Studio Sound Engineering

• Anechoic chambers are designed to eliminate sound reflections and are used for audio testing purposes.
• The Audio Tools app, offers dB testing with a $30 subscription fee.
• "Hearos" are recommended headphones.
• Waves Abby Road Studio and Ocean Way Studio are plugins that simulate the mixing environment of Abby Road studios through headphones.
• Middle C corresponds to a frequency of 261.5 Hz.
• The proximity effect can increase the bass frequencies from 100-200Hz of a singer's voice when the microphone is held closely; reducing these frequencies helps compensate.
• Singing primarily sustains vowels; consonants ensure intelligibility, while vowels provide tone.
• A "worse" microphone can sometimes mitigate harsh transients in audio.
• Avoid connecting a microphone preamplifier into another microphone preamplifier; instead, use the line input on a patch bay.

DANTE

• DANTE (Digital Audio Network Through Ethernet) provides interconnectivity for audio devices.
• It utilizes a central hub connected to multiple sources/consoles via a gigabit switch, using Ethernet ports and Cat V cables.
• A single cable can transmit 512 channels simultaneously.

Microphones

• Microphones are transducers that convert acoustical energy into electrical energy.
• There are no strict rules in audio, only guidelines.
• The chain is only as strong as its weakest link.
• A good sound relies on a combination of a good musician, acoustics, microphone, microphone placement, and microphone preamplifier.

Dynamic Microphones

• Dynamic mics operate on electromagnetic induction, are the most durable, and commonly feature a cardioid pattern.
• Typically includes a Mylar diaphragm attached to a copper coil around a magnetic structure.
• These mics have a slower response and are less sensitive to transients and high frequencies due to their heavy construction.
• Examples: SM57, SM58, Sennheiser MD 421, SM7B.

Ribbon Microphones

• Ribbon mics are the most delicate type, functioning similarly to dynamic mics but with a thin, corrugated metal ribbon as the diaphragm.
• The ribbon is suspended between strong magnets, vibrating to create an electrical current.
• They are highly sensitive to transients, ideal for vocal capture, and have the fastest response.
• Ribbon preamps, such as those made by Audio Engineer Associates, can provide 20 dB of gain.
• NEVER use 48V phantom power with ribbon mics.
• Examples: R44 series, M160, Coles.

Condenser Microphones

• Condenser mics utilize a capacitor or electrostatic principle, and has a capsule consisting of two plates: a stationary back plate and a movable plate, both charged to create an electrical current.
• Requires 48V phantom power.
• They are available in small (pencil), medium, and large diaphragm sizes.
• Lacking a copper coil, they more easily capture sound, especially high frequencies, and have a medium response.
• Examples: AKG, Audio-Technica XLR, Audio-Technica AT-4050.

Shotgun Microphones

• Shotgun mics feature long, narrow tubes with slits along the side and a capsule at the rear.
• Designed to capture sound from the front while canceling off-axis sounds through phase cancellation from sounds entering the side slits.
• They offer high accuracy and are commonly used on film sound stages.

Directional Responses (Polar Patterns)

• Polar patterns indicate a microphone's sensitivity to sound from different angles relative to its axis.
• The front of the mic is 0 degrees, the back is 180 degrees, and the sides are 90 and 270 degrees.
• Front address mics have the diaphragm facing what appears to be the front, while side address mics have the diaphragm facing the side.

Omnidirectional Response

• Picks up sound equally from all directions.

Bi-directional Response (Figure 8)

• Sensitive to sound from the front and back but rejects sound from the sides.

Directional Cardioid

• Sensitive to sound from the front and rejects sound from the back.

Hyper-Cardioid

• Highly sensitive to sound from the front, with good rejection from the sides but some pickup from the rear.

Fletcher-Munson Curve

• Illustrates how perceived loudness varies with frequency; also known as equal-loudness contours.
• Conversation typically occurs around 60 dB.

Hearing Loss

• Exposure to 90 dB can start causing hearing damage after approximately 8 hours.
• Exposure to 115 dB can cause damage after 15 minutes.
• Discomfort begins around 120 dB.

Microphone Output Characteristics

• Key output characteristics include sensitivity rating, overload characteristics, and equivalent noise rating.

Microphone Impedance

• Impedance is used to match the microphone's signal output to the input, measured in ohms.
• Matching microphone preamp impedance to the microphone's impedance maximizes performance; set the preamp impedance to 10x that of a condenser mic or 5x that of a ribbon mic.
• Most microphone preamps default to the highest impedance setting if there is no manual adjustment option.

Microphone Preamplifiers

• Microphone preamps amplify the weak signal from microphones to line level.
• Essential features include gain, 48V phantom power, high-pass filter (HPF), pad, and phase reversal.

DI (Direct Injection) Box

• DI boxes serve two main functions: converting unbalanced signals to balanced signals and converting line level signals to mic level signals.
• Balanced signals allow for long cable runs without noise, unlike unbalanced signals which can act as antennas and pick up interference when used in cables longer than 20ft.

Microphone Techniques

Distant Miking

• Typically involves placing the microphone three or more feet away from the sound source.
• Captures more ambiance.

Close Miking

• Typically involves placing the microphone less than two feet from the sound source.
• Provides a higher direct-to-ambient sound ratio and is useful for isolating sound sources.
• With an SM58, position the microphone above eye level and angled towards the mouth to avoid capturing unwanted frequencies.

Accent Miking

• Accent miking is used in combination with distant microphones.

Ambient Miking

• Ambient miking is used to capture the acoustics of a given environment, often with distant or close mics.

Stereo Miking Techniques

• Most stereo miking techniques employ two identical microphones.

Spaced Pair

• Involves placing two microphones apart from each other, following the 3:1 rule: the distance between the mics should be three times the distance from each mic to the source.
• This technique is prone to phase cancellation issues.

X/Y

• Uses two identical directional microphones with their diaphragms positioned at a 90-degree angle, as close as possible without touching.

Blumlein

• Employs two bi-directional (figure-8) microphones set up like cardioid mics in an X/Y pattern.
• Captures both the sound source and the room's ambience.

Decca Tree

• Consists of a T-shaped bar with three omnidirectional microphones spaced 70-100 cm apart.
• Often used for recording large ensembles.

ORTF (Office de Radiodiffusion Télévision Française)

• Uses two cardioid microphones with diaphragms 17cm apart, angled at 110 degrees from each other.
• Aims to emulate human hearing.

Audio Connectors

Cables

• Single conductor shielded cables have a central conductor for the signal, surrounded by copper strands and PVC for the ground; they cannot carry balanced signals.

Balanced Signals

• Require a 2-conductor shielded cable that terminates in an XLR or stereo/TRS (tip, ring, sleeve) 1/4” plug/jack.
• Good for long cables and noise rejection.

Unbalanced Lines

• Use single conductor shielded cables, which usually terminates in a mono TS (tip, sleeve) 1/4” or RCA plug/jack.
• Used for line level signals.
• Should be short to avoid noise.

XLR (Mic Cable)

• Mic cable connector.

¼” Connectors

Include TRS and TS variations, see below.

TRS (Tip, Ring, Sleeve)

• Can carry either a mono balanced signal or two unbalanced mono signals (essentially a stereo unbalanced signal).

1/8” Mono TS

• Mono unbalanced connector

1/8” Stereo TRS

• Stereo connector

Aux Cable

• Carries unbalanced stereo signals

RCA Cable

• Commonly used for audio/video (A/V) connections.

TT (Tiny Telephone) Patch Cable

• Uses a TRS connector, enabling balanced signal transmission.

Patch Bay

• Top jacks are outputs (sources).
• Bottom jacks are inputs (destinations).

Half-normal Patch Bay

• The signal still flows through, and a copy is sent to the top jack without interrupting the main signal path.
• Internally connected, top jack doesn’t break, bottom does.