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Capabilities of Realtek ALC655 sound on 7N400Pro2 motherboard
Just passing on a few things I learned while trying to answer these
same questions for my own system: 1. What's the sound subsystem on the Gigabyte 7N400Pro2 motherboard? It's the Realtek ALC655 chip, which supports the AC97 sound standard with 6 channels and digital SPDIF input and output capability. Realtek's site for information and up-to-date drivers: http://www.realtek.com.tw/ Note that the 7N400Pro2 does NOT have the same capabilities as the original 7N400Pro (these boards should really not have been labelled so similarly). The original Pro had the more expensive nVidia MCP-T chip with "SoundStorm" in addition to the Realtek codec (the MCP-T has a DSP providing extra audio functions like real-time Dolby Digital encoding). 2. Does the Realtek ALC655 on the 7N400Pro2 support 6-channel surround sound? Yes. It can generate 6 separate analog channels for full 5.1 surround sound, just like a Sound Blaster Live card, for example. You can plug it into an external 5.1 speaker system with a set of 3 analog audio cables. If you have the audio extension bracket supplied with the 7N400Pro2, you will find the Rear L/R and Center/Sub channel connectors on the bracket. Otherwise, you must change a driver setting to switch the Microphone In and Line In jacks on the rear panel to provide those extra connections. You must select 6-speaker configuration on the sound control panel to activate all 6 channels. You can test each channel individually from the control panel, and you can use the HRTF demo function on the control panel to hear music circle around the channels continuously. If you don't have these functions on your control panel, download the latest driver from Realtek. 3. Does it support digital audio input and output? Yes. The 7N400Pro2 has SPDIF (Sony-Phillips Digital Interface) digital audio input and output connectors on the motherboard, which are fully supported by the Realtek chip. If you have the audio extension bracket, you will find digital coax and digital optical (TOSLink) output connectors on it, which are internally connected to the SPDIF output on the motherboard. 4. Does anything have to be done to enable the digital output? In WinXP, with the current Realtek driver installed, the digital output seems to be always on. It continuously provides a two-channel digital PCM data stream with the same sound you hear on the stereo or front channels of the analog audio. It can be connected to external digital audio devices like a digital speaker system using the coax or optical connectors. Other users with different audio setups have mentioned driver settings or WinXP settings which have to be changed to enable digital output, but I have not found any applicable to the this 7N400Pro2 setup, other than the SPDIF Mute checkbox on the Sound Mixer control panel, which does affect it. You do not need to select 5.1 speaker mode or a room type on the sound control panel to activate the digital output, and those settings don't affect the digital output (only the 6-channel analog output). 5. Can this system produce Dolby Digital surround sound output? Yes and no. If you are playing a sound source like a DVD which has a pre-encoded Dolby Digital 5.1 sound track, and your player software supports "pass through" mode (PowerDVD and NeroVision Express do), then the driver will pass the encoded digital sound track through to the SPDIF output without changing it. If you have an external Dolby Digital decoder, it will get the full DD 5.1 surround sound signal. If your player software does NOT support pass-through mode, then you will get a "downmix" of only two channels supplied by the player software. This sound system doesn't have the signal processing horsepower to encode 6 analog channels to a compressed Dolby Digital 5.1 signal in real time, unlike the SoundStorm version mentioned above. If your source is not pre-encoded, you will get only two channels on the digital output. However some player programs and some games like Unreal Tournament have the ability to produce Dolby Pro Logic surround sound encoding on two channels in real time. If you have an external Dolby Pro Logic decoder hooked up to the digital output, you will get a limited form of surround sound from just the two source channels. This is not as good as full Dolby Digital 5.1 surround sound though. 6. Can I control the level, balance, tone of the digital output? With the current Realtek driver, no. These settings appear greyed out on the mixer control panel. However if your player software supports an equalizer function, you can control some items there. And you can still control the WAV input level. 7. Does this system support EAX surround-sound effects for games? Yes, the Realtek driver supports EAX (a Creative Labs standard supported by many games), and will generate surround sound for games that support it. This is done in software rather than hardware, so you need a fast processor, and it will have a small impact on game performance (about 5-10%). It's controlled by the game program settings, so you don't have to do anything in the driver or control panel to enable it. 8. Is the quality of the sound as good as a separate Sound Blaster card? That depends on your point of view. The built-in subsystem on the motherboard sounds fine - there isn't any excessive noise or distortion, and the frequency response is good. You don't get 24-bit sound or 7.1 channel capability as you would with a high-end Sound Blaster Audigy, but you probably wouldn't miss that for most PC sound applications. You don't get the EAX extensions and hardware performance boost that the Sound Blaster card has for game sound. You don't get the CMSS capability to produce surround sound from stereo sources. The Sound Blaster has more software accessories and better support. But no version of the Sound Blaster can do real-time Dolby Digital 5.1 encoding either. |
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Comparing most motherboard sound to an Audigy is kinda not relevant. The
ALC655 is basically Sound Blaster compatible, i.e. hardware acceleration albeit minimal. So, it meets the minimum requirements for sound for gaming which should be enough for most. I have a K8VT800M Athlon 64 mobo with the ALC655, and while not as good as the ALC658 it is more than okay. Of course, I prefer the SoundStorm that I have in my NF7-S - which is hooked up to a DD home theater - but begars can't be choosers. Oh, and before I forget, my Stereo Home Theater A/V Receiver - which is in the room with my Athlon 64 - has 5.1 inputs for previously decoded DD, so basically I can hook my 5.1 from the ALC655 to it without needing the hardware DD encoder of the SoundStorm. Most A/V Receivers of high quality have this feature, and I mention it because you can usually get one cheap - especially the old DD *ready* ones ( i.e. no built in decoding ) - cheap at a pawn shop along with an old set of 5.1 speakers... "Exp315" wrote in message om... Just passing on a few things I learned while trying to answer these same questions for my own system: 1. What's the sound subsystem on the Gigabyte 7N400Pro2 motherboard? It's the Realtek ALC655 chip, which supports the AC97 sound standard with 6 channels and digital SPDIF input and output capability. Realtek's site for information and up-to-date drivers: http://www.realtek.com.tw/ - snip - 8. Is the quality of the sound as good as a separate Sound Blaster card? That depends on your point of view. The built-in subsystem on the motherboard sounds fine - there isn't any excessive noise or distortion, and the frequency response is good. You don't get 24-bit sound or 7.1 channel capability as you would with a high-end Sound Blaster Audigy, but you probably wouldn't miss that for most PC sound applications. You don't get the EAX extensions and hardware performance boost that the Sound Blaster card has for game sound. You don't get the CMSS capability to produce surround sound from stereo sources. The Sound Blaster has more software accessories and better support. But no version of the Sound Blaster can do real-time Dolby Digital 5.1 encoding either. |
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