S
Sequence2
Member
What is the difference between the two? (I am reading the Camel Audio - Alchemy user manual and the filter section has these types of filters)
Thanks
Thanks
bandcoach
Zukatoku - Mod Scientist
A state variable filter can provide simultaneous outputs that have
1) low pass characteristics
2) high pass characteristics
3) bandpass characteristics
i.e. for one input signal you can obtain 3 different output signals; each a different filter characteristic or state.
A biquad filter is a filter whose transfer function is the ratio of two (bi-) quadratic (quad) equations (ax[sup]2[/sup]+bx+c (the basic formula for any parabola)), i.e. the transfer function for the filter is something like
a[sub]1[/sub]x[sup]2[/sup]+b[sub]1[/sub]x+c[sub]1[/sub]
a[sub]2[/sub]x[sup]2[/sup]+b[sub]2[/sub]x+c[sub]2[/sub]
All filters have a transfer function that describes how the signal is altered by the action of the filter.
A bi-quad filter uses both feedforward and feedback paths (aka combined IIR and FIR) to create the desired filter transfer function.
A bi-quad filter is a typical implementation path for a state variable filer, as it can provide the required low-pass, band-pass and high-pass outputs as part of its design/implementation
1) low pass characteristics
2) high pass characteristics
3) bandpass characteristics
i.e. for one input signal you can obtain 3 different output signals; each a different filter characteristic or state.
A biquad filter is a filter whose transfer function is the ratio of two (bi-) quadratic (quad) equations (ax[sup]2[/sup]+bx+c (the basic formula for any parabola)), i.e. the transfer function for the filter is something like
a[sub]1[/sub]x[sup]2[/sup]+b[sub]1[/sub]x+c[sub]1[/sub]
a[sub]2[/sub]x[sup]2[/sup]+b[sub]2[/sub]x+c[sub]2[/sub]
All filters have a transfer function that describes how the signal is altered by the action of the filter.
A bi-quad filter uses both feedforward and feedback paths (aka combined IIR and FIR) to create the desired filter transfer function.
A bi-quad filter is a typical implementation path for a state variable filer, as it can provide the required low-pass, band-pass and high-pass outputs as part of its design/implementation
S
Sequence2
Member
I really appreciate the reply bandcoach
I was wondering if you had a simpler explanation? (Or else I could keep this post on-going asking the difference between feedforward/ feedback, transfer function, Combined IIR/ FIR)
I am definitely more use to the regular Lp/Hp/Bp/Notch/Combo filter set-up with most of my hardware. The math/ complicated in-depth routing of the effects (Not just filters) really boggles me when it comes to music production (although I wish I knew more - the more knowledge the better I always say)
I was wondering if you had a simpler explanation? (Or else I could keep this post on-going asking the difference between feedforward/ feedback, transfer function, Combined IIR/ FIR)
I am definitely more use to the regular Lp/Hp/Bp/Notch/Combo filter set-up with most of my hardware. The math/ complicated in-depth routing of the effects (Not just filters) really boggles me when it comes to music production (although I wish I knew more - the more knowledge the better I always say)
bandcoach
Zukatoku - Mod Scientist
any filter can be designed to be feed-forward, take the signal and mix it with the signal delayed by one or more samples, or feed-back, take the signal and send it back after delaying it by one or more samples
Z in the above is simply an arbitrary number of samples to delay the signal
A biquad filter combines two of each of these units summing in the middle of the two delay lines or one of each and summing on the outside of each. A designer would choose the optimum configuration of these two units to implement a specific design.
Each delay line contributes to the creation of bandpass, lowpass or high pass output and can be tapped to provide these outputs
IIR = Infinite Impulse Response aka a feed-back filter design
FIR = Finite Impulse Response aka a feed-forward filter design
unfortunately when it comes to discussing thee types of filters, it requires at least a passing understanding of the concepts described above - Moses may have some input on this, as may foggy.
Z in the above is simply an arbitrary number of samples to delay the signal
A biquad filter combines two of each of these units summing in the middle of the two delay lines or one of each and summing on the outside of each. A designer would choose the optimum configuration of these two units to implement a specific design.
Each delay line contributes to the creation of bandpass, lowpass or high pass output and can be tapped to provide these outputs
IIR = Infinite Impulse Response aka a feed-back filter design
FIR = Finite Impulse Response aka a feed-forward filter design
unfortunately when it comes to discussing thee types of filters, it requires at least a passing understanding of the concepts described above - Moses may have some input on this, as may foggy.