Strange noise when recording voice

[mancshaun]

i am in the middle of recording some narration for a powerpoint presentation and i have a strange noise problem. when i commence recording i get around 1 - 3 seconds of aubible noise then silence and when the person speaks it is very noisy and distorted. if the person speaks during the noise (within the 1st seconds) their voice is recorded fine. it has also happened mid recording where suddenly the voice is distorted and noisy. anybody come across this before???

[steve]

This kind of problem is quite common with external USB audio devices. What's your set up?

[mancshaun]

i'm running a Shure PG58 mic with mini jack straight into a Dell latitiude laptop. the laptop has a sigmtel audio card.

[steve]

My guess would be the sigmtel - is it "on board" (built into the motherboard rather than a discrete device)?

Microphone inputs on computers are usually "powered". They have a voltage present so that they can power "electret" microphones which are commonly used with computers. Your microphone is a "dynamic" microphone and should not really be used with a powered socket.

Main stream sound cards, and particularly on-board sound cards, have a reputation for using very cheap low quality components for the microphone input, and I think it is likely that this is where the problem is coming from. If you also have a "line in" socket, there is a good chance that the quality will be significantly better, however you will need to amplify the microphone by some means before it goes into the soundcard. Microphones have a very low output compared to "line level". You may be able to use a tape recorder or a little microphone mixer to boost the signal to a suitable level for the line input.

[mancshaun]

Many Thanks, i had suspected that the laptop was causing the problem. i will get a small mixer or preamp and try the line in.

cheers