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Final Answers
© 2000-2020   Gérard P. Michon, Ph.D.

Audio  101
Recording Digital Sound for Video

Sound is half the picture.   George Lucas (1944-)
 Michon
 

Articles formerly here  (now on  Microphones  page) :

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Related articles on this site:

Related Links (Outside this Site)

Sound on Sound (SOS):  "The World's Best Recording Technology Magazine"
Matthew McGlynn :   Recording Hacks  >>  Microphone-Parts  >>  Roswell
Gearslutz :   "The #1 Website for Pro Audio."
Son et Image.  French magazine.   |   Stereophile.  Listening.
 
Production Sound Fundamentals for Film and Video:
Online course ($79) by  Curtis Judd.
Review of Curtis Judd's Audio Course, with $20 off
(9:29)  by  Basic Filmmaker  (2016-08-06).
 
Audacity® :  Free, open source, cross-platform audio software
for multi-track recording and editing.
 
Manufacturers  (besides microphone makers)   Zoom  (N. America)  |  Sennheiser  |  RØDE  |  AKG  |  Audix  |  Behringer  |  Sony  |  Telefunken  |  Azden  |  Samson  |  Marantz  |  Warm Audio  |  Groove Tubes  |  Bose  |  Bang & Olufsen  |  Harman (Samsung)
 
Retailers :   B&H  |  Amazon  |  Sweetwater  |  Thomann  |  Guitar Center  |  Reverb  |  Sam Ash  |  zZounds  |  Full Compass  |  American Musical  |  Front End Audio  |  Parts Express

Videos :  Get Good Sound with a DSLR  (40:36)  by  Alex  (RØDE, 2013-03-05).
Sound recognition  (15:38)  by  Chris Mitchell  (Computerphile, 2017-05-24).
Recording Vocals Masterclass  (24:08)  by  Marcel van Limbeek  (2015-04-26).
Favorite Audio Gear  (12:57)  by  Caleb Pike  (2018-11-20).
LBMBuild your own LBM (15:43)  by  Naomi 'SexyCyborg' Wu  (2018-11-26).
Recording a grand piano is tricky (12:42)  by  Nahre Sol  (2020-08-25).

 
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Audio Recording


(2017-05-25)   Microphones
The heart and soul of audio recording.

This topic is discussed at length in a  dedicated page  which introduces the fundamentals and explains the meaning of the various characteristics which appear in microphone spec sheets.

To help you choose the right microphone,  more than  150 models  are presented there to illustrate the discussion of half-a-dozen different categories.  Current prices and specifications are provided with links to specific reference pages.

Numericana :   The physics of sound
 
Recording Audio for Digital Video (21:04)  by  John P. Hess  (Filmmaker IQ,  2014-09-15).


(2018-01-22)   "Au clair de la lune" predated "Mary had a little lamb".
From tinfoil to wax, to vinyl.  From magnetic wire to tape, to digital.

 Scott de Martinville  Edouard-Léon Scott,  1860 :
 Au clair de la lune, mon ami Pierrot,
 prête moi ta plume, pour écrire un mot.
Ma chandelle est morte, je n'ai plus de feu.
Ouvre-moi ta porte, pour l'amour de Dieu.
Au clair de la lune,  Pierrot répondit...
Thomas Alva Edison,  1877 :
Mary had a little lamb.
Its fleece was white as snow
and everywhere that Mary went
the lamb was sure to go
...

Those  spoken  words were the first which  Thomas Edison  himself  played back  on his 1877 phonograph.  At the time,  his tinfoil records could be played back only a couple of times before the stylus ruined the groove.  Yet,  this was a dramatic improvement on the  phonautographe  patented in 1857 by the Frenchman  Edouard-Léon Scott de Martinville (1817-1879)  which recorded sound graphically but couldn't play it back!  With modern technology, we can hear Scott's phonautograms now.  The oldest extant recording of a human voice is a 20-second slow rendition of  Au clair de la lune  by Scott himself,  dated April 9, 1860  (unearthed in 2008,  it was originally played at twice the correct speed and was mistaken for the voice of a young woman).  We also have a phonautogram of a cornet from 1857.

The phonautograms produced by Edouard-Léon Scott were calibrated with a parallel track made by a  125 Hz  tuning fork.  This makes it possible to reproduce their sound accurately in modern times.  The team led by  David Giovannoni  and  Patrick Feaster  originally mistook Scott's unusual indication  (500 "simple vibrations" per second)  to mean 250 Hz,  according to the old practice  of counting half-periods as  beats.  Little did they know that Scott was actually counting quarter-periods and meant to say he was using a 125 Hz tuning fork.  So, originally, they played back the record at twice the correct speed and publicized their finding as a 10-second clip of the voice of a young woman...  Actually,  the lone experimenter was just testing his own recording instrument by himself in the Spring of 1860.  Makes sense.

The next step was the introduction of wax cylinders to produce more permanent recordings which could be played back many times. 

 Come back later, we're
 still working on this one...

First Sound Recording (2:21)  Newsreport   (Technow,  2008-07-02).
Oldest recorded voice: Paris, April 9, 1860 (55:21)  by  David Giovannoni   (First Sounds, 2014-06-26).
Earliest extant tin-foil record:  St Louis, 1878 (44:23)  by  David Tanner   (Schenectady GE,  2012-10-26).
Earliest recording of Beethoven; 13 Sept. 1889 (13:37)  by  Jack Gibbons   (2013-01-21).
Aristide Bruant, 1912:  Nini peau d'chien (3:42)  1909 song recorded by its famous author   (2015-12-05).
First test recording on an Edison 1878 phonograph replica (6:53)  by  Benjamin Jane   (2014-08-13).
 
High-fidelity (hi-fi, 1948)
The Truth About Vinyl (14:09)  by  Modern sound effects (3:18)  Sound Basics #1, by  Stella Gotshtein  (Waves Audio, 2016-08-15).
The fundamentals of sound recording (26:16)  by  Samori Coles  (2013-06-06).


(2017-11-03)   Room Acoustics.  Dry room, audio booth, sound stage.
Avoiding two pitfalls:  Outside noise and inside echoes.

You can listen to recorded sound anywhere and you can record it anywhere.  In either case,  however,  unacceptable degradation will result if a few simple precautions are not taken concerning isolation from outside noise and prevention from echoing within the room.  One echo is not necessarily that bad in a small room; it's the reverberation from multiple echoes that's unacceptable.

Soundproof Curtains

This cuts down on noise from the street  (if you don't want the inconvenience of plugging the windows).  Thick curtains also dampen the echoes from the room almost as well as  acoustic panels.  Consider hanging such curtains in front of a mirrored wall, if you have one  (either that, or treat the opposite wall more thoroughly).

Acoustic Absorber Panels   (Sound Traps)

Indow  window inserts.

Window Plugs

 Come back later, we're
 still working on this one...

How to Soundproof a Room Cheaply  (2:12)  by  Arthur Noxon  (Expertvillage, 2008-06-27).
DIY acoustic panels for voiceover  (21:34)  by  Mike DelGaudio  (Booth Junkie,  2016-10-21).
EEVblog #172 - DIY Acoustic Sound Panels  (14:40)  by  Dave Jones  (2011-05-22).
Improve the Sound of Your Room for $150 or Less  (1:50:08)  by  Bobby Owsinski  (Nimbus, 2016-06-15).
High Performance Sound Absorption Panels for $5  by  Matt  (2016-08-08).
Things nobody tells you about DIY Acoustic Panels  by  Norman Wink  (Hyperlaze, 2017-02-27).
DIY Professional 2'x4' Acoustic Panel Tutorial  by  Norman Wink  (2017-08-24).


(2018-02-11)   Reverbs and Delays
Adding natural or unnatural dimension to sound,  using echoes.

A reverberation unit mixes a signal with a delayed attenuated version of itself  As the result of the mix is processed the same way,  we obtain multiple echoes of decreasing intensities.

There are only two control paramters which can be adjusted at will:  The delay time  t  and the attenuation  r < 1. 

As the echoes are added to the original signal,  the average  volume  is increased by a factor of  1/(1-r)  which is the  sum of a geometric series.

Reverb and Delay Explained (6:29)  Sound Basics #4, by  Stella Gotshtein  (Waves Audio, 2017-03-28).


(2018-02-03)   Microphone Stands and Booms
By far,  the most common thread for microphone mounts is  5/8''-27.

 Shure 55   5/8''-27  means a diameter of  5/8''  (15.9 mm)  and  27  threads per inch.
 
In the old days,  the microphones themselves were threaded.  Such was the case for the legendary  Model 55 Unidyne Microphone  introduced by  Shure Brothers  in 1939  and once described as the  most recognized microphone in the world.  The so-called  Elvis microphone  was a scaled-down version of the 1939 model introduced in 1955.  This vintage look is still preserved by  Shure  in current "55" microphones which encase different shock-mounted modern capsules  (Super 55  and  55SH II).

With just a few such exceptions,  today's full-sized microphones are rarely threaded.  Instead,  they fit into threaded  mic clips  or  shockmounts,  which provide an external isolation from vibrations.

Because microphones are so often used in close proximity to cameras,  they sometimes have to share the same  threaded studs  and it's useful to keep a couple of  thread adapters  handy,  to fit either  3/8''-16  or  1/4''-20.

An Inside Look ar rge Shure 5575LE (Limited Edition) (5:07)  Sound Basics #4, by  Stella Gotshtein  ( Vintage King, 2015-02-06).


(2018-02-07)   Pop filters  =  Pop screens  =  Pop shields
Eliminating plosives and guarding from spit.

For  studio mics  at least,  I like  cylindrical pop filters  best  ($10 a piece).  They're even more effective  (with directional mics)  if you  point the microphone at your mouth, but not your mouth at the microphone.

This way,  you can look directly at a camera without hiding your face behind the microphone  (again, cylindrical pop filters are the least obtrusive ones in that situation too).

When designed by people who know their craft,  all computer graphics look as if they're lit from the upper  left  of the screen.  (This applies, in particular, to common action  buttons.)  If at all possible,  a video meant to be viewed primarily on busy computer screens should be lit the same way  (key light to the left of the camera or to the right of the talent).

Consequently,  when a studio microphone is visible at the same level as the face of the talent,  it's often best to put it to the  left  of the talent so the key light won't cast a shadow from the microphone on the face.

Stop consonant (a.k.a., plosive)
 
Pop Filters (21:24)   by  Mike DelGaudio   (Booth Junkie,  2017-04-29).


(2018-02-04)   Audio Connectors:  Sizes and Pinouts.
Balanced XLR for microphones.  Audio jacks:  ¼'',  3.5 mm,  2.5 mm.

By definition,  a  socket  is a plug  (usually female)  affixed to a box or a panel.

tail  is a (male) jack mounted on a short piece of cable hardwired into an appliance.

The venerable  ¼''  phone jack was introduced in 1878 by  George W. Coy  for the first commercial  manual telephone switchboard,  installed in New Haven, CT.

 Come back later, we're
 still working on this one...

For a TRS 3-line jack, use the "R" mnemonic, namely:  Ring = Red = Right = Return.  (Conversely,  Tip = White (or black) = Left = Send.)

Insert  (Send and Return) :

In a standard (unbalanced) TRS insert jack,  tip (T) is send and ring (R) is return.  Sleeve (S) is the common ground.  Because inserts are used at line levels, there's little or no need for balanced lines  (which are only possible with separate send and return jacks).

Pinout of a TRS Phone Jack for Balanced Audio  (1/4" or 1/8")
Tip (T)Ring (R)Sleeve (S)
Hot  (+ phase)Cold (- phase)Shield  (signal ground)

XLR connectors   |   Phone connectors   |   Insert Jack (send/return)


(2018-02-07)   Microphone Cable
Shielded against electrostatics,  twisted against magnetic noise.

A mucrophone cable is nominally a 600 W balanced line.  Not all microphone cables are created equal.

 Come back later, we're
 still working on this one...

XLR connectors   |   Phone connectors


(2018-01-14)   Volume   =   Perceived Loudness
Loudness normalization to broadcast standards.

Humans may perceive the loudness of identical  sound levels  (dB SPL)  differently according to their frequencies.  For normalization purposes,  the most commonly used calibration of that effect  (in North America, at least)  is called A-weighing.  Decibels of perceived loudness,  following that standard ponderation,  are indicated by the symbol  dBA.  This can be used to measure the loudness of various types of sounds containing diverse mixtures of frequencies:

LoudnessIndoor exampleOutdoor example
194 dB SPLSinewave of 2 atm amplitude, peak-to-peak SPL
185 dB SPLSaturn V  rocket launch
175 dB SPLSperm-whale call  (above water)
165 dB SPL0.44-magnum revolver at arm's length
155 dB SPLTrumpet at one inch  (high register)
150 dBAEardrums may rupture instantly.
135 dBA Air-raid siren
130 dBA Jet engine on a flight deck  (100 ft)
120 dBAOxygen torchChainsaw,  thunderclap, 9mm handgun
115 dBAWhistlePassing emergency siren
110 dBAAverage threshold for pain
Rock bandJet-plane flyover  (1000 ft)
105 dBA Passing motorcycle.  .22' rifle
100 dBANewspaper pressLanding DC-9 at one nautical mile
90 dBAEar damage is likely after prolonged exposure  (8 hours).
Loud snoringPropeller-plane flyover (1000 ft)
85 dBAVacuum cleaner  (3 ft)Passing diesel truck
80 dBA Busy New-York street.
75 dBAVacuum cleaner  (10 ft)
70 dBARestaurant conversation
65 dBAAir conditioner 
60 dBABackground music 
55 dBASoft conversationQuiet suburb  (daytime)
50 dBARefrigeratorLight traffic
45 dBALibraryBird calls
40 dBAUrban living roomBabbling brook
30 dBA Quiet rural area
20 dBAWhisperRustling leaves
10 dBACalm breathingDesert without wind
0 dBAConventional limit of audibility

If you double the distance to a localized sound source, you reduce its loudness by  6.02 dB  (20 log 2).  Tripling that distance reduces the loudness by almost  10 dB  (9.54 dB).  Multiplying the distance to the sound source by  10  reduces perceived loudness by  exactly  20 dB.

A  1 kHz  sound at  1 dB SPL  is nearly  1 dBA, by definition  (IEC 651).

What is Loudness and Why is it Important?   (TC Electronic).
How to get Consistent Loudness for Video (10:38)   by  Curtis Judd   (2017-03-04).
Don't Just Normalize (8:17)   William Williams   (Aliso Creek Voice Over Classes,  2016-02-24).
Loudness normalization service by  Auphonic.com.
LKFS  =  LUFS   |   International Telecommunication Union (ITU)   |   European Broadcasting Union (EBU)
 
Loudness   |   Ear protection for shooters
Comparative examples   |   Loudness Comparison Chart (dBA)   |   Noise Level Chart
 
Recording the sounds of nature's quietest places (8:15)  CBS Sunday Morning   (2017-04-23).
 
Bark scale (1961)   |   Eberhard Zwicker (1924-1990)   |   Heinrich Barkhausen (1881-1956)
Numericana :   Decibels (db)  |  Sound levels (SIL & SPL)


(2018-02-12)   Frequency Response  &  Equalization  (EQ)
Bass, midrange, treble and everything in-between or beyond.

Besides  volume,  the equalization controls are the most common in sound systems  (from the most rudimentary  bass  and  high  knobs to multi-band equalizers and notch filters). 

 Come back later, we're
 still working on this one...

infrasound   |   ultrasound   |   Bass   |   Treble   |   Equalization (EQ)
 
EQ Explained (5:20)  Sound Basics #2, by  Stella Gotshtein  (Waves Audio, 2016-11-22).
How the Pros Use EQ (36:43)  by  Rick Beato   (2017-01-11).


(2018-01-15)   Automatic Gain Control,  Limiters and Compressors
Three ways to make the best of imperfect recording setups.

The input levels of an audio recording device are best adjusted manually to account for the different  sensibilities  of microphones and widely varying recording conditions  (intrinsic loudness and distance from the sources).

 Come back later, we're
 still working on this one...

Automatic gain control (AGC)   |   Audio limiter   |   Audio compressor
MAX9814 Preamp with AGC   |   Adafruit MAX9814 Evaluation Kit
 
Compressors Explained (5:53)  Sound Basics #3, by  Stella Gotshtein  (Waves Audio, 2017-03-28).
How the Pros Use Compression (29:56)  by  Rick Beato   (2017-07-31).
Art Pro VLA II ($299Cheapest Tube Compressor (9:36)  Glenn Fricker  (Spectre Sound Studios, 2018-06-20).


(2018-01-10)   Microphone Preamplifiers
External preamplifiers or built-in camera preamplifiers.

Often,  you just plug your microphone into the built-in preamplifier of a camera  (to be avoided)  a  portable recorder,  a  mixer  or some audio interface.

Stand-alone dedicated preamps are usally much better,  especially if you can bypass the aforementioned built-in preamps entirely  (e.g.,  using a  return  jack on a mixer).

If you must go through a regular audio input with built-in preamp,  the best rule of thumb to minimize noise is to set it to the lowest available setting and adjust the external gain so that the meters peak between -18dB and -12dB.  This will keep you safely at no more than 25% of the level beyond which hard clipping occurs.

 dbx286s Channel Strip

 dbx286s Channel Strip

The Best Channel Strips Under $500  by  Jason Horton  (Gearank, 2016-01-20 / 2017-08-16).
The Best Microphone Preamps  by  Alexander Briones  (Gearank, 2017-02-02 / 2018-02-28).
 
Comparing preamp noise of different recording devices (9:12)  by  Julian Krause  (2017-10-10).
Design Your Own Tube Preamp (14:55)  by  Roger Modjeski  (Music Reference, 2012-11-14).
Tube Preamp Construction Techniques (14:55)  by  Roger Modjeski  (Music Reference, 2014-08-08).
Vacuum Tube Amplifier Theory (29:45)  TF11 3419  (US Army, 1963).
 
Juice Link RM222  /  Sound Devices MP-1  /  Zoom H5  (21:28)  by  Tim Kyle  (2016-06-24).
Sound Devices MM-1 Portable Microphone Preamp (9:02)  by  Mike DelGaudio  (Booth Junkie,  2017-07-05).
Sound Devices MM-1 Single Channel Portable Preamp  ($599) (9:11)  by  Alan Halfhill  (2017-04-01).
DBX 286s Mic Preamp and Processor Walkthrough (20:21)  by  Mike DelGaudio  (Booth Junkie,  2017-06-28).
Microphone pre-amplifier comparisons (13:40)  by  Project studio handbook  (2013-12-06).


(2018-02-09)   Low Pass   =   High Cut
A good low-pass  analog  filter is paramount for proper digitization.

Everything above  20 kHz  is utterly useless.  The human ear is unable to detect is.  Only kids can hear  20 kHz.  Young adults are lucky if they can detect a sinewave at  18 kHz.  Middle-aged people can't hear a thing above  14 kHz  or  15 kHz,  at best.  At the age of 62,  I can still hear  10 kHz  (D#9 more than one octave beyond the range of the piano)  but only sporadically beyond that.

Furthermore,  with a  48 kHz  sampling rate anything above  24 kHz  will  actually damage the digitized audio signal beyond repair  (in the form of additional audible noise).

For the utmost in quality,  we must attenuate everything in that part the spectrum as much as possible with  analog filtering  prior  to digital sampling.  Any leftover ultrasonic component  (beyond exactly  24 kHz)  will  cause audible noise in the digitized audio signal.

Do keep that in mind if you happen to use a fancy  Earthworks  microphone with an unusually wide bandwidth.  Those need more low-pass filtering...  In the analog to digital conversion process,  any ultrasound translate into muddy hiss,  not  added clarity!

The best place to put extra low-pass filtering, if needed, is after the microphone preamplifier and before the  ADC  in the  audio interface,  assuming that those two components are separate or have  insert capability.


(2018-04-26)   Analog-to-Digital Conversion  (ADC).
Generation loss  is the degradation which occurs with each pair of conversion.

  • AKM Semiconductor
  • Cirrus Logic
  • Burr-Brown.

 Come back later, we're
 still working on this one...

Burr-Brown   |   R. Page Burr (1922-1998)   |   Thomas R. Brown, Jr. (1926-2002)


(2018-04-26)   Digital-to-Analog Conversion  (DAC).
At least one of those is needed so we can actually  listen  to digital audio,

 Come back later, we're
 still working on this one...

Analog Audio Generation Loss Demonstration (using Audient iD14 interface) (11:12)  by  Scott Murphy  (2015-07-15).


(2018-04-26)   Generation Loss
A degradation occurs with each ADC/DCA pair in the signal path.

Nowadays, wireless microphones use digital transmission for greater reliability and greater fidelity.  However, the signal received is rarely kept in its digital form, if ever.  Instead, it's immediately converted back to analog form throughh a DAC.  This degraded signal is all the rest of the signal chain will ever see.  It may well be less than the degradation undergone by audio signals which are modulated and demodulated in an analog radio transmission, but it's a degradation all the same.

A signal generation loss is usually not audible, but three or four can be. 

Looping...

 Come back later, we're
 still working on this one...

Generation loss demonstration, using Audient iD14 interface) (11:12)  by  Scott Murphy  (2015-07-15).


(2018-01-17)   Lavalier microphone  digital  wireless systems.

I'll just mention a few good alternatives  (with links)  and give a full review of the Sennheiser AVX system, which I ended up purchasing  (I'll give my reasons).

Azden  Pro XD  ($199)

Azden PRO XD Review  (9:29)  by  Curtis Judd  (2015-10-26).
Azden PRO XD Rechargeable 2.4 GHz  (10:43)  by  MrCheesyCam  (2015-10-26).

Saramonic UwMic9  ($300)

1 Receiver, 2 Wireless Lav Mics: Saramonic UX9/UX10 Review  (4:28)  Tony Northrup  (2017-04-04).
Best Budget Wireless Lav Mic? Saramonic UwMic9 Review  (5:25)  Andy  (2016-08-10).

RØDELink Filmmaker  ($300)

The actual street price is $400 but the bundled lapel mic retails for $250...

Røde  also sells the  NewsShooter  kit  ($499)  with the same receiver paired to a more flexible transmitter,  featuring both an XLR socket  (with phantom power)  and a  3.5 mm  socket for  third-party lavalier mics.

Initial Test  (8:03, 2015-05-19)  &  Final Review  (9:44, 2015-06-20)  Curtis Judd.
RODELink Wireless Filmmaker Kit Review (18:04)  Two Bit da Vinci  (2015-06-20).
 
Rode NewsShooter wireless XLR microphone kit (7:59)  by  David Johns  (TubeShooterMag, 2016-11-28).

Sony UWP-D11  ($600)

Sony UWP-D11 vs. Sennheiser EW100 G3  (13:23)  Video Gizmology  (2015-10-11).

Sennheiser  AVX  wireless system  ($600)

The above price is only an estimate of what the system would cost if it was sold  without  a  lavalier mic,  which isn't the case  (it's actually either bundled with a $150 ME2 for $700 or with a $400 MKE2 for $900).  The system uses proprietary rechargeable batteries and, arguably, you should have at least one extra battery for the transmitter and one for the receiver,  for an additional cost of $100 or so  (there are no third-party suppliers).

Sennheiser's AVX system is the digital successor to their very popular EW100 G3 analog model.  It's the  Rolls-Royce  of wireless microphones;  superb user-friendly engineering at a hefty price.  Extremely easy to use.  What made me buy it in spite of the cost is the small size of the receiver,  which is a perfect match for the  XLR1  (whose other XLR mic input can then be used to capture ambient sound on the other audio track).

The radio part is designed from the ground up to provide no interference from any source in the  foreseeable future.  Both units are constantly in two-way communication to maintain a clear channel in the allotted band.  All data is continuously transmitted on two separate channels for seamless switching from one channel to the next if needed.  Up to 8 AVX systems can share the same airspace and negotiate between themselves for trouble-free communications without any human intervention.

For good measure, the audio data is encrypted,  to prevent electromagnetic eavesdropping.

Radio communications are entirely digital, using GFSK modulation  (Gaussian Frequency Shift Keying)  which is to say that the digital signal passes through a Gaussian filter before being frequency modulated  (this method allows narrower radio bandwidth; it's what Bluetooth® uses).  The audio signal is digitized with  24-bit resolution  at a  48 kHz  sampling rate.

We're very far from yesteryear's one-way analog transmission of an audio signal over a single analog FM channel selected once and for all among a dozen choices or so.

In Sennheiser's parlance, the small receiver  (actually a transceiver)  is called EKP AVX and its battery is  BA 20.  The body pack  (SK AVX )  takes a  BA 30  battery.  You need at least one extra  BA 30  for prolonged use,  since the body pack cannot be recharged while in use  (it's on a untethered moving body, after all).  Either battery can be recharged whether it's mounted to the corresponding unit or not, using a standard USB-A to USB-C cable, from any powered type-A socket  (one such cable and a small AC adapter are included).  The LED indicator  (red when charging, green when fully charged)  isn't designed for color-blind people.

Also available is a handheld microphone  (SKM AVX)  which takes a third kind of battery pack  (BA 10)  which,  surprisingly,  can't be charged when mounted  (unlike the other AVX batteries).  It takes  4½ hours  to fully charge a  BA 10  or  BA 30  (good for up to 15 hours of continuous use).

The tiny  BA 20  battery can be fully charged in  1¼ h  and will power the  EKP AVX  receiver for  4 hours.  A 4-level battery status is provided when the left button is pressed.  A blinking alert indicates there's less than 15 minutes of battery power left.  You can power the  EKP AVX  with the USB cable for an unlimited time when working tethered.

If an  EKP AVX  receiver is plugged into an  XLR  socket with phantom power,  it will turn on and off automatically  (to save battery power)  by sensing the presence of power in the socket.  One less switch to worry about.

The  EKP AVX  turns itself off about  10  seconds after it sees phantom voltage drop.  Modern cameras take some time to switch off and there may also be a significant delay due to the slow discharge of capacitors with little resistive load on them.  All told,  an  EKP AVX  connected to an  XLR1  (with phantom power)  on a  Lumix GH5  turns itself off about  13  seconds after the camera is switched off.  One benefit is that there's no loss of pairing if you reset the camera by power-cycling it for whatever reason.  On the other hand,  be aware that the GH5 turns the XLR1 off  (along with phantom power)  when it's used for previewing clips on the back of the camera.  To get out of this power-saving mode,  half-press the shutter button and wait up to 10 seconds for a new pairing to take place  (the camera shouldn't be too far from the mic).

The  SK AVX  bodypack input socket accepts either a line input or a microphone  (including third-party replacement microphone with Sennheiser/Sony locking jacks).  The bandwidth for a line source is  20Hz  to  20kHz.  For a microphone, it's limited to  50Hz  to  20kHz  (which is more than enough).

The  Sennheiser EW  plug  (Evolution Wireless)  is a  3.5 mm  locking audio plug with  TRS  connections  (tip-ring-sleeve).  It's used for audio input from either a microphones  (tip)  or line signals  (ring; 1 MW input impedance).  Whichever input is unused must be grounded  (i.e., connected to the shielding sleeve)  within the input plug and/or the input device.

The  AVX  system has a constant latency of  19 ms  which would correspond to a sound source located  6.5 m  (21 ft)  away from the listener.  There's usually no need to adjust that in post-production,  except possibly for an extreme close-up shot of a person talking,  in which case reducing the latency ought to be reduced down to  1 ms  or  2 ms  (never less)  to reproduce more precisely the time-delay our brains are accustomed to when carrying a conversation up close  (1 ft or 2 ft away). most accustomed to.

Likewise, if you have to synchronize sound based on the image of a  clapper,  make sure you introduce a delay corresponding to a delay of about one millisecond per foot of distance between the camera and the subject  (the brain will effortlessly compensate for slightly more delay but will be confused by less).

Future Proof?  Worldwide usage?

Sennheiser chose to use the  1900 MHz  which is currently relatively free of interference from competitive devices.  This is much less crowded than the  2400 MHz  band.

 Come back later, we're
 still working on this one...

AVX System Manual   (Sennheiser,  June 2015).
 
Sennheiser AVX Wireless Microphone System vs. RødeLink  (10:44)  by  Curtis Judd  (2015-10-13).
Sennheiser AVX:  ME2 and MKE2 Comparison  (7:44)  by  Tomas Villegas  (2015-08-31).
An In-Depth Look at The Sennheiser AVX & G3 Mic Kits  (6:33)  by  The LensPal  (2017-02-02).
Sennheiser AVX Super Wireless in 4k UHD  (7:16)  by  Craig Shipp  (2017-05-05).
Sennheiser AVX wireless microphone system  (51:10)  B&H Event  (2016-03-21).


(2018-01-10)   Panasonic's  XLR1  adapter for the Lumix GH5
The pricey  ($400)  XLR1 is a key audio accessory for the GH5 camera.

The  XLR1  bypasses entirely the regular audio input of the GH5 and communicates digitally with the camera via the hot-shoe contacts.  The only other way to achieve the same audio quality is to use a good external recorder to produce an independent soundtrack for later synchronization...

Turn the camera off before connecting or disconnecting the  XLR1  to the hot-shoe.  (I don't think you could damage the camera by ignoring this recommendation but this would definitely confuse the software.)  Mounting the unit disables the single 16-bit microphone input of the camera  (unless the user chooses to disable the XLR1 by software).

The unit provides the  GH5  with two  XLR connectors with or without  48 V  phantom power.

The  XLR1  contains a pair of audio preamplifiers and 24-bit converters.

To save battery power,  the XLR1 will turn itself off when the camera goes into viewing mode.  That will turn off the connected devices which depend on 48 V phantom power  or those which merely sense  it,  including the Sennheiser AVX wireless microphone system  (after exiting viewing mode, allow 10 seconds for the AVX system to properly re-establish its radio link).  If you absolutely can't leave with that, give up the AVX auto-off feature by not feeding it phantom power at all  (this will force you to turn the AVX receiver on and off manually).

DMW-XLR1 manual
 
XLR Microphone Adapter DMW-XLR1 (11:38)  by  Curtis Judd  (2017-04-22).
XLR1: XLR Adapter for LUMIX GH5 Explored (43:18)  by  Joseph Linaschke  (2017-05-05).
GH5 DMW XLR1 Audio Adapter Setup and Tests (9:11)  by  Alan Halfhill  (2017-04-01).


(2018-02-02)   Analog Mixers
Mixing sound from several audio sources in real time.

Setting Microphone Levels on a Mixer (4:34)  by  Ray Ortega  (2015-04-27).
AOKEO USB Mixer 6 feature demonstration (18:31)  by  Mike DelGaudio  (Booth Junkie,  2017-09-05).
Talent MIX-06  &  Talent MIX-R (USB) (1:59)  Parts Express   (2015-12-09).


(2018-05-03)   Mic Level,  Line Level,  Amp Level

 Come back later, we're
 still working on this one...


(2018-05-03)   Evaluating Audio Compression Curves
The THD of a  recorded  sine wave is a function of the compression ratio.

To prevent hard clipping,  a signal  u(t)  is recorded as  f (u(t))  as time (t) varies.  In this,  f  is always chosen so that its values remain between the  output rails  (normalized to -1 and +1).

The quality of the compression for a given amplitude  x  must be defined to be a decreasing function the  total harmonic distortion  (THD)  of the signal  f (x sin u(t)).  We may choose it that to be the linear function which is 0 fot the THD of a square wave  (the hardest clipping case)  and  1  (100%)  for a THD of 0  (undistorted sine wave).

The problem is to abandon the requirement of 100% quality for small signals in order to handle with reasonable distortion larger signals.  This trade-off will utimately depend on a single user-defined parameter which determines the position of the "knee".  For a given position,  the shape of the knee can be optimized. 

 Come back later, we're
 still working on this one...


(2018-02-16)   DI Boxes  (Direct injection  or  Direct insertion)
Active and passive  DI boxes  fetch clean instrument signals directly.

Generally speaking,  you should use an active DI box  (requiring phantom power)  with a passive instrument and a passive DI box with an active instrument  (unless the output is really weak).

Some modern active DI boxes are designed with widely separated voltage rails  (9V in the case of Radial's RJ48)  which allows them to be used also with strong signals without clipping.

Typically,  DI boxes are placed on the way from an electric guitar to its amplifier and provide a secondary low-impedance balanced output line.  That can be directed to an audio interface to record the output of the guitar cleanly, without the tonality added by a specific amp  (which is what a microphone would record).  The process by which a DAW gives such a clean track the coloration of some virtual amp  (chosen in post-production)  is called  re-amping.

 Passive DI Box

Passive DI Boxes
MakeModelPriceBandwidthInOutNotes
Radial JDI Mk 3 $200 10Hz-40kHz140 kW150 WMono
Kopul SDI-PPC $130 20Hz-18.5kHz67 kW600 WStereo
RapcoHorizon LTIbLox $33 40Hz-20kHz 600 W3.5mm tail
RapcoHorizon DBblox $21 40Hz-20kHz  Mono
Behringer DI400P $20 40Hz-20kHz  Mono

Active DI Boxes
MakeModelPriceBandwidthInOutNotes
A-DesignsRedDI $775 20Hz-60kHz1 MW600 WTube, Mono
Groove TubesDitto $399 20Hz-60kHz1 MW600 WTube, Mono
RadialJ48 $200 10Hz-40kHz220 kW600 WMono
BSS Audio AR-133 $169 30Hz-20kHz1 MW600 WMono

DI Unit (Wikipedia)   |   The Best DI Boxes (Gearank)   |   Jensen Direct Boxe Transformers
 
Recording Electric Guitar with a DI Box (9:38)  & Re-amping (10:38)  by  Bob Sell   (June 2017).
Radial J-48 DI Box (8:20)  by  Peter Janis   (Radial Engineering, 2009-11-12).
Direct Recording:  Preamp vs. DI Box (2:29)  by    (Your Home Recording, 2017-02-15).
Good DI Boxes for recording guitars (24:57)  by  Adam Steel   (Hop Pole Studios, 2017-04-27).
Advantages Of Recording With A DI Box (8:17)  by  Mike   (MasterYourMix, 2017-04-10).
 
D.I. boxes,  by  Bruno Goh Luse  (GLB Productions):
12:36 (2013-11-21) | 26:08 (2014-01-16) | 26:06 (2014-03-20) | 26:53 (2015-03-20) | 17:15 (2017-09-14)


(2018-02-05)  Audio transformers  with male plugs:
Step-up transformers are used to match microphones to high-Z inputs.

passive  direct box  is essentially just a step-down audio transformer.  Conversely,  a step-up transformer  ("lo to hi")  can be used to match a microphone output to a high-level high-impedance input,  like that of a guitar amp.

Being just a transformer, a  passive  direct box can be used backwards as a step-up transformer to match a microphone to a hi-Z input.  However, a DI-box only has a male XLR output which can be used as input only with a gender change  (for example, using a female-female XLR cable).

Adapters  are available from various manufacturers,  with a low-impedance input on an XLR female socket and a high-impedance output on a mono phone jack  (either 3.5mm for a video camera or a laptop,  or  ¼''  for PA or guitar amps).  For field use,  it's mechanically good to have the phone jack mounted on a short cable  (i.e,  a tail). (either that or build a small extender yourself with a female jack and a male jack,  which could be either straight or cornered).

Output Transformers for  Dynamic Microphones  (or self-powered mics)
MakeModelPriceGain PrimarySecondaryJackTail
ShureA85F $18 21 dB300 W40 kW ¼''No
HosaMIT 435 $20 24 dB200 W50 kW ¼''No
AudixT50K $20 17.6 dB600 W35 kW ¼''Yes
KopulLMT100 $20 600 W 3.5 mmYes

In a transformer the (inductive) impedancce  Z  of either side is proportional to the  square  of its number of windings.  (HINT:  The voltage is proportional to that number and the current is inversely proportional to it.)  The  gain  (the ratio of the voltages)  is thus the square root of the impedance ratio.  Expressed in decibels,  this gives:

G [dB]   =   10 log ( Zout / Zin )

Note that a passive impedance transformer can't be used to raise the voltage level into an amplifier of low input impedance,  because that low impedance would produce a collapse of the signal from a high-impedance source which would cancel the gain produced by a passive impedance transformer.  This misconception is so common that Shure saw fit to put a warning to that effet on the package of the aforementioned  A85F  unit.

Jensen transformers


(2018-05-07)   Impedance matching
How to extract the most power from a source of given output impedance?.

The answer is to feed it into a receiver whose input impedance is the  complex conjugate  of said output impedance.  Let's establishe this:

 Come back later, we're
 still working on this one...

Impedance matching


(2018-01-07)   Portable Audio Recorders
The handy Zoom recorders:  Broadcast quality at an affordable price.

Thanks to  Evyn Charles Schonbuch  for his initial recommendations.

The two audio tracks  (left and right)  of a video are simply not enough to solve all recording situations.  In some cases,  it's not even an option  (no audio is recorded with  variable frame-rate  (VFR)  slow-motion footage.

An external  digital audio  recorder adds considerable flexibility to common recording situations.

Handy Recorders from Zoom

All of Zoom's "H" handy recorders share the same high audio quality going from compressed MP3 to CD-quality  (16-bit resolution, 44.1 kHz sampling rate)  and video-track standards from  16-bit 48kHz  to  24-bit 96kHz.

Chronologically, Zoom introduced the H2 first,  in 2007.  The popular entry-level H1 was released in 2011.  It fits the needs of most video bloggers.

The news from the CES show in Las Vegas  (January 2018)  is that the H1 is being discontinued and replaced by a new model, the H1n, which will be widely available this month.  The new H1n retails for $120 while unused H1 units are still available on Amazon for $70, while they last:

 Zoom H1n and Zoom H1, side-by-side   The H1's custom amber LCD is replaced by a bluish (96 by 64) dot-matrix LCD of the same size  (1¼").
 
The front panel of the H1n has controls formerly located on the side or rear panels of the H1.
 
There's now a dedicated dial to control input level.
 
The H1's rear sliders have been replaced by buttons whose status is updated on the bottom line of the LCD.
 
The H1n counter is able to display hundred of hours;  32GB in MP3 is up to 555 h 33 min.  (Early H1 firmware was limited to 2GB files; at most 34 h 43 min in MP3.)
 
New features include a switchable limiter and several low-cut filters.
 
The  H1n  now uses two AAA batteries  (the H1 used one AA).  Rechargeable batteries recommended.

The Zoom H1n  (1:40)  by  ZoomSoundLab  (2018-01-10).
Zoom H1n Unboxing & Sound Comparison (15:47)  by  CityMusic Sg  (2018-01-15).
Zoom H1n vs. Zoom H1 (10:08)  by  Gus DaCosta  (2018-01-19).
Zoom H1n Review (9:11)  by  Steven Michael Zack  (Ranger 7 Studios, 2018-01-24).
Zoom H1n Review for Filmmakers  (13:12)  by  Curtis Judd  (2018-04-28).
Beginner's Guide to the Zoom H1n audio recorder  (10:25)  by  Julian Krause  (2018-07-18).

The entire  Zoom  line of handy recorders :

  • H1.  A great affordable classic, discontinued in January 2018.
  • H1n.  New ergonomics, new screen, new features, wider body.
  • H2n.  Four different stereo patterns.
  • H4.  Discontinued.
  • H4n.  Upgraded looks.  Discontinued.
  • H4n Pro.  Upgraded preamplifiers for the two XLR inputs.
  • H5.  Interchangeable capsules.  Great for XLR field recording.
  • H6.  The flagship.  Up to 6 channels.

The Zoom line of "F" field recorders :

The line was inaugurated with two professional models with XLR inputs:

They both feature the same proprietary 10-pin extension connector as the H5 and H6 which allows either two additional microphone XLR inputs  (without phantom power)  or one of their own microphones  (preferably with an ECM-3 extension cable).

In February 2018,  Zoom introduced nominally in their F-series, a model which might be better classified with their H-series of handy recorders  (but they didn't dare call it H0).

The  Zoom F1  is a  very  compact digital stereo recorder without any built-in microphone.  Instead, it has the same 10-pin proprietary port as the H5 and H6 and can accept the same capsules.  Either that or it can use a 3.5mm microphone/line input,  like the H1 or H1n  (especially for lavalier mics).  The F1 is available in two different bundles:

The first one gets rave reviews.  The second one disappoints.

Zoom Recorders Compared:  H1, H2n, H5, H6  (22:35)  by  Jake Hubert  (2017-09-14).
Why is the Zoom H5 Useful in Video Production  by  Sam Mallery   (2014-09-22).
Unboxing the Zoom H5 Four-Track Portable Recorder (8:29)  by  Gabriel Kim   (2015-05-31).
Zoom H5 Detailed Review (14:29)  by  Max Yuryev   (2014-11-02).
Zoom H5:  How to record (10:37)  by  Deb Erney   (2016-08-20).
Love letter to my Zoom H5 (10:20)  by  Mike DelGaudio   (Booth Junkie,  2016-07-02).
Zoom H5 Review: Is it still a good purchase in 2017? (7:25)  by  Fadzai Saungweme   (channel 8, 2017-07-17).
Zoom H6 for video (8:15)  by  Ray Ortega   (2014-10-13).


(2018-01-07)   On the  original  Zoom H1 ultra-portable recorder:
Tips for setting up and using the  Zoom H1  handy recorder.

With the  Zoom H1,  I highly recommend the  APH1  accessory pack  ($20)  which includes a nice branded protective case,  mini-tripod stand,  AC adapter,  USB cable,  foam windscreen  &  conical adapter for standard mic clips.  (The APH1n, for the Zoom H1n, has a different protective case.)

Right-angle adapters  ($6.25 a pair,  $6.99 for three)  are a must for the microphone input and/or headphone output,  if you want to put the unit in your pocket  (secured with Gaffer tape or an elastic band around the whole thing).  Right-angle cables  ($6.99 a pair)  are an even better and slimmer option.  The cables from  Cable Creation  are the best as their right-angle slim connectors will be flush with the unit, which is highly desirable.

For the  Zoom H1  to generate accurate time stamps,  you  must  first  set the time and date:  This is accomplished by holding the red button before you turn the unit on.  That way, you can access the six successive components of the date and time by pressing the  play  button and change the blinking number up or down by pressing either  forward  or  rewind.

Next thing you have to do is choose your recording format.  Select WAV on the bottom of the unit for uncompressed recording  (compressed MP3 is only useful for cramming many hours of stand-alone sound on the micro SDHC card).  Then pressing either  forward  or  rewind  allows you to select one of 6 choices;  the combinations of 3 sampling rates  (44.1kHz, 48kHz and 96kHz)  and  2 resolutions  (16-bit or 24-bit).  If you intend to create video soundtracks, forget 44.1kHz  (this is exclusively for audio-only CDs).  96kHz is a definite overkill,  both in theory  (Nyquist-Shannon theorem)  and in practice  (you end up discarding the extra information anyway on current delivery platforms).  Therefore, consider only 48/16 or 48/24.  I use exclusively the latter mode myself, for the utmost in quality  (lower digital noise, greater dynamic range and perfect match with the best digital video formats).  This is consistent with the quality of Panasonic's  XLR1  audio interface and with Sennheiser's  AVX  wireless system.

Even if the ultimate goal is to deliver CD-quality sound  (16-bit)  it's good to record at a higher resolution.  In theory,  the extra 8 bits correspond to an additional  48 dB  in dynamic range,  for a grand total of  144.5 dB.  The range of some microphones is up to that.  In post-production and later compression,  at most a  96 dB  portion will be used,  but you rarely know which part it will be...  So, keep some headroom and  always  record at 24-bit & 48 kHz.  Just make absolutely sure that you never clip while remaining well above the noise floor.  No hiss, no clipping and let the chips fall where they may.

With a 32GB card,  the Zoom H1 can record 30 hours 46 minutes and 11 seconds of audio at 48 kHz in 24-bit resolution.  (The 2GB card bundled with the unit is only good for  115 minutes and 23 seconds.)  Once this setup is done, once and for all, the use of the unit is extremely simple and intuitive,  with or without the help of its  Quickstart Guide  (which is actually identical to the official  operating manual).  The only delicate part,  as usual,  is to properly adjust input levels manually.  There's a substantial degradation in sound quality if you trust  AGC,  which is best reserved to special situations  (like low-quality recording questions from an entire classroom with a single fixed microphone).

Besides creating high-quality audio clips in WAV format,  I also use the  H1  to record voice memos in highly-compressed MP3  (which still sounds much better than the dictating machines of yesteryear).  Since the unit remembers what type of WAV and what type of MP3 is preferred,  I can switch between the two with the flick of one finger.  When using the files,  there's no question about the nature of the contents because the file types are different.  Note that pressing  play  during recording creates a mark.  You can jump back and forth to such marks during playback by using  rewind  and  forward.  Each audio file can have up to  99  such marks.

For best results, set the input level manually to 37 or more  (the equivalent input noise is higher at 36 or below).  Increase the level until the audio peaks at -12dB or so on the H1 meters.  If you need to go well above 60 to do so, your input signal is probably too weak.  If you need to go below 37,  it's probably too strong.  In either case, consider changing the volume of the input device itself,  if you have any way to do so  (or else, there's no great harm in going outside of the optimal 37-59 range).  Out of the box, the H1 input level is set at 50.

With firmware 2.0 and above  (2013)  the Zoom H1 can also be used as a card reader or a USB audio interface.  Zoom's corresponding supplement to the H1 user manual is mirrored here.  Just connect the unit to a computer via USB before turning it on.  The display will alternate between "Card" and "Audio"; press the red button when your desired choice is displayed  (if no selection in made within 10 seconds, the unit defaults to a card reader).

In practice, once you put a 32 GB card into this unit  (that's the largest SDHC capacity)  and format it, you'll never have to remove it.  Just connect the computer with a USB cable to fetch files and erase them  (or you may format the card each time you start a new job, by pressing  trashcan  while turning the unit on).  The H1 derives its power from the USB connector if available and you can run it indefinitely this way, without ever draining the battery  (don't expect it to be recharged, though).

In January 2018, when the H1 unit was being discontinued, the latest version of the firmware was 2.10  (displayed as 2/10 upon any ordinary power-on).  If you need that final (?) firmware update, the relevant update file is  mirrored here.  Put that file  (H1MAIN.bin, 852,224 bytes)  at the root of a micro SD card and power up the H1 with that card in it; you'll be asked to confirm that you really want to perform the update.  (See user's manual.)

Audiophile or Audio-Fooled?  (10:28)  by  Rick Beato   (2017-10-12).
Zoom H1 Optimal Input Level  (10:32)  by  Curtis Judd  (2014-04-11).  Answer:  37 to 60.
How to Use the Zoom H1 Handy Recorder  (19:01)  by  Michael Bednarsky  (2013-07-17).
Zoom H1 Handy Recorder Beginners Guide  (45:16)  by  Rob Nunn  (2015-03-15).
Zoom H1 Tutorial  (7:45)  by  Penn State Commedia  (2013-08-11).
Zoom H1 Date/Time Setup  (4:00)  by  Lo Neinlara  (2017-07-27).
Zoom H1 and Zoom H5 Demo  (12:32)  by  Joyvel Osorio  (2016-05-09).
How to Use the Zoom H1 / H1n as an On-Camera Mic  (9:48)  by  John Chow  (2019-04-16).


(2018-02-08)   The  Zoom H5  four-channel handy recorder:

For $270,  the  Zoom H5  delivers more recording capabilities than most small indy producers need  (just add a couple of cheap single-channel units  for those rare occasions where sound is needed from widely separated sources, or when the H5 itself is deemed too bulky).

The audio quality is great, although some quieter preamplifiers are available.

Phantom power  (12V, 24V or 48V)  can be brought to either of the two built-in inputs  (female combos accepting either XLR or quarter-inch jacks).  The inputs on the optional  EXH-6  head  ($70)  which may replaces the standard XY stereo microphone  cannot  provide phantom power  (they're thus suitable only for dynamic microphones, self-powered microphones or line-level connections).

Zoom H1 and Zoom H5 Demo  (12:32)  by  Joyvel Osorio  (2016-05-09).


(2018-02-12)   Audio interfaces  (between audio signals and computers).
Sound cards,  USB interfaces and USB microphones.

Two components of an audio interface deserve special consideration:  The  microphone preamplifier(s) and the  analog-to-digital converter(s).  The number of (digital) channels of an audio interface is the number of its ADCs.

An audio interface is mostly confined to studio work, since it's directly connected to a computer, which is usually not as mobile as other options:  In the field, you normally use either a dedicated  sound recorder  or the specialized audio interface of your video camera  (either built-in or external).

Sound Cards:

sound card  fits inside a desktop computer and provides it with analog audio inputs.  Just like the built-in microphone socket of a laptop,  this has the disavantage of exposing sensitive microphone signals to the noisy electrical environment of a computer.  Current audio gear avoid that by processing all analog signals in an outside shielded enclosure which communicate only digitally with the main computer.

USB Microphones:

For greater simplicity and lower cost, beginners often settle for an all-in-one solution which provides three hardwired components in a single enclosure:

  • An entry-level condenser microphone.
  • A microphone preamplifier.
  • An analog-to-digital converter  (ADC)  and a USB digital interface.

Commonly called  USB Michophones,  such contraptions offer the utmost in simplicity  (there's just one USB cable to hook up)  but they only provide a fixed single-microphone configuration which can't be upgraded.

USB Interfaces:

By contrast,  a  USB interface  can convert to digital signals the analog audio signals form several sources.  They usually include at least one microphone preamplifier, but the better ones also have  insert  inputs which bypass all internal preamps and allow the use of external preamplifiers and/or analog signal processors  (the dbx286s  channel strip  is popular).

Some USB Audio Interfaces
MakeModelPrice DIMic InputsInsert ADAT MIDI
RMEOctaMic XTC $2649 48RME Yes Yes Yes
FocusriteClarett 8Pre $800 8Clarett No Yes Yes
AudientiD44 $699 24Audient Yes YesYes No
ArturiaAudiofuse $599 22Audient Yes Yes Yes
AudientiD22 $499 12Audient Yes Yes No
FocusriteClarett 2Pre $400 2Clarett No Yes Yes
AudientiD14 $299 12Audient No Yes No
FocusriteScarlett 6i6 $250 22Scarlett No No Yes
Behringer  U-Phoria UMC1820 $250 8Midas  Yes Yes Yes Yes
Native Instruments Komplete Audio 6 $229 22 Yes No Yes
AudientiD4 $199 11Audient No No No
FocusriteScarlett 2i2 $150 12Scarlett No No No
PreSonusAudiobox iTwo $150 2 No No Yes
SteinbergUR 22 mkII $116 2D-Pre No No Yes
SteinbergUR 12 $100 11D-Pre No No No
Behringer  U-Phoria UMC404HD $100 4Midas  Yes Yes No Yes
PreSonusAudiobox iOne $100 11 No No No
PreSonusAudiobox 96 $100 2 No No Yes
FocusriteScarlett Solo $99 11Scarlett No No No
Behringer  U-Phoria UMC204HD $80 2Midas  Yes Yes No Yes
Behringer  U-Phoria UMC202HD $60 11Midas  Yes No No No
BehringerU-Phoria UMC22 $40 11Midas  Yes No No No
BehringerU-Phoria UM2 $30 11Xenyx  No No No No

In  Behringer models,  only Midas  preamps are recommended.

The Audient-iD14 costs twice as much as the comparable top-selling Focusrite Scarlett 2i2 but it has better mic preamps and also allows an ADAT extension of up to 8 additional digital channels.

8-channel extensions for USB interfaces with an ADAT optical input :
MakeModelPrice DIMic InputsInsert
AudientASP880 $1399 28Audient Yes
MidasXL48 $899 8MidasNo
AudientASP800 $849 28Audient No
FocusriteClarett OctoPre $700 8Clarett Yes
FocusriteScarlett OctoPre $350 28Scarlett No
BehringerADA8200 $200 8Midas No

Audient iD14 & ASP800 Demo (36:30)  by  Warren Huart   (Produce Like a Pro, 2017-01-14).
Behringer UMC Interface:  Driver Install and Audio Preferences Setup (3:40)  Behringer KnowledgeBase  (2016-04-28).

USB Mixers:

A USB interface yields as many digital channels  (over a single USB cable)  as it has analog inputs.  Some rare interfaces  (known as USB mixers)  also integrate an analog mixer which irrevocably combines several inputs into one channel.  One advantage of this combination is that it allows fast real-time reverbs ans echoes at little more than the cost of an extra digital-to-analog converter (DAC).

Hooking up your first studio (30:01)   by  Mike DelGaudio  (Booth Junkie,  2018-02-13).
AOKEO USB Mixer 6 feature demonstration (18:31)  by  Mike DelGaudio  (Booth Junkie,  2017-09-05).

 Sync slate
(2018-01-18)   Sync Slate
The clapboard subculture.

Sound slates used to be called  clappers  or  clapperboards.  Originally, they consisted of hinged sticks nailed on black chalkboards.  Now they're white or translucent  acrylic  plates on which dry-erase markers are used.  Magnets help the sticks snap shut.  A full-size slate is about  9½" by 12"  (bargain size: 8" by 10").  A smaller version,  used for tight shots,  is called an  insert slate  and measures about  6" by 6", including marker sticks.

There's still no better way to match video and audio clips recorded separately.  Even when timecodes are used,  an old-school slate helps identify everything.  Below is a summary of how professionals go about it.

Slating is normally the responsibility of the  2nd AC  (second assistant-cameraman)  also called  clapper-loader,  for that reason.  (The  1st AC  is the  focus puller.)  The  second AC  also maintain a camera record.

Sound recording is always started first  (film used to be expensive).  The word  speed  is yelled to confirm that sound is being recorded  (in the old days, it used to take a short while for the reels of the recorder to reach their operational speeds).

If there are several shots in a scene  (different angles, different lenses, etc.)  they are identified by one of 23 letters  (skipping I, O and S,  which could be mistaken for numerals).  Use two such letters if there are more than 23 shots,  starting with  AA, AB, etc.  It's best to use the  radiotelephony spelling alphabet  (Alfa, Bravo, Charlie...)  or any  older variant thereof  (Able, Baker...).  Funny alternatives are sometimes improper.

The information on the slate should be accurate and updated for each "take".  The clapper is always brought into the frame in the open position and the essentials are read  (shot ID and take number, at least)  the actual clap is preceded by the word  marker  or  mark.  (Possibly preceded by the identifier(s) of the camera(s) involved.  E.g.,  "A mark", "A and B mark", "A and B common marker", etc.)

Some graceful recoveries from slate  snafus  include:

  • AFS:  After false start.  This acronym is placed under the take number  (and pronounced aloud)  when a shot is interrupted for any reason and restarted from scratch.
  • Second stick :  The term identifies a second marker performed when a the camera or an audio recorder missed the first one.
  • Tail marker :  Those words precede a marker done with an upside-down slate at the end of a shot if there was no marker at the beginning.  Put the slate right-side up after the clap.

When the slate is used just to identify the image  (without associated sound)  it's held between the sticks,  In North America  (not the UK)  such a thing is called  MOS,  an acronym for one of many equivalent meanings:

  • Mit-out Sound.  ("Ve'll shoot dis mit-out sound"  Eric von Stroheim).
  • Mit ohne Stimme  (German for "without voice").
  • Mute on sound.
  • Microphone off stage.
  • Minus optical sound.
  • Motor-only shot.
  • Motor-only synchro.

The ultimate expression of slate etiquette is the  soft stick  call,  which is used to indicate that the clapper won't be used with full force out of respect  (for example, the slate may be very close to an actor's face in a quiet scene).

Clapperboard   |   Leon M. Leon (1903-1998)  invented the clapboard and the fish-pole mic.
 
What is a second AC? (9:24)  by  Ryan Connolly  (Film Riot, 2016-09-01).
How to use a clapper board (3:24) by  JP Caldeano  (Cinematic J, 2016-01-30).
How to slate (3:39) by  Tomm Jacobsen  (RocketJump Film School, 2015-05-13).
How to slate Properly (25:08) by  Mark W. Gray  (Pocket Film School, 2016-01-22).


(2017-11-05)   Copyright-Free Music  &  Special Licenses
Adding music to low-budget videos without ripping off musicians.

 Come back later, we're
 still working on this one...

How to achieve a Film Look: DSLR film making   |   How to Make a Music Video
 
Creating a Voiceover Demo with AudioBlocks (24:11)  by  Mike DelGaudio  (Booth Junkie,  2017-04-30).
 
Imitating a Lot of Hollywood Music in Four Easy Steps (10:12)  by  Scott Murphy  (2015-07-11).
Imitating it Even More Closely with One More Easy Step (11:12)  by  Scott Murphy  (2015-07-15).


(2018-01-22)   Foley   (French:  bruitage)

Sound design   |   Foley   |   Jack Foley (1891-1967)
 
Le bruiteur de cinéma (INA, France 1958)
The Magic of Making Sound (6:32)   Great Big Story  (2017-01-12).
Introduction to Foley and Sound Effects for Film (15:39)   Filmmaker IQ  (2014-11-17).
Foley Artists:  How Sound Effects are Made (7:11)   Academy Originals  (2016-06-13).
The Beautiful Lies of Sound Design (17:01)   by  Tasos Fratzolas  (TEDx Athens,  2016-03-21).


(2018-02-11)   Voice Over   (VO)

Dog-Clickers for Audio Editing !

A dog-clicker produces a loud click which trainers use as an audio feedback for dogs and other pets.  It's also a great instrument to speed-up voice-over editing with a  DAW.

The trick is to click after each fumble to clearly mark where the fumble ends and the do-over begins.  The sharp waveform of the clicker is easily recognized visually and it has to be removed from the final cut along with a short segment that precedes it.  The beginning of that segment matches what comes just after the click mark.

Our secret ingredient:  Dog clickers  (The Socratica Method)
Voiceover mistake marking (1:08)  Digital Sound Magic Recording Studios  (2016-04-30).
Dog-clicker makes VO editing so much easier! (6:07)  by  Mike DelGaudio  (Booth Junkie,  2016-02-27).
Edit voiceover faster with REAPER (9:21)  by  Mike DelGaudio  (Booth Junkie,  2016-02-18).
Essential Voiceover Jargon (17:37)  by  Mike DelGaudio  (Booth Junkie,  2016-05-08).


(2018-02-06)   Digital Audio Workstation   (DAW)

Digital audio workstation (DAW)   |   Comparaison of digital audio editors
REAPER   |   Pro Tools   |   Ableton Live   |  
Wave Editors :   Audacity   |  
 
Audacity Editing 101:  12 tips in 10 minutes (9:58)  by  Stephen Beale  (CyberdogStudios,  2012-12-07).
8 time-saving tips & tricks for Audacity (39:08)   The Audacity to Podcast  (2013-01-22).
 
How to Master Your Music in 5 Steps (22:04)   by  Michael Wynne  (In the Mix, 2018-06-30).

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