Stereo Mic Techniques Flashcards
AB - preferred polar pattern
omni
AB - mono compatibility
causes an unfocused center image
generally has poor mono compatibility
if pair is too far apart will cause a ‘hole in the middle’
AB relies on ____ for localisation
relies on time difference of signals reaching each mic for localisation
distance between mics dictates time delay
time delay dicates sound source position in stereo field
XY relies on ____ for localisation
XY relies on level difference of signals reaching each mic for localisation
XY - mono compatibility
has a very solid centre of image
very mono compatible
XY - qualities
produces sharp detailed images
narrower spread than other techniques
spaced pair
2 x parallel omnis
coincident pairs
XY
blumlein
MS
blumlein
2 x bidirectional at 90 degrees, off axis facing centre of sound
MS
1 x cardioid
1 x bidirectional at 90 degrees
XY
2 x Cardioids at 90 degrees
Near coincident pairs
ORTF
NOS
DIN
OSS/Jecklin Disk
Faulkner Array
Boundary Array
Dummy Head
ORTF
2 x cardioids, 17 cm apart at 110 degrees
NOS
2 x cardioids, 30 cm apart at 90 degrees
DIN
2 x cardioids, 20 cm apart @ 90 degrees
OSS (Jecklin Disk)
2 x omnis, 16.5 cm apart, separated by 28 cm diameter disk
Faulkner Array
2 x bidirectional, 20 cm apart, perpendicular to source
can be futher away for better balance and is effective at ear height
Boundary array
2 x omnis in boundary construction
dummy head
2x omnis, 6.5 inches apart
“in ear” of head to replicate how we would hear
standard listening environment
60 degress listening angle or sound field
different stereo setups give you independent control over what factors?
stereo recording angle
angular distortion
reverb distribution
ER localisation
positional information of a sound between two speakers provided by
level difference between L and R
time difference between L and R
combination of level and time difference
DEF:
SRA
Stereophonic Recording Angle
the space in the sound field in front of the mic system which will produce a virtual sound image between the loud speakers
and part of the sound source within the SRA will be reproduced between the speakers
any part of the sound outside the SRA will be preproduced at the speakers
angular distortion result from:
interaction between:
polar pattern
mic angle
distance between mics
major considerations for stereo zoom
angular distortion
balance between direct sound and reverb
basica decca tree measurements
max of 274-320 cm high
anything higher causes mics to act as ambient pickups and you’ll need stop mics for direct sound
A = B = C = 25.5” - 27”
D = 36”
Decca tree positioning
basic triangle mounted so centre mic is 15-30cm in front of orchestra (measured from R leg of lead vln chair and L leg of lead cello chair)
outriggers usually same hight as basic triangle
L outrig in line with back of 2nd desk of 1st vln chair
R outrig in line w/ back of 2nd desk cellos
both outrig set back 142-158cm from orchestra
Where to point mics - decca tree
mic at eyes of 5’6” person
L outrig - btwn chairs of Vln 1 desk, three rows back
L triangle - btwn chair sof 2nd desk of Vln 1
Centre triangle - btwn chairs of 2nd desk Vln 2/Vlas
R triangle - btwn chairs of 2nd desk of Cellos
R outrig - btwn chairs of Cello desk, 3 rows back
listen for (decca tree set up)
centre of focus for L triangle (2nd desk of 1st vlns)
centre of focus for R triangle (1st cellos)
sense of depth field where 1st/3rd desks are also in focus, 4th/5th desks less focues
how do you know when your setup is too high or too low? (decca tree)
too low: hear individual desks, strings sound to dry and edgy, too much HF content instings (scratchy)
too high: too much room not enough direct sound, feels far back in orchestra
gains and pans for decca tree - 3 mic setup
Left (0 dB / - inf)
Centre (L: -3dB / R: -3dB)
Right (-inf / 0 dB)
basic tree - 3 mic setup
used for…
small orchestras
basic tree + 2 Out Riggers
used for…
large orchestra
variation on basic tree + 2 outriggers
gains and pans for 5 mic LCR decca tree w/ outriggers
Left OR (0 / -inf)
Left (L: -0.4 / R; -13.5)
Centre (L: -3 / R: -3)
Right (L: -13.5 / R: -0.4)
Right OR (-inf / 0)
gains and pans for 4 mic decca tree w outriggers
Left OR (0 / -inf)
L main (-0.9 / -8.5)
R main (-8.5 / -0.9)
Right OR (-inf / 0)
mics for decca tree
M50 (small diaphragm boundary mic, described as omni but is only really omni at low freq, HF shelf boost 5dB at 2kHz)
any omni mics w/ similar high end boost
Schoeps MK2H w/ 50mm sphere
Shoeps MK2S (brighter)
can use cardioid or wide cardioid for ORs
Shoeps MK21
KM 84
