious musicians, it has no CD-ROM drive interface or backward compatibility with Sound Blaster or other FM synthesis-based cards.

Turtle Beach MultiSound (Turtle Beach Systems, 717-767-0200, $599). This is another professional-quality board designed for serious audiophiles. it provides 32-voice wave-table synthesis using a Motorola DSP chip. Its General MIDI synthesizer requires only a MIDI playback device to create gorgeous music. There's no CD-ROM drive interface or backward compatibility.

Microsoft Windows Sound System 2.0 (Microsoft, 800-426-9400, $219). The original Windows Sound System was a business-oriented sound board that made no attempt to provide sound to games and other Sound Blaster-compatible programs. Instead, it concentrated solely on bringing sound to Windows. In the new version, 2.0, Microsoft has added Sound Blaster compatibility, audio compression/decompression, and a directional microphone for voice work. It's especially well suited for voice recognition applications.

Conclusion

There's no shortage of excellent sound cards to choose from, but each has a different design, each is based on a different idea of what users want and need, and each offers a different set of compromises between cost and quality.

The DSP-based units hold great promise; if I were bying a sound card today, I'd be looking at cards that use the Aria Chip Set or another DSP, simply because they're software-upgradable, they provide backward compatibility, and their prices are surprisingly reasonable.