Twenty questions about recording in stereo

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20 QUESTIONS about (drum roll please)

recording in stereo

APPLICATIONS OF ALL OF THE STEREO TECHNIQUES:

            XY             AB          M-S          

    AMBT     ORTF     

BLUMLEIN

click to see microphone polar patterns:   http://www.sengpielaudio.com/Visualization-Blumlein-E.htm
stereo recording links:  http://www.stereosoundbook.com/pages/chapter4.html

1.  WHAT ARE THE THREE QUALITIES OF A MUSICAL IMAGE THAT ARE CONVEYED WHEN USING STEREO MIKING?

  1. DEPTH OF EACH INSTRUMENT
  2. PERSPECTIVE (DISTANCE OF THE INSTRUMENTS FROM THE LISTENER)
  3. AMBIENCE (SPATIAL SENSE/ REVERB OF THE ACOUSTIC ENVIRONMENT)

2.  WHAT DOES ORTF STAND FOR? 

“Office de Radiodiffusion Télévision Française”

3.  WHAT IS THE TECHNIQUE?

USING TWO CARDIOID MICROPHONES WITH CAPSULES SPACED 6 1/2 INCHES (17 CM) APART AT 110 DEGREES

4.  WHEN IS IT USED?

  1. BACK OF THE ROOM
  2. POOR ACOUSTICAL ENVIRONMENT OK
  3. CONCERT TAPING AT DEAD-CENTRE OF VENUE

5.  WHY?

  1. GOOD STEREO IMAGING
  2. SIMPLE TECHNIQUE
  3. PRODUCES AN EVENLY SPREAD STEREO IMAGE WITH GOOD LOCALIZATION WITHOUT THE NEED FOR SPOT OR AMBIENT MIKING\
  4. GOOD FOR NEWBIES!!

6.  WHAT IS ANOTHER NAME FOR THE X-Y STEREO MICROPHONE METHOD?

  1. COINCIDENT PAIR
  2. INTENSITY STEREO METHOD

7.  WHAT IS THE X-Y TECHNIQUE?

TWO DIRECTIONAL MICS ARE MOUNTED WITH GRILLES NEARLY TOUCHING AND DIAPHRAGMS, ON ABOVE THE OTHER , SYMMETRICALLY ANGLED FROM THE CENTRE LINE

FROM “HOME RECORDING FOR MUSICIANS FOR DUMMIES”:

When you record using the X-Y technique, keep these points in mind:
  • The stereo image (the placement of the instruments in the sonic environment) isn’t as wide or realistic as it is in real life. The X-Y technique is easy to set up and results in a decent sound, so (as with all things in life) you have to deal with the compromise this ease creates.
    No solution to this exists, so if a wide stereo image is important to you, consider using a different stereo technique, such as the spaced pair or perhaps a Jecklin disk.
  • Don’t use two mics when one is enough. After you get a pair of nice mics for X-Y miking, you’ll want to use them on everything. A stereo-mic approach to a classical guitar composition is nice, but honestly, recording the acoustic guitar in a rock ballad with five other instruments playing isn’t necessary and just makes life more complicated when you mix the song.
  • Keep some distance between the mics and the sound source. The X-Y technique has no benefit over a single mic if you place your mics within a couple of feet of the sound source.
    You simply don’t have enough space for a stereo image to develop until you’re at least 6 feet from the instrument or group of instruments. In fact, you should be at least 10 feet from the sound source before using the X-Y stereo miking approach.

8.  WHAT IS THE BLUMLEIN ARRAY?

A COINCIDENTAL PAIR METHOD USING TWO BI-DIRECTIONAL MICS ANGLED AT 90 DEGREES APART AND FACING THE LEFT AND RIGHT SIDES OF THE BAND/ENSEMBLE

9.  WHAT IS MS RECORDING?

  1. A FORM OF THE COINCIDENTAL PAIR TECHNIQUE WHERE A MIC (USUALLY A CARDIOID MID) IS FACING DIRECTLY AT THE SOURCE TO PICK UP ON-AXIS SOUND WHICH IS  SUMMED AND DIFFERENCED WITH A BIO-DIRECTIONAL MIC FACING LEFT AND RIGHT PICKING UP OFF-AXIS SOUND
  2. TWO SIGNALS ARE COMBINED VIA THE M-S MATRIX TO PROVIDE A VARIABLE CONTROLLED STEREO IMAGE
  3. ADJUSTING THE LEVEL OF MID VERSUS SIDE SIGNALS, A NARROWER OR WIDER IMAGE CAN BE CREATED

10.  WHERE WOULD YOU USE THE MS TECHNIQUE?

  1. WHEN LOCALIZATION ACCURACY IS IMPORTANT
  2. LIVE CONCERTS WHERE YOU CANNOT PHYSICALLY ADJUST THE MICS DURING THE PERFORMANCE.  STEREO SPREAD CAN BE REMOTE CONTROLLED
  3. MONO-COMPATIBILITY IS DESIRED
  4. BROADCAST AND FILM APPLICATIONS

11.  WHAT IS THE A-B TECHNIQUE?

  1. TWO IDENTICAL MICS (CARDIOID OR OMNI-DIRECTIONAL) ARE PLACED 3-10FEET APART, AIMING DIRECTLY AHEAD TOWARD THE BAND/ENSEMBLE
  2. THE GREATER THE DISTANCE BETWEEN THE MICS, THE GREATER THE STEREO SPREAD
  3. POTENTIAL FOR UNDESIRABLE PHASE CANCELLATION OF THE SIGNALS ESPECIALLY WHEN CONVERTING TO MONO- A MONO REFERENCE SOURCE SHOULD BE USED TO CHECK FOR PHASE PROBLEMS

12.  WHAT HAPPENS IF ONE INSTRUMENT IS CLOSER TO ONE MIC THAN THE OTHER?

  1. SOUND REACHES ONE MIC BEFORE THE OTHER
  2. BOTH MICS PRODUCE ALMOST THE SAME SIGNAL BUT ONE MIC SIGNAL IS DELAYED WITH RESPECT TO THE OTHER

13.  HOW DOES THE BRAIN DECODE THIS ?

  1. IT DECODES TIME DIFFERENCES INTO CORRESPONDING IMAGE LOCATIONS
  2. IT TAKES ABOUT 1.5 MILLISECONDS OF DELAY TO SHIFT AN IMAGE ALL THE WAY TO ONE SPEAKER

14.  HOW DO YOU CONTROL THE IMAGE USING INSTRUMENT PLACEMENT?

  1. TO REPRODUCE THE INSTRUMENT AT THE RIGHT SPEAKER, SOUND MUST ARRIVE AT THE RIGHT MIC ABOUT 1.5 MILLISECONDS BEFORE IT REACHES THE LEFT MIC
  2. PLACE MICS 2FT APART

15.  WHAT HAPPENS WHEN YOUR SPACING BETWEEN MICS IS FAR APART – 10 OR EVEN 12 FT FOR EXAMPLE?

INSTRUMENTS SLIGHTLY OFF-CENTRE PRODUCE INTERCHANNEL DELAYS GREATER THAN 1.5 MSEC, WHICH PLACES THEIR IMAGES AT THE LEFT OR RIGHT SPEAKER

16.  WHAT IS THE TERM(S) COMMONLY USED TO DESCRIBE THIS EFFECT?

  1. EXAGGERATED SEPARATION
  2. PING-PONG EFFECT

17.  WHY WOULD YOU USE THIS SPACED PAIR A-B MIC SET-UP?

  1. TO MAKE OFF-CENTRE IMAGES UNFOCUSED OR HARD TO LOCALIZE
  2. TO ENSURE CENTRED INSTRUMENTS ARE STILL HEARD CLEARLY IN THE CENTRE EVEN WHEN OFF-CENTRE INSTRUMENTS ARE DIFFICULT TO PINPOINT BETWEEN SPEAKERS
  3. SONIC IMAGES ARE TO BE DIFFUSED OR BLENDED RATHER THAN SHARP
  4. TO PROVIDE A WARM SENSE OF AMBIENCE WHERE IT FEELS LIKE THE ROOM REVERB IS SURROUNDING THE INSTRUMENT

18.  WHAT ARE THE MAIN DISTINGUISHING FEATURES OF THE COINCIDENT PAIR TECHNIQUE?

  1. LEVEL DIFFERENCES BETWEEN CHANNELS PRODUCE THE STEREO EFFECT
  2. IMAGES ARE SHARP
  3. SIGNALS ARE MONO-COMPATIBLE

19.  WHAT ARE THE MAIN DISTINGUISHING FEATURES OF THE NEAR-COINCIDENTAL-PAIR TECHNIQUE?

  1. LEVEL AND TIME DIFFERENCES BETWEEN CHANNELS PRODUCE THE STEREO EFFECT
  2. STEREO SPREAD TENDS TO BE ACCURATE
  3. IMAGES ARE SHARP
  4. IMPROVEMENT OVER COINCIDENT METHODS FOR PROVIDING A GREATER SENSE OF “AIR” AND DEPTH

20.  WHAT ARE THE MAIN DISTINGUISHING FEATURES OF THE BAFFLED-OMNI TECHNIQUE?

  1. USES TWO OMNI-DIRECTIONAL MICS A FEW INCHES APART, SEPARATED BY  A BAFFLE
  2. LEVEL, TIME AND SPECTRAL DIFFERENCES BETWEEN CHANNELS PRODUCE THE STEREO EFFECT
  3. IMAGES ARE SHARP
  4. STEREO SPREAD IS ACCURATE
  5. LOW-FREQUENCY RESPONSE IS EXCELLENT

Microphone Types and Positions

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