Howto: Adjusting C-Media USB Audio Volume in Windows 7

The Plugable UD-160-A Universal Docking Station and the Plubable DC-125 Zero Client Docking Station provide 2 channel USB audio via a CM-6300 chip. The CM-6300 is a “driverless” solution in that it complies with the USB audio class standard, and uses Microsoft’s own drivers provided in Windows 7. That also means that the software options for controlling the device are all in the hands of Windows 7 itself.

The UD-160-A and other powered CM-6300 devices can be configured in hardware to deliver high power audio output, so it’s great even with unpowered speakers. But for headsets and self-powered speakers, the defaults may be too loud.

For those cases and others, here are some details and tips for adjusting the volume in Windows 7 with USB audio.

First off, it helps to bring up some music in Windows Media player so you can hear the affect of your settings changes. Most Windows 7 installs will have some sample music to play in Libraries->Music->Sample Music

Then, go to where the settings are collected — in the “Sound” settings from the Windows 7 Control Panel.

This will bring up the list of available audio devices, one of which should be your USB audio device. By default, Windows 7 makes a new USB audio device the default — even if it doesn’t have any speakers attached! So this is also the place where, if you’re not actually using your USB or docking station audio, you can select a different audio output (e.g. your laptop’s built-in audio) and click “Set Default” to make it the default for new default sound output and/or for communications (messenger/skype/voip). Windows will persist this setting.

For adjusting the USB audio level, right click on the USB audio device to bring up the context menu and select “Properties”.

The main volume for the device is in the “Levels” tab. When this audio device is the default device, this level is the same as the Windows master audio volume controls (the one you adjust from the sound icon in the Windows system tray) — adjusting one will adjust the other. The default in Windows is a max volume of “100”.

For the high-power audio of the Plugable dock, combined with powered speakers, “100” is often too loud, and you may find that even setting the level to “1” is still too loud.

The solution is the “Custom” tab which has an optional “Loudness” checkbox (provided by the Microsoft USB audio class drivers). Windows 7 sets this on by default, but in most cases it should be unchecked. Then, go back to your levels tab and re-adjust the volume to the right and comfortable level.

For most speaker combinations, you should no longer be having to peg the volume down at “1”.

And once you have master volume at a comfortable level – you also have another means of control. Each application has its own volume, which acts in combination with the Windows master settings. So if system sounds or media playback are still to loud or not the right relative volume, look within the particular application for its own sound slider (and most applications will persist this setting).

We hope this helps for anyone experiencing audio which is too loud or too quiet with any Plugable or other USB audio devices on Win 7. Please feel free to comment with any questions or other suggestions.

[Update March 2, 2011]

If you’re on Windows, and the above steps don’t help enough, there is a Windows driver solution to bump the volume down further.

This driver replaces Windows’ default USB audio driver, it’s compatible with the CM6300 in the Plugable Universal Dock. Most functionality doesn’t apply to the CM6300, but the fine grained control over volume is better and helpful.

Here’s where you can download the lower-volume CM6300 driver. Please let us know in the comments if you have any problems or feedback. Thanks!

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