FIC KT-748
Stephen Cooper, September 22nd, 2003
..:: Realtek ALC655 6-Channel Audio Codec ::..
The FIC KT-748’s onboard audio is provided by the Realtek ALC655 six-channel audio codec, one of the latest releases from Realtek that fully supports the new Rev. 2.3 specifications. These news specs provide support for features such as jack sensing, and eliminate the need for a clock crystal by utilizing a 14.218MHz -> 24.576 PLL. Recently, Realtek has released a higher end ALC658 “Professional” AC 97’ audio codec. Realtek also has released the first eight-channel codec, the ALC850. In the past we have experienced some fairly good onboard audio from Realtek products, although the overall quality does depend on the implementation into the motherboard by the manufacturer. The audio for the KT-748 followed in line with what we are used to hearing from Realtek implementations, and we were pleased with the sound quality provided. Here’s some more information from Realtek concerning the ALC655.
General Description
The ALC655 is a 16-bit, full-duplex AC'97 Rev. 2.3 compatible six-channel audio CODEC designed for PC multimedia systems, including host/soft audio and AMR/CNR-based designs.
The ALC655 incorporates proprietary converter technology to meet performance requirements for PC99/2001 systems. The ALC655 CODEC provides three pairs of stereo outputs with 5-bit volume control, a mono output, and multiple stereo and mono inputs, along with flexible mixing, gain, and mute functions to provide a complete integrated audio solution for PCs.
The digital interface circuitry of the ALC655 CODEC operates from a 3.3V power supply for use in notebook and PC applications. An integrated 50mW/20ohm headset audio amplifier for Front-Out and Surround-Out, a 14.318MHz -> 24.576MHz PLL, and a PCBEEP generator cut BOM costs. The ALC655 also supports S/PDIF input and output for easy connection of PCs to consumer electronic products, such as AC3 decoders/speakers and mini-disk devices.
The ALC655 CODEC supports host/soft audio from Intel ICHx chipsets as well as audio controller-based VIA/SIS/ALI/AMD/nVIDIA/ATI chipsets. Bundled Windows series drivers (98/ME/NT/2000/XP), EAX/Direct Sound 3D/ I3DL2/A3D compatible sound effect utilities (supporting Karaoke, 26 types of environment sound emulation, 10-band equalizer), HRTF 3D positional audio and Sensaura™ 3DPA (optional) provide an excellent entertainment package and game experience for PC users. In addition, the ALC655 is embedded with an impedance sensing capability to detect when a device has been connected to input or output jacks.
Features
Meets performance requirements for audio on PC99/2001 systems
Meets Microsoft WHQL/WLP 2.0 audio requirements
16-bit Stereo full-duplex CODEC with 48KHz sampling rate
Compliant with AC'97 Rev 2.3 specifications
Three analog line-level stereo inputs with 5-bit volume control, LINE_IN, CD, AUX
High-quality differential CD input
Built-in 50mW/20ohm amplifier for both Front-out and Surround-Out
External Amplifier Power Down (EAPD) capability
Power management and enhanced power saving features
Supports Power-Off CD function
Adjustable VREFOUT control
Supports 48KHz S/PDIF output, complying with AC'97 Rev 2.3 specifications
Supports 32K/44.1K/48KHz S/PDIF input
Power support: Digital: 3.3V; Analog: 3.3V/5V
EAX™ 1.0 & 2.0 compatible
Direct Sound 3D™ compatible
A3D™ compatible
I3DL2 compatible
HRTF 3D positional audio
Standard 48-Pin LQFP Package
Applications
Multimedia PCs
3D PC Games
Information Appliance(IA)
Voice Recognition
Audio Conferencing
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