Re: [linux-audio-user] Recording Level using Audacity and a Multiface card

On Sat, May 13, 2006 at 08:03:48AM +1000, D. Sen wrote: That is a microphone, indeed. A B&K measurement microphone, that is. (A note to those not familiar with B&K measurement equipment: These are not quite like "normal" microphones. But they are of very high quality.) According to your linke, this microphone has a sensitivity of 50mV/Pa. And this is the preamplifier. (Which would, in audio, normally be considered part of the microphone.) This one has, according to the link, a peak output of 7 volts, corresponding to an SPL of 138dB for a 50mV/Pa microphone. Your 94dB signal is 44 dB below that. Which means that the output level after the preamplifier will be l = 7 * 10^(-44/20) = 0.044 And 0.044 volts is quite a bit below full scale line-level. However, adding the 10x gain of your amplifier you should be at 0.44 v, which is certainly in the ballpark of consumer line-level. After looking closer at it, your setup actually seems to make some sense. Your amplifier (the 4416) is not one normally used for amplifying microphone signals, but rather accelerometers and the like. (As your links says: "conditioner for use with ISOTRON(R) or other piezoelectric voltage mode transducuers.") But the preamplifier (the 2111) _seems_ to be of a special kind intended just for interfacing microphones to this kind of amplifier, so you are probably right in that it should work. Asbjørn