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Showing results for tags 'digital crossover'.
Assuming that you have taken a measurement using REW (Room EQ Wizard freeware), you probably have a plot that looks something like this: What you have is a frequency response that's not quite as flat as you'd like. So for that particular plot, you'd like to find the digital crossover equalization filters to make it flat--but without a lot of cut-and-try and doing a bunch of measurements (upsweeps) along the way. So you look at the REW window and you see the function bar across the top of the window: The next-to-last button is "EQ", which you push, and the following window pops up: The window has two plots: the plot that the started with (frequency response) and a second plot area (blank) which can provide a waterfall, impulse, or Pole-zero plot. There are two arrows next to the left border of this window. If you punch the arrow pointed down, the bottom plot is replaced by the upper plot whose size now occupies the space that both windows did. (Do it now.) On the right top side of the window, there are 5 bars with text embedded in them, namely: Equalizer, Target Settings, Filter Tasks, Modal Analysis, and Resonances. If you click on the first bar, it opens a menu downward and shows you a list of equalizers that are supported directly by REW. If you don't see your equalizer model in that list, fear not. You can pick one that's close in terms of your options. For example, using the EV Dx38 or Yamaha SP2060, I used "miniDSP", and it works. If using Xilica, then select "XP2040", etc. If you sequentially choose each equalizer, and look at the PEQ filters (which we'll generate in a moment), you'll find one that give you the best fit to the features of your crossover. Once you select a crossover type, minimize the Equalizer sub-window by clicking on its top bar again. Now click on the next menu bar - Target Settings: The important settings here are "Full Range" if using you're equalizing a full range loudspeaker. REW can also help you with subwoofers and "bass limited", i.e., HT surround loudspeakers that are intended to cross above a certain subwoofer crossover frequency. LF slope indicates intended the slope of the roll-off of the low frequency end (12 or 24 dB/octave) corresponding to the crossover filter slope used between the loudspeaker and the subwoofer. If you look at the measurement plot that you are using to equalize, it will show you the lowest crossover frequency that you should use. For my Jubilees and K-402-MEH, that frequency is about 30 Hz. If you're using HT loudspeakers, it may be as high as 100 Hz. Set that LF roll off point to match your loudspeaker. The same settings are used for the high end. All of these settings are settable to new default values within the "Preferences" menu on the top bar of the REW main window. This is the place to put in your "house curve" if you choose to have non-flat loudspeaker response. You can boost or cut highs or lows using the above controls, and the resultant curve is visible, so you can see what your "goal curve" is. I use flat response everywhere since I unmaster my recordings, but you may choose to use a "one size fits all" house curve to compensate for non-flat EQ used on your recordings. In the context of home theaters, that's what a "house curve" is doing. The last item on this menu is extremely important. It tells REW what SPL (loudness) to aim for overall when it optimizes the equalization PEQs. You want to get this right, or, not only does REW yell at you, it also will produce too many PEQs to try to flatten the response. For the measurement above, 70 dB is the right answer. If you use a higher value, REW will try to boost all frequencies below your target level. If you use a setting that's too low, REW will attenuate everything to make that lower SPL. It's better to set this value 1 dB too low than 1 dB too high. It's better to attenuate using PEQs than to boost. Use the overall channel gain setting on your digital crossover to generally boost or attenuate one driver channel of your loudspeaker. It will be apparent when you need to change the gain of a channel. Next up: Creating your optimized PEQs using REW