Quote:
|
why wouldn't I want to use the FBQ2496 or DSP1124P to correct that big hump around 4khz
|
Well, generally we consider the mains signal to be pristine and should be 'messed with' the least of all the signals. To put that signal through an A to D convertor and then pass it through a DSP and then back through a D to A convertor and through line amps on input and output is a crime. You won't go to jail - but you should
. To add insult to injury, it's a $180 device attached to your mains signal. Did I mention that you would land in jail if you did it.
Great rigs for a sub though.
Oh my, oh my, oh my......... I just looked up your speakers. Pipedreams Ref 18's are $50,000 a pair. OK, jail isn't good enough.
Holy cow.
Quote:
|
Perhaps it's possible to play the Lexicon's sub "distance" setting to control the phase?
|
Of course, it amounts to almost the same thing. A phase control is a very reasonable approximation to a time delay.
Quote:
|
would I want to start with a very low target level -- one that's below the bottom of the dips, say 60db -- and then pull all the peaks down to that level, and then boost the bass output level to compensate? Or is there some reason to stick with 75db as the target level, and only pull the peaks down less drastically to that level and leave some of the dips in?
|
Yeah, you have the right idea. You have to realize that you can go too far with cutting and you end up with a signal that's too low feeding the sub, and then trying to compensate with the sub amp and run out of headroom.
When you set up REW, calibrate the target and levels to 75dB and then once the measurement is taken, you can move the target up and down to include as much or as little of the measured signal for REW to consider as you like. Set a new target level while watching your measurement plot, and then Find Peaks and if you don't like what you see, clear the peaks and lower the target and Find Peaks again, etc, etc. Then let REW suggest its filters and then you can add your own and tweak until you like the corrected waveform. Enter the filters and the actual measurement will be very close.
Do all this with the mains off (in stereo). Then turn the mains on and see what the crossover looks like. Adjust the phase (or time delay of the sub) to get the best response. Simply adjust and measure over and over. Takes seconds.
Hopefully that waveform you showed above didn't include your 2 18" subs.......................
brucek