Rec 103 Final
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When did Edison create the phonograph?
How does Edison's phonograph work?
inscribed vibrations on tin foil
What was material was later used on the phonograph?
wax cylinders that could be molded and duplicated
Who make the gramophone and when?
Emile Berliner in 1887
How did the gramophone work?
inscribed onto a round flat shellac-coated disc
When was electronic amplification started?
When and where was magnetic recording started?
1930's, Germany (Hitler recording speeches and then playing them on radio)
What material was first used for magnetic recording, and then what was it replaced with?
first with a wire/metal bands; replaced by PVC recording tape
Les Paul's contributions to recording (and dates)
- Sound on sound: 1946
- Multitrack recording: 1950s
Who developed the first 8-track recorder?
When did stereo replace mono? When was the cassette tape developed?
Other 1960's recording developments:
- quad recording
- "Walkman" personal stereo
When and who announced the CD in development?
1979 by Philips
When was the CD launchd?
What developments happened in the digital revolution?
- CD launched
- digital recording
- MIDI introduced
- tape-based digital recording
- software-based recording introduced
Internet and beyond:
- internet technology, world wide web
- revolutionized all media production (MP3, MP4)
- computer-based workstation
Parts of a Pro Studio:
- Pro staff
- up-to-date equipment, expertly maintained
- comfortable/pro work environment
- optimized acoustics
- optimized control/mix room
Recording signal path:
transducer -> amplification -> recording system
What is a transducer?
any component that converts one form of energy to another corresponding form
Recording signal path: Tranducer
- phonograph pickup
Recording signal path: Amplification
- preamp/live amp
Recording signal path: Recording system
- analogue tape
- tape-based digital
- hard drive-based computer system (AKA DAW)
What is sound?
atmospheric disruption in the air
What is audio?
the electronic signal of sound
Studio signal path:
tracking room -> control room -> machine room
Studio signal path: Tracking room
- panels with XLR sockets
- window that looks into the next room
Studio signal path: Control room
- console or HUI
- engineer at console
- equipment rack (also producer's desk w/ couch behind it
- near-field monitors
- soffit (party speakers)
- monitor screen for edit/mix
Studio signal path: Machine room
- rack of protools
- keyboard and mouse
- monitor screen
- maybe a rack of modulars
- analogue tape machine
- multitrack panel going to the patchbay
What company introduced the XLR cable and what was its original purpose?
Canon; camera audio
What are XLR cables now used for?
balanced audio connection, timecode and sync in video
What does the AES/EBU protocol allow?
lets 2 channels of digital down 1 cable
What is DI and what does it do?
DI= Direct Injection; takes high impedance and makes it low impedance
What is the metal part at the end of an XLR cable called?
What is underneath the metal part at the end of an XLR?
XLR pin designations:
- 1: shield
- 2: signal +
- 3: signal -
Male and Female XLR pinouts: (read clockwise)
- Male: 2(+), 1(shield), 3(-)
- Female: 1(shield), 2(+), 3(-)
Which phone plug is balance and which isn't?
- TRS: balanced
- TS: unbalanced
What is "Tiny Telephone" used for in the industry?
exclusively for patch cables
RCA: (Radio Corporation of America)
usually used for consumer audio+video; unbalanced
SPDIF: (Sony/Philips Digital Interface)
consumer version of AES/EBU for RCA; sometimes call "coaxial" for 2 channels down one cable
sends modulated digital data down a fiber optic cable; multichannel digital I/O
multi-pin multi-channel connectors for analogue
for Elco, have different sizes and configs; digital+analogue
digital interface to computer connections
MIDI standard cable; introduced at NAMM in 1983 so that an electronic instrument could talk to each other; also European consumer audio standard
1st law of electrostatics:
like charges repel, unlike charges attract
What is a positive and negative ion?
- positive: lacking electrons
- negative: excess electrons
Why are metals so good at conducting electricity?
their atomic structure allows the electricity to flow in exchange for electrons
What does DC mean for electricity?
electricity flows in one direction
What does AC mean for electricity?
electricity flows in both directions
Which is more efficient with long cables, DC or AC?
what is its measurement?
quantity of electrons passing a point; Ampere
What is 1 ampere equivalent to?
6.28 x 1018 electrons in 1 second = 1 ampere
electrical pressure/force, "potential"
what is it measured in?
"work" performed by an electrical current; watts
what is it measured in?
resist current in a conductor or circuit; ohms
what does each part of the water tank model represent?
- water in tank= voltage (potential)
- faucet= resistance
- water coming out of faucet= current
- paddle wheel turning= work
What is a circuit?
any arrangement of components that lets an electrical current to flow
current that must pass through one component to reach the next
2 or more components are connects so a current flows through one component without flowing through another
What is a wave?
periodic fluctuation in current or voltage
What is a square wave useful for?
can be used for timecode since it's either all up or all down (1 and 0 in binary code)
(maybe on board) point in a circuit where there is 0 voltage
connects earth ground to interior component using 3rd prong on power cable
metal rod or pipe in the ground connected to electrical system
usually metal like copper; stranded or solid core
Switches - pole:
# of connections in switch (like how many things that get turned "on")
Switches - throw:
how many connections can be made at once
electromagnetic switch; current goes through coil and magnetizes new contacts
converts sound wave variations into electrical currents
coil of wire vibrates in a magnetic field, .35mil mylar is attached to coil and vibrates with it; vibrations sent down wires to cable
diaphragm of VERY THIN ALUMINUM suspended in strong magnetic field; vibrations of ribbon produces its own current, step-up transformer boosts output and fixes impedance
What else is included on the pre-amp board in a condenser mic?
low freq. roll off and attenuation pad (decrease voltage and avoid distortion)
fixed back plate with moveable plate (diaphragm) from capacitor; voltage potential change is the output
works in reverse of dynamic mic
limits current; controls current to an appropriate level for the component behind it
stores electrons (a charge); smoothes and conditions current; can also split frequencies
if you have 2 values, you may calculate the 3rd
Ohm's law equation:
Voltage (V) = Current (I) x Resistance (R)
- Kilo = 1000
- Mega = 1,000,000
- Milli = .001
How does current flow?
current flows through a wire by the exchange of electrons; positive ion in conductor attracts extra electrons in the current's negative ions
How to read resistor bands:
- first band: first digit
- second band: second digit
- third band: multiplier
- fourth band: tolerance
What is to be assumed if there is no fourth band on a resistor?
assume ±20% tolerance
brief, fast change in sound pressure
selective frequency manipulation
boost/cut around a century frequency; bandwidth and frequency can be selected
how much of either side of center is affected
What does "dynamics" refer to?
altering the natural range of signal (0-140db in nature); often used to reduce the range of volume
Time Based Effects:
at the core of all the time based effects is delay
can select freq., boost/cut, and bandwidth independently usually with rotary pots
typically high or low freq., pick a freq. and boost/cut all freq. above/below selected freq.
using the thinnest bandwidth possible to boost/cut a certain frequency
- like shelving, but it drops to infinity
- *They are passive, so they don't add to noise
pick out very narrow bands and infinitely drop them
when you combine delayed signal with a varying delay of the same signal, phase cancelation and reinforcement takes place (delays need to be very short)
when input signal is too much for amp and distorts
Average signal level:
overall signal level
signal is too low and is buried in the mix
control only peak voltages to protect against saturation (distortion); anything surpassing threshold is gain reduced an equal amount that it goes above
reduces overall dynamic range (allows us to increase gain back up to original level); used to even out an inconsistent performance to increase its presence in the mix
"electronic switch" that allow signal ONLY of sufficient amplitude through the circuit; can be used to cut out amp noise, mic bleed, or triggering things
voltage level at which gain reduction begins; a low threshold means it works sooner
High Threshold, low ratio =
minimal gain reduction
- when the signal goes above the threshold, the ratio tells the device how much gain reduction you want on the signal
- ex: 4:1 means for every 4dB over the threshold level, 1dB will come out over the threshold level
in milliseconds, determines how long after the signal surpasses the threshold gain reduction begins (how quickly gain reduction starts)
in milliseconds, adjust how long after the signal falls below threshold does gain reduction continue
how hard the gain reduction is applied, helps make it sound less compressed
helps make up the gain you lose from gain reduction
Gates - Hold:
allows gat to stay open after signal has dropped below threshold
Gates - Range:
feather the undated signal into the gated signal
Sample and hold circuit:
takes snapshots of analogue signal's voltages
CD audio sample rate:
44.1kHz, means it samples the voltage 44,100 times/second
assign digital value (0 or 1) in bits to each sample
CD audio bit depth:
16 bits resolution
Typical sample rates:
44.1, 48, 88.2, 96
Typical bit depths:
16, 20, 24, 32
What happens when one sound is slightly louder than another in the same frequency?
they are canceled out (masking)
to get an accurate digital recording, you must use a sample rate at least 2x that of the highest frequency to capture
low pass filter (high cut), ends at about 22.05 kHz (when Nyquist is applied, you get the 44.1kHz sample rate)
low level white/pink noise inserted to make up for when early digital systems would cut off signal when it got really low
repair/replace any missing or corrupted data
repackages the data for computer use (bytes)
converting multiple tracks at once by adding extra data to tell the receiving end what goes where
- Line Amp
- Error Correction
How Analogue Recording works
two magnets are each wrapped in wire (head) without touching each other, they create a magnetic flux; signal goes to record electronics, and then to console
magnetic field that magnetizes oxide particles on tape (particles don't move, the poles change)
What needs to be constantly calibrated on analogue machines:
- operating levels
- record/playback EQ
- bias level
sine wave constantly on by the bias oscillator at 75-150kHz
How often does the bias level need to be set?
for every new project and every new reel of tape
What happens to the magnetic flux without the bias level?
the magnetic flux won't be strong enough to magnetize the tape
how high of a signal to send the tape
nW/m is how much change of magnetic flux
Why would you use a higher dB setting for tape?
analogue tape moderately compresses the signal, so higher dB is used to make up for it
Magnetic Resonance Labs; series of sine wave tones from 20Hz to 20kHz
borrow the record head to playback or punch in
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