Audio Hardware - Major Sound Chip Makers

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Most companies other than Creative Labs depend on third parties to make their audio chips. Some of the major vendors include:

• Atech. The Sonix SN11116 USB audio controller is designed especially for the USB interface. It supports up to 48KHz sampling for digital and analog recording and playback. It supports six-channel analog output and SPDIF digital stereo output and can transmit AC-3 5.1 data via SPDIF to an external Dolby Digital decoder for 5.1 digital audio.

• Cirrus Logic/Crystal Semiconductors. The top-of-the-line Sound Fusion CS4630, an enhanced version of the CS4624, features 3D acceleration, support for both EAX and Sensaura positional audio, unlimited-voice wavetable synthesis, and S/PDIF support for AC3 and Dolby 5.1 input and output at rates up to 48KHz. The CS4630 is used in the Hercules Game Theater XP, Voyetra Turtle Beach Santa Cruz, TerraTec SiXPack 5.1, Video Logic Sonic Fury, and SonicXplosion audio adapters. The CS4624 is used by the Hercules Gamesurround Fortissimo II/III 7.1, Hercules DigiFire 7.1, TerraTec DMX Xfire, and Hoontech SoundTrack I-Phone Digital CS audio adapters.

• ESS Technology. The Canyon3D-2 (ESS1990/1992) is ESS Technology's flagship audio chip, featuring four-channel analog output, support for Dolby and THX digital sound, SPDIF input and output, and Sensaura 3D positional audio, and it is optimized for use with DirectX 8.0. It is used by the I/O Magic Hurricane Extreme, Diamond Monster Sound 3D, Hercules MaxiSound Fortissimo, and TerraTec DMX audio adapters.

  The Maestro-2 series features wavetable, positional 3D from Sensaura, and 3D audio acceleration; the Maestro 2E and 2EM also support S/PDIF output for DVD movie support. The Maestro series chips are optimized for notebook computers, and Maestro chips are used in recent models of Dell, Toshiba, Gateway, Compaq, and HP portables.

  The Allegro series (ESS-1989 for desktops and ESS-1988 for notebook computers) features DirectSound, Direct3D, S/PDIF output, and Sensaura 3D positional sound. The ESS-1989 is used by the Philips Harmonic Edge (PSC602) sound card as well as models sold by Pine Technologies and others.

  ESS's earlier AudioDrive series was popular with many notebook computers and second-tier sound card makers in the mid-1990s.

• C-Media Electronics. The CMI 8738 series features 4.1 and 5.1 speaker support for quadraphonic and Dolby Digital output, Direct Sound 3D and A3D positional audio, and wavetable and is available for desktop or notebook computers; some versions also integrate a software modem and SDPIF port. It is used by sound cards such as Guillemot's MUSE, Leadtek's WinFast 4x Sound, and various generic sound cards; and motherboards made by Asus, Soyo, Shuttle, Chaintech, and others.

• ForteMedia, Inc. The FM-801 is the first audio chip to feature Dolby Digital 5.1 output to analog speakers for both DVD movies and games. The FM-801 also features QSound's Q3D 2.0 3D API and optional support for SPDIF input/output. It uses host signal processing (HSP), which shifts some of the signal processing load onto the CPU, so it's a less desirable choice for slower systems than some other audio chips. The FM-801 is used by many smaller sound card makers and some motherboard makers, such as Shuttle. For a review of the sound chip and a feature comparison of some sound cards using this chip, see http://www.3dsoundsurge.com/reviews/FM801/FM801.html.

• VIA Technologies. VIA Technologies produces a wide range of audio controller chips sold under the Envy24 brand, all of which feature 24-bit resolution and DirectX 3D acceleration. The original Envy24 is designed for professional sound recording. The Envy24HT and Envy24HT-S are designed for use in high-performance (up to 192KHz sampling) sound cards for gamers and audiophiles; the Envy24PT features up to 96KHz sampling rate for use on low-cost motherboards with integrated audio. These chips are paired with the VIA Six-TRAC AC'97 codec for 5.1 audio. To achieve 7.1 audio, the Six-TRAC codec and an additional DAC are required, or the VIA Eight-TRAC AC'97 codec can be used instead of the Six-TRAC codec. The Envy24HT is used in the Audiotrak Prodigy 7.1, Aureon 7.1 Space, Aureon 5.1 Sky, and M-Audio Revolution 7.1 PCI sound cards. Envy24PT is used in motherboards from Albatron and Chaintech.

Discontinued and Orphan Sound Chips and Sound Card Producers

The following sound chips are no longer being sold, and ongoing support is limited or no longer available. If you use an audio adapter based on one of these products, you might need to upgrade if you can't get drivers for new and forthcoming operating systems.

Discontinued products include

• Oak Technology OTI-601 series. Oak left the audio chipset business in early 1998.

• Trident 4DWave-NX series. This 3D audio chipset was used on some cards from smaller audio adapter vendors, such as Aztech, Jaton, and Hoontech.

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Note - The former Diamond Multimedia division of S3 (later Sonic Blue, now out of business) sold sound cards using chips from various vendors, including ESS Technology, Aureala, and others. The current Diamond Multimedia product line of graphics cards and modems is sold and supported by Best Data Products; the new Diamond Multimedia offers limited support for old Diamond Multimedia modem and graphics card products, but not sound cards. You can search the Web to locate drivers for S3-built Diamond sound cards.

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Motherboard Chipsets with Integrated Audio

The Intel 810 chipset was the first mainstream chipset for a major CPU to integrate audio; it works with Celeron CPUs. Its inspiration might have been the Cyrix/National Semiconductor Media GX series, which used a trio of chips to substitute for the CPU, VGA video, onboard audio, memory, and I/O tasks.

Thanks to improvements in chipset design and faster CPU performance, today's best integrated chipsets can provide solid mid-range performance. Almost all recent chipsets from Intel, VIA, ALi, and SiS have integrated audio (see Chapter 4, "Motherboards and Buses," for details). In almost every case, integrated audio supports the AC'97 audio standard.

AC'97 Integrated Audio

The phrase AC'97 integrated audio can be found in the descriptions of most recent systems. Because AC'97 can replace the need for a separate audio card but might not be a satisfactory replacement, you need to understand what it is and how it works.

AC'97 (often referred to as AC97) is an Intel specification that connects an audio codec (compression/ decompression) architecture to a section of a South Bridge, an I/O Communications Hub chip called the AC-Link control, or an audio controller such as the VIA Envy24 series. The AC-Link control works with the CPU and an AC'97 digital signal processor (DSP) to create audio.

The AC'97 audio codec could be a physical chip on the motherboard, a chip on a small daughterboard called a communications and networking riser (CNR), or a software program. Thus, a motherboard with AC'97 integrated sound support doesn't require the use of a separate audio card for sound playback. Sometimes AC'97 is also used to refer to audio chips on a sound card, but in this discussion we will use it to refer only to integrated audio. Sometimes motherboards also integrate an analog modem through an MC '97 codec chip, or they might have an AMC '97 (audio/modem) codec chip to combine both functions.

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Note - Some low-cost sound cards and some USB-based audio products use AC'97 codec chips along with additional components instead of traditional single-chip audio solutions.

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It's important to realize that, although most recent chipsets support AC'97 audio, this does not mean that every motherboard built on a particular chipset uses the same AC'97 codec, or even the same method of creating sound. In most cases, AC'97 is implemented through a small AC'97 codec chip on the motherboard (see >Figure 16.8). It can be surface-mounted as shown in Figure 16.8, but many vendors use a small socket instead.

Figure 16.8 The VIA VT1612A is a typical AC'97 2.2–compliant codec chip. Photo courtesy of VIA Technologies, Inc.

A few motherboards use an AMR or a CNR riser card to implement AC'97 audio along with audio ports.

For various reasons, including audio codec features and price, different motherboard vendors might use different AC'97 codec chips on motherboards that use the same chipset.

For example, compare the following motherboards based on the Intel 865PE chipsets as listed in Table 16.5.

Table 16.5 Sample AC'97 Codecs Used with Intel 865–Based Motherboards

Vendor	Motherboard Model	AC'97 Codec Chip
FIC	P4-865PE Max II	Analog Devices AD1980
Soyo	Sy-P4I865PE Plus Dragon 2	C-Media 9739A
Giga-Byte	GA-8IPE1000-G	Realtek ALC850

Major vendors of AC'97 codecs include Analog Devices (SoundMAX), C-Media, Cirrus Logic (Crystal Audio), National Semiconductor, Realtek (includes former Avance Logic products), SigmaTel (STAC C-Major), VIA Technologies, and Wolfson Microelectronics plc.

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Note - The drivers for a particular AC'97 codec chip are supplied by your motherboard vendor because they must be customized to the combination of codec and South Bridge/ICH chip your motherboard uses.

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Although the AC'97 specification recommends a standard pinout, differences do exist between AC'97 codec chips. Some vendors of AC'97 chips provide technical information to help motherboard builders design sockets that can be used with different models of the AC'97 codec chip. However, in other cases, AC'97 codecs are surface-mounted to the motherboard.

The four versions of the AC'97 codec are as follows:

• AC'97 1.0. Has fixed 48KHz sampling rate and stereo output

• AC'97 2.1. Has options for variable sampling rate and multichannel output

• AC'97 2.2. Has AC'97 2.1 features plus optional S/PDIF digital audio and enhanced riser card support; released in September 2000

• AC'97 2.3. Has AC'97 2.1/2.2 features plus support for true Plug and Play detection of audio devices; released in July 2002

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Note - Audio solutions that use AC'97 2.3–compliant codecs can detect whether you have connected a speaker to the microphone jack or a microphone to the speaker jack and warn you that the wrong jack is being used for the device. This helps eliminate one of the most common causes of audio failures.

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Most recent motherboards with integrated audio support AC'97 2.2 or 2.3. To learn more about the AC'97 specifications, see the Intel – Research and Development, Audio Codec site at http://www.intel.com/ labs/media/audio/index.htm.

To determine whether a particular motherboard's implementation of AC'97 audio will be satisfactory, follow these steps:

1. Determine which codec chip the motherboard uses. Read the motherboard manual or see which driver the motherboard uses for audio.

2. Look up the chip's features and specifications. If you are not sure of the chip manufacturer, look up the part number with a search engine such as Google.

3. Use a search engine to find reviews of the chip's sound quality and performance (typically found as part of a motherboard review).

4. Look at the motherboard's features to determine whether it uses the full capabilities of the codec chip. Chips that support AC'97 2.1 can offer up to six-channel analog audio; those that support AC'97 2.2 can also offer S/PDIF digital audio. However, motherboard makers don't always provide the proper outputs.

5. Analyze how you use audio. If you play a lot of 3D games, you're not likely to be satisfied with the performance of any integrated audio solution, no matter what its features might be. You can disable onboard audio with a BIOS setting if you prefer to install your own audio card.

For details on how to enable and disable onboard audio, see "Peripheral Configuration," p. 437.

This chapter is from Upgrading and Repairing PCs, 16th edition,by Scott Mueller. (Que Books, 2004, ISBN: 0789731738).  Check it out at your favorite bookstore today. Buy this book now!

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