Home |
Search |
Today's Posts |
#1
Posted to rec.audio.tech
|
|||
|
|||
IIR v FIR
Are there any benefits to using FIR filters compared to IIR eg
Butterworth, in digital crossovers? Anyone know how they sound in comparison? Dirk |
#2
Posted to rec.audio.tech
|
|||
|
|||
IIR v FIR
Dirk Bruere at NeoPax writes:
Are there any benefits to using FIR filters compared to IIR eg Butterworth, in digital crossovers? Anyone know how they sound in comparison? You could almost make a career out of answering that question. First of all, note that there is no such thing as a Butterworth digital filter. There are techniques for approximately analog Butterworth filters using digital filters, but they're not really Butterworth digital filters. There are distinct numerical advantages in FIR filters and those could translate to audible advantages. The most obvious ones are that they are unconditionally stable and never have limit cycles. On the other hand, FIR filters require more computation than IIR filters, and so if you're constrained in processor speed you could very well end up with a better achievable IIR filter than achievable FIR filter. For some references, see for example [mitra] and [proakis]. --Randy @BOOK{mitra, title = "{Digital Signal Processing: A Computer-Based Approach}", author = "Sanjit~K.~Mitra", publisher = "McGraw-Hill", edition = "second", year = "2001"} @BOOK{proakis, title = "{Digital Signal Processing: Principles, Algorithms, and Applications}", author = "John~G.~Proakis and Dimitris~G.~Manolakis", publisher = "Prentice Hall", edition = "third", year = "1996"} -- % Randy Yates % "Midnight, on the water... %% Fuquay-Varina, NC % I saw... the ocean's daughter." %%% 919-577-9882 % 'Can't Get It Out Of My Head' %%%% % *El Dorado*, Electric Light Orchestra http://www.digitalsignallabs.com |
#3
Posted to rec.audio.tech
|
|||
|
|||
IIR v FIR
Randy Yates writes:
Dirk Bruere at NeoPax writes: Are there any benefits to using FIR filters compared to IIR eg Butterworth, in digital crossovers? Anyone know how they sound in comparison? You could almost make a career out of answering that question. First of all, note that there is no such thing as a Butterworth digital filter. There are techniques for approximately analog Butterworth filters using digital filters, but they're not really Butterworth digital filters. There are distinct numerical advantages in FIR filters and those could translate to audible advantages. The most obvious ones are that they are unconditionally stable and never have limit cycles. On the other hand, FIR filters require more computation than IIR filters, and so if you're constrained in processor speed you could very well end up with a better achievable IIR filter than achievable FIR filter. I forgot to add a couple of more points. Another potential advantage of FIR filters is that they can easily be made to be linear-phase. You can also with IIRs, but you have to play tricks. However, some have said that linear-phase filters don't sound good, so it may be that IIRs which approximate analog filters like Butterworth, Chebychev, etc., actually sound better. Finally, it is possible to combine the potentially good sound of an analog filter (e.g., Butterworth) with an FIR filter using the FDLS filter design method [berchin]. For some references, see for example [mitra] and [proakis]. --Randy @BOOK{mitra, title = "{Digital Signal Processing: A Computer-Based Approach}", author = "Sanjit~K.~Mitra", publisher = "McGraw-Hill", edition = "second", year = "2001"} @BOOK{proakis, title = "{Digital Signal Processing: Principles, Algorithms, and Applications}", author = "John~G.~Proakis and Dimitris~G.~Manolakis", publisher = "Prentice Hall", edition = "third", year = "1996"} @article{berchin, title = "{Precise Filter Design}", author = "Greg Berchin", journal = "IEEE Signal Processing Magazine", month = "January", year = "2007"} -- % Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven. %% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and %%% 919-577-9882 % Verdi's always creepin' from her room." %%%% % "Rockaria", *A New World Record*, ELO http://www.digitalsignallabs.com |
#4
Posted to rec.audio.tech
|
|||
|
|||
IIR v FIR
On 25 Oct, 21:04, Randy Yates wrote:
Randy Yates writes: Dirk Bruere at NeoPax writes: Are there any benefits to using FIR filters compared to IIR eg Butterworth, in digital crossovers? Anyone know how they sound in comparison? You could almost make a career out of answering that question. First of all, note that there is no such thing as a Butterworth digital filter. There are techniques for approximately analog Butterworth filters using digital filters, but they're not really Butterworth digital filters. There are distinct numerical advantages in FIR filters and those could translate to audible advantages. The most obvious ones are that they are unconditionally stable and never have limit cycles. On the other hand, FIR filters require more computation than IIR filters, and so if you're constrained in processor speed you could very well end up with a better achievable IIR filter than achievable FIR filter. I forgot to add a couple of more points. Another potential advantage of FIR filters is that they can easily be made to be linear-phase. You can also with IIRs, but you have to play tricks. However, some have said that linear-phase filters don't sound good, so it may be that IIRs which approximate analog filters like Butterworth, Chebychev, etc., actually sound better. Finally, it is possible to combine the potentially good sound of an analog filter (e.g., Butterworth) with an FIR filter using the FDLS filter design method [berchin]. For some references, see for example [mitra] and [proakis]. --Randy @BOOK{mitra, title = "{Digital Signal Processing: A Computer-Based Approach}", author = "Sanjit~K.~Mitra", publisher = "McGraw-Hill", edition = "second", year = "2001"} @BOOK{proakis, title = "{Digital Signal Processing: Principles, Algorithms, and Applications}", author = "John~G.~Proakis and Dimitris~G.~Manolakis", publisher = "Prentice Hall", edition = "third", year = "1996"} @article{berchin, title = "{Precise Filter Design}", author = "Greg Berchin", journal = "IEEE Signal Processing Magazine", month = "January", year = "2007"} -- % Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven. %% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and %%% 919-577-9882 % Verdi's always creepin' from her room." %%%% % "Rockaria", *A New World Record*, ELO http://www.digitalsignallabs.com Thanks. I guess I'll have to code some examples and listen. I really hate the subjective nature of audio :-) Dirk |