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100 Cards in this Set

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Dynamic Range=
Wordlength X -6
How do you get 20 Bit resolution from 16 bit Recording
Noise Shaped Dither and a High Sample Rate
Wavelength=
1130/freq
Frequency
1130/wavelength
1/time
Frequency
1 Vari Mu
Slow Attack Long Release
Optical
Slow Attack long Release
Fet
Fast Attack Fast Release
VCA
Fast Attack Fast Release
DCA
Can emulate older devices
Digital/PWM
Look-Ahead Attack, Fast Release
Plug in Modeling
Functional, but often lacking character
Feed Forward vs FeedBack
Most older compressors are Feedback design output signal triggering reduction unit.
Newer VCA DCA and PWM use a feed forward.
What has the hardest knee?
Limiter- forms absolute ceiling.
WHat is more musical soft or hard knee?
SoftKnee
What controls the high frequency response on a compressor?
Attack Time
What controls the resonant (low/mid) frequency response?
Release Time
What is the feedback based design of Filter called? How does it create a cut or boost?
Infinite Impulse Response (IIR)- Routes a signal back onto itself slightly out of time either in standard or reverse polarity to create a cut or boost.
If your finding yourself having to boost more than 3-4dB of any frequency with an EQ in recording consider adjusting what instead?
The source Tonality
The microphone selection/design
The microphone polarity pattern
Microphone placement
The acoustics of the environment
Analog tape has how much dynamic range?
70dB
What is the ideal signal processing chain for recording?
Filters
Subtractive EQ
Compression
Additive EQ
Microdynamics
Are automatic processors, like compressors
Macrodynamic
Are manipulated by faders, or "manual compression".
Downwards Compression
Brings High Levels Down
Upwards Compression
Raises levels of low passages (parallel compression. Dolby Encoding,)
Upwards Expansion
Brings High Levels Up Further
Downward Expansion
Brings Low Levels Down (Gates, Noise reduction.)
Attack Times for mixing/Recording
pg121-122
15ms-100ms
Attack times for mastering
50ms-300ms
Common Release times for musical content.
50ms to 500ms often times longer for mastering.
What is an example of upwards compression?
Parallel Compression
What is an example of upwards expansion?
Compressor with ratios under 1:1 Often has a brightening effect by increasing level of transients
Types of Non traditional Dynamics Processors
Tape Saturators/ Simulators
Harmonic Enhancers
ADSR Envelope Modifiers
Reampers
What is dither?
Randomized Noise which averages 0 Volts DC (having an equal number of1's and 0's).
What is the LSB?
Least significant bit in the word length.
WHen Should Dither be applied?
As the last step before creating the final master.
Rules for Dithering
Always add dither when reducing word lengths.
Avoid dither to 16 bit more than once in a project
Audition to find the right dither
SRC before Redithering
Drop gain of peak limited material by .1dB
Why do higher sample rates sound "better" when most of the content captured by them is either inaudible or not reproducible with standard transducers?
Problem with digital low-pass filters used in oversampling A/D and D/A converters. Causes distortion, Ripple/Aliasing artifacts heard as time smearing or short echoes.
What are the three Bands of a LPF?
Passband: Unfiltered Range below LPF
Transition: Beginning of cutoff frequency
Stop: point at which maximum loss of the filter is reached
WHat is the minimum freq for an anti aliasing LPF to get rid of pre echo aliasing?
50K
When recording in digital What levels are best for peaks and average amplitude?
Peaks should be under -3dB and the Average should be under-6db.
What is the crest factor?
The difference in dB between the average and peak amplitudes.
What is the average crest factor for each recording medium.
Digital=20dB
Analog=14dB
What is oversampling?
Using a Gentle LPF with a High sample rate.
What does Oversampling do?
moves the filter distortion above the audible range.
What does peak normalization do? and what does average do?
Works for multiple songs for mastering but is very invasive for song by song basis. adds quantization distortion to already mixed material and does not help loudness or improve dynamic range.
Average is better than peak but still causes unwanted artifacts.
What is Jitter?
Timing error between converter and another device.
What is the minimum timing fluctuation an ear can hear?
10 pico seconds
What are two types of jitter?
Interface Jitter: present in the interconnections between equipment.
Sampling Jitter: present in the clock that drives the converter
What causes interface jitter?
Resistance found in any cable regardless of quality.
What causes sampling Jitter?
Clock irregularities.
what is a PLL?
Phased Lock Loops generate a frequency that is a multiple of the input frequency.
What is clock recovery?
When the PLL realigns incoming asynchronous clock to "clean" internally generated clock as the clock pulse land within the acceptance time of each incoming bit
what is an ASRC?
asynchronous sample rate converter
Internal Clock
built-in stable crystal clock to directly drive circuitry
External Clock
not preferable to internal. utilizes a PLL and cabling.
Set peak meters to overload at what value?
-.3dBFS
when setting your VU with a sine wave what value should you set it to?
-20dBFS=0VU
For proper headroom use what level for your PPM?
-5dBFS
What is the main causes for bad digital audio?
Poor ADC/DAC LPFs
Bad conversion technology
Low sample rates
Low bit resolution
Improper dither
Jitter
Clock Leakage
Inferior power supplies and internal sheilding
Advantage and disadvantage of analog summing bus.
Has a musical distortion that can seem like an improvement in separation and depth. Worse actual fidelity than digital.
What is the Golden Source quality Rule?
Start with the highest resolution possible and maintain that quality for as long as possible in the production process.
What is the wavelength of 250hz
4.52 ft
What is the wavelength of 500hz
2.26ft
What is the wavelength of 1khz
1.13ft
What frequency has a wavelength of 5ft?
226hz
what is the frequency that has a wavelength of 4 ft?
282.5hz
what is the frequency that has a wavelength of 3 ft?
376.6hz
what is the frequency that has a wavelength of 2 ft?
565hz
what is the frequency that has a wavelength of 1 ft?
1130hz
What is the equation to find time from frequency?
1/freq=time
What is the equation to find frequency from time?
1/T=f
Where is the first comb filter null?
1/2 the fundamental frequency
Where is the first comb filter null?Distance 4ft
Distance 4ft f=250
nulls at 125, 375, 625,875
crests at 250,500,750,1k
Where is the first comb filter null?Distance 1ft
f=1khz
Nulls at 500, 1500, 2500, 3500
Crests at 1k, 2k, 3k,4k,
What does engaging phase inversion do to the signal of two mics when comb filtering?
it switches the placement of the crests and nulls.
what is the first null of the comb filter with phase inverted and mikes set 2 feet away.
f=565
Nulls at 565, 1.13k, 1.7k
Crests at 282.5, 847.5, 1.4K
Depth
governs the amount of ambiance or reverberation on a recording.
Height
governs the brightness and "front to back ratio" of the recording.
Recommended Placement for Coincident pair
Near Field Placement
Recommended Placement for Near-Coincident pair
Mid Field Placement
Recommended Placement for Spaced Pair
Far Field Placement
Recommended Placement for Baffled Omni
Binaural/ headphones
Coincident Patterns such as x/y, m/s, and Blumlien use what to create a stereo image?
Interaural Level Differences (ILD)
Best technique for mono compadability.
How do you setup a M/S?
1 cardioid facing forward and 1 Bi-Directional facing perpendicular to it. You must bring the side mic back on two channels and hard pan them, with one side placed in reversed polarity.
What does ORTF stand for?
Office de Radiodiffusion Television Francaise.
How do you set up an ORTF?
Place two cardioid microphones Spaced 17cm between capsules at a 110 degree angle. Utilizes Interaural Timing Differences and ILD
How do you set up an NOS?
How do you set up an DIN?
Cardioid Mics
NOS
capsules 30 cm apart
90 degree angle
DIN
capsules 20 cm apart
90 degree angle
How do you setup a baffled omni?
2 Omni mics setup on either side of a 35cm disk about 2cm thick and covered with absorbent material. Mics placed with capsules 36cm apart and at a 40 degree angle from each other.
What does a spaced pair rely on for stereo image
ITD
What is the 3-1 rule?
The distance between the spaced stereo pair should be 3 times the distance of either microphone to the source. the minimum distance of the spaced pair should be 21.6 inches from the source.
What are 3 rules of using spot mics with a stereo pair?
Spot Mics should:
Never be louder than the array.
Match the panning.
Match the timing within 20ms
Things that kill depth.
Multitrack recording
Multi-mic Recording
Dead Acoustics in the record environment
Overapplied compression
Improper Dithering
LowRes Processing
What is the slew rate?
the maximum speed at which an amplifier can change states. Usually expressed in V/µs (volts per microseconds),
What is Bob Katz first secret in digital audio?
Word Lengths Expand
Explain how a jeklin disk increases the separation of a spaced pair?
It creates greater separation between the two channels.
What are the three types of masking?
Temporal, Directional and Amplitude.
what is another name for a Multi-band compressor?
Dynamic EQ
What compressor has the fastest attack time
VCA, they have a feed forward system. not to be confused with look ahead which allows for a zero attack time compressor on digital systems
What is the purpose of the ribbon test?
Makes the phantom center versus direct speakers even to accurately represent the mono instrument signals.