home | index | units | counting | geometry | algebra | trigonometry & functions | calculus
analysis | sets & logic | number theory | recreational | misc | nomenclature & history | physics

Final Answers
© 2000-2018   Gérard P. Michon, Ph.D.

Audio  101
Recording Digital Sound for Video

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

Related articles on this site:

Related Links (Outside this Site)

Types of Mics and Their Uses   Alexander Briones   (Gearank, 2015-12-18).
Large and Small Diaphragm Microphones   (Neumann).
Microphone Geeks  (mic reviews):   Lapel | Shotgun | Studio | Live | USB
MicReviews :   Budget | Dynamic | Ribbon | Vlogging | Wireless | Boundary
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  (in random order)   Zoom  (N. America)  |  Sennheiser  |  RØDE  |  AKG  |  Shure  |  Audio-Technica  |  Earthworks  |  Electro Voice  |  Heil Sound  |  Lewitt  |  AEA  |  Audix  |  Blue  |  Behringer  |  MXL (Marshall)  |  Sony  |  Telefunken  |   |  ShuaiYin  |  Azden  |  Samson  |  Schoeps  |  Golden Age Project  |  Coles Electroacoustics  |  Marantz  |  Sterling  |  Aston  |  Beyerdynamic  |  Warm Audio  |  ...
Retailers :   B&H  |  Amazon  |  Sweetwater  |  Thomann  |  Guitar Center  |  Reverb  |  Sam Ash

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).
Microphone electronics  (9:03)  by  Project studio handbook  (2016-01-28).
Recording Vocals Masterclass  (24:08)  by  Marcel van Limbeek  (2015-04-26).


Audio Recording

(2017-05-25)   Sound in air
Reversible local oscillations.

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

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

(2018-01-22)   Evolution of Sound Recording  (Edison 1877)
From tinfoil to wax, to vinyl.  From magnetic wire to tape, to digital.

Mary had a little lamb
Its fleece was white as snow
And everywhere that Mary went
The lamb was sure to go

Those are the words which  Thomas Edison  himself first recorded on the phonograph he invented in 1877.  At the time,  his tinfoil records could be played back only a couple of times before the stylus ruined the groove.

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

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)
Modern sound effects (3:18)  Sound Basics #1, by  Stella Gotshtein  (Waves Audio, 2016-08-15).

(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.

Acoustic Absorber Panels   (Sound Traps)

 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 that notable exception,  today's full-sized microphones are rarely threaded,  if ever.  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.

(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.

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...

XLR connectors   |   Phone connectors

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

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
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
115 dBAWhistlePassing emergency siren
110 dBAAverage threshold for pain
Rock bandJet-plane flyover  (1000 ft)
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
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).

(2018-01-14)   Noise Floor   (Hiss)
Signal to Noise Ratio   (S/N or SNR).

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

Signal-to-noise ratio   |   Noise figure   |   Shannon-Hartley theorem
Dolby noise reduction for magnetic tapes   |   Dolby Laboratories   |   Ray Dolby (1933-2013)

(2018-01-25)   Rating the Sensitivities of Microphones
Sensitivity is the ratio of voltage  output  to sound pressure  input.

The  sensitivity  of a microphone is defined as the ratio of the  variation  in its  electromotive force  output  (i.e., the open-circuit voltage it produces)  to the corresponding  variation  in sound pressure input.  When neither is too large, that's a constant.

In engineering terms,  it's useful to think of it as the ratio of two  time-derivatives.  That much is clear at the outset when  designing a microphone.  Voltage is unrelated to static pressure.

That  sensitivity  is most commonly expressed in  mV/Pa  (millivolt per pascal)  assuming a standard sinusoidal sound signal of 1 Pascal amplitude  (94 dB SPL)  at  1 kHz.

When  decibels  are used,  the  dBV/Pa  scale is  usually  understood.  Thus,  the stated  dB  sensitivity rating is  20  times the  decimal logarithm  of the sensitivity expressed in V/Pa  (which is the standard SI unit for sensitivity).

For example,  Audio-Technica  presents the high sensitivity of their  BP4071  shotgun microphone  by giving two equivalent figures:

Sensitivity of   35.5 mV/Pa   is  -29 dB    (re:  1 V  at  1 Pa).

Indeed,  we have:   20 log (0.0355 V/Pa)   =   -28.99543... dBV/Pa

A microphone is said to be  loud  when its sensitivity is high  (the opposite of  loud  is  soft).  Normally, the louder the better, because of a lesser need for amplification  (as a signal is amplified,  so is the accompanying noise).  However, there's such a thing as too much of a good thing:  If a microphone is too loud,  it may generate unexpectedly high voltages at the input of the next circuits  (preamplifiers).  That won't damage them but they'll  saturate  or  clip  (same thing)  which will introduce unacceptable distortion.

Today,  microphones are rarely designed with a sensitivity exceeding  50 mV/Pa  (that's  -26 dBV/Pa).  The discontinued predecessor of the aforementioned  BP4071  was the  AT4071a  which had a nominal sensitivity of  89.1 mV/Pa  (that was -21 dB).  This is considered  way  too loud by today's standards for general-purpose use  (although bird lovers still like this kind of sensitivity in a directional microphone).

The sensitivity rating of a microphone is always stated for  on-axis  sound  (coming from the preferred direction of the microphone, which gives the maximum sensitivity).  Polar patterns  are charts giving relative sensitivity as a function of direction by reference to that basic sensitivity  (de facto,  the  0 dB  level for a particular microphone).

Warning :   An older decibel scale for microphone sensitivity is still floating around which differs from the modern one by  20 db.  In that obsolete scale,  the aforementioned  BP4071  would have been quoted as having a sensitivity of  -49 dB  (which could be misinterpreted as quite low).

The discrepancy comes from the former use in acoustics of the units of pressure still preferred by many meteorologists.  When meteorologists in France and elsewhere were criticized for issuing TV reports expressed  in  millibars  (1 mb = 100 Pa)  instead of a proper  SI unit,  they didn't change their numbers but started using the  SI-equivalent  hectopascal  (which is correct albeit arguably  somewhat weird).

In the old days,  audio engineers were routinely using the  microbar  (0.1 Pa)  as their unit of pressure  (this was an alternate name for the official unit of pressure in the CGS system,  namely the  dyne per square centimeter).  This made the  volt per microbar  (10 V/Pa)  their unit for microphone sensitivity.  Using that unit,  the numerical values of sensitivities are ten times smaller than the values in  V/Pa.  Expressed in decibels,  they're thus  20 dB  lower,  as advertised!

In  Numericana,  microphone sensitivities are only given in  mV/Pa.  Not only does this avoid the aforementioned ambiguity of decibels,  but it also serves as a constant reminder of what sensitivity is all about.

Unit conversions is a known source of distress.  NASA  once crashed a spacecraft on Mars because of that.  As I was looking for data relevant to this page,  I came across a  discussion between audio afficionados  where the above  20 dB  offset is mistaken for real substance.

Electromotive force vs. measured voltage :

Microphone sensitivities are best expressed in terms of  open-circuit voltages  (the common name given to  electromotive forces).  So defined,  sensitivity  depends only on the microphone itself,  not on whatever load it may have to drive  (usually, the input impedance  A  of some preamplifier).

Nevertheless,  some manufacturers give the actual voltage  V  that would be observed per unit of sound pressure into a load of specified impedance within the range they recommend  (e.g.,  A = 1 kW).  That number is slightly smaller than the aforementioned intrinsic sensitivity  U.  The relation between the two is obtained by observing that the microphone's output current is equal to the amplifier's input current.  Let  R  be the microphone's output impedance and  A  be the amplifier's input impedance.  This means:

U / (R+A)   =   V / A     Therefore:

U   =   ( 1 + R/A ) V

For example, if a  200 W  microphone is said to yield  10 mV/Pa  into a  1 kW  load,  then we just quote its  intrinsic sensitivity  U  as  12 mV/Pa.

Such a microphone would drive a  2.5 k  load with

12 / (1 + 200 /2500)   =   11.111 mV/Pa.

(2018-02-05)   Microphone directionality.  Polar pickup patterns.
Omnidirectional, bidirectional, cardioid, etc.

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

(2018-02-05)  Dual-Diaphragm Microphones for variable pickup patterns.
A cardioid is the  sum  of omnidirectional and bidirectional patterns.

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

Multi-pattern and variable pickup pattern:

Mixing equal parts of an omnidirectional pickup pattern and a bidirectional one  (figure-8)  yields a cardioid pattern.  Other proportions in this type of mixing also yields the other  traditional  microphone pickup patterns:

  • Subcardioid  pattern  (between omnidirectional and cardioid).
  • Supercardioid  pattern  (between cardioid and figure-of-eight).

The above five patterns and the four intermediate ones between them yield a palette of nine patterns,  which are commonly available at the flip of a switch in  some  multi-pattern  microphones.  The term  hypercardioid  is sometimes applied to any such mix but it's most often reserved to patterns with a wide  cone of silence  up to  (but excluding)  the bidirectional figure-of-eight itself  (90° angle of silence).

Variable-pattern  microphones  (e.g., CAD Audio M179)  even allow you the freedom to dial anything in-between.

Note that a two-diaphragm microphone which is capable of recording at least two pickup patterns from the above standard family can also be used to reconstruct  any  of them in post-production.  For example, if the omnidirectional signal is on the left channel and the figure-8 bidirectional signal is on the right channel,  Then, you obtain a forward cardioid by adding the two channels and a backward cardioid by subtracting them  (opamps were originally intended do perform exactly this sort of operations).  This way, you can choose the pickup pattern  after  recording.

Any dual-diaphragm microphone could be modified into a pseudo-stereo microphone capable of recording the two separate phase-tracks just described.  Two products offer this capability straight out-of-the-box:

  • The  Lewitt LCT 640 TS  microphone  (TS stands for  twin system)  whose secondary output is on a mini-XLR connector  (sideways).
  • The  MS ("Mid Side")  attachment for the 10-pin connector of Zoom recorders  (H5, H6, F1, F4, F8)  records separately the signals from two capsules:  Forward  cardioid and  sideways  bidirectional.

Other multiple-diaphragm configurations would provide other capabilities.

Multi-pattern dual-diaphragm microphones  (data is for cardioid pattern)
MakeModelPrice mV/PaHiss Max.BandwidthW
TelefunkenU87 $8999 24.59 dB127 dB20Hz-20kHz400
sE ElectronicsRNT $3249 1618 dB151 dB18Hz-20kHz30
NeumannU87 Ai $3200 33.612 dB117 dB20Hz-20kHz200
BlueKiwi $1999 198.5 dB138 dB20Hz-20kHz50
SonyC38-B $1880 424 dB140 dB30Hz-18kHz250
AKGC414 xls$1074 236 dB140 dB20Hz-20kHz200
RoswellDelphos $8994012 dB 20Hz-16kHz200
Lewitt  LCT 640 TS $89931.410.5 dB134 dB20Hz-20kHz110
ShureKSM 44A $999 29.84 dB134 dB20Hz-20kHz50
ShureKSM 44 $99929.87 dB132 dB20Hz-20kHz150
Audio-TechnicaAT4050 $699 15.817 dB149 dB20Hz-18kHz100
Røde [tube]K2 $699 1610 dB162 dB20Hz-20kHz200
Warm AudioWA-87 $599 ?17 dB?125 dB20Hz-20kHz150
AstonSpirit $449 2614 dB138 dB20Hz-20kHz
RødeNT2-A $399 167 dB147 dB20Hz-20kHz200
Audio-TechnicaAT2050 $229 7.917 dB149 dB20Hz-20kHz120
CAD AudioM179 $199 1611 dB123 dB10Hz-20kHz200
SenalSCM 660 $175 22.418 dB130 dB20Hz-20kHz100
CADGXL3000 $159 1320 dB125 dB35Hz-20kHz200
BehringerC-3 $70 1023 dB142 dB40Hz-18kHz350

Multi-pattern microphones  by  Davida Rochman   (Shure Blog,  2014-08-11).
Choosing a mic for vocalist Sammi O'Rourke (5:36)  by  Jason de Wilde   (AIM Sidney,  2015-07-30).
KSM 44, New Dual-Diaphragm Condenser, in 2008 (3:21)  by  Tim Vear   (the improved KSM 44A appeared in 2010).
Lewitt LCT 640 TS:  A true next-gen microphone (5:36)  by  Lewitt   (2016-09-19).

(2018-01-29)   Accurately Measuring Sound
Calibrated  ¼''  or  ½''  omnidirectional  measurement microphones.

Most prosumer  measuring microphones  have a  ¼''  capsule  (6 mm diaphragm).  Professionals sometimes use smaller membranes  (3 mm)  which are more accurate in the upper-part of the audio spectrum.  They tend to prefer expensive low-noise  ½''  units for general use.

Acoustic Calibrators  (1 kHz,  94 dB SPL) :

By convention,  absolute calibration  of a sound-measuring instrument is always done at  1000 Hz.  For that purpose,  standard sound sources  are available which deliver precisely  94 dB SPL  into a  force-fit  microphone port allowing cylindrical microphone heads up to  1''  in diameter  (sometimes only ½'').  Smaller microphones require adapters which may or may not be included with calibrating units.  Below is a list of current models of such  acoustical calibrators.  All of these can work either at  94 db  or  114 dB  (the latter setting is helpful in a noisy environment).

  • Brüel & Kjær 4231.  0.2 dB accuracy.  $1000 used!
  • General Radio 1562-A.  0.172 dB accuracy.  $2694 new.
  • Cirrus CR 515.  0.2 dB accuracy.  ½" port.
  • Brüel & Kjær 4230.  Discontinued.
  • Landtek ND9.  0.3 dB accuracy.  $129.   [ Fail ]
  • Cirrus CR 514  0.4 dB accuracy.  ½" port.
  • Reed R8090.  0.5 dB accuracy.  ½" diameter.  $175.
  • Ruby Electronics SC-05.  0.5 dB accuracy.  $180.
  • Amprobe SM-CAL1.  0.5 dB accuracy.  $187.
  • Sper scientific 850016.  0.5 dB accuracy.  $256.   [ Video ]
  • Fluke SM-CAL1.  0.5 dB accuracy.  $270.
  • Extech 407766.  0.5 dB accuracy.  $313.

Now, the calibrators themselves drift out of calibration and have to be recalibrated yearly by the manufacturer.  Most people will only trust  Brüel & Kjær  (or possibly Cirrus)  for that follow-up.

Sound Meters,  Measurement Microphones :

Measurement microphones  are designed to be as linear as possible,  They have a flat frequency response throughout the audio range and deviations must be carefully documented  (see example below).  Tiny diaphragms help keep resonant frequencies safely outside of the audio domain.

Many uncalibrated consumer models are just intended for the analysis of  room acoustics  and cannot be trusted beyond a precision of  2 dB  or  3 dB.  The following models are thus  not recommended  for scientific applications:

A much better precision is offered at a similar cost with any of the models listed  below.  Each such unit comes with an individual calibration curve made with a professional instrument.  The resulting on-axis  frequency response  is typically made available online  (tied to the serial number of every microphone)  in a digital form suitable for audio-analysis software.  Sonarworks  also provides an off-axis curve.

Some measurement microphones which come with individual calibration curves :
MakeModelPrice mV/PaHiss Max.BandwidthW
Dayton AudioEMM-6 $50 1224 dB127 dB18Hz-20kHz200
MiniDSPUMIK-1 $75USB20 dB133 dB20Hz-20kHzusb
SonarworksXREF 20 $851426 dB132 dB20Hz-20kHz 
BeyerdynamicMM-1 $2001537 dB122 dB20Hz-20kHz160
AudixTM1-Plus $400 7.228 dB130 dB20Hz-25kHz200
EarthworksM23 $5003420 dB138 dB9Hz-23kHz65
EarthworksM30 $7003420 dB138 dB5Hz-30kHz65

Earthworks  also sells the  M30  in matched sets  (for about $1500 a pair)  for  stereo  recording.  They're the industry standard for true-to-life response.

All  measurement microphones could be used for recording,  but their tiny diaphragms  (usually  6 mm)  makes them about as noisy as  lavalier mics.

Dayton Audio's  Electret Measurement Microphone  EMM6

With a street price of $50  (I got mine on sale for $40)  the EMM6 is the most affordable of the above.  Packed with each unit is a dated plot of its frequency response.  The corresponding data is also available online  (tied to the serial number)  in the form of a tab-separated text file  (ready to import into Excel or other specialized software).  That file contains measurements at a precision of  0.1 dB  for  256  frequencies whose logarithms are evenly spaced,  from  20 Hz  (n = 0)  to  20000 Hz  (n = 255).  That's to say:

fn   =   (20 Hz) 10 n/85     (for  n between 0 and 255 = 3 x 85)

The values are given in decibels relative to the level at frequency  f145 = 1016.0436 Hz  which is given tersely in absolute terms  (in dBV/Pa)  on the first line of the data which reads,  in the example of my own unit:

*1000Hz	-39.6

This misleading header actually indicates that the sensitivity of this particular microphone is  -39.6 dBV/Pa  (i.e., about 10.47 mV/Pa)  at precisely  1016.04 Hz  (not 1000 Hz).

 Blowup   The blow-up at right shows the frequency-response near 1 kHz of my own new EMM6.  Each black square is precisely a single data-point  (it covers exactly one pixel in the full graph shown below,  where the height of each pixel is just  0.1 dBV/Pa.)
 Dayton Audio EMM6 Electret Measurement Microphone

To obtain a very precise value of the sensitivity at exactly  1 kHz  (which is the usual standard)  we remark that 1000 Hz = fn  when

n   =   85 log 50   =   144.4124503685615984...   =   145 - 0.58754963...

The  data for my own unit  says that the sensitivity for  f144  is 0.2 dB  above the level for the aforementioned  ad hoc  reference frequency  (f145 ).  Thus,  the response at  1000 Hz  is best obtained by linear interpolation:

-39.6  +  0.2 (0.58754963...)   =   -39.5 dBV/Pa   (or about  10.6 mV/Pa)

Because this a voltage measurement into a  1000 W  load  for a  200 W,  the intrinsic sensitivity  (open circuit)  is  20%  (or 1.58 dB).  Before rounding,  that's:

-37.899... dB/Pa   or   12.7367 mV/Pa

Brüel & KjærMeasuring microphones  (August 1994).
NTI Measurement Microphones Overview   |   NTI Web Shop
Measurement microphones in the  Thomann Catalog  (Germany).
11 measuring microphones compared  by  Ethan Winer   (RealTraps, 2013-08-11).
Dayton Audio's  EMM6, UMM6 and OmniMic V2 (2:48)  Parts Express  (2016-07-01).

(2018-02-09)   Low Cut Filter   =   High Pass Filter  (HPF)
Filtering out the lowest audio frequencies.

On many microphones,  a switchable  low cut  filter is provided to get rid of the low-audio and sub-audio hum and rumble.  Typically,  a corner frequency of  80 Hz  is used.

Most manufacturers are content with a simple  first-order filter (6 dB/octave)  which provides a modest  12 dB  attenuation at  20 Hz.

Others, like  Audio-Technica  will do more and they should be commended for it.  If you need low-cut in an urban environment,  the more attenuation the better.  Even in their entry-level  AT2035,  the low-cut filter they provide is  second-order (12 dB/octave)  for a  24 dB  attenuation at  20 Hz.

On  Audio-Technica  shotgun microphones  (AT897, BP4073, BP4071)  the switchable low-cut filter is third-order  (18 dB per octave)  and provides an attenuation of  36 dB at  20 Hz  (that's 12 dB at 50 Hz).

Low-cut filter  vs.  low-frequency shelf (2:48)  Parts Express  (2016-07-01).

(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 badies can hear  20 kHz.  Young adults are lucky if they can detect a sinewave at  18 kHz.  Middle-aged people can hear a thing above  14 kHz  or  15 kHz,  at best.

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!

(2017-11-22)   Characteristics of Full-Size Wired Microphones
Condenser type  (varying capacitor)  or  dynamic type  (varying inductor).

Microphones currently being produced range in price from  $1.67  to  thousands of dollars  (the  AKG C12 VR  sells for &5999).  Used vintage  Neuman U67  tube LDC  microphones are typically sold for $9000-$16000, depending on condition.  At least part of that madness is due to a nostalgia for the particular type of  distortion  introduced by  tube  (or  valve)  circuits.

For some obscure reason,  tube amplifiers tend to distort a waveform symmetrically,  which is another way to say that they introduce more  even  harmonics  than odd ones.  The type of sound so produced is normally associated with female voices  (it would seem that  Adam's apple  on a male  voice box  is responsible for producing asymmetrical waveforms rich in odd harmonics).  Whatever the exact reason may be,  this is just one example of an acquired taste among audiophiles which has little or nothing to do with high-fidelity.  If anything,  modern semiconductor circuits have better fidelity qualities,  quantitatively speaking.  The good news is that those high-price instruments are not a necessary part of high-fidelity home recording.

Designing microphones  is an  art form  in itself.  Microphones are a crucial tool for musicians and an object of worship for countless  audiophiles.  Just enumerating the main aspects on which that subculture is based will serve to demonstrate that we can only scratch the surface here  (focusing, as usual, on nontrivial numerical aspects besides cost).  All these aspects are interrelated:

  • Price, cost of ownership.
  • Options and customizability.
  • Look, feel and durability.
  • Size and weight.
  • Possible mounts  (handheld, tabletop, lapel, stand, arm, boom).
  • Sensitivity at various frequencies  (bandwidth  &  microstructure).
  • Impedance magnitude and phase shift  (as functions of frequency).
  • Directivity  (polar pattern)  at various frequencies.
  • Proximity effect at various frequencies.
  • Noise figure,  noise floor  (hiss).

The previously introduced concept of  sensitivity  influences greatly overall noise performance because lower sensitivity demands greater subsequent amplification,  which magnifies hiss just as much as the useful signal.

The  self-noise  (or  equivalent noise level,  henceforth tabulated as  hiss)  of a microphone is the loudness of the signal it produces by itself in an isolated soundproof enclosure  (it would be cheating to report only the electric noise of the apparatus without the microphone capsule).  The same figure of merit is sometimes reported as a  signal-to-noise ratio  (SNR)  assuming a  1 kHz  sinusoidal  standard soundwave  of  1 Pa  amplitude  (94 dB SPL):

SNR   =   94 dB  -  (self-noise, dB)

The  dynamic range  of a microphone is defined as the  decibel  difference between the aforementioned self-noise and the top loudness it can record,  with less than  1%  THD  (total harmonic distortion).

The  nominal output impedance  is expressed in ohms  (W).  A microphone is normally plugged into a  preamplifier  whose input impedance shouldn't be lower than whatever is specified by the microphone manufacturer  On the other hand,  it shouldn't be too high either because high impedance breeds noise.  A time-honored  rule of thumb  is to load a microphone with five to ten times its own output impedance.

Some compact microphones sold with on-camera mounts :
MakeModelPrice mV/PaHiss Max.BandwidthW
MovoVXR10 $40 4018 dB 35Hz-18kHz200

Download Official Microphone Drivers
How to get professional DSLR audio: The RØDE VideoMic Guide  (16:57)  by  Alex  (2014-11-25).
Audio Filmmaking Basics (18:08)   Basic Filmmaker  (2015-08-20).
Best Microphones for Video (0-$500)  by  Tony Northrup  (2016-08-30).
This Light and Mic Stand Changes Everything  by  Caleb Pike  (2017-11-02).
Every Rode Shotgun Video Mic Compared! $59 - $299  (23:46)  by  Max Yuryev  (2017-11-24).
Great $40 Camera Microphone  Movo VXR10 Review  (7:52)  by  Caleb Pike  (2017-12-05).
$25 vs. $299 - Takstar beats the Rode VideoMic Pro?  (11:52)  by  Max Yuryev  (2017-10-13).
Numericana :   Decibels (db) & Sound levels   |   Microphone design

(2018-02-01)   Acoustical Properties of Large Circular Diaphragms
Resonant frequencies and frequency-dependence of pickup patterns.

 Neumann U87  The  diaphragm  of a condenser microphone consists of a thin circular membrane whose rim is attached under tension to a rigid hollow cylinder.  In the so-called  center terminated  variant,  the diaphragm is also anchored by a small screw at the center,  where it can neither move nor tilt...
That method is used, in particular, in good  ½''  measurement microphones.  It presents three major advantages:

  • The center point can be used for electrical contact.
  • Resonances are suppressed if the center isn't a  node.
  • Resonances are suppressed if the gradient at the center is nonzero.

Those last two properties eliminate the lowest resonant frequencies for a circular membrane  of prescribed size,  areal weight and tension.  That helps remove all resonant frequencies away from the audio range.  However, the central contact restricts the amplitude of the diaphragm's motion at lower frequencies and thus reduces the basic  sensitivity  of the microphone.

condenser microphone  is formed by the varying capacitor consisting of one such diaphragm opposite a rigid  backplate  (polarized by an external voltage and/or an electret).  When those two form a closed  capsule,  an  omnidirectional  pickup pattern is obtained  (at least at low frequencies). 

A microphone capsule is never completely closed,  or else it could bend  (or even pop)  in response to slow changes in atmospheric pressure.  There are just tiny vents which allow air to go in and out of the capsule fairly slowly,  with little or no impact at audio frequencies.  The best designs will make the vents just large enough to cancel hum just below the audio range  (which is usually assumed to start at  20 Hz,  although that's definitely not audible).
 Standing Wave in a Circular Membrane

The mathematical simplicity of the above configurations makes a complete theoretical analysis possible,  which may serve as a useful basis for experimental refinements in the actual design of commercial microphones.

Another aspect amenable to pencil-and-paper analysis  (barely so)  is the pickup pattern  (sensitivity as a function of direction)  of a large-diaphragm for a sound having a wavelength commensurate with its size  (for much larger wavelengths,  the pickup pattern is omnidirectional).

Vibrations of a circular membrane

(2018-01-22)   Large-Diaphragm Condenser Microphones   (LDC)
Quintessential capacitive microphones.  Every voiceover artist has one.

Most condenser microphones use the  48 V  phantom power normally found on  XLR  sockets  (one more reason to get an  XLR1  audio adapter,  if you shoot video with a Panasonic  Lumix GH5).

What's the fuss about large diaphragms?   Well,  the larger the diaphragm the quieter the microphone,  but too large a diaphragm will struggle with the upper part of the audio spectrum,  especially off-axis,  as different parts of the membrane see different phases of the soundwave  (at  20 kHz  the wavelength is only  17 mm).
Earthworks  achieved the extreme bandwidth  (30-33kHz)  of their  SV33  flagship by limiting the diameter of the diaphragm to  14 mm.  The price they paid was a  15 dB  noise-floor  which is unimpressive for a microphone at that price-point  ($2499).  The membranes of more typical LDC microphones are about  1''  in diameter  (25.4 mm).

One popular LDC microphone is the affordable  AT2020  from  Audio-Technica  ($99 bundle).  I went instead for its big brother,  the  AT2035  ($149 bundle)  because of a side-by-side sound comparison on  YouTube.

Also,  unlike the  AT2020,  the  AT2035  has two desirable features:

  • Switchable  10 dB  in-line attenuator  ("pad")  whose effect is equivalent to tripling the distance from the sound source.
  • Switchable  second-order high-pass filter  with  80 Hz  corner frequency,  which helps cut out hum and rumble in an  urban environment.  (Other makes often provide only first-order.)

The  AT2035  gets  rave reviews  as the best in its class  (I wouldn't consider a higher class for home use,  following the  law of diminishing returns).  That microphone comes with a soft pouch and a shockmount  (including a plastic thread adapter; 5/8''-27 male to 3/8''-16 female).  I got mine with a complimentary 10-ft XLR cable and Neewer® pop screen.  All for $149.  The shockmount by itself  (AT8458)  would sell for  $79.  (Third-party shockmounts go for  $10,  a short cable is about $9 and the pop shield is $7.)

 AT2035 frequency response

The  AT2035  was released in 2008.  It's built around a  center-terminated  24.3 mm  diaphragm  (0.96").  It uses  back electret  polarization,  which helps accommodate a wide range of phantom voltages  (from 11V to 52V).  Some purists still scoff at this approach,  compared to what they call  true  condenser microphones,  in spite of the fact that the electret technology has been around for more than 50 years and helps deliver  superb  performance.

To address such queasies within the  Audio-Technica  ladder,  the  AT2035  is bracketed by two condenser microphones which are purely DC-biased without electrets,  the AT2020 and the AT4040  (which both demand 48V phantom power).  The latter costs twice as much as the  AT2035  without offering any improvement in self-noise.  (Since it's  1 dB  more sensitive,  it's technically just  1 dB  quieter.) 

This isn't the whole story, though:  The noise figure of the AT4040 was achieved in spite of the fact that it uses only a  smaller diaphragm of  20.4 mm  (0.8'')  which helps with transient response.
Although my own ears couldn't detect those subtleties  (I'm now on the wrong side of sixty)  I could easily see that the AT4040 grille is more transparent,  which can be acoustically desirable.
Røde's  NT1-A  still looks like a better upgrade,  as a true condenser microphone which is  8 dB  quieter than the  AT2035  (for only  $80  more).  For another $40,  I find their  NT1  even more tempting with its true-to-life flat-response sound and praised shockmount  (Rycote lyre).

Audio-Technica  reports  that they incorporated into the  AT2035  the honeycomb diaphragm design used in their own  $3000  AT5040  flagship,  for increased surface area and enhanced performance.

In the following table,  we give a wide selection of the medium-to-large condenser microphones available today.  All of those are single-diaphragm microphones  (we list separately  dual diaphragm microphones  featuring selectable pickup patterns).  They're all cardioid microphones,  except :

  • Earthworks SR40V  (hypercardioid).
  • CAD Audio E100s,  (supercardioid).

Some LDC microphones   (Data with all pads and filters disengaged.)
MakeModelPrice mV/PaHiss Max.BandwidthW
Audio-TechnicaAT5040 $299956.25 dB142 dB20Hz-20kHz50
EarthworksSV33 $24991015 dB145 dB30Hz-33kHz65
NeumannTLM 49 $17001412 dB129 dB20Hz-20kHz50
VioletGlobe $138623.16.5 dB134 dB20Hz-20kHz50
NeumannTLM 103 $1300 247 dB138 dB20Hz-20kHz50
BlueMouse $1250 218 dB138 dB20Hz-20kHz150
RoswellRA-VO $9991010 dB50Hz-15kHz112
EarthworksSR40V $9992020 dB145 dB50Hz-40kHz65
ShureKSM42 $79914.18.5 dB131 dB60Hz-20kHz147
NeumannTLM 102 $699 1112 dB144 dB20Hz-20kHz50
LewittLCT 550 $699363 dB143 dB20Hz-20kHz150
CAD AudioE100s $499 283.7 dB140 dB20Hz-20kHz150
sE ElectronicssE2200 $429 23.712 dB113 dB20Hz-20kHz50
Blue Baby Bottle SL $39939.810.8 dB134 dB20Hz-20kHz50
AKGC214 $3992013 dB136 dB20Hz-20kHz200
GaugeECM-87 $329 12.517 dB128 dB20Hz-20kHz200
RødeNT1000 $329 15.86 dB140 dB20Hz-20kHz100
SennheiserMK 4 $3002510 dB140 dB20Hz-20kHz50
Roswell  Mini K47 $2991813 dB20Hz-16kHz114
BlueBluebird $29928.511.8 dB138 dB20Hz-20kHz50
Audio-TechnicaAT4040 $29925.112 dB145 dB20Hz-20kHz100
LewittLCT 440 $26927.47 dB140 dB20Hz-20kHz110
RødeNT1 $269 354.5 dB132 dB20Hz-20kHz100
OktavaMK 319 $2601314 dB122 dB20Hz-18kHz200
RødeNT1-A $229 255 dB137 dB20Hz-20kHz100
MXLV250 $200 1520 dB130 dB30Hz-20kHz200
Blue (Blackout) SparkSL $200 34.916.4 dB136 dB20Hz-20kHz50
Audio-TechnicaAT2035 $14922.412 dB148 dB20Hz-20kHz120
LewittLCT 240 $149 16.719 dB142 dB20Hz-20kHz100
BehringerB1 $100 2013 dB138 dB20Hz-20kHz50
Audio-TechnicaAT2020 $9914.120 dB144 dB20Hz-20kHz120
MXL990 $90 1514 dB130 dB30Hz-20kHz200
AKGP120 $89 2419 dB130 dB20Hz-20kHz200
MXL770 $75 1520 dB137 dB30Hz-20kHz150
SamsonC01 $72 22.4 136 dB40Hz-18kHz200
MXLV67G $70 1520 dB130 dB30Hz-20kHz200
AKG  Perception 100 ($50)1816 dB135 dB20Hz-20kHz200
AokeoAK-70 $29 2016 dB130 dB20Hz-20kHz150
NeewerNW800 $22 12.616 dB132 dB20Hz-16kHz150
NeewerNW1500 $16.50 12.616 dB132 dB20Hz-16kHz150

Because of its  4 dB  sensitivity advantage,  Audio-Technica's  AT2035  ends up being  12 dB  less noisy than the  AT2020  (or 18 dB less noisy than the multi-pattern Behringer C-3).  Likewise at the high-end,  the  AT5040  is  8 dB  more sensitive and  15 dB  less noisy than the  AT2035.  It's twice as sensitive and  4.7 dB  less noisy than the  Equitek E100s.

The Samson C01 mic gets mixed reviews;  it's reportedly rather hissy.

Audio-Technica AT2035 (product page).
Blue Yeti vs. Audio Technica At2020 & Scarlett 2i2  by  Matt Kjer  (2016-02-26).
AT-2020 vs. AT-2035 Comparison  by  Bandrew Scott  (Podcastage, 2016-08-12).
Comparison tests:  AT2035, C01, C-3, sE2200aIIMP  by  Robin How  (2015-01-02).
Shootout:  Blue Spark,  Neumann U87ai,  Sennheiser MKH 416 (5:36)  Russell Cory  (WWK TV,  2013-08-13).
Blue LDC Microphones, SL Series:  Spark, Bluebird, Baby Bottle (6:09)  Jon VonRentzell,  Blue  (2017-06-21).
Lewitt LCT 240Pro vs. Audio Technica AT2035  (13:57)  by  Mike DelGaudio  (Booth Junkie,  2018-04-05).
DIY upgrades for the MXL 990  (4:24)  by  Matt  (Microphone-Parts.com,  2018-04-05).
Can you make music with a $30 Mic? (16:16)  by  Warren Huart   (Produce Like a Pro, 2016-08-30).
NW-700 vs. NW-800 vs. NW-1500 (5:15)  by  Bandrew Scott   (PodcastAge, 2016-04-29).

(2017-11-22)   Dynamic Microphones  (French:  bobine mobile)
Rugged inductive microphones,  usually with limited bandwidth.

moving-coil dynamic microphone  functions exactly as an ordinary speaker.  Actually,  a moving-coil speaker can be wired to work as a dynamic microphone,  albeit a lousy one.  Because a dynamic microphone is a passive component,  it generates no noise besides thermal  Johnson-Nyquist noise.

Unlike condenser microphones,  dynamic microphones don't require any outside  polarization voltage  to work.  There are two very different types of dynamic microphones:

As part of an old-school PA system I purchased years ago,  I got the rugged  Radio-Shack 3303043 Super-cardioid Dynamic Microphone  (RS catalog number 33-3043)  which is a perfect voice microphone in that capacity  (great proximity effect).  That unit is still available  new  on eBay, between $25 and $50 or so  (it goes for less than $20 used).  It has the exact same look and feel as the  legendary  Shure SM58S  (SM58 with a mute switch).  Both feature the exact same spherical grille  (51 mm diameter).  The built quality is the same, except that the RadioShack body is a half-inch longer and has a black grille coupling  (which is silver on the Shure unit).

Some Dynamic Microphones   (moving-coil microphones)
MakeModelPricemV/Pa HissMax.BandwidthW
SennheiserMD 441 U $899 1.8  30Hz-20kHz200
Electro-VoiceRE27 Nd $499 2.52  45Hz-20kHz150
Electro-VoiceRE20 $449 1.5  45Hz-18kHz150
ShureSM7B $399 1.1  50Hz-20kHz150
SennheiserMD 421-II $380 2  30Hz-17kHz200
Heil SoundPR 40 $308 2 148 dB28Hz-18kHz600
Electro-VoiceRE320 $299 2.5  30Hz-18kHz150
ShureSuper 55 $249 2.24  60Hz-17kHz290
RødeProcaster $229 1.6  75Hz-18kHz320
Heil SoundThe Fin $220 1.8 142 dB50Hz-18kHz600
ARTD7 $199 2 136 dB50Hz-16kHz250
Shure55SH II $179 1.33  50Hz-15kHz270
Golden Age ProjectD2 $150 2.5  50Hz-20kHz250
Electro-VoiceRE 635 $139 1.4  80Hz-13kHz150
ShureSM58S $104 1.3  160 dB 55Hz-14kHz270
SennheiserE835 $100 2.7  40Hz-16kHz350
sE ElectronicsV7 $99 2.0  40Hz-19kHz300
Audixi5 $99 1.6 140 dB50Hz-16kHz280
ShureSM57 $99 1.6  40Hz-15kHz310
AKGD5 $89 2.6  70Hz-17kHz600
Blue  Encore 100i $80 1.1 154 dB50Hz-16kHz150
SamsonQ7 $58 1.4 150 dB50Hz-18kHz200
ShurePGA58 $54 1.79  50Hz-16kHz150
Radio-Shack3303043 $452.5  50Hz-15kHz600
SamsonCS $40 1.7 150 dB55Hz-18kHz250
BehringerXM8500 $20 3.2  50Hz-15kHz150
PylePDmic58 $12 2.0  50Hz-15kHz600

The 33-3043 microphone was manufactured by Shure specifically for RadioShack.  So were other dynamic microphones.  All were made in Mexico and none had any direct equivalent in the regular Shure line  (they were typically loosely related to more expensive Shure models sporting the same grille).  Examples include:

  • Highball by Shure  (33-984E).
  • Shure Unidirectional Dynamic Microphone (33-3010A).
  • Omni Directional Microphone by Shure (Realistic 33-1070).

Radio Shack 3303043 User Manual
Behringer XM8500 vs. Shure SM58 (9:35)  by  Scott Lamp   (2017-05-23).
I bought a counterfeit mic so you won't have to (16:20)  by  Mike DelGaudio  (Booth Junkie,  2017-11-03).
Shootout:  SM7, MD421, RE20, SM57 and Audix i5 (14:26)  by  JustinSonicScoop  (B&H,  2016-02-24).

Output transformers for dynamic microphones :

Two similar models from different makes are available for about the same price  ($18).  Both feature a low-impedance input on an XLR female socket and an high-impedance output on a  ¼''  mono phone jack.

Output Transformers for Dynamic Microphones
MakeModelPriceGain PrimarySecondary
ShureA85F $18 21 dB300 W40 kW
Hosa TechnologyMIT 435 $18 24 dB200 W50 kW

Jensen transformers

(2018-02-04)   Ribbon Microphones
A very special type of dynamic microphone.

The  engine  (or  motor)  of a ribbon microphone is a very thin corrugated strip of metal  (usually aluminum)  which fits tightly between very strong magnets without touching them  (today, neodymium magnets are used).  The ribbon thus separates two symmetrical cavities formed by the walls of the magnet.  As the ribbon moves in response to sound pressure,  a tiny electromotive force appears between its extremities which are connected to the primary windings of a step-up audio transformer.

The natural acoustical symmetry of such microphones translate into a figure-8 directional pattern.  They pick up sound equally well from the front or the back and very little from the perpendicular directions.

Ribbon microphones include legendary  lip microphones  like the  Coles 4104  for dramatic voice reporting in very loud environments.

Examples of Ribbon Microphones   (special type of dynamic microphones)
MakeModelPricemV/Pa HissMax.BandwidthW
AEAA440 $5220 216 dB136 dB20Hz-15kHz92
Coles4038 $1332 5.6 125 dB30Hz-15kHz300
RoyerR-121 $1295 3.2 135 dB30Hz-15kHz300
AEAR84 $1035 2.5 165 dB20Hz-20kHz270
MesanovicModel 2 $999 2.217 dB140 dB20Hz-20kHz250
Audio-TechnicaAT4080 $9991122 dB150 dB20Hz-18kHz100
RødeNTR $799 315 dB130 dB20Hz-20kHz200
Coles4104 $726 3.2 120 dB60Hz-12kHz300
Audio-TechnicaAT4081 $6997.925 dB150 dB30Hz-18kHz100
sE Electronics  Voodoo VR2 $4991020 dB135 dB20Hz-18kHz200
sE Electronics  Voodoo VR1 $3991.617 dB135 dB20Hz-18kHz300
sE Electronics  se X1 R $2491.7 135 dB20Hz-16kHz200
CAD Audio  Trion 7000 $2392.2  25Hz-10kHz940
MXLR144 $82 1.6 130 dB20Hz-17kHz250

Modern ribbon microphones come in two different flavors:

  • Traditional  passive  ribbon microphones, with sensitivities below 6 mV/Pa.
  • Active  ribbon microphones, with phantom power and higher sensitivities.

In the above table,  the listed sensitivities indicate which is which.

Ribbon microphones
AEA ribbon microphone (5:00)   How it's made   (2012-10-27).
DIY Ribbon Microphone (7:16)  by  Fred Gabrsek   (FreddysFrets, 2012-12-17).
Royer ribbon microphones (6:23)   How stuff's made   (Discovery Channel, 2009).
Royer Labs R-Series Ribbon Transducer (7:49)  by  John Jennings   (Royer Labs, 2017-01-06).
Steve Levine interview:  Ribbon Microphones (7:41)  Audio Technica   (2011-11-13).
Royer 121, Mesanovic 2, AEA R84, Coles 4038 (41:56)  by  Warren Huart   (2016-10-06).

(2018-02-14)   Small-diaphragm pencil microphones  (matched pairs)
Without  interference tubes,  they're less  directional  than  shotgun  mics.

Small-diaphragm condenser microphones generate more noise than large-diaphragm  ones but they are arguably superior in every other respect.

Some small-diaphragm condenser microphones are available in matched pairs.
MakeModelPrice mV/PaHiss Max.BandwidthW
AKGC636 $499 5.620 dB150 dB20Hz-20kHz200
AKGC535 EB $350721 dB 20Hz-20kHz200
RødeNT5 $219 12.616 dB143 dB20Hz-20kHz100
RødeM3 $149 1021 dB142 dB40Hz-20kHz200
RødeM5 $199/2 2019 dB140 dB20Hz-20kHz200
LyxProSDPC-2 $100/2 12.630Hz-18kHz
SamsonC02 $84/2 1022 dB134 dB40Hz-20kHz200
BehringerC-2 $60/2 8.919 dB140 dB20Hz-20kHz75

LYX Pro SDPC-2 Rode M5 Comparison (4:21)  by  James Tyler  (2016-12-17).
3 Cheap Mics for Interior Dialog (4:26)  by  Jeff Ello  (2017-02-10).

(2018-02-02)   Shotgun Microphones
Small-diaphragm condenser microphones with high directivity.

A shotgun microphone consists of a standard standar capsule monted at the rear of a long  interference tube  with a number of slots on it.  On-axis sound passes through the tube unimpeded or theough the different slots in phase  (constructive interference).  On the other hand,  destructive interference attenuates off-axis waves as they pass through the slots with different phases.

Because of their natural cylindrical shape,  shotgun microphones often feature a compartment for a single AA battery to power them as an alternative to  phantom power  (units primarily intended for use with DSLR or  hybrid cameras  don't even allow phantom power).

According to the specifications of  Røde  and other manufacturers,  the battery  must  be a  1.5V  cell  (i.e.,  a single-use alkaline battery).  A rechargeable NiMH battery has a nominal voltage of only  1.2V,  which makes it unsuitable.  A well-conditoned fully-charged NiMH cell may work at first  (the initial voltage of a freshly-charged battery is about  1.46V)  but it will struggle and fail very soon.  You've been warned.

The  Audio-Technica  models  AT4071a  and  AT4073a  are discontinued.  They've been superseded by the  BP4071  and  BP4073,  respectively.

Some shotgun microphones :
MakeModelPrice mV/PaHiss Max.BandwidthW
SchoepsCMIT 5 $2199 1714 dB132 dB40Hz-20kHz50
DPA4017B $1800 1925 dB133 dB20Hz-20kHz150
SennheiserMKH 60 $1500 408 dB125 dB50Hz-20kHz150
SennheiserMKH 8060 $1250 6311 dB129 dB50Hz-25kHz25
SennheiserMKH 416 $999 2513 dB130 dB40Hz-20kHz25
Audio-TechnicaBP4071 $799 35.513 dB141 dB20Hz-20kHz50
AT4071a 89.112 dB124 dB30Hz-20kHz100
Audio-TechnicaBP4073 $699 35.513 dB141 dB20Hz-20kHz50
AT4073a 70.814 dB126 dB30Hz-20kHz100
RødeNTG3 $699 31.613 dB130 dB40Hz-20kHz25
SennheiserME 66 $460 5010 dB125 dB40Hz-20kHz200
RødeNTG4+ $399 2516 dB125 dB40Hz-20kHz200
RødeNTG4 $369 2516 dB135 dB40Hz-20kHz200
AputureDeity $359 2512 dB130 dB50Hz-20kHz75
SennheiserMKE 600 $330 2115 dB132 dB40Hz-20kHz 
RødeNTG2 $269 1518 dB131 dB20Hz-20kHz250
RødeNTG1 $249 1518 dB139 dB20Hz-20kHz50
Audio-TechnicaAT897 $249 1017 dB129 dB20Hz-20kHz200
AzdenSGM 250 $229 12.617 dB132 dB20Hz-20kHz120
Audio-TechnicaAT875r $169 31.620 dB127 dB90Hz-20kHz100
VidProXM-88 $90 12.6100Hz-16kHz1 k
XM-55 $78 5.6100Hz-16kHz1 k
Boya  BY-PVM1000 $65 12.614 dB 25Hz-20kHz380
MarantzSG-5B $36 17.834 dB120 dB200Hz-16kHz250

A few comments are needed about the bottom of that table,  which lists low-end consumer product,  as the listed prices indicate:

The  VidPro  models  (14-inch XM-88 and 10-inch XM-55)  come with plenty of accessories  (each as a 13-piece kit in a molded case).  Their noise figures are undisclosed by the distributor.  The audio quality is modest but either microphone can be very cost-effective,  as it can be plugged directly into the 3.5 mm socket of a DSLR  (cable included)  running off its own internal AA battery.  They can also use XLR phantom power.

The BY-PVM1000 is consistently reported to suffer from crackling noises when operated off 48V phantom power.  This problem is reported in some written reviews and can be heard even in favorable video reviews.  That seems to be a design flaw present in all units  (it may be caused by capacitors with borderline voltage ratings).  Not recommended at all for use with 48V phantom power  (and audio quality is downrated on battery power).  Could be OK with 24V phantom power,  who knows?

The cheapest XLR shotgun microphone,  sold as  Marantz SG-5B,  is just adequate for experimentations and educational projects  (dissecting a microphone).  It has been on sale at $16 or less.  Its restricted bandwitdth and high noise make it unsuitable for any type of video production.  (It's apparently not a fake; the official Marantz site does report the poor specs.)

For completenes,  the  Neewer  bargain brand also sells short (10") and long (14.37") shotgun microphones on the cheap  (for $23 and $24,  respectively).  They can't use phantom power and will work for up to  26  hours off a single  AA  battery.

How Shotgun Microphone Work  by  Hugh Robjohns  (Sound on Sound, Dec. 2013).
DIY Shotgun Microphone Project  by  John Heisz  (2015-08-10).
Marantz SG-5B;  Cheapest XLR Shotgun Mic (6:28)  by  Jordan Keyes  (2017-03-07).
Shotgun Mic Shootout:  XM-55 vs. NTG2 vs. NTG3 (3:42)  by  Christian Taylor  (2016-02-15).
VidPro XM-88 Review:  Best Microphone Bundle under $100 (7:49)  by    (TechMischief, 2016-12-18).
Shotgun Mic Shootout:  MKH416, NG4+ and XM-55 (13:38)  by  Tom Antos  (2016-07-13).
Aputure Deity Shotgun Microphone Review (8:09)  by  Curtis Judd  (2017-01-05).
Aputure Deity  vs.  Sennheiser MKH416 (6:45)  by  Tomas Villegas  (2017-01-21).
5 Shotgun Microphones:  SGM250, NTG2, Deity, NTG4+, 4017B (11:56)  Curtis Judd  (2017-03-10).
Aputure Deity Mic Review (13:30)  by  Neil Kesterson  (Media Unlocked, 2017-08-13).
Audio-Technica AT875r & AT897 vs. Sennheiser ME-66 & MKH-60 (15:11) The Video Pro Guys (2017-11-30).
How to use shotgun microphones (5:35)  by  Shure  (2012-04-20).

(2017-11-01)   Lavalier Microphones  (Lapel Mics) :
The best way to isolate a voice from ambient sound.

It's an unavoidable part of the  physics of sound  that tiny microphones will produce more hiss than full-sized ones.  Lavalier mics are appealing in other ways.  Draw your own conclusions.

All  commercially available lapel mics are condenser mics which need either their own battery or  plug-in power  from the audio socket,  typically from  2 V  to  10 V  (more than  10 V  may damage the mic and  48 V  will  fry it). 

Properly taking sensitivities into account,  the shocking truth which emerges from the nonexhaustive table below is that the least noisy lavalier mics are the ME2 and the Giant Squid  (the latter being only 0.2 dB behind, which isn't significant).  The MKE2,  which costs three times more than the former and eight times more than the latter,  is actually  2 dB  worse than either!  The  J 044  and the  HQ-S  are respectively  5 dB  and  10 dB  worse than the  ME2.  (I don't have data yet for the Purple Panda and the lowly Neewer.)

Noise is only part of the whole story and the less-than-stellar performance of the expensive  MKE2  in that department is entirely due to its tiny size.  The relatively low noise of the  ME2  is partly due to its limited bandwidth.

Some Omni-Directional Lavalier Microphones   (a.k.a.  Lav mics, lapel mics)
MakeModelPricemV/Pa HissMax.BandwidthW
SennheiserMKE2 $390526 dB142 dB20Hz-20kHz1 k
SennheiserME2-II $1302036 dB130 dB50Hz-18kHz 
RødesmartLav+ $60 25.541 dB 20Hz-20kHz 
Giant Squid$49 1832 dB 20Hz-20kHz 
Aspen micSHQ-S$45 6.336 dB 20Hz-20kHz 
JK®Mic J 044$29 6.331 dB   
Purple Panda$26      
SonyECM-CS3$17 12.6  50Hz-15kHz 

Sennheiser's cost-no-object  MKE2  is fairly bright  (+4 dB at 10kHz)  to compensate for the fact that it's normally worn under a shirt.  It comes with several caps to adjust its frequency response.

Sennheiser's mics come with locking plugs ("EW" = "Evolution Wireless").  JK's very popular  Mic-J 044  (which may well be the best value for the money)  is available with many plugs to choose from  (including Sennheiser's locking connector).  Usually,  all others only have regular TRS and/or TRRS 3.5mm audio jacks.

The Neewer 0077 microphones are extremely cheap  (I just got  three  of them for a grand total of  $4.99.)  You can't buy fewer than three at a time.  They are essentially  disposable  microphones.  They are reportedly prone to failure and are supposed to produce only junk boomy sound...  However, they're certainly  not  a total waste of money.  They do sound better than most on-camera mics.  With low expectations, I was even surprised to find the sound rather pleasant on my initial test!

New  Giant Squid Audio Lab Lavalier (2014-03-16, 3:15)  In Depth Review (17:08, 2014-02-20)  Curtis Judd.
MicJ 044 Lavalier Microphone Review:  Good sound, small price  (7:39)  by  Curtis Judd  (2014-11-13).
Aspen Mics HQ-S vs. Giant Squid and JK MicJ 044  (6:08)  by  Curtis Judd  (2015-02-09).
$2 Neewer Lapel Microphone  (3:43)  by  Jordan Keyes  (2017-06-05).

(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)   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  a sound-board or a USB 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.

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).

Panasonic's  XLR1  adapter for the Lumix GH5  ($400) :

Although fairly pricey,  the XLR1 is a key audio accessory for the GH5 because it bypasses entirely the regular input amplifiers and replaces them by low-noise ones which communicate 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).

(2018-02-16)   DI Boxes  (Direct injection  or  Direct insertion)
Axtive and passive  DI boxes.

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)

(2018-01-07)   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).

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.
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).

(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)   USB interfaces,  USB microphones,  sound cards.
(In order of preference.)

These are useful in studio work when direct input into a computer is desired,  without going through a separate  sound recorder  or a video camera.

sound card  fits inside a 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.

By contrast,  a  USB interface  will accomplish exactly the same thing but perform the delicate analog-to-digital conversion away from the computer.  (Only digital signals enter the computer enclosure.)

A cheap alternative is to buy a microphone combined with a USB interface.  Those so-called  USB microphones  have entry-level audio quality and provide neither an upgrade path nor any flexibility of use  (it's even chancy to run just two USB microphones at once).  Also,  a USB microphone is useless when you're away from you computer...

The better solution is clearly a USB interface  (yielding as many digital channels as there are analog inputa)  or a small  USB mixer  (which combines irrevocably several analog inputs into a single digital channel).

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)
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)
Edit voiceover faster with REAPER (9:21)  by  Mike DelGaudio  (Booth Junkie,  2016-02-18).
Voiceover mistake marking (1:08)  Digital Sound Magic Recording Studios  (2016-04-30).
Essential Voiceover Jargon (17:37)  by  Mike DelGaudio  (Booth Junkie,  2016-05-08).

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

Digital audio workstation (DAW)

visits since January 14, 2018
 (c) Copyright 2000-2018, Gerard P. Michon, Ph.D.