on 9/2/02 12:25 AM, Lang Elliott at wrote:
> The near-coincident technique, also referred to as ORTF, is described here
> near the bottom of the page. I suggest using the actual ORTF spacing and
> angle (7", 110 degrees), rather than some variation on this:
>
> http://www.tape.com/Bartlett_Articles/stereo_microphone_techniques.html
>
>
Lang and All,
I recommend this article to anyone puzzled about the different stereo
techniques. Over the years I've heard recordings made by others using these
different stereo miking techniques, but I've never truly understood all the
pros and cons, until now! The summary at the end of the article is worth
including here:
.............
STEREO MICROPHONE TECHNIQUES
By Bruce Bartlett
Comparing the Four Stereo Miking Techniques
The coincident-pair technique has the following features:
*It uses two directional mics angled apart with grilles nearly touching, one
mic's diaphragm above the other.
*Level differences between channels produce the stereo effect.
*Images are sharp.
*Stereo spread ranges from narrow to accurate.
*Signals are mono-compatible.
The spaced-pair technique has these features:
*It uses two mics spaced several feet apart.
*Time differences between channels produce the stereo effect.
*Off-center images are diffuse.
*Stereo spread tends to be exaggerated unless a third center mic is used.
*It provides a warm sense of ambience.
*It may cause record-cutting problems.
The near-coincident-pair technique has these features:
*It uses two directional mics angled apart and spaced a few inches apart.
*Level and time differences between channels produce the stereo effect.
*Images are sharp.
*Stereo spread tends to be accurate.
*It provides a greater sense of "air" and depth than coincident methods.
The baffled-omni-pair technique has these features:
*It uses two omnidirectional mics a few inches apart, separated by a baffle.
*Level, time, and spectral differences between channels produce the stereo
effect.
*Images are sharp.
*Stereo spread tends to be accurate.
*Low-frequency response is excellent.
...................
As I understand it, from the above article, each of these different stereo
recording methods uses a different way of "reading" the stereo effect.
Co-incident and widely spaced mics depend only on micro-time differences in
the sound reaching the two mics. Near-co-incident depends on time
differences and also loudness differences. Baffled omnis (e.g. binaural,
SASS, Jeklin disk etc.) have a three-fold effect, using, for stereo clues,
time differences, loudness differences, and "spectral" differences (which I
take to mean kHz frequency effects, rather than ghosts?)
I won't try converting my ME 64 mics to ME 62s, I'm sure now that it won't
work properly, and thanks for your comments here Klas, Walt, Rich and all.
But I will certainly try some "near co-incident" ORTF techniques, which will
be be somewhat more "spacious" than the "co-incident" method I've been
using. Thanks for the tips Lang and all! I have learned so much from this
group!!
Vicki Powys
Australia
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