At 11:35 PM -0400 4/12/07, Steve Pelikan wrote:
>Friends:
>
>I've been slowly going through the great tests/comparisons of
>microphones and recorders that people have made available. These are
>very helpful, but I still have lots of questions about what I'm looking
>at and hearing.
>
>Here's a starter question. I viewed Rob Danielson's comparison of Rode
>NT1-A's with Shure 183's and Rode NT-4's. This is at the page:
>
>http://www.uwm.edu/~type/audio-art-tech-gallery/pages/page_37.html
>
>The overall noise levels I hear agree qualitatively with the output
>noise spec's I've found for these microphones. I was fascinated to hear
>the different quality of the noises.
>
>It seems that the power spectrum (is that what it is called?) of the
>NT1-A recordings all have a large peak at approx 13 KHz (independent of
>preamp used and recorder) while this peak is absent from the displays
>for the other microphones.
>
>Based on what I can see, I attribute the signal the the NT1-A's. Is that
>reasonable? Am I correct in thinking that this signal is pretty
>significant in magnitude but not reflected in the A-weighted output
>noise measure because it is either 1) at a pretty high frequency or 2)
>in a narrow frequency range?
>
>Is this sort of signal generally common in many microphones or usually
>unique to particular models (eg. NT1-A's) or is it more reasonable to
>attribute it to the individual microphones used and not to entire models?
>
>
>Thanks,
>Steve Pelikan
>
Hi Steve--
Yes, there is a peak in Rode NT1-A's response curve up there (wish
_I_ could hear it). My attic studio has high Hz pollution in the
minimum background sounds even after I turn everything off and run
the recorders on batteries. The recent test we did in the isolation
booth should not have this high-Hz pollution so it should be better
able to show what Rode's is doing around 13KHz, noise-wise, at least.
Here a test combining the same mics and recorder at the same gain in
the two different settings:
NT1-A's-> 744T (in the isolation booth mar 07) vs, NT1-A's-> 744T (my
attic studio in Dec 06 ) In theory, the differences you hear should
be entirely from the locations, not the gear. Both have 16/48K tracks
if you want to analyze them:
http://www.uwm.edu/~type/audio-art-tech-gallery/mediafiles/NT1A-744T_IsoBoo=
th_AtticStudios.mov
I think the "power spectrum" is regarded as ~1600-2500Hz where out
ears are most sensitive and the octave above. Quite a few mics have
a "lift" in the upper range like this,.. especially omni's. Rob D.
--
Rob Danielson
Peck School of the Arts
University of Wisconsin-Milwaukee
http://www.uwm.edu/~type/audio-art-tech-gallery/
six, new media faculty positions:
http://www.uwm.edu/~type/FilmDept/Hirings/base.htm
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