A Conversation for Ask h2g2
dB or not dB?
Mycelium Started conversation Apr 20, 2003
What is 0dB?
How come loudness is measured in decibels from zero (silence) upwards, yet mixing desks measure from minus infinity to zero (full volume) and beyond (+3dB is distorted & overdriven)?
I thought it might be to do with the signal strength an amplifier would expect, but that's usually -22dB or -48(ish)dB.
So, if a shotgun blast is about 100ish dB, and absolute silence is 0dB, how come I end up trying to record stuff peaking at -6dB?
dB or not dB?
Bald Bloke Posted Apr 20, 2003
To avoid trying to explain & getting it wrong (college was 20+ years ago)
Have a look at
http://www.digitaltheater.com/hints/tp_feb98.html
dB or not dB?
Mycelium Posted Apr 20, 2003
cheers, man. i understood most of it, but it didn't say why mixers have negative dB values.
dB or not dB?
Bald Bloke Posted Apr 20, 2003
Thats because they are calibrated in dbv (voltage) rather than dba (sound pressure) so 0db = 1v (typically) which is the maximum input voltage to the pre amp before it distorts, hence any values need to be less than that and so have -db values.
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dB or not dB?
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