Title: How to get it right or very nearly right the first time By John Eargle
1How to get it right - or very nearly right- the
first timeBy John Eargle
- A close look at stereo and surround recording in
both live and studio settings
22-track jazz recordings
- Arrange players, left to right, to match the
stereo sound stage - Lay out console faders the same way
- This gives you intuitive visual cues and
consistent leakage between panned images - Heres an example
3Live to 2-track jazztypical studio setup and
target sound stage
42-track chamber music
- When the players agree to it, have them depart
from the usual concert setup - Arrange them in circular fashion so they can see
each other, and mic them accordingly - This gives both engineer and producer greater
control for on-the-fly balance changes
5Classical example 1
6Classical example 2
7Classical large forms
- When a conductor is present, there are fewer
opportunities to make fundamental changes - Some left-right/fore-aft adjustments can easily
be made in the orchestra - The most likely major change that can be made is
when chorus and soloists are involved - Here is a good example
8Put chorus behind the conductor
9This has the following advantages
- Gets the chorus away from the back of the
orchestra, where percussion and brass can leak
into the chorus mics - Lets the chorus communicate directly with the
live ambience of the hall, as opposed to the dry
ambience of up-stage
10Live classical recording of orchestras
- This has become common in recent years because of
escalating costs - Conductors, players and soloists almost always
prefer it - There are certain musical advantages (i.e.,
performance spontaneity and avoidance of
over-exertion of players)
11What are the disadvantages?
- Audience noises
- Acoustical matching (4 concerts are the norm,
with a finishing session scheduled after the
audience has left the last concert)
12We normally handle these by
- Having orchestra management personnel TELL the
audience to be quiet (beepers, watches, cell
phones, rustling programs and coughs are all
problems) - No applause until the conductor has lowered the
baton - Coming up with a strategy for matching the sonic
signature between the hall, empty and occupied
13What are these strategies?
- Modern halls usually have variable acoustics
drapes can be deployed to deaden the room when
the audience leaves - Some halls have adjustable reverber- tion for
making a good acoustical match between full and
empty halls - Have a good reverberation unit on hand to make up
the differences
14How well can recordings be matched?
- Two examples
- Full-to-empty house (DSO Mahler 2 McDermott
Hall) - Same house, from 1987 to 2001(OSO Feste Romane
trumpet insert Schnitzer Hall)
15Session efficiency
- Keep a detailed log of all professional recording
assignments/activities - Log all pertinent console settings, mic models,
channel/pan assignments, EQ, reverb send/receive
settings, calibration values, on-stage mic
positions, piano serial numbers, etc. - Dont forget to list all pertinent personnel,
including recording, artistic and general
support technical credits are important
16How to reduce the time required for a sound check
- In todays commercial world you should be up and
running in no more than 5 minutes after down-beat - The industry goal is to get 10 minutes of usable
recording for each scheduled hour of studio time
(each studio hour includes 20 minutes break time) - You must have a template in mind for each new
project - These templates define a basic microphone array
which you determine to be best suited for the
project, based largely on your experience - Lets look at some of these
17Microphone array hierarchy
- Main arrays determine the basic perspective on
the ensemble - Spot mics are used for internal highlighting
(delay often required) - House mics are used to define, as needed, the
overall room signature - Remember, we are still talking about
direct-to-stereo recording
18The aim is to provide stereo image specificity
and spatiality in the recording
- Specificity refers to hearing instruments where
they are placed on the stage - Spatiality implies that there is a sense of
location, large or small, in which these
instruments are played - This is a tall order for only two loudspeakers in
the listening space
19Basic microphone layout for DSO recording of
American in Paris
20Examples of basic orchestral perspectives
- ORTF pair (cards at 7-inches splayed at
110-degrees) - Flanking omnis alone (spaced 1/3 stage width
about the center line) - House mics alone (cards at 24 facing back)
- ORTF plus flanks
- ORTF plus flanks and house
- The above 3 pairs plus internal spot mics -- the
final stereo mix
21Why use spot mics
- Spot mics are used
- To correct fore-aft balances in the orchestra
- To correct balances for weak instruments (e. g.,
harp, celesta) - To correct for spectral imbalances (e. g.,
basses) - To add presence (primarily percussion and back of
orchestra) - Delay of spot mics always correct, but not
always necessary - Always pan spot mics to their natural positions
in the basic stereo pickup - Roll off LF slightly
22Approximate guidelines for delaying spot mics
23Other mic arrays
- Spaced omnis (good sense of space slightly
compromised sense of specificity mainstay of the
early US stereo catalog) - Decca tree flanks (rich spatial cues hallmark
of Decca and EMI recording, even today) - Heads, baffles, etc. flanks (largely
experimental)
24Spaced omnis
- These tend to emphasize spatiality, largely
through in increase in time cues and pickup of
reverberation - Number depends on width of ensemble
- Separation of about 12 is the maximum
25Excellent for organ and large choruses
- To get a broad sound front with emphasis on
diffuseness, not image specificity - To produce a big sound suggesting more
performers than are actually present - Example of organ pickup
- Examples of chorus pickup
- 2 spaced omnis Piccolo Hear us, O Lord
- 3 spaced omnis Mahler Symphony 2
- 4 spaced omnis Lauridsen O Magnum Mysterium
26Other microphone arrays
- Decca tree makes use of Neumann M50 microphones
- These are omni at LF, increasing in both output
and forward directivity at HF - A flanking pair com-plements the main array
27Omnis and a pair of subcardioids
- Flanking omnis as before
- Splayed separated subcards at center
- Imaging rich in time cues
- Excellent in not-too-live halls
28 Franssens data on stereo localization
29The signal path microphones
- Salient specs sensitivity noise floor
impedance 0.5 THD level pattern integrity
axial response and limits - How good can a microphone be?
- Consider the BK 4179 noise floor -2 dB(A)
however,max level is about 102 dB LP,and
frequency response is erratic above about 10 kHz.
Polar response is that of a 1-inch diaphragm
30The eternal triangle
- Dynamic range, bandwidth, and polar response. Any
improvement in one of these attributes comes with
a compromise in one or both of the others - Dynamic range Make diaphragm larger (compromises
polar response) Increase spacing and reduce
tension (compromises frequency response) - Polar response Make diaphragm smaller (reduces
output level and increases noise) - Bandwidth Make diaphragm stiffer (reduces output
and decreases dynamic range)
31The signal path consoles vs. stand-alone preamps
- Phantom powering options
- Impedance adjusting
- Maximum input capability
- Noise floor
- Common mode rejection
- Padding/gain adjustment
32The signal path line level
- Keep as simple as possible
- Output busses vs. direct outs aux outs
- EQ capability
- Monitoring flexibility (line out 2 machines for
stereo what about surround?) - Communications interface with stage and conductor
33The signal path recorders
- Metering setting reference level (typically,
-14 to -20 dBFS) - Monitoring all tracks? How often?
- Accurate note taking log sheets
- How many operators are needed?
- The producer should be given a set of DATs and
complete log indicating PNOs, start/end times and
score locations
34Metering confusion
- The various PPMs are all electronic and have very
fast attack time (10 ms) and slow recovery time
(3 seconds) - The VU meter typically has 0.3 second attack and
recovery times - In this modern era we need digital meters
35Audio monitoring
- Loudspeakers vs. headphones
- (producer and engineer should agree beforehand)
- Nearfield vs. large loudspeakers
- (You rarely have room for large loudspeakers)
- Monitoring levels
- (85 - 90 dB maximum is recommended)
- How to calibrate monitor levels
- (a set dBFS level a set LP)
36What can go wrong? The following things have
actually happened to me
- On-stage video monitor showing a mirror image of
what was being monitored over loudspeakers. A
noisy mic developed -- and guess what I did! - Noisy microphone due to improper seating of XLR
cable at microphone - RF noise (not present during morning/afternoon
sessions but evident in the evening) - Organ solenoids inducing clicks in mic lines
- Problems with installed house mic wiring (noise,
polarity, mislabeling) Check carefully before
using!!
37Digital timeline I
- Soundstream (1976)
- 14 bits at 32 kHz
- Eventually 16 bits at 50 kHz
- Stereo recording segments 20 minutes
- Three editing centers worldwide - a real
bottleneck
38Digital timeline II
- Early 80s JVC and Sony U-matic models plus
editing systems - SPDF and AES-EBU standards
- 3M and Mitsubishi reel-to-reel
- DAT machines
- 3rd party converters
- Evolution of DASH and Pro-digi standards
39Digital timeline III
- Rise of DAWs and interface standards
- Rise of DSP and internet based tech
- Rise of tape based MDMs bit-splitting
- Rise of disc based MDMs
- Eventual relegation of reel digital recorders to
dinosaur status? - Multitrack analog recorders may outlive us all
40Surround sound consumer media
- Dolby AC-3 on DVD-V
- DTS encoded Redbook standard CDs (with decoder)
41New consumer media
- DVD-A versus SACD,or, PCM versus DSD
- PCM sample rate/bit depth related
- Signal is quantized at each sample sinx/x filter
reconstructs the signal exactly, if it is below
the Nyquist rate. Noise shaping improves
resolution at low signal levels - Easy access to EQ and 3rd-party DSP equipment
- DSD 1-bit/high sample rate
- Signal is defined as the moving average of many
1-bit approximations. Noise shaping essential for
system operation - Access to EQ by way of PCM chain used only when
necessary
42Surround sound rationale
- Stereo provides
- image specificity at the sweet spot
- conveys a sense of spatiality
- Surround sound
- frees the listener from the sweet spot
- adds a new dimension of envelopment
- Use more channels if
- More image specificity is needed, or
- Larger audience area is required
43Surround mic techniques
- The Soundfield microphone samples air pressure
and particle velocity in 3 dimensions - These four elements can synthesize first-order
cardioids aimed in any direction - These directions normally correspond to the
locations of loudspeakers in the listening space
44A seven microphone array
- Presented at 2000 AES Convention, LA
- Loudspeaker locations should match mic angles,
but normal 5.1 performance is quite good, with
vertical signals summed and fed to the 5
loudspeakers at reduced level
45Schoeps KFM 360 array
- The array, as seen from above, consists of both
front and back pairs of MS microphones - Patterns, as shown, can be chosen differently for
front and back - A front-center channel can be derived from the
front L/R pair - Control unit provides additional processing,
including delay of back channels
46The SPL (Sound Performance Lab) array
- Telescoping arms can be adjusted
- Microphones can be rotated and patterns adjusted
- Note resemblance to Decca tree
47Frontal arrays I
- These are 3-channel arrays that optimize frontal
pickup - Goal is to minimize double phantom images
- Used in conjunction with a back pair of
microphones
48Frontal array II
- Proposed, but not yet designed
- Will provide 15 dB isolation between A and E
- Polar equation r (.5 .5cosq)(cosq)