USB Vs. PCI

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Double edged sword...

I would say that it mostly will depend on the quality of the card itself. In theory the USB option would be the "better" way to go because you are taking the card out of the VERY noisy environment of the computer itself.

With that said, if the card is a cheaply made card or if you are keeping it near a "noisy" environment such as near the antenna of your wireless routers or WIFI card in your PC etc, or using cheap unshielded audio cables then being outside the PC no longer is a benefit because you will still pick up all the interferences that are in the local PC environment.

I personally use an internal card, and try to isolate all my cables for the feed as far away from the PC as possible to avoid any more interference that's absolutely need be.

I hope that helps you out.
 

datainmotion

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Also, if you are using a USB extension cable, you may want to try and plug the USB device directly into the PC (if possible).

FWIW - I use one of the $1 Chinese USB sound cards and had intermittant audio quality issues until I plugged directly into the PC.
 

gmclam

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Regardless of which sound card you use, you need to get the audio level within the input range of the device you are using, and then set the audio level of that device to your stream. I use a digital meter to monitor the levels I am streaming.

I happen to have several PCI cards and several of those $1 USB sound cards here. I happen to like the quality of sound through the USB cards by leaps and bounds over the PCI cards. My only complaint is the fact they are USB and have to be enumerated upon boot up whereas PCI cards don't.
 

lowerrollin

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My audio isn't clipping from high input as far as I know. I'll check it when I get home tho. Best way I can describe it, is it sounds like a 996t decoding a digital signal. It sounds digitized. They are analog btw. From 3 feeds, the 2 on usb sound this way. The feed running from the built in sound card is crisp tho. Does this problem sound unusual?
 

gmclam

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You can overdrive the input of the sound card. The level could be adjusted to look ok on a meter, but would not be correct. If you can capture and look at the wave file, you'd see the distortion.

Because most of the $1 USB sound cards only have a MIC input, it is much easier to overdrive them. The PCI cards often have line and mic inputs, or one input that can be switched to accept either signal range.

My solution was to use a step down and isolation transformer. I wanted isolation between the scanners and computer anyway, so rather than just use a 1:1 transformer I used a 10:1 transformer. That dropped the signals to be more in range of a mic input. It could also be done with resistors, but it was too many resistors and it look as nice as using a single transformer (or give me isolation).
 

talkpair

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Does anyone if there exists any documentation on the cheapo USB sound cards from overseas?

I bought a handful, just to try out, and they squeal with NOTHING connected to them.....I really don't know if they're even Linux compatible to begin with.
 
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