CEA Recording Techniques & Equipment 2 — Questions and Answers
Question 1: What is the primary advantage of using a transformer-balanced microphone input over an unbalanced input?
- It boosts the signal by 6 dB without adding noise
- It rejects common-mode noise and provides galvanic isolation (Correct answer)
- It converts condenser microphones to dynamic operation
- It increases the impedance of the input for better high-frequency response
Correct answer: It rejects common-mode noise and provides galvanic isolation
Transformer-balanced inputs reject common-mode interference (noise induced equally on both conductors of a balanced line) through common-mode rejection, and provide galvanic isolation between signal source and recorder, reducing hum and interference.
Question 2: What does 'proximity effect' cause in directional microphones?
- A reduction in sensitivity when placed close to a source
- A boost in low-frequency response as the microphone is moved closer to the source (Correct answer)
- Increased high-frequency distortion at close distances
- An increase in directional rejection at off-axis angles
Correct answer: A boost in low-frequency response as the microphone is moved closer to the source
Proximity effect is a low-frequency boost that occurs in directional (cardioid, supercardioid, figure-8) microphones when placed within a few inches of the source. It is caused by the pressure-gradient operating principle and is exploited for warmth or managed to prevent muddiness.
Question 3: What is the function of a 'pad' switch on a microphone or preamp?
- It engages a high-pass filter to reduce low-frequency noise
- It reduces the input sensitivity by a fixed amount to prevent clipping on loud sources (Correct answer)
- It increases gain by 10 dB for quiet sources
- It activates phantom power for condenser microphones
Correct answer: It reduces the input sensitivity by a fixed amount to prevent clipping on loud sources
A pad switch attenuates the incoming signal by a fixed amount (typically 10, 15, or 20 dB) before it reaches the input stage. This prevents distortion and clipping when recording very loud sources such as kick drums or guitar amplifiers.
Question 4: In a recording session, what is 'gain staging' and why is it important?
- Setting equal gain on all microphone channels for consistency
- Managing signal levels at each stage of the signal chain to optimize the signal-to-noise ratio and avoid clipping (Correct answer)
- Automating fader moves during the recording process
- Configuring headphone amp levels for performer monitoring
Correct answer: Managing signal levels at each stage of the signal chain to optimize the signal-to-noise ratio and avoid clipping
Gain staging ensures each component in the signal chain operates within its optimal range — hot enough to maintain a good signal-to-noise ratio, but not so high that it clips or adds distortion. Poor gain staging compounds noise and distortion through each stage.
Question 5: What recording technique does a 'mid-side (M/S)' microphone configuration use?
- Two cardioid microphones angled at 90 degrees facing left and right
- A cardioid microphone facing forward (Mid) and a figure-8 microphone placed at 90 degrees (Side) (Correct answer)
- Two omnidirectional microphones spaced 17 cm apart
- A hypercardioid and a shotgun microphone in an ORTF arrangement
Correct answer: A cardioid microphone facing forward (Mid) and a figure-8 microphone placed at 90 degrees (Side)
M/S recording uses a Mid (forward-facing cardioid or omni) and a Side (figure-8 facing left/right). The stereo image is decoded by summing M+S for the left channel and M−S for the right. It offers variable-width stereo and excellent mono compatibility.
Question 6: What is the purpose of a 'high-pass filter' (HPF) during tracking (recording)?
- To add air and presence above 10 kHz
- To remove low-frequency rumble, handling noise, and HVAC sounds from the recording (Correct answer)
- To limit the dynamic range of a microphone input
- To convert unbalanced inputs to balanced for noise rejection
Correct answer: To remove low-frequency rumble, handling noise, and HVAC sounds from the recording
A high-pass filter (also called a low-cut filter) attenuates frequencies below a set point (typically 80–120 Hz). During tracking it removes low-frequency interference — such as room rumble, mic stand vibration, and air conditioning noise — that would otherwise clutter the recording.
CEA Recording Techniques & Equipment 2
What is the primary advantage of using a transformer-balanced microphone input over an unbalanced input?