6616567
Description
Flashcards by Toby Zheng, updated more than 1 year ago
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Created by Toby Zheng
about 8 years ago
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| Question | Answer |
| What is soldering? | The process of using filler material (solder) to join pieces of metal together |
| XLR Pin Outs: | 1. Ground / shield 2. Hot / positive 3. Cold / negative |
| What are the 4 signal levels? | 1. Mic 2. Instrument 3. Line 4. Speaker |
| Professional and Consumer audio equipment use line levels of: | Professional: +4 DBV Consumer: -10 DBU |
| Speaker level refers to | the amount of electricity present between the power amplifier and loudspeaker |
| What is a DI Box | Direct Inject: converts line/instrument level to mic level [also converts unbalanced inputs AKA instrument level to balanced output AKA mic level] |
| How are DI boxes powered? | Passive: No power needed Active: 9V battery or 48V phantom power |
| What is electricity? | The flow of electrons through a conductive material |
| What is the flow of electrons called? | Electrical current |
| What is DC (Direct Current)? | Type of electricity often used with an electrical component. Electrons flow in ONE DIRECTION in a steady state. |
| What is AC (Alternating Current)? | Electricity used widely across North America. Electron flow ALTERNATES in direction 60 times every second (60Hz) |
| What is Ohm's Law? | One Volt can push one Amp through one Ohm of resistance |
| What is Voltage? | Measurement of electrical potential. Voltage is the potential difference between 2 points in an electrical field. |
| What is Amperage? | The strength of an electrical current. A measurement of how many electrons are flowing through a conductor. Amperage is the rate of flow of electrical charge |
| What is Resistance? | A measure of the difficulty (in Ohms) to pass electrical current through a circuit. When working with AC, use 'impedance' |
| What is Wattage? | A measurement of power consumed. |
| What is Mark Taleski's version of Ohm's Law? | One Watt is consumed when one Volt pushes one Amp through one Ohm of resistance |
| What are Resistors? | Add resistance to a circuit and reduce the flow of electrical current |
| What is a Variable Resistor? | Devices that allow us to vary the amount of current that is allowed to flow through a circuit [ex. linear faders, pan pots] |
| What is a Capacitor? | An electrical component that temporarily stores energy and releases it when a specific voltage is reached. Have low impedance to HF |
| What are Inductors? | Coils of wire that create a magnetic field when current is applied. Have low impedance to LF |
| What is a Transformer? | A device that transfers electrical energy from one circuit to another through means of induction. Can be used to change amount of electricity getting to a device or eliminate buzzes in audio systems (isolation transformers) |
| Balanced Cables | 3 conductors: 2 signal wires + ground wire. The 2 signal wires are twisted around each other and the ground is twisted around them. Balanced signals called 'differential', both wires carry copy of signal |
| Tip Sleeve (TS) 1/4" | Unbalanced, commonly used with instrument cables |
| Tip Ring Sleeve (TRS) 1/4" | Commonly used for balanced line level signals. Also used to carry 'stereo unbalanced' signals |
| Speaker Cables | 1/4" cable, looks like TS but cable is thicker. Large gauge and unshielded twisted pairs |
| What is a Crossover? | A device that splits the full range audio (20Hz-20kHz) into the various ranges that each driver wants to use |
| What is a Passive Crossover? | Live inside the speaker and have capacitors (High pass filters) and inductors (Low pass filters). Require no outside power source. |
| Passive Speakers | Require amplifiers [have passive crossovers inside] |
| What are Full Range Speakers? | Passive Speakers with a Passive Crossover (because we are sending them a full range signal) |
| What is an Active Crossover? | Piece of outboard gear that electronically divides the signal into the various frequency ranges required by the speaker. Each signal component is individually amplified and then sent to the loudspeaker |
| What are Bi-Amped Speakers? | Passive Speakers with 2 drivers that require an external active crossover (called 'bi-amped' because they need 2 channels of amplification for the HF and LF drivers) |
| Active Speakers | Do not require amplification, the amplifier is built into the speaker. Do not require an external crossover, it is also built into the speaker. Can be sent line level signal and require electricity |
| Series Circuit and Speaker Impedance | Resistors are set up one after the other. Add all values of resistors together for total resistance. |
| Parallel Circuit and Speaker Impedance | Adding resistors in different branches of the circuit. The total resistance will be less than the largest individual resistor. (Most speakers are hooked up in Parallel) |
| Why is knowledge about Series and Parallel Circuits relevant in Live Sound (Speakers)? | Every loudspeaker connected to an amplifier acts like a resistor in a circuit. Knowing how much impedance each speaker adds and how much impedance the amplifiers can handle tells us how many speakers we can use |
| Resistance vs. Impedance | Both talk about inhibiting the flow of electricity. Resistance = talking about electrical circuits and DC voltage Impedance = talking about AC current |
| What is Impedance? | The total opposition to AC current. A combination of resistance and reactance. |
| When setting up speakers in parallel, how do you calculate speaker impedance? | Speaker impedance / number of speakers [if the result is more or less ohms than the amp is capable of, run risk of damaging speakers/amp or distorting the audio signal] |
| What can be done when speaker impedance does not align with what the amp can handle? | Add another amp to power the extra speaker(s) OR choose a different amp that can handle the (lower) impedance |
| What is a power amplifier? | Device that increases the power of a signal. In live sound, used to convert line level to speaker level |
| Speaker Cables | 1/4" Tip Sleeve with heavier gauge wires. 2 twisted conductors |
| What are the Amplifier Operating Modes? | 1. Parallel 2. Stereo 3. Bridged Mono |
| Parallel Amplifier Operating Mode | Whatever is sent to Input 1 will be output on Outputs 1 and 2 |
| Stereo Amplifier Operating Mode | Whatever is sent to Input 1 will be output on Output 1 Whatever is sent to Input 2 will be output on Output 2 |
| Bridged Mono Amplifier Operating Mode | Output 1 handles the positive portion of the sound wave Output 2 handles the negative portion of the sound wave |
| What are terms used to describe amplifier power outputs? | 1. Peak Power 2. RMS 3. Continuous Power 4. Average Power |
| What is Peak Power? | The maximum power an amplifier can output [clipping level]. Cannot output for a long time without overheating |
| What is RMS? | Root Mean Square The effective value of of a varying voltage or current. The RMS value of an alternating current is the equivalent steady value produced by a DC circuit. In terms of amplifier wattage, it is made up |
| What is Continuous Power? | The wattage that a speaker or amp can handle continuously without overheating. (This number is often used interchangeably with RMS and Average Power) |
| What is Feedback? | When the output of our system is routed back into the input (creating a loop) |
| 3 Guiding Ideas for Mic Techniques in Live Sound | 1. Maximize the pick up of suitable sounds from desired instrument 2. Minimize the pickup of undesired sounds from other instruments or sound sources 3. Provide sufficient gain before feedback |
| What signal level typically flows through an audio system? | Line level |
| What are the 2 common types of Rigging? [that we will encounter] | 1. Theatre Rigging (Permanent) 2. Arena Rigging (Temporary) |
| What are the four K's of Rigging? | Know the equipment you are using. Keep it in safe working condition. Know how to use it. Keep your concentration! |
| What are the four types of applied forces we have to be aware of in rigging? | 1. Tensile 2. Compressive 3. Shear 4. Torsion |
| What is the Working Load Limit? | The force or load a piece of rigging equipment can safely handle without fear of breaking. This is a percentage of the Ultimate Breaking Strength of the equipment. |
| What is a Design Factor? | Ratio of the Ultimate Breaking Strength to the Working Load Limit. |
| What Design Factor is used in the entertainment industry? | (At Least) 5:1 |
| What knots are most commonly used in rigging and how much strength do they reduce? | Bowline: Reduces strength by 50% Clove Hitch: Reduces strength by 25% |
| What is Fatigue? | Stress caused by repeated applying and removing of force on an object. Fatigue is progressive, hard to see and hard to predict. |
| What is Shock Loading? | The rapid application of force to an object. Usually caused by rapid acceleration or deceleration. |
| How do you estimate Shock Loading? | [(W * F) / S] + W = Shock Load W = weight of object that's falling F = the free falling distance S = the stopping distance |
| What are Slings? What are the 2 most common Slings in the entertainment industry? | A flexible strap/belt in the form of a loop used to raise/support a weight. 1. Wire Rope (steel) 2. Round Slings (Span sets) |
| What information must be displayed on all Shackles? | 1. Working Load Limit 2. Name of manufacturer 3. country of origin |
| We must NOT side load shackles. At various degrees of loading, how much will the WLL be reduced (or what percentage of the WLL will be able to be used)? | Straight up and down: 100% 45 degrees: 70% 90 degrees: 50% |
| What are the 3 ways to make the connection to a building? | 1. Direct hitch 2. Choker hitch 3. Basket hitch |
| What is a Direct Hitch? | Connects the sling's eye to a fitting and the beam. |
| What is a Choker Hitch? | Wraps a sling around the beam and shackles the eyes to the standing part of the sling. It tightens up on/chokes the beam as load is applied. (Used the least as it is the weakest) |
| What is a Basket Hitch? | Wraps the sling around the beam so the cable eyes are brought together and shackles to each other. (The strongest hitch) |
| What is required when you wrap a Basket or Choke hitch around a beam and why? | Burlap. Used to prevent kink in the wire rope or general wear and tear of steel as it is attached to the building's beams. |
| What is a Dead Hang? (When to use) | If the beam is directly over where we want our load to live, we use a dead hang. (Load hangs straight down from beam) *Most ideal situation |
| What is a Breast Line? | Slings that pull a dead hung object a few feet from vertical. The load weight is supported by the dead hang and the tension in the breast line is a small fraction of that weight. (Uncommon, least desired) |
| What are Bridles? | A bridle has 2 legs, one for each beam to the bridle junction. It is used when desired point location is not directly under a beam. (Our second choice) |
| What are the 2 most common rigging knots and when are they used? | Clove Hitch: used for securing a line to a pipe or truss Bowline: used to create a loop in a line that will not slip |
| What parameters must be met to constitute as a Line Array? | 1. Radiates omnidirectional 2. Arrayed in a straight line (a large number of points) 3. Closely spaced (separated equal distance apart) 4. Equal phase (and strength) 5. Equal amplitude |
| What is a loudspeaker line array? | A group of loudspeakers set up in a line to create a line of sound. |
| What are the 4 main purposes of stage lighting? | 1. Visibility 2. Draw your attention 3. Establish the environment 4. Create a mood |
| What are 5 concept of (stage) lighting? | 1. Intensity 2. Angles of direction 3. Colour 4. Shape of the light 5. Movement |
| What does Three Point Lighting consist of? | Key light: the main light focused on subject [warm colour] Fill light: fills in any shadows left by key light [cool colour] Downlight: from above and behind [adds a subtle 3rd dimension] |
| What is (a) Fresnel? | Refers to any lighting instrument using a Fresnel lens. The focus can be adjusted by moving the lamp forwards and backwards in relation to the lens. Can also shape the beam by using barn doors. |
| How do Lighting Consoles work? | Used to control the dimmer/fixture. Transmits 512 channels of data simultaneously. Each dimmer/fixture only 'listens' to its designated channel. |
| One DMX output on a (Lighting) console contains how many channels and is called...? | 512 channels, a 'universe'. |
| What is the maximum length of a DMX cable and up to how many devices can be run on one? | 4000 feet, but manufactures recommend 1000 feet. 32 devices |
| What is an Opto Splitter? | Splitter that accepts one DMX input and outputs multiple copies of the DMX signal [similar to MIDI] |
| What is a Radio Wave? | An electromagnetic field created by varying voltages or currents in certain physical sources. Can be described by frequency and amplitude. |
| What is Modulation (for RF)? | In a wireless audio system we need to convert audio to RF signal 'modulating' a carrier frequency. Must then 'demodulate' to recover the original information. |
| What is Squelch? | A circuit that acts as a noise gate on the audio output of the receiver. The function of this circuit is to mute the audio output in the absence of the desired radio signal. If there is no RF signal present, the receiver may pick up a different (undesired) RF signal. This is to prevent that. |
| What is a Traditional Squelch Circuit? | The gate opens when an RF signal is present. |
| What is Noise Squelch? | The gate opens when an RF signal is present and the demodulated audio signal of the appropriate 'quality'. |
| What is Tone-key Squelch? | The gate opens when an RF signal is present and a specific sub-audible tone that was generated by the transmitter is also present. [usually tone humans can't hear like 3Hz] |
| What is Multipath? | When direct RF signal and the reflected signals arrive at the receiving antenna at different times. Results in differing levels, arrival times and phase relationships between the radio waves. |
| What is Diversity (when talking about RF)? | The principle of using multiple (usually 2) antennas to lower the probability of dropouts at 2 different locations. The audio signal from the strongest antenna would be used. |
| What is the shortest antenna (size) that could work with an RF signal? | 1/4 the wavelength of the carrier signal. (Though to increase efficiency, 1/2 the wavelength antennas are more commonly used) |
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