sound reinforcement final
A 10 band, 15 band, and 31 band graphic EQ can affect how much of an octave per slider?
1 octave 1/2 of an octave 1/3 of an octave
What are the different types of distortion in a sound system?
1. Overdriven sound 2. Harmonic Distortions 3. Intermodulation
Do you know the differences between dB(A), dB(B), and dB(C)?
= diff. Frequency ratings (A=Critical band, C=Fletcher Munson Curve, B=in between)
What is a coaxial speaker and what are its advantages/disadvantages?
A coaxial loudspeaker is a loudspeaker system in which the individual driver units radiate sound from the same point or axis. Timed delay, less phase cancellation Difficult to design, tweeter gets in way of woofer and can have distortion
What happens when we have a ground loop and how can I safely remove it from my system?
A ground loop occurs when a voltage difference is seen across the ground cables when using two separate ground points Convert system to a single point ground, Isolate one of the ground paths with an isolation transformer
Can you describe the differences between a Mixer bussing and matrix sections?
A matrix mixer is an audio electronics device that routes multiple input audio signals to multiple outputs. It usually employs level controls such as potentiometers to determine how much of each input is going to each output, and it can incorporate simple on/off assignment buttons. Busses are where the signals all come together from the standpoint of the analog mixer.
What is RT60?
A measurement of reverb time the measure of the time after the sound source ceases that it takes for the sound pressure level to reduce by 60 dB.
What is a transistor and how does it work?
A transistor is when electricity collected and is only let out when the base is sending out the same amount of electricity
What are the components to a wireless system?
A(n) unidirectional antenna is used to focus transmission energy in one direction. A(n) dynamic key is the component of a wireless system that encrypts the information being sent using a continuously changing key.
What is Three Phase Power and how many connections do you have when using this system?
Alternating current electric power generation 5 wires used: 3x (120 or 240V each), 1x neutral, 1x ground
How do you connect an NL4 to a bridged amplifier? What does it mean to have a bridged amp?
Bridged: Two channels going to one amp I move the switch to Stereo and plug my Sub speakons into the NL4's for the speakons.???
What are the best practices for Wireless Antenna placement?
Choose the Right Antenna Size. Ideally, the antenna length should be equivalent to the wavelength of a signal. ... Select the Right Antenna Type. ... Optimize Line-of-Sight. ... Clear Obstacles in the Antenna Vicinity. ... Orient the Antenna Properly. ... Use Low-Loss Connectors and Cables.
Can you identify the differences between amplifier classes?
Class A: It has only 1 transistor, which is always on. Forward Bias. Always drawing power. Very low distortion. 20% efficiency Class B: There are 2 transistors. Not always running. Reduces heat. Crossover distortion. 70-80% efficiency. Not used for live sound. Class A/B: 2 transistors that process +/-Each have standing/ forward bias. Always staying on at a low level. No distortion cross over. 50-60% efficiency Class D: Creates squares waves. Pulses. The amplifier is not always on. 80-90% efficient. Can causes distortion if it's not fast enough in switching.
What are the basic audio components of a drive rack?
Compressor/Limiter, EQ, Delay
Why is a baffle/enclosure needed for a speaker to function properly?
Creates extra surface for driver to push against in order to create lower frequencies at louder volumes
How can you safely prevent a ground-loop in your system?
DON'T SHARE GROUNDS. ... MINIMIZE LOOP AREA WITH TWISTED PAIR WIRING. ... DON'T GROUND REMOTE SENSORS. ... USE SHIELDED WIRE GROUNDED ONLY TO THE CONTROLLER. PLACE AUXILIARY POWER SUPPLIES AS CLOSE AS POSSIBLE TO THE CONTROLLER
How do you calculate delay times for speakers? Can you calculate delay?
Delay in sec= Distance/ Speed of Sound Ds=X/C C= 1130 ft/sec
What is the ground wire used for in electrical systems?
Drains excess electricity to earth Everything in the circuit is connected to it
Can you identify the parts of a moving coil and compression driver?
Dynamic: Diaphragm Cone Dust cap (dome) Suspension Surround Spider Voice Coil Magnetic structure Magnet Top pole plate Yoke (bottom pole plate + pole piece) Basket Horn Voice Coil Magnet Diaphragm Phase plug Throat Sound compressed by throat and couples to horn for amplification
What is the basic signal flow of a drive rack?
EQ/Comp-->Comp/EQ-->Crossover-->Individual EQ-->Individual Limiter-->Delay
What is condensation effect and what mics are most/least susceptible to it?
Effect when condensation collects on the diaphragm of a condenser mic dynamic is least, condenser is most because of their need for electricity/phantom power
What is EMI and RFI? How do we prevent it in our cabling?
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. EMI/RFI shielding encases the cable assembly conductor to protect the assembly from electrical noise. EMI/RFI shielding works in two ways: It deflects electromagnetic energy or it picks up electromagnetic energy and grounds it.
What is an optical cable, how is signal transmitted through it?
Fiber-optic cable transmits digital signals represented as light pulses. A digital optical cable is used to transfer data, usually audio or video, from one source to another
Can you explain compansion and how it works?
Fits audio signals onto smaller radio signal bandwidth
What are Side fill monitors? Why do we use them?
Full range speakers on stage used when the stage is large and the group is spread out. Musicians on one side can hear musicians on the other.
What is the difference between a hard patch and a soft patch? What is "Local I/O"?
Hard Patch=physical connection (insert, patchbay, etc) Soft patch=digital connection (sends, digital patchbay, etc) Local I/O=Inputs and Outputs on board (usually the back connectors) Remote Preamp/Stage box=inputs and outputs from external source connected via digital signal or snake
What is "ground" and how does it affect my audio signal?
In audio, radio, and digital equipment it represents an undesirable condition since the noise can get into the signal path of the device, appearing as interference in the output. ... In effect the ground current "tricks" the component into thinking it is in the signal path.
What information needs to be put onto an input list?
Input lists should include every instrument, every DI, and every vocal
What are the advantages/disadvantages of a portable and permanently installed system?
Installed PA Advantages: System designed for THAT Space, equipment is always set up, System is built into room (can be hidden). Disadvantages:Can be costly to build & inflexible if I need to add to it. Portable PA advantages: much more flexible (system can be scaled easily) Disadvantages: More time to set up/tear down. Not made for specific room, equipment takes more abuse
What is the difference between a point source and a line source?
Line array systems work best with low and mid-range frequencies, while point sourcesystems provide a full range of sound without additional modifications.
What is Line level? How many volts is line level?
Line level is in the region of 0 dBV (1.000 volt). A line-level signal is approximately one volt, or about 1,000 times greater than a mic-level signal
Can you describe the different types of cable shielding?
Metallic Braid Shields are usually formed from bare, tinned or silver plated copper strands. Steel and other metals can be used for physical protection. They are woven over a conductor or conductors in the same manner as a textile braid. Foil Shields are usually constructed of an aluminum and mylar composite tape. The appearance is much like the foil in a gum wrapper. Foil shields are light weight, inexpensive and easy to apply. Foil can face in or out. The drain wire must be in contact with the metallic part of the shield. Spiral or Serve Shields Tape Shields Combination Shields
What is transient response and frequency response?
Mic's ability to respond to quick, loud transients., Response +/-3 dB
How does squelch affect my wireless signal? What does it do?
Mutes receiver when no signal is present Thefunction of this circuit is to mute or silence the audio output of the receiver in the absence of the desired radio signal. ... Higher settings of squelch level require higher received signal strength to unmute the receiver.
What is a DCA and a VCA? How do they differ from a standard Bus on a console?
One is analog (VCA) and one is a digital representation (DCA) Both do the same thing. A DCA is a digital emulation of a VCA (Voltage Controlled Amplifier). A VCA is implemented as an analog circuit where a control voltage effects the audio level of an input at the channel fader.
Understand the differences between PFL and AFL, and destructive vs Non- destructive solo.
PFL stands for Pre-Fade Listen. It allows you to monitor the channel in question's signal level at a point immediately prior to the channel fader, and will therefore include any EQ or dynamics that might have been applied on that channel. AFL, which stands for After-Fade Listen, is similar to PFL in function, but takes its signal from a point immediately after the channel fader, showing the level of the channel's contribution to the mix. AFL is also mono on mono channels. destructive solo- the mix is changed and listeners can only monitor the particular track or tracks that are soloed. non-destructive solo- pass any soloed track(s) out through a separate solo bus, preserving the mix in the main output path.
Define the difference between Continuous, Program, and Peak power output.
Peak power: Max power speakers can handle (momentarily without damage) Continuous Power: RMS of power used over time period (typical signal input) Max power: Max power a speaker cab handle without damage. About to explode. This does not sound good!
Can you describe phase time and how it affects your sound?
Phase specifies the location or timing of a point within a wave cycle of a repetitive waveform. Two waves that are out of phase exactly cancel each other when added together
What are the different types of monitor setups?
Physical monitors placed strategically to avoid feedback- considering mic polor patterns Single, Double (mon/stereo), Diva, Side-fill In ears
What happens when I place my subs close to a wall? How can I take advantage of this effect?
Placing your speakers close to the front wall helps drive them, providing more output and less distortion. However, it also causes low shelving, a boost in the bass response (akin to the proximity effect that happens when you place a sound source close to a directional microphone).
What is the difference between a consumer and professional "line level" signal?
Professional=+4dbu Consumer=-10dBV
How can I reduce Proximity effect?
Reducing the size of the conductor. Increasing the distance between the two conductor. Reducing the frequency and increasing the voltage we can reduce the proximity effect.
Why is a speaker enclosure necessary? What are the types of enclosures?
Sealed: Accurate, good transients, frequency limited by cabinet size, power hungry Ported: Bad transients, larger for same power as sealed, more bass, louder Bass Reflex: faster roll off, can be smaller than sealed (basically just ported for low end)
Can you calculate impedance load for speakers hooked up in series and parallel?
Series: S1 +S2 2AMP+2AMP= 4AMP Parallel: 1/[(1/s1)+(1/s2)] 1/(⅛)+(⅛)=4AMP Complex: Uses both formulas. Start with whichever one came first
What is the absorption coefficient and what do the numbers represent?
Sound absorption coefficient is used to evaluate the sound absorption efficiency of materials. It is the ratio of absorbed energy to incident energy and is represented by α. If the acoustic energy can be absorbed entirely, then α = 1.
What is a 2 way, 3 way, or 4 way crossover network? What is a complex crossover network?
Splits the audio signal at specific points to only send certain bands to each driver using a band-pass eq 2-way/3-way/etc. Means the number of drivers in the crossover and number of bands in the crossover eq
What is an active and passive crossover? What are this differences between them, and where are they placed in the signal flow of a drive rack?
Splits the audio signal at specific points to only send certain bands to each driver using a band-pass eq Active: takes line level signals, crossover freq. set by user, located before preamp Passive: non adjustable, located after the power amp inside of speaker
What is dampening and how does it affect your sound?
The ability to control drivers. Ringing time or smearing (how fast it can move the speaker) Want it to be greater than 100
Can you read the pinout of a power amplifier and hook it up for a speaker in Bi- Amp or Bridged mode?
The box in the back that explains which outputs go where. Channel A is pins 1 +/- Channel B pins 2 +/- This is important because if the speaker needs high frequency and that needs pin 1 then you know you need to hook up to Channel A
What does the horn do to the sound of a speakers driver?
The horn serves to improve the coupling efficiency between the speaker driver and the air. The horn can be thought of as an "acoustic transformer" that provides impedance matching between the relatively dense diaphragm material and the less-dense air. The result is greater acoustic output power from a given driver.
What equipment/information does a stage plot show?
The most basic show the position of musicians and monitor mixes on stage. More advanced stage plots can also show things like drum riser dimensions, distances between musicians, AC power drops, and any other pertinent info.
What is bit depth, sample rate, and clock? What must we do to these things to connect multiple digital devices together?
The rate of capture and playback is called the sample rate. The sample size—more accurately, the number of bits used to describe each sample—is called the bit depth or word length. A world clock governs the sample and hold process
What does a system diagram (line diagram) show?
The single line diagram of a power system is the network which shows the main connections and arrangement of the system components along with their data (such as output rating, voltage, resistance and reactance, etc.)
Why is antenna diversity important in a wireless system?
Utilizes multiple reviewer channels/antennaPrevents dropouts
What are the frequencies of VHF and UHF wireless systems?
VHF wireless systems generally operate within the 174 to 216MHz range (the range of TV channels 7-13), while UHF uses the 470 to 805MHz range (the range for TV channels 14-69).
Can you use Ohms Law calculation to calculate the Wattage, Amperage, or Voltage of a circuit?
Voltage Formulas Solve for voltage using these formulas: Voltage = Current × Resistance Voltage = Power ÷ Current Voltage = Power × Resistance Power Formulas Solve for power using these formulas: Power = Voltage × Current Power = Voltage2 ÷ Resistance Power = Current2 × Resistance Current Formulas Solve for current using these formulas: Current = Voltage ÷ Resistance Current = Power ÷ Voltage Current = Power ÷ Resistance Resistance Formulas Solve for resistance using these formulas: Resistance = Voltage ÷ Current Resistance = Voltage2 ÷ Power Resistance = Power ÷ Current2
Can you calculate the amount of power needed for your equipment?
W = A * V
Can you calculate the wattage delivered to a speaker(s) in a circuit?
W = A * V
What is the Haas Effect (Precedence effect)?
When a sound is followed by another sound separated by a sufficiently short time delay, listeners perceive a single auditory event; its perceived spatial location is dominated by the location of the first-arriving sound
What is White noise? What is Pink noise?
White noise uses a mix of sound frequencies to create a static-like sound. It can be intense and high-pitched, like a fan or a vacuum. Pink noise uses a consistent frequency, or pitch, to create a more even, flat sound, like a steady rain, wind rustling through trees, or waves on a beach
What are the pin-outs of an XLR, TRS, TS, NL4, and NL8?
XLR, TRS, TS: pin 1(g) pin 2(+) pin 3(-) NL8: 1+ 1- 2+ 2- 3+ 3- 4+ 4- NL4: 1+ 1- 2+ 2-
What is Occlusion and how does it affect my musicians?
a measureable increase in low frequency sound pressure that is created by plugging up or occluding the outer ear canal.
What does it mean to run my speaker in bi-amp mode?
a technique which uses one amplifier for the low frequencies and a second amplifier for middle and high frequencies. ... To properly bi-ampa system, the amplifiers' power must be balanced and the speakers must be well within their frequency and power limits
How does cupping a mic affect it's sound?
creates proximity effect
What is dBSPL?
dB of sound pressure level (dB SPL) is defined as: 20 log10 p1/p0 where p1 is actually measured sound pressure level of a given sound, and p0 is a reference value of 20μPa, which corresponds to the lowest hearing threshold of the young, healthy ear.
What is the crossover slope?
describes the rate which the audio level increases/decreases per octave as the frequency increases/decreases. It is usually given as a number (6, 12, 18, 24...) of dB per octave. Electronic crossovers commonly have a 12dB/octave slope.
How do the following types of drivers work? Dynamic, Compression, Piezo, Ribbon
dynamic- Using magnetic technologies to cause a flexible diaphragm to 'move' air (moving coil) and produce sound, are usually capable of louder, tighter bass and more attack, without using too much power. compression- A compression driver (CD) is a professional loudspeaker driver usually intended for mid or high frequency use with waveguides or horns. A transducer, designed for use with a horn, which utilizes a diaphragm (rather than a cone) to reproduce mid and high frequencies Piezo- uses the piezoelectric effect for generating sound. The initial mechanical motion is created by applying a voltage to a piezoelectric material, and this motion is typically converted into audible sound using diaphragms and resonators. Ribbon-It features an ultra-thin metal diaphragm (... the ribbon, often made out of a deposition of aluminium vapour - which is about as thin as you get!) power from the amplifier is applied across the metal ribbon, which in turn develops a magnetic field. As we remember, this moving magnetic field opposes and attracts the permanent magnets along the side and thus it moves, pressurizing the air and we hear music.
What is a "distributed" sound system?
for Background music, intercoms and room stereo systems.
Can you identify different icons on a system diagram?
https://belmont.blackboard.com/ultra/courses/_84780_1/outline/edit/document/_1615241_1?courseId=_84780_1
Can you identify the locations on a stage using common stage terms?
https://belmont.blackboard.com/ultra/courses/_84780_1/outline/edit/document/_1615242_1?courseId=_84780_1
Can you identify different microphones' pattern, manufacture, model, and transducer by a photo?
https://learn-us-east-1-prod-fleet01-xythos.content.blackboardcdn.com/blackboard.learn.xythos.prod/59021e593cdb8/5607795?X-Blackboard-Expiration=1618369200000&X-Blackboard-Signature=2QXL9dgJEqT38R8AXA5rFecVxf7RSNvAu1q%2Bl97iUbc%3D&X-Blackboard-Client-Id=834537&response-cache-control=private%2C%20max-age%3D21600&response-content-disposition=inline%3B%20filename%2A%3DUTF-8%27%27AET2560_Microphones_Study_Guide.pdf&response-content-type=application%2Fpdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20210413T210000Z&X-Amz-SignedHeaders=host&X-Amz-Expires=21600&X-Amz-Credential=AKIAYDKQORRYTKBSBE4S%2F20210413%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=2da4b3bffb4be1f54a5f4c528568753647be45903677a3ebf549ee980d0c5576
Can you identify different cables via photo?
https://learn-us-east-1-prod-fleet01-xythos.content.blackboardcdn.com/blackboard.learn.xythos.prod/59021e593cdb8/5607799?X-Blackboard-Expiration=1618369200000&X-Blackboard-Signature=h8RSuu3U8PhDQQHWamqfHz8Za3TJzO8y58Qkz2QFV0g%3D&X-Blackboard-Client-Id=834537&response-cache-control=private%2C%20max-age%3D21600&response-content-disposition=inline%3B%20filename%2A%3DUTF-8%27%27cables_and_connectors_study_slides.pdf&response-content-type=application%2Fpdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20210413T210000Z&X-Amz-SignedHeaders=host&X-Amz-Expires=21600&X-Amz-Credential=AKIAYDKQORRYTKBSBE4S%2F20210413%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=12696a09476d275ee13647570fe7540a869d01914bba8bc9a95d104a88c1b468
Why would we place our subs together and in mono at the center of the stage rather than in stereo?
less phase issues, not as many "hot spots and "low spots
What is the power ally? How is it created and at what frequencies is it most noticeable?
line between subwoofers where output from each subwoofer is in phase and is noticeably louder comb filtering, out of phase, destructive interference 150 Hz
What microphones are not susceptible to wind noise?
omnidirectional
Can you describe the difference between a personal PA, band PA, and touring PA?
portable PA: Can be taken from one location to another personal PA: Smallest; can usually fit into a carRange of 10-20 ft. band PA: Designed to reinforce small to large venues Easily scalable Best for groups of 10-2,000 people tour/stadium PA: Extreme end of PA systemsRequires small army of people & trucks Use same components - just more & bigger versions Needs more set up time & knowledge
How does a room's acoustics play into the way we set up our system?
states that the intensity of sound decreases by approximately 6 dB for each doubling of distance from the sound source.
What is a digital signal processor?
take real-world signals like voice, audio, video, temperature, pressure, or position that have been digitized and then mathematically manipulate them. A DSP is designed for performing mathematical functions like "add", "subtract", "multiply" and "divide" very quickly.
What frequency bands (ranges) are illegal to operate wireless microphone systems? (hint: there are 2 bands)
the 600 MHz service band and on the 700 MHz band - specifically the frequencies between 698 and 806 MHz.
What does a speakers polar plot show you and why is it important?
usually displays the normalized response of a speaker or microphone versus measurement angle at one specific frequency. In a multi-plot view such as the one shown in Figure 1, each trace represents a different frequency. This is useful in that it allows you to see the directivity effects.
