Cheap USB Sound Cards

[timkilbride]

I bought some of those cheap USB sound cards off eBay. I plugged them into my Windows 7 machine and the audio is way over driven for my feed. On my previous order of them, I could "un-check" the AGC. This secnd order of them doesn't even have a AGC option. I have the microphone input set to Ø. Is there a web site to download an updated driver? Any Ideas?

Thanks,
Tim K.

 

[CoolCat]

What input are you using?

It sounds like you are using the microphone input. Line-level source voltages are much higher than microphones and can easily overload the Mic input. You should use the "Line In" input for line-level sources such as a scanner's external speaker output.

If for some reason you must use the Mic input, and your sound card settings do not allow you to change it to line-level source voltage (set the Mic input to act as a Line Input), then you can use an in-line attenuator to drop the line voltage down to a suitable level. These are cheap to buy as in-line volume controls, or you can build a simple attenuator circuit with just 2 resistors.

Good luck.

 

[datainmotion]

What input are you using?

As he's using a USB audio device, it may be one of the dongle sized devices which only has one input and one output.

To the OP, I haven't tried one of my cheap-o USB audio dongles on my Win 7 yet, but try clicking on the speaker in the task tray and then mixer. Click on the mic icon and then check the levels tab to see if the boost is above 0...

Hope that helps.

*EDIT* - I just re-read your post (OP) and have you tried these on Win 7 before?

 

[datainmotion]

I bought some of those cheap USB sound cards off eBay. I plugged them into my Windows 7 machine and the audio is way over driven for my feed. On my previous order of them, I could "un-check" the AGC. This secnd order of them doesn't even have a AGC option. I have the microphone input set to Ø. Is there a web site to download an updated driver? Any Ideas?

Thanks,
Tim K.

On Win 7:

Control Panel>Sound>Recording>Microphone (USB Audio Device)>Properties>Custom

That should take you to the AGC checkbox (which is on by default when you insert the USB sound device into a Win 7 machine). You can click the Levels tab next to the Custom tab as well.

 

[timkilbride]

What input are you using?

It sounds like you are using the microphone input. Line-level source voltages are much higher than microphones and can easily overload the Mic input. You should use the "Line In" input for line-level sources such as a scanner's external speaker output.

If for some reason you must use the Mic input, and your sound card settings do not allow you to change it to line-level source voltage (set the Mic input to act as a Line Input), then you can use an in-line attenuator to drop the line voltage down to a suitable level. These are cheap to buy as in-line volume controls, or you can build a simple attenuator circuit with just 2 resistors.

Good luck.

The only choice is MIC INPUT, no LINE IN option. I did take your offer up on the in-line attenuator. I ended up using a 18K resistor. 10K wasn't enough and 33K was way to much. Again, thanks for the link! It really helped.

Tim K.

 

[timkilbride]

As he's using a USB audio device, it may be one of the dongle sized devices which only has one input and one output.

To the OP, I haven't tried one of my cheap-o USB audio dongles on my Win 7 yet, but try clicking on the speaker in the task tray and then mixer. Click on the mic icon and then check the levels tab to see if the boost is above 0...

Hope that helps.

*EDIT* - I just re-read your post (OP) and have you tried these on Win 7 before?

I'm using two Win 7 machines. One machine has 3 feeds using 3 USB Sound Cards, all have the AGC option under the custom tab in the recording properties. On a remote feed with a Win 7 machine, none of the USB Sound Cards have the custom tab in the recording properties. Each batch of USB Sound Cards came from two different vendors. One from China and the other from the West Coast. Visually, they look identical.

Tim K.

 

[timkilbride]

On Win 7:

Control Panel>Sound>Recording>Microphone (USB Audio Device)>Properties>Custom

That should take you to the AGC checkbox (which is on by default when you insert the USB sound device into a Win 7 machine). You can click the Levels tab next to the Custom tab as well.

For whatever reason, this batch of sound cards doesn't have the CUSTOM tab.

Tim K.

 

[CoolCat]

I did take your offer up on the in-line attenuator. I ended up using a 18K resistor. 10K wasn't enough and 33K was way to much. Again, thanks for the link! It really helped.

Tim K.

Happy to hear it Tim. I'm glad I could help