Stereo Mic Techniques

Question 1

AB - preferred polar pattern

Answer 1

omni

Question 2

AB - mono compatibility

Answer 2

causes an unfocused center image

generally has poor mono compatibility

if pair is too far apart will cause a ‘hole in the middle’

Question 3

AB relies on ____ for localisation

Answer 3

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

Question 4

XY relies on ____ for localisation

Answer 4

XY relies on level difference of signals reaching each mic for localisation

Question 5

XY - mono compatibility

Answer 5

has a very solid centre of image

very mono compatible

Question 6

XY - qualities

Answer 6

produces sharp detailed images

narrower spread than other techniques

Question 7

spaced pair

Answer 7

2 x parallel omnis

Question 8

coincident pairs

Answer 8

XY

blumlein

MS

Question 9

blumlein

Answer 9

2 x bidirectional at 90 degrees, off axis facing centre of sound

Question 10

MS

Answer 10

1 x cardioid

1 x bidirectional at 90 degrees

Question 11

XY

Answer 11

2 x Cardioids at 90 degrees

Question 12

Near coincident pairs

Answer 12

ORTF

NOS
DIN

OSS/Jecklin Disk

Faulkner Array

Boundary Array

Dummy Head

Question 13

ORTF

Answer 13

2 x cardioids, 17 cm apart at 110 degrees

Question 14

NOS

Answer 14

2 x cardioids, 30 cm apart at 90 degrees

Question 15

DIN

Answer 15

2 x cardioids, 20 cm apart @ 90 degrees

Question 16

OSS (Jecklin Disk)

Answer 16

2 x omnis, 16.5 cm apart, separated by 28 cm diameter disk

Question 17

Faulkner Array

Answer 17

2 x bidirectional, 20 cm apart, perpendicular to source

can be futher away for better balance and is effective at ear height

Question 18

Boundary array

Answer 18

2 x omnis in boundary construction

Question 19

dummy head

Answer 19

2x omnis, 6.5 inches apart

“in ear” of head to replicate how we would hear

Question 20

standard listening environment

Answer 20

60 degress listening angle or sound field

Question 21

different stereo setups give you independent control over what factors?

Answer 21

stereo recording angle

angular distortion

reverb distribution

ER localisation

Question 22

positional information of a sound between two speakers provided by

Answer 22

level difference between L and R

time difference between L and R

combination of level and time difference

Question 23

DEF:

SRA

Stereophonic Recording Angle

Answer 23

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

Question 24

angular distortion result from:

Answer 24

interaction between:

polar pattern

mic angle

distance between mics

Question 25

major considerations for stereo zoom

Answer 25

angular distortion

balance between direct sound and reverb

Question 26

basica decca tree measurements

Answer 26

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”

Question 27

Decca tree positioning

Answer 27

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

Question 28

Where to point mics - decca tree

Answer 28

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

Question 29

listen for (decca tree set up)

Answer 29

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

Question 30

how do you know when your setup is too high or too low? (decca tree)

Answer 30

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

Question 31

gains and pans for decca tree - 3 mic setup

Answer 31

Left (0 dB / - inf)

Centre (L: -3dB / R: -3dB)

Right (-inf / 0 dB)

Question 32

basic tree - 3 mic setup

used for…

Answer 32

small orchestras

Question 33

basic tree + 2 Out Riggers

used for…

Answer 33

large orchestra

Question 34

variation on basic tree + 2 outriggers

Answer 34

Question 35

gains and pans for 5 mic LCR decca tree w/ outriggers

Answer 35

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)

Question 36

gains and pans for 4 mic decca tree w outriggers

Answer 36

Left OR (0 / -inf)

L main (-0.9 / -8.5)

R main (-8.5 / -0.9)

Right OR (-inf / 0)

Question 37

mics for decca tree

Answer 37

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