Normal
Re: FIR filtersBennett,Sure. As a practical matter I'm limited to 384 samples at fs = 48kHz because of the DSP I'm using (Powersoft) so a total filter length of 8 ms. Since after optimization the peak of the filter falls somewhere near the center of the window the processing delays are running around 3 to 5 ms, which for an outdoor main speaker I consider just fine. Monitors might be a different story. I experiment with longer filters to see what they do on paper but I can't actually listen to them.One observation for the general reader is that the minimum phase part of the FIR filter has essentially zero processing delay as it is one-sided or "causal" as SP types say. It is not necessary to use excess group delay compensation (for a well behaved speaker) or uniform group delay crossover filters (we got along for years without them) so the processing delay can be kept very short for, say, a monitor.Right now I'm looking at adding compensation for the phase shift of the natural high-pass of the speaker (mid-high only) without compensating the magnitude. There are really a lot of different things you can do with these tools. The hard part is knowing what are real problems that need to be solved. I'm taking suggestions.Best,--Frank
Re: FIR filters
Bennett,
Sure. As a practical matter I'm limited to 384 samples at fs = 48kHz because of the DSP I'm using (Powersoft) so a total filter length of 8 ms. Since after optimization the peak of the filter falls somewhere near the center of the window the processing delays are running around 3 to 5 ms, which for an outdoor main speaker I consider just fine. Monitors might be a different story. I experiment with longer filters to see what they do on paper but I can't actually listen to them.
One observation for the general reader is that the minimum phase part of the FIR filter has essentially zero processing delay as it is one-sided or "causal" as SP types say. It is not necessary to use excess group delay compensation (for a well behaved speaker) or uniform group delay crossover filters (we got along for years without them) so the processing delay can be kept very short for, say, a monitor.
Right now I'm looking at adding compensation for the phase shift of the natural high-pass of the speaker (mid-high only) without compensating the magnitude. There are really a lot of different things you can do with these tools. The hard part is knowing what are real problems that need to be solved. I'm taking suggestions.
Best,
--Frank
