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How do soundcards work?

Discussion in 'General Hardware' started by rectifryer, Jun 17, 2012.

  1. rectifryer New Member

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    Seemingly simple question but I really am unfamiliar with what they actually do. I know they have A/D decoders and preamps, but what else do they do? Do they offload the cpu from any processing?

    I have a home studio that I record local musicians in. I have noticed that my M-Audio 1010lt works great but when I use just an onboard video card I get pops in the recordings and excessive latency.

    I am just trying to piece this together so I know what to look for in the future.
     
  2. Frag Maniac

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    Only certain sound cards have been made that will minimize how much the CPU is used (in games for instance) due to having hardware decoding. Creative being the most common. Since the HAL (hardware audio layering) support XP had was removed in Vista and W7, that has become less of an issue though because even Creative cards now have to run off their Alchemy software to support surround sound properly.

    Even aside from CPU cycles though there is system RAM use to consider. On XP Creative cards use the least CPU cycles, but they're not the most efficient on RAM use. Conversely, software supported cards can also vary quite a lot on how many CPU cycles they use. My M-Audio Revo I used on XP used roughly 3-5% CPU, but I've seen tests on cards that use upwards 10% or more.

    What you're experiencing in sound pops may be either driver, connection port or even static build-up issues, but more commonly on the driver side. One thing sound cards have in common is most don't have very good driver support. The problem is EVERY sound card manufacturer has to rely on the maker of the DSP chip for drivers, and most chip makers are slow to update them.

    Some sound card users have even resorted to using drivers from another product that uses the same chip when they can't get their cards to work or have lingering issues that are unacceptable. It usually involves a workaround via editing the device ID though.

    For gaming, movies etc, a great alternative to sound cards is a multi channel home theater receiver. You can get them for pretty much the same the better sound card start at when on sale. The hardware alternatives for music use are fairly expensive though. In gaming though, the primary reasons sound cards have declined in use is the advent of onboard HD audio, and the price at which you can get a pretty good receiver.

    As far as AD conversion and decoding though, sound cards can vary greatly. This is esp true when you are shopping for a multi use sound card like I was. I wanted something that would work with my all in one sys that I use for gaming, movies, internet, and TV. The problem I discovered was most sound cards cannot take a PCM surround encoded stereo signal from a TV and convert it to 5.1 analog surround.

    Only HT Omega makes a sound card (the Claro) that will convert a TV's PCM audio to 5.1 analog surround, and it does it via simulated surround vs true decoding. As expensive as that card is and considering it's limitations in sound quality and features, not to mention the ongoing worry of sound card drivers in general, I went with a 5.1 receiver instead.
     
    Last edited: Jun 18, 2012

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