I have purchased a USB microphone, but the volume is very quiet, even when set to max. I can view the device in alsamixer and set the "Capture" bar to 100, but even so it is very quiet and unusable. Much quieter than the poor quality inbuilt mic from my computer.
Is there a way to increase the volume further?
Edit: This image shows the inbuilt mic on the left and the USB on the right, recorded in audacity, both at 100.
I have the ability to set my headset mic to (IIRC) 140-150% -- but this depends on having hardware gain available in the sound digitizer system, which I do when using the on-board sound hardware on my desktop motherboard. You're limited to whatever hardware your USB mic provides.
If you have headphone and microphone jacks (3.5 mm, usually) or a combined three-ring headset jack on your computer, you may be able to get better input gain using that with a conventional microphone.