AOpen AW744S sound card

Review date: 14 July 2000.
Last modified 03-Dec-2011.


Want a cutting edge sound card? Buy a Sound Blaster Live!, from Creative. It's pretty much your only option, now that Aureal have gone broke and their technically excellent Vortex audio chipsets are thus rapidly vanishing from view, right?

Well, no, actually. You can get all of the fancy sound features that audio hobbyists, home theatre fans and fanatical game players want, for rather less than the price of a Creative card.

A basic Original Equipment Manufacturer (OEM) SB Live! (no fancy box, no nifty software bundle) will set you back $AU120 or so. Retail-boxed ones are more than $AU170. And the all-singing, all-dancing Live! Optical with front-panel knobs and connectors will set you back $AU450.

AW744S sound card

AOpen's AW744S card, on the other hand, costs less than $AU75 including GST. But it gives you quad speaker output, an optical digital S/PDIF output, and positional and environmental audio support for the gamers.

What's not to like?

What you get

The AW744S appears to be the same as the AW744 Pro; I think the only difference is the name.

Along with the card itself in the AW744S box there's a slim but serviceable English-and-Chinese manual, and one CD with the driver and support software on it. You can get the latest drivers from here, and I recommend you do.

There's not much bundle software beside the driver. There is, of course, another one of those audio interfaces that looks like a stereo system, for the same reason that word processor interfaces look just like typewriters.

No, wait. They don't. My mistake.

Setting up

Installing the AW744S is no harder than installing any other PCI sound card - open computer, remove old sound card if necessary, insert new one, screw it in, close the box, power up. Windows 98 will detect the new sound card automatically and ask for the drivers; Windows 2000 has its own drivers for cards using this chipset already built in, but you can later replace them with the newer, better ones from AOpen.

If you want Linux drivers, you either write 'em yourself, pay for the 4Front Technologies Open Sound System package, whose readme file for its YMF7xx-series driver is here, or grab the apparently-functional Advanced Linux Sound Architecture drivers from here.

If you're running an NT-series operating system - NT4 or 2000, which is really NT5 - you can only use the card as a plain stereo unit. There's no support in the drivers for quad output or positional audio on anything but Windows 95/98. The S/PDIF output still ought to work, but that's it.

If you're running a dual-boot system with 95/98 for games and NT4 or 2000 for more serious applications, the AW744S therefore still a perfectly good card. If you're only running an NT-series OS, though, its only advantage over a dirt cheap plain stereo card is its S/PDIF output, which doesn't excite most buyers.

NT4 is a dead loss for positional audio no matter what hardware you choose. It's not exactly the Red Hot Game Players' Operating System. You can do 3D sound on Win2000, because it comes with the essential DirectX 7. But, to my knowledge, the only sound cards whose drivers currently make it possible are the Sound Blaster Live! line.

The AW744S, like some other higher-quality sound cards, has no on-board amplifier. You must use some sort of amplified speaker system, or hook it up to a stereo, or use headphones. If you're at all interested in decent PC audio, crummy unamplified computer speakers aren't likely to be on your shopping list anyway.


Along with the standard optical S/PDIF output, the AW744S also has a header on the card for an optional S/PDIF input - for CD-ROM or DVD-ROM drives with 44.1 or 48kHz S/PDIF output.

Of course, you also get the usual complement of MPC2 analogue connectors for modem, CD-ROM and auxiliary sound sources inside the PC, and the joystick port will as usual double as a MIDI input/output connector, if you use an optional adaptor cable.

And, like pretty much every other sound card on the market, the AW744S can pretend to be an old Sound Blaster Pro if you run DOS games.

The AW744S is powered by Yamaha's YMF744 sound chip. On the face of it, it doesn't look like a terribly exciting piece of hardware, primarily because it supports only two simultaneous stereo DirectSound streams, plus another two DirectSound 3D streams. Each stream is one sound; you need a lot more streams than that for games.

When sound cards don't have enough hardware audio channels, the drivers do real-time mixing. This means you lose a little quality (though it's generally impossible to notice), and a lot of performance. In theory, you can do all the positional and environmental audio you like in software, but in practice the CPU hit is intolerable.

A card with only a couple of hardware 3D sound channels, therefore, is a dodgy proposition; the usual strategy employed by under-powered cards is to mix a few more channels up from the ones it's got, then dump any sounds it can't handle in 3D to the easier-to-calculate plain stereo channels. And bang goes your 3D sound.

Fortunately, the Win95/98 drivers for all YMF744 cards are startlingly well written, and their real-time mixing of even large numbers of streams seems to cause a negligible CPU hit. Make the AW744S play 32 CD-quality DirectSound 3D streams at once and it'll eat only a few per cent of the CPU time of a modern 700MHz-or-so PC. Even if you're running an older machine, the performance loss should be thoroughly acceptable; 10% or so, for a 400MHz P-II or Celeron. And the sound quality remains excellent.

The standard Windows 95/98 drivers give the card compatibility with games that use DirectSound 3D, Aureal's A3D v1.x (converted to DS3D, which means it won't sound quite as good as it would with a real Aureal card), Creative's Environmental Audio Extensions (EAX) v1.0 for reverb effects, and the lesser-used Interactive 3D Audio Rendering Guidelines Level 2.0 (I3DL2).

It's all based on Sensaura's 3D sound technology. This means that if you download the current-as-I-write-this v2.013 drivers, you get the recently-released improved Sensaura reverb engine, which makes the environmental audio effects significantly better overall. The new drivers also include support for EAX 2.0.

Like the Sound Blaster Live! models, and unlike the Aureal Vortex boards, Sensaura-based cards in four speaker mode use proper HRTF output for both front and rear speakers, which delivers better results for surround effects than the HRTF-front, stereo-pan rear approach the Aureal cards use.

Unless you've got rather good speakers and time to set them up, though, you'll probably prefer the 3D audio you get from simple two-channel headphones, and for this the rear channel implementation is irrelevant.

The general tide of opinion is that Sensaura cards sound about as good as Aureal ones for two-channel sound - perhaps with a slight edge to Aureal - but they're both clearly better than Creative ones.

Aureal's driver development, unsurprisingly, stopped dead when the company did. And Sensaura offer significant improvements in the future - some of them, like non-point sound sources so a passing train can emit sound from its entire length, are already there and just waiting to be supported in games. So any advantage the Vortex cards had is being eroded day by day.

In English, this all means that the AW744S will do a decent job of delivering funky sound in pretty much any game that has some kind of 3D audio support.

The oddities of different card and driver combinations mean that it's quite common for cheaper cards to produce odd results in some games. There are, for instance, often level imbalances that mean that reverb effects are either barely audible, or so loud that they drown out gunfire. But you can always turn environmental audio off if it's screwed up in some particular game, and positional audio always works in games that support it.

For the money, and especially with the current drivers, the AW744S delivers excellent results.

Sound quality

3D sound aside, the AW744S delivers audio results as good as you'd expect from a Yamaha chipset. They make a lot of music gear. They have their act together.

This isn't a huge selling point, though. It's actually quite hard to find PC sound gear these days that doesn't have superb linearity, signal-to-noise ratio and interference rejection. But the AW744S is certainly up to scratch.

The drivers include a "stereo expansion" feature, which may make very nasty computer speakers sound as if they're further apart, but is far too heavy-handed for my taste. This is not super-clever expansion such as is done in software and hardware by SRS Labs (grab their free Winamp plug-in from here to see what I mean); it's a curio. It defaults to "off", and if you ask me, you should leave it that way.

The AW744S uses the Yamaha XG sound-sets for its MIDI tone generator, which is superior to the "General MIDI" (GM) system used by many other cards. Most users will only ever hear MIDI as background music for the odd game or Web page, so they won't care.

But this card also supports Yamaha's real-time acoustic modelling system, which actually simulates acoustic instrument behaviour, and has been included in some rather expensive performance synthesisers. You need serious music software to muck about with the sounds properly, but if you've got it, you can get results not far shy of those from proper stand-alone synthesisers out of this cheap card.

For single-instrument performance purposes where you don't need a million voices, this card, a MIDI adaptor cable and a cheap MIDI controller keyboard will give you recordable results at a very palatable price indeed.

MIDI Board

Casual noodlers can use an included "MIDI Board" application to play any of the default instruments (with or without cheesy Casiotone rhythm section) and see what I'm on about without getting other software or fooling around with endless MIDI files. MIDI Board's mapping of notes to keyboard keys is rather bizarre, though.

The S/PDIF output sample rate's locked at 48kHz, as with the Sound Blaster Live! models. This makes it eminently suitable for Dolby AC-3 audio output to a surround sound decoder, and it'll work OK for recording audio to devices with lower sample rates, like MiniDisc players, too. The recording device just converts the sample rate, and generally does it very well. Pro audio types may be disappointed, but, allow me to remind you - the thing's $AU75, folks.

Non-AC-3 output is only stereo, of the front two channels.

DVD sound

You don't get DVD playback software with the AW744. If you want it, what software you should choose depends on what sound output you want.

If stereo sound is adequate, then any DVD playback program, including the rather questionable ones that get bundled in with some cheap DVD drives, will do fine. If you want surround sound, things are more complex.

InterVideo's popular WinDVD package works with YMF744-based cards' S/PDIF output, but not their quad speaker connectors; Cyberlink's PowerDVD supports four speaker output (mixing down 5.1 speaker sound appropriately) and S/PDIF, which would seem to make it a good choice. PowerDVD's a full-price application, though, so it'll practically double the price of the AW744S.

Then again, none of the Sound Blaster Live! models come with DVD playback software, and the basic ones don't have digital output, either. So the AOpen board still ends up looking pretty spiffy - it's just not quite as cheap as it seems, if you want Serious Home Theatre Connectivity.


If you're a home theatre fan who's got an amplifier with optical S/PDIF input, it's hard to go past an AW744S plus a DVD-ROM drive and PowerDVD for a really cheap DVD playing solution. And you just happen to get a good 3D sound card for your PC into the bargain.

If the optical output's no good to you - and it probably isn't; optical inputs are fairly rare, and a lot of hardware that's got them has electrical inputs that work just as well - then this is just a high quality sound card, great for games, without silly bundled software you don't want, at a bargain price.

If you're running Windows NT or 2000, there's not much reason to bother with this board unless the optical output's important to you. For Win95/98 users, though, you will not find anything nearly as good as a YMF744-based card for this kind of money, and the AW744S is a good example of the breed.




  • Excellent price
  • Quality sound
  • Optical S/PDIF output
  • Windows 2000 drivers not good

AOpen's page for the AW744S

3D audio info

Any half-decent sound card these days has impressively quiet input and output, and can be used for quite serious studio digital audio work, as long as you're happy with basic stereo analogue input and output and don't need fancy digital connectors. But funkier cards have hardware that lets them do positional and environmental audio. They are for sound what 3D accelerators are for video.

Positional audio uses advanced psychoacoustic tricks to give you the impression of true 3D sound. In front, behind, above and below; sound sources can be quite clearly localised. This extra realism is more fun, and can be quite handy; as you crouch behind a crate with machine gun in hand, it doesn't hurt to be able to definitely tell which side of the box your enemy is about to walk around.

The positional audio is really only coming from two or four actual transducers - dual or quad speakers, or the twin transducers in headphones. But the Head Related Transfer Functions (HRTFs) used by the different positional audio systems fool your brain into thinking otherwise.

The theory behind HRTFs is, in essence, pretty simple. Humans only have two audio-detecting devices - those little tympanic membranes in our ears - but, without moving our heads, we can locate sounds all around us. The way we do it is by analysing the spectral and phase changes in the sounds that are picked up by each ear; the head, the ears and the environment all change the sound that's emitted by things, and the brain decodes the phase rotation and reverberations and relative delays and frequency emphases. Fake enough of those tell-tale distortions, and you fake the location information too.

Actually doing it, of course, is a heck of a lot more complicated than the basic idea. But it can be done, and it has been done; real honest-to-goodness 3D sound, even if all you've got is two speakers. With headphones, it can be spookily good.

Environmental audio is, usually, simpler. It's the simulation of what sounds do in particular spaces. It can be simple, just applying canned reverb effects to the sound you hear, or it can be complex, actually "wavetracing" the sound so you get proper wall reflections and sound occlusion by objects.

Even the simple kind of environmental audio doesn't just pick from its few dozen presets and stop there; game developers can specify the level of the reverb and the ratio of reverb to unaffected sound.


5.1 channels: Surround sound systems with six speaker outputs (left, right, centre, left rear, right rear, subwoofer) are often referred to as "5.1 channel", because the subwoofer Low Frequency Effects (LFE) channel outputs only low bass sound, not the full range of frequencies.

7.1 channels: The 7.1 channel format adds extra left-centre and right-centre channels to the standard 5.1 format. It's supported in DVD only by discs with an MPEG-2 soundtrack, and even then is very rare. Which is just as well, because practically nobody has an audio-visual setup that can play it.

AC-3: This was the original name for the Dolby Digital sound system used on the majority of DVDs, and it's still the name for the kind of compression it uses. Dolby Digital uses lossy compression, conceptually similar to the ATRAC encoding used by MiniDisc and the MP3 (MPEG 1 Layer 3) computer audio format, to squeeze audio data into a much smaller space. AC-3 sounds better for a given data rate than the older ATRAC and MP3 formats.

The normal data rate for plain two-channel stereo AC-3 is 192 kilobits per second (kBps; one kilobit is 1000 bits), and the format supports bit rates from 64 to 448 kBps. 384 kBps is the normal bit rate for 5.1 channel AC-3 surround, and this bit rate is used by many DVD movies and all laserdiscs (the old LP-sized analogue video discs) that have an AC-3 surround soundtrack.

For well-encoded MP3 audio, 64 kBps per channel is enough for near-CD quality (better than FM radio) sound reproduction; 80 kBps per channel tidies up pretty much all of the remaining artifacts.

In 5.1 channel mode at 384 kBps, AC-3 uses 64kBps, but its superior sound quality at a given bit rate makes it about as good as CD for even critical listening. It's widely agreed that AC-3 surround at the full 448 kBps speed sounds only slightly better than 384 kBps. The AC-3 standard actually technically supports bit rates up to 640 kBps, but the implementation of it used in DVD doesn't. The general consensus is that 448 kBps AC-3 sounds as good as any other 5.1 channel system, including the much heftier DTS (explained, along with the other DVD movie audio flavours, here).

PC 99: Microsoft's latest standardised PC design specification, which like Microsoft's previous specifications will no doubt be adhered to in whimsical ways by different manufacturers.

For more information on PC 99, see the Design Guide here.

MIDI: Musical Instrument Digital Interface, the standard protocol for hooking together electronic instruments. PC sound cards have on-board MIDI music capabilities, and can also have a special cable connected to their joystick port to allow the connection of external MIDI devices.

MPC2: Another software and hardware standard, created by a computer company consortium led, again, by Microsoft, but rather older than PC 99. In this context, MPC2 just describes the kind of connector used by various sound cards for internal analogue audio, for instance from CD-ROM drives and internal modems.

MPU-401: An old dedicated MIDI interface card for IBM compatibles, which is emulated with varying degrees of success by various sound cards.

S/PDIF: Sony/Philips Digital Interface Format is an audio transfer protocol that can use either optical or electrical connectors - the data's transferred in exactly the same format on both. It's used to transfer either 16 bit stereo audio data between various components (CD players, Digital Audio Tape decks, some sound cards), or to transfer Dolby Digital (formerly known as AC-3) 5.1 channel audio for movies.

Give Dan some money!
(and no-one gets hurt)