some useful things for ya
Signal Processors - can be divided into 3 categories
Amplitude and level processors, compressors and limiters, expanders, noise gates,
Time based processors, delays, echos reverb, chorus flanger phasing
Spectrum based processors, harmonizers , exciters de-essers ,EQ , pitch correcting devices
Equalizer - spectrum processors a device that enables you the engineer to control the frequency response of a signal passing through it Equalizers were invented to compensate for low hi frequency loss which accrued in long cable runs during transmission of early telephone lines
Eq used in 2 ways in general * correction - compensate for deffenceis in the transmission medium (tape wear/cassettes) Correcting acoustic problems in a studio control room home theatre night club and concert hall correcting frequency problems in a recording (vocals and frequency masking the instruments)
enhancement / to enhance an already great sounding instrument / helping a sound to be heard in a mix
2 Classifications of EO's 1) active most common these units use active electronic components , transistors op amps tubes active component is capable of producing signal gain
advantages - lower cost small and light more boost than passive
disadvantages- generate some noise
2) passive EO's older EQ's or retro systems passive components designed around filters not capable of signal gain cut only
inductor and capacitor established frequency LPF HPF
advantages sound vary warm / generate no noise
disadvantages more difficult to achieve any boost expensive large and heavy
EQ terminology
cut decrease a certain amount of dB
boost add a certain amount of dB
EQ filter types LPF low pass filter hi cut cut off freq. is the freq. at which the output level has fallen by -3dB
HPF high pass filter low cut
BPF band pass filter a hight pass and a low pass put together
BSF band stop filter notch filter
the slop or steepness of the filter expressed as an amount of attenuation in dB per ocvtive
6dB per oct 1st order 12 dB 2nd 18 3rd
Most common EQ types shelving / multi-band / sweeping / parametric / graphic / para graphic
Shelving EQ bass treble controls on a home hi-fi set / car audio
-/+ response of the filter eventually flattens out or shelves at some low or high freq. turnover freq. freq. where the slope begins to turnover or flatten out to a shelf
Multi-band EQs bell type (peak)
when a control for the middle region is incorporated on a shelving EQ 3 knobs , bass, treble, mid (fixed freq.) when the mid freq. is variable it is called a sweeping EQ sweeping EQ has 2 knobs +/- select freq.
the parametric EQ has 3 controls 1) +/- or dip 2) freq. 3) Bandwidth or q factor
center freq. is the freq. at which the bell shape EQ has the most effect on the signal FC max boost or cut
high q / narrow bandwidth low q wide bandwidth
Q=fc/bw or fc/q = bw
Graphic EQ
provides +/- over many center freq. that are equally spaced with relation to octaves also known as bands as in a 31 band graph
vertical motion slide faders side by side their positions give a graphical representation of the EQs freq. response
faders can be placed at 1 oct 1/2 oct 1/3 1/16 and 1/12
Amplitude based processors (compressor limiter)
the compressor is a device whose output level decreases as its input level increases
the limiter a device whose output gain remains constant above threshold regardless of input gain
compressors ratio compression
determines the amount of compression (steepness of the slope) input to output a ratio of 1;1 means no change 2;1 means every 2 dB increase in input level above the threshold gives 1 dB increase in output level
Threshold the level at which compression is applied above this signal level gain reduction takes place
output gain make up this is meant for compressing the loss of output level due to compression
gain change meter visual indication for the amount of gain reduction in dB
input control allows compressor to accept a wider range of signals from guitar pick ups to pro console levels change the display vu to read input and set for vu
different methods of gain controls
hard-knee when the level of the signal crosses the threshold the ratio is immediately applied
soft knee (over easy) introduce compression more gently slightly before threshold with the ratio gradually increasing as the input rises
release controls the amount of time the compressor take to stop compression after the signal crosses under the threshold
Pumping and Breathing
Inherent in release times at high compression ratios the noise floor will rise and fall with the signal level when using fast release creating a breathing like sound
if the compressor has a relatively slow release time restoring itself after a high signal level has caused gain reduction then other low level signal will also be reduced in gain this is called pumping as the lower levels (noise included) slowly fade back up to their normal level
Other parameters
rms. allows no adjustment for attack & release time
auto release de-terming the rate of release according to the program dynamics
look ahead used in conjunction with limiting , anticipates the required amount of limiting (mastering - live sound)
leveling keeping the output constant with slow attack / medium release fast peaks are not compressed threshold relatively low and the ratio high (6;1 8;1) typical rms. compression
limiting compressing only the high signal peaks high threshold and a fast attack time ratio high (10;1 20;1)
Brick wall limiting ratio 30;1 infinity to 1 nuke fast attack times cuts all signals above threshold radically transient sounds more brilliant b/c clipping is the same as block distortion square waves or adding harmonics where the fundamental is clipped
stereo link master slave
to compress stereo signals you can link the 2 compressors with the stereo link left & right channels treated equally
side chains side chains / ducking patch another instrument or signal into the the side chain tells the compressor when 2 compress
Time based processors ---- delays---- FX that result from the use of delay (signal echo-multiple echo-reverb-tremolo-chourus-flanging)
Analog Delays sample and hold chip_volatile memory cascaded (bucket brigade) 1 to 300-ms of possible delay-- max delay approx. 300ms...not long enough to capture upper harmonics of instruments.
Manufactures: yamaha, mxr, dod. electro-harmonix memory man
DDL's Digital delay lines , digitized by the a to d converter digital numbers stored via the random access , feedback controls how many repeats there are longer delays effect high frequencies. 10-15khz bandwidth emphasize hf then de-emphasis to HF hiss stereo splits mono to 2 s/h circuits
Echo- old school substitute term for reverb like delay, can produce limitless signal reps via feedback control / single echo is called "slap-back"
delay times of 50 to 250 ms.
Similar to an early reflections in a large room E/R: initial short delay clusters that make up the room size of the reverb space.
used in a lot in 50's records, rock & roll and reggae records
Tape echo first echo effect triple head 2 track machine. you send signal from desk to the 2 track and:
1) the erase head erases any previously recorded material
2) the record head records the new head information
3) you hear the echo by monitoring the playback head
three playback heads each picking up less of the signal on tape (-3dB) so the echo's will decrease in level
makers gibson , roland guild
Doubling
double tracking, adt (automatic double tracking or artificial double tracking.)
delay times 15-50 ms
sounds as if there is more then 1 performer, pan original one way and delayed the opposite
fat wide sound
Haas-Effect always check in mono
22 ms delay (20-30)
Chorusing , Flanging , Tremolo & phasing all rely on a LFO
chorus: delay of 15 to 40 ms
stereo flanging delay of 1 to 15 ms
phasing LFO modulating a high Q filter
LFO low frequency Oscillator
low frequency sine wave that oscillates at a given speed and width...(more info after chorusing)
Chorus delay 15 to 40 ms doubling
no or very little phase canceling due to long delay times
no use of feedback
double tracking
delay time and level is modulated by an LFO
LFO sub sonic 1 to 10 HZ (not audible) low frequency wave that modulates the audio
2 controls ; speed (rate) and width (depth, intensity)
1) the speed determines how fast the delay time changes (1 to 10 HZ)
2) the width determines how much the delay changes
displayed as a percentage / ratio small settings create subtle effects, larger become very obvious
Flanging delay 1 to 15 ms
phase canceling due to short delay times
LFO modulating delay (frequency)
no amplitude modulation
greater amounts of feedback
Vibrato : change in frequency (pitch) & level ... doppler shift
Tremolo: change in dB (level) i.e. fender rhodes piano
like chorusing ... with longer delay times & deeper modulation
LFO modulates the delay & exaggerated level
The Doppler effect (vibrato
example ;
car or train passes by , horn of a leslie cabinet on a hammond organ
Stereo phasing / phaser / phase shifter
like flanging, achieved in a different way
Phasing is ; An LFO modulating a high Q notch filter , no amplitude modulation , and omitting feedback
resulting sound is a sweeping " jet like" sound
Exciters : Psycho acoustic device
invented Aphex , 1975- Aural Exciter
very easy to use and very east to abuse
available as a plug-in type lll
BBE sonic maximizer
compensates for the phase shifting between your high low and mid frequencies "time Aligns'
Direct X & VST plug-in...99.95
Multi-effects
acoustic chambers
spring reverb
plate reverb- vintage early 71
digital reverb's
A totally flexible reverb system will provide independent control of
. early reflections (echo) delay time & intensity
. reverberation (later reflections)
. decay (RT-60 time) time (reverb time -60)
. pre-delay (the delay time before the onset of reverb )
. size (the room size) display in meters rhythm 8m-12m lead vocals 16m-22m
. diffusion ( changing the angle of the sound wave travel)
. damping ( materials of the room )
. x-over ( crossover makes different times on low and mids )
Doubling
-double tracking, ADT (automatic double tracking) or artificial double tracking
-delay time 15-50 ms
-sounds as if there is more than one performer, pa original one way, and delay opposite
"fat, wide" sound
-Haas-effect......22ms delay, 20-30 ms,
-always check in mono
delay time calculation fro slap echo's
see handout.
distance
------------------- x 1000 = delay time
speed of sound
150
--------------- = .1327 x 1000
1,130 ft./sec =132.7 ms
delay towers-outdoor event
quick delay calculations-start stopwatch, on 11th beat stop (make sure it can measure hundreth of seconds) ex. 4.60 reads-means 460 ms per beat
Chorusing, Flanging, Tremolo & Phasing all rely on a LFO
-chorus: delay of 15 to 40 ms....or 15-50 depending on equip.
-stereo flanging: delay of 1-15ms
-phasing: LFO modulating a high "Q" filter
-LFO...Low Frequency Oscillator
-low frequency sine wave that oscillates at a given speed and width...more info after chorusing
Chorus
-delay 15-40 doubling
-no or very little phase canceling due to long delay times
-no use of feedback
-double tracking
-DELAY TIME and LEVEL is modulated by an LFO (1-10 HZ...CPS)
LFO
-subsonic 1-10 hz (not audible) low frequency wave that modulates the audio.
-two controls: SPEED (rate) and WIDTH (depth, intensity)
-1-the speed determines how fast the delay time changer (1-10 hz).
-2-the witdth determines how much the delay changes.
-displayed as a %/ratio. small settings create subtle effects, larger become very
obvious.
Flanging:
delay 1-15 ms
-phase canceling due to short delay times.
-LFO modulating delay (frequency)
-no amplitude modulation
-greater amounts of feedback
-combo of delay LFO & feedback....used to thicken sounds or produce the "aircraft" sound popular among guitar player. short delay time varied with LFO modulation.
Vibrato:
change in frequency (pitch) & level...doppler shift
The Doppler Effect:
ex-car or train passes by, Horn of a Leslie cabinet on a Hammond organ
(along w/ vibrato)
Tremolo:
change in dB (level) i.e. fender rhodes piano
like chorusing...with longer delay times and deeper modulation
LFO modulates the delay and exaggerated level
Stereo Phasing/ Phaser/ Phase Shifter
-like flanging, achieved in a different way.
-phasing is: an LFO modulating a high "q" notch filter, no amplitude modulation, and omitting feedback.
-resulting sound is a sweeping "jet like" sound
Exciters: "psycho acoustic device"
-invented aphex, 1975-Aural Exciter
-very easy to use and very easy to abuse
-available as a plug-in Type III
BBE Sonic Maximizer
-compensates for the phase shifting between your high, low, and mid frequencies "time aligns"
-directX & VST plug-in...99.95
Multi-effects
-acoustic chambers
-spring reverb
-plate reverb-vintage early 1971
-digital reverb's
A totally flexible reverb system will provide independent control of:
-early reflections (echo)
-reverberation (later reflections)
-decay (RT-60 Time)
-pre-delay
-size
-diffusion
-damping
-x-over
pre-delay: the delay time before the onset of reverb
effects test review:
20 mult. choice questions.
shelving eq's-area where you establish what freq. it's at-3dB downpoint
flanging-how to create...delay times, feedback, regeneration, delay modulation, what the LFO does...
noise gates-threshold point, what is it? reaction-opening and closing above/below threshold.
filters-have slope/steepness-exdpressed in a ratio or something form order or dB's per octave
noise gates-additional features-outside instrument to cause gate to open/close. what's the input called? key
define pre-delay
compressers-threshold, what happens when it gets above/below threshold
compressor ratios-4:1, output will be 2
slap-back-what's the feature that makes it turn from slapback delay to slapback echo?
early reflections-area in echo section-define, what they are,
given tempo-come up w/ delay time on one of the notes in milliseconds (formula)
flange, chorus, echo, doubling-delay times
how a chorus works, what an LFO is, area on vibrato, understand how phasing works
Q=fc/bw
given low and high freq., figure out Q.....Q=fc/fl fh (bw)
hope this helps everyone in some way and its free to u i am still paying it off
peace