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<blockquote data-quote="Peter Morris" data-source="post: 147685" data-attributes="member: 652">Re: FIR filtersIn simple terms FIR crossovers have no phase shift. If needed they can have very high crossover slopes, greater than 100 dB per octave.&nbsp; This can have advantage for power handling and directivity issues in some cases.The issue is often the time or latency required to implement a FIR crossover. The time required is proportional to the crossover frequency. It is a mathematical requirement and cannot be reduced by better / faster processing.In terms of EQ - think of using an almost unlimited number of normal PEQs to create a transfer correction curve. Such a curve will only require one FIR filter / processor.Internally FIR filters / processors are like a bunch of delay taps that feed forward and then add together. The output (EQ shape) is adjusted by modifying the delay tap coefficients.If you consider a speaker and its enclosure as being able to be represented as a set of mathematical equations like you can with an electric circuit (we are only considering the linear behaviour) then you can mathematically adjust the input signal with an opposite equation to correct the response. Many people don’t understand this - the output is the sum of both the mechanical and electrical bits. FIR filters are very good at these types of corrections.&nbsp; FWIW the DIY Mid-High on this board was designed with this approach in mind. What you can’t do is fix the non-linear bits.&nbsp; If you try it will sound wrong and processed.&nbsp;FWIW FIR filters require a lot of processing power and as such are not cheap.</blockquote>

[QUOTE="Peter Morris, post: 147685, member: 652"] Re: FIR filters In simple terms FIR crossovers have no phase shift. If needed they can have very high crossover slopes, greater than 100 dB per octave. This can have advantage for power handling and directivity issues in some cases. The issue is often the time or latency required to implement a FIR crossover. The time required is proportional to the crossover frequency. It is a mathematical requirement and cannot be reduced by better / faster processing. In terms of EQ - think of using an almost unlimited number of normal PEQs to create a transfer correction curve. Such a curve will only require one FIR filter / processor. Internally FIR filters / processors are like a bunch of delay taps that feed forward and then add together. The output (EQ shape) is adjusted by modifying the delay tap coefficients. If you consider a speaker and its enclosure as being able to be represented as a set of mathematical equations like you can with an electric circuit (we are only considering the linear behaviour) then you can mathematically adjust the input signal with an opposite equation to correct the response. Many people don’t understand this - the output is the sum of both the mechanical and electrical bits. FIR filters are very good at these types of corrections. FWIW the DIY Mid-High on this board was designed with this approach in mind. What you can’t do is fix the non-linear bits. If you try it will sound wrong and processed. FWIW FIR filters require a lot of processing power and as such are not cheap. [/QUOTE]

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