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Re: Boundary Mics & Low Hz (was <$500US/pair...

Subject: Re: Boundary Mics & Low Hz (was <$500US/pair...
From: Rob Danielson <>
Date: Sat, 5 Nov 2005 23:27:01 -0600
At 8:21 PM -0600 11/5/05, Curt Olson wrote:
<snip>

>when I'm standing there taking the
>headphones on and off, comparing what I hear with "naked" ears to what
>I hear through the recording chain, I realize that the mics are often
>picking up and amplifying a whole lot more low end than my "naked" ears
>ever perceive.

Yes, the lowest 3-4 octaves often seem disproportionately amplified-- 
especially when the headphone volume is up (as it often is). All mics 
I've tried exhibit this accentuation including some praised for very 
smooth, extended low end response. Frequency response for mics is 
measured at much higher sound levels than those we record in quiet 
settings. I suspect that low frequency response and distortion is 
quite irregular for low sound levels and that some odd things are 
going on.

The sound energy from a distance that is ~30 Hz and lower is 
perceived as a "heaviness" more than traditional tones.  Lots of the 
energy is down here and when the gain goes up, this content does too.

Does the undesirable bass occur as sustained tones (drones) between 
~80-200Hz or does the offensive bass vary in frequency and amplitude? 
Variation would be expected with recordings from natural settings. 
If the offensive bass occurs as a constant, low, chord and it sounds 
the same with recordings from several locations, it may be a fixed 
tonal structure and not a boost in low end amplitude.  Sustained 
tones stand out to the ears and efficiently mask adjacent tones with 
more dynamic. If you suspect the boundary is creating exaggerated low 
Hz chords, you can sweep a narrow band of parametric EQ across the 
bottom end of files that were recorded with the boundary and then 
with the mics in the open. If the same bands are accentuated, its not 
the boundary.  Rob D.




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