Best USB Mike

[steve]

As koz said, one of the limitations of USB microphones is that the microphone, pre-amp ad A/D converter are all built into the same unit. They have to able to cope with people with powerful voices singing loudly at close range, and with people with quite voices who are whispering.

Internally the microphone gain will be set so that maximum sound pressure level that the microphone can handle safely will give a digital output of approximately 0dB (+1.0 to -1.0 on Audacities vertical scale). Any sound that is quiter than that will give a smaller waveform.

It would be possible for the manufacturer to add a "volume control" to the microphone itself, but in practice there would be little point as the microphone itself has a fixed sensitivity range. Too loud and it will distort - too quiet and there will be "self noise" (hiss). Changing the gain of the microphone pre-amp can do nothing to change that, so the only benefit is that it would allow the analogue output of the microphone to fit within the dynamic range of the A/D converter, however, 16 bit converters that are used have a theoretical dynamic range of around 96dB, which is considerably greater than the SNR of the microphone.

The upshot of this is that for this type of microphone, using the Amplify or Normalize effects in Audacity will be just as effective as increasing the microphone pre-amplifier gain (which is not available).

[gmatkin]

Thanks Koz!

Gav

[gmatkin]

Hi Steve - thanks for your comments too. I understand about the s/n ratio point. I'll use the mic with confidence now, and won't worry about possible faults.

Now I need to investigate the question of whether one can buy seriously long USB cables so that I can place the mic far from the hum and hiss of my computer's fans.

Gav

[stearman65]

Hi Steve - thanks for your comments too. I understand about the s/n ratio point. I'll use the mic with confidence now, and won't worry about possible faults.

Now I need to investigate the question of whether one can buy seriously long USB cables so that I can place the mic far from the hum and hiss of my computer's fans.

Gav

Hi Gav
I have used my USB mike a Samson C03U and a zoom H2 with a 5 metre usb extension cable bought from Ebay with no problems.
Stearman65

[steve]

USB is not good with long leads, but you should be OK with a lead up to about 5m (I know another Audacity user that has that same setup). BTE, the Zoom H2 is a great bit of kit - good quality sound, easy to use and truly portable (care should be taken not to drop it).

[gmatkin]

Well, I bought a 5m USB lead, but was still getting loads of noise when I plugged it into my PC, even when I lead the cable out into the next room.

So I thought I'd try my acoustically quieter Win2000 laptop. No dice once again, so I fiddled around for a while and finally found an option to use input from 'the USB device'. Eureka, I thought. But again, no dice, as the signal is coming from the laptop's built-in mic. Then I found the Audacity preferences menu had a gizmo for toggling between ESS Allegro input and Windows Sound Mapper for both input at output. Switching to Windows seems to have fixed all my difficulties - I'm getting a signal on the laptop, which I wasn't previously, and there's there's much less noise. And unlike the XP PC, there's plenty of the signal.

Thanks for your help, folks.

Gav