Re: Frequency Response/Contour EQ in full range systems.
Hi Phil,
I think there are three different meanings of "window" in play here. First, if I have this straight, to do the DFT, the block of samples is multiplied by a window function (Hann, Hamming, or what have you). Second, the length of the DFT implicitly imposes a time window and, as you say, there are modes in Smaart (FPPO or MTW?) where different length DFTs are performed for different frequency ranges, thus giving different time windows.
Third, at least in Smaart 5 (which is what I use routinely), there's an optional "Time window" (specified in milliseconds) that can be applied after the TF has been derived by dividing the measured signal DFT by the reference signal DFT and which is achieved by doing an IDFT to get the IR, truncating it, and DFT'ing back to give the windowed magnitude response. It's this last windowing option that I was talking about.
The question of the practical usefulness of the implicit windowing involved in the DFT itself is fascinating. It's undoubtedly a good means of decimating data for display but, beyond that, I've always been sceptical of the claimed benefits. You may be able to help convince me! It certainly doesn't achieve the effect that IDFT'ing, truncating the IR, and DFT'ing back achieves.
Nick
