X-bit labs

Contemporary Integrated Sound Solutions: Storm is Coming (page 3)

Category: Multimedia

by Sergey Samarin

[ 08/25/2003 | 03:57 PM ]

Among negative points of this approach, I can name extra heat dissipation and worse sound quality because of the reciprocal EMI produced by the elements inside the package. However, ALC650 has two weighty advantages from the mainboard makers’ point of view: low cost and compatibility with an infinite list of chipsets. The codec works with Intel 810/815/820/845 as well as chipsets from VIA/SiS/ALi. Now, let’s discuss its features in detail.

Basic characteristics of Realtek ALC650:

• Signal/noise ratio above 90dB;
• 18-bit ADC and 20-bit six-channel DAC;
• Four auxiliary analog stereo inputs for connection of internal audio sources (Line-in, CD, Video, Aux);
• Two auxiliary analog mono inputs (for PC-beep and Phone-in);
• One mono output;
• Stereo output;
• One standard microphone input plus one specific Front-Mic input (user-selected);
• Line-in is joined with Surround output; the Mic1 and Mic2 are joined with Center and LFE outputs;
• 3D Stereo Enhancement;
• External amplifier turn-off function;
• Digital S/PDIF output (S/PDIF-input is implemented in a later, “E”, revision of the codec).

The Realtek ALC650 codec is the strongest product in the market. For some other chip to achieve the same or higher popularity, it has to offer more functions and higher sound quality for less money. Which is quite implausible. However, new codecs do come out, while the competition issues are resolved by using new chips in the mainboards developed by codec makers themselves. A glaring example is VIA Technologies.

VIA’s Solutions: “Vinyl” Audio

People at VIA have already realized that ordinary users use their computers for entertainment rather than text typing. The growing capabilities of PCs in audio recording and playback, in special surround effects for games, etc. pushed VIA to create its own audio division. This company, known mostly for its chipsets, has released so many audio-related projects in the last two years, that it would suffice for a lifetime of any other establishment. So, VIA bought up ICEnsemble, a sound controllers developer, and founded a special department to be engaged in audio projects.

For the VIA Apollo KT400 chipset, the company developed a combination of software/hardware audio solutions under the name of Vinyl Audio (“Vinyl Audio Six-TRAC” for VT1616 and “Vinyl Audio” for VT1616A). The new South Bridge, VIA VT8235, along with the full communication package, also includes six-channel Surround Sound AC’97 support via the digital AC-Link interface. VT8235 doesn’t have its own APU as NVIDIA’s nForce2 and thus loses to it in many service capabilities. Moreover, the lack of hardware audio processing results in overall system slowdown.

VT8235 South Bridge is the major element
of VIA’s “audio mosaics”

Any South Bridge is just a digital part of the integrated audio subsystem. The analog components, on the other side of the Bridge, are responsible for the sound quality. Any manufacturer wants to use his own electronic chips, so VIA developed an AC’97 codec aka VT1616. It completes the chain from KT400 and VT8235 to the audio inputs/outputs. The codec includes both: an ADC and DAC to compete successfully with the hero of our time, Realtek’s ALC650.