[quote author="PRR"]>
a few Barry White records
That will give your recordings a
colored sound!
Capsules a few inches out from the center of a 12" circle will show STRONG midband resonances. You really want some kind of fuzz on it. With enough fuzz, the disk material is moot. Carpet, foam, old plaid shirt cloth, old glam-rock wigs, whatever. And off-center on a non-circular shape seems wise.[/quote]
Sounds as that off-center is the best way to do it indeed, yet that's the way that it seems to pop up most frequently, the first pic above from a respected manuf. included :roll:
But given enough damping the resonances will become less or vanish again one could say, but there
is also the so-called Schneider-disc out there which does an additional something:
The Schneider disc is a
variation of the Jecklin disc developed by Jürgen Jecklin
for his stereo microphone technique known as Optimal
Stereo Signal (OSS). The idea behind OSS is to
use a pair of spaced omnidirectional microphones
approximately 6 inches apart (roughly the distance between
the human ears) with a disc placed in between the
spaced pair. The disc is covered with a thin layer of
foam intended to absorb high frequencies - thus improving
stereo separation between the microphones. The
difference between the two types of discs is the foam
sphere at the center of the Schneider disc, which reduces
the amount of high-frequency energy reflected from
the disc, and results in an increase of stereo separation.
Below approximately 200 Hz, the Schneider disc has
little (if any) effect on the stereo signal because the
audio wavelength is large enough to bend around the
disc, equally reaching both microphones. However as
frequency increases above 200 Hz, the Schneider disc's
foam sphere increases stereo separation between the
spaced pair.
> the table on this page for a starting guideline
What, the diffuse distance? IMHO, if you can't already estimate that within seconds of walking into a room, you should just mike everything and re-arrange it on the 24-track desk.
I see what you mean, just was having a let's these folks see some use of that table mood... while I know that in practice it'll just be slammed onto a stand in a hurry since we need to get started, despite the neat thoughts before.
Get a pocket radio and a $29 SPL meter. Crank the radio on bad AM pop music (nice consistent level) and walk away. At first the SPL drops 6dB for each double distance. At the far end of the room, level is constant everywhere. Walk from the far end until SPL rises 3(?)dB, that is Dc. Work between Dc and 3*Dc for clarity. If the room don't suck, many types of music can stand going much further than 3*Dc.
Nice idea to do such a measurement, it should serve as the last argument that was missing to make me undust'n'finalize my DIY-version with the way too expensive AD636JH I once bought :thumb:
(Some types music sound best outside the building.........g)
Round circle, we're back to Barry again :wink:
But that's kidding, I sure like his music now & then.
Regards,
Peter