> I've maxed out a 125dB SPL mic at 18" with a trombone. And I still
> had more to give. Put a group of 100 trombones in front of that mic
> and no good can come of it.
James,
I believe someone tried 76 trombones once. :-) That would give a 19dB
rise in level (100 would be 20dB), but only if all 76 could get within
18" of the mic. By the time you've got them all spaced out so they
don't poke each other's eyes out with the spittle valve on the end of
the slide (I used to play the trombone) the sound level will have gone
down to loud orchestral levels. Did you know that the trombone has the
greatest sound output of any musical instrument except an organ? It
can peak to 6 watts when most instruments are below 1 watt.
I'll grant you the "headroom" argument. You don't want to drive a mic
to the limits, and a mic can overload on some frequencies more than
others, but I was just pointing out how big 140dBA is.
I've recorded many gunshots and explosions in my time including
blowing up a hillside in a quarry. If you peak these to 100% they
sound puny and pathetic, so you have to drive the mic/mixer into
severe distortion and pick up as much reverb as you can. This is why
kids playing cops and robbers go "kshew kshew" because Hollywood has
taught them that's what gunfire sounds like. The noise used in films
and TV actually comes from a gunfire generator which uses "pink noise"
to make the kshew sound. A foley artiste just presses a button.
BTW atomic explosions, distant explosions and explosions in space
don't go bang, but everybody has come to expect them to, so a bang is
dubbed on. I once saw an interview with a woman who had witnessed a
huge volcanic explosion, and she ended with: "One thing was weird,
though - it didn't make any noise!". I wanted to shout: "No lady, if
you had been close enough to hear it go bang, you would have been
dead."
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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