Spectral Processors Flashcards
(44 cards)
What are the three types of spectral processors?
- Filters
- equalizers
- aural exciters
What are the 6 types of filters?
- LPF (low pass filter)
- HPF (high pass filter)
- band-pass filter
- band-reject filter
- notch filter
- all-pass filter
In a low-pass filter, what is the cutoff frequency?
frequency where the output is -3.01 dB
In a low-pass filter, what is the slope?
dB per octave attenuation (below cutoff frequency)
In a low-pass filter, what is the order?
-first order is 6.02 dB/oct, second is 2x6.02 dB/oct -also called poles
What is a high-pass filter?
- allows high frequencies below a certain frequency to pass through
- slopes up from left to right
What is a low-pass filter?
- allows low frequencies below a certain frequency to pass through
- slopes down from left to right
Why is cutoff frequency defined at -3dB?
- electrical engineers define 3dB as doubling of power
- slope becomes mostly linear after this point
- it is the point at which the effect is clearly audible
What are band-pass filters?
-high-pass filters and low-pass filters together
In a band-pass filter, what is the equation for bandwidth?
difference between two cutoff frequencies
In a band-pass filter, what is the equation for cutoff frequency?
cf=√(cf1*cf2)
ex. cf1=220, cf2=880
cf=√220*880
cf=√193600
cf=440
What is a band-reject filter?
reduces gain at a particular frequency
What is a notch filter?
band-reject filter with extreme attenuation at a single frequency and a very narrow bandwidth
What is an all-pass filter?
- passes all frequencies equally, without attenuation
- changes the phase relationship between frequencies
- described by the frequency where the phase shift crosses 90° (¼ wavelength delay)
How is a phase shift achieved in an all-pass filter?
varying the filter’s propagation delay by frequency
What are all-pass filters used for (3 things)?
- compensate for unwanted phase shifts
- create intentional comb filter effects
- multiple are used for a phase shifter
How do equalizers differ from filters (5 ways)?
- EQs are made of a collection of filters (bands)
- EQs allow control over the gain of the filter
- EQs can boost and attenuate
- EQs leave the gain of frequencies outside of the band-pass/band-reject filter at zero dB
- bandwidth is measured 3dB below the peak of the curve
What is a peaking equalizer?
a band-pass filter that leaves the gain of the frequencies outisde of it at zero dB
How does an asymmetrical filter work?
bandwidth is measured 3dB below zero on the cutting side and 3dB below peak on boosting side

How does a symmetrical filter work?
bandwidth is measured 3dB above zero for boosting and 3dB below zero for cutting

What is a constant range (proportional Q) EQ?
Q narrows as boost or cut increases
What is a constant Q EQ?
Q remains constant as boost or cut increases
In an EQ, which frequency controls are peaking filters?
mid frequencies
What is a shelving equalizer?
-allows for boost or cut of frequencies above or below a given frequency


