Kaotica Eyeball

[jnorman]

Has anybody tried using something like the kaotica eyeball, or similar products from alctron, etc, to minimize extraneous ambient noise?  It seems like a potentially effective idea...

[Gutbucket]

These things are designed for close vocals, for use in lieu of a proper isolation booth - talking into an acoustically dead bucket in essence.  Not sure how well they really work for that, at least in comparison to sticking the mic in a closet full of clothes, or building a sofa cushion fort, which I suspect would likely achieve similar results.  Might be applicable to other forms of close-mic'ing like amps or instruments.. Come to think of it, one the the King Crimson musicians was using one onstage last summer to isolate.. can't remember what specifically, flute or hand percussion maybe?  Awkward for that as there was a giant ball directly in front of him, although he sat sideways to the audience when performing into it.

Pickup of more distant sources from at or beyond the room's critical distance of reverberance entails quite a different acoustic situation though, and I suspect it might not work as well there, at least in comparison to just going to a more directional pickup pattern.  I am somewhat curious how a figure 8 might perform with its null-plane at the opening and back lobe vectors enclosed by the isolation space.  Might that achieve a significantly tighter front lobe than a supercardioid with similar rear/side rejection?  Interesting to speculate about, but too awkward for me to consider seriously.  Jecklin disks are awkward enough yet not nearly as big or invasive as these.

[Gutbucket]

Pickup of more distant sources from at or beyond the room's critical distance of reverberance entails quite a different acoustic situation though, and I suspect it might not work as well there, at least in comparison to just going to a more directional pickup pattern.

Conceptually, it should be able to reduce the level of direct arriving sound from the rear and sides, but only above some threshold frequency determined by the diameter of the sphere.  Frequencies lower than that have wavelengths long enough that the spherical baffle will not be effective in blocking/reducing them.   In other words, regardless of the microphone pattern used, the isolation the hemispherical shell provides will be frequency dependent, with increased isolation at higher frequencies and none at significantly low frequencies.

Consider an omni placed in it.  The resulting polar pattern will remain omnidirectional at low frequencies, but will be directional at high frequenceis, as determined by the geometry of the mic within the hemispherical window 'opening' through which direct sound arrives.. along with some acoustic diffraction around the lip of the opening at some frequencies.  It will have a complicated polar with regards to pickup of sources not directly in front of the window.

Seems like it would be useful when one wanted to use an omni for whatever reason, such as its flat natural response without proximity effect, yet some degree of increased ambient isolation is needed.  Like for on stage percussion table stuff and the like, similar to how the KC guy last summer seemed to be using one.

Not saying it couldn't work for taper situations.. thinking specifically of how I've used the cushioned backs of front row seating as a rear baffle to reduce pickup of audience sound into omnis placed low up front in the past.  That baffling should also produce a frequency dependent reduction as mentioned, and in practice it worked pretty well in reducing level and presence of the audience reaction into the omnis.

[jnorman]

I was considering using it in a studio situation for spot micing woodwind instruments.  The room is somewhat boxy sounding, even with several 2"x2x4' acoustic panels, and it comes through in the recordings.  Moving the mics in closer renders an unnatural sound for the instruments - a distance of around 6' is about right sound wise, but gives too much of the "small room" sound (the room is 17'x23' but only has an 8' ceiling (ceiling has some acoustic treatment but wife will not allow any more).  I have tried using schoeps mk41, but still too much room sound.  Hence the investigation into other methods of trying to keep the room sound out of the mics, while still maintaining an adequate distance from the instruments. 
Thank you for your informative responses above.

[Gutbucket]

Remember this is all speculation on my part as I've not actually used one of those things.

You might try arranging your gobo panels so as to form sort of a box, open on one side, even if it takes a few extra couch cushions.  I suspect it may be more productive to place the acoustic absorption around the source rather than around the microphone, because even if the ball sufficiently attenuates far off-axis reflections arriving at the microphone, the on-axis window will still include a lot of small room reflections as long as the source is strongly illuminating the room.

Might try "boxing in" both the microphone and the source separately with acoustically absorbent panels, with the open side of the two boxes facing each other from your preferred mic'ing distance.

Easy enough to try before committing to the specialized piece of equipment.


Alternately, you might try an omni placed pretty close and see if you can get the sound you want that way.. the close placement providing increased source level verses the level of reflections, without the tonal proximity-effect a supercardioid has when moved closer.  Perhaps a combination of that with the panels reducing illumination of the rooms early reflections.

[jnorman]

Thanks for your thoughts.  Indeed, I know I cannot completely get rid of all reflected sound.  This is specific to the times where I have a soloist across the room, facing the pianist - spot mics at the piano lip and spot on the soloist, no room mics since the room is not wanted.  So the soloist mic is picking up reflected piano from all directions, and I was trying to reduce as much of that as possible by blocking off the sides and top of the cardioid pickup pattern.  In the past I have used a iso booth of packing blankets on a pvc frame, and I also have acon deverberate, but the booth thing was too much of a PITA and deverberate is fairly ineffective.
On the "taper" aspect of this, I thought perhaps the eyeball might help reduce audience noises being picked up from the sides of the mics...

[Gutbucket]

If the PITA packing blanket iso booth method does the trick with the mic placed just inside it and the soloist standing outside of it, the Kaotica eyball may substitute with less PITA.  Best in combination with with a blanket or angled panel behind the soloist I'd think.

I'd be curious to hear what a pair might do in a taper situation, say in a small crowded bar with low ceilings.  Seems it would alter the timbre of the room and close audience sound primarily, making it darker in comparison to on-axis.  Now I have in mind of the general trend in response curves, which tend to have something of a smiley shape 180-degrees off-axis, and this knocking down the higher frequency portions of that, perceptually.

It might behave somewhat like a more extreme version of large-diaphragm directionality, or omnis with sphere attachments on them, in that the pattern becomes tighter or a bit bumped up on-axis at higher frequencies.