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In Reply to: Re: Crossover question posted by Sparky on February 25, 2007 at 21:07:23:
the overlap you're talking about is entirely determined by the impedance at the crossover frequency and the values of the parts you choose-- so don't sweat that!meanwhile-- don't forget-- if you're using first order crossovers--to have the 'knee' of the crossover be a half octave high (on the horn) and a half octave low (on the woof) of your ACTUAL impedance at that frequency-- cause nominal doesn't mean much of anything! those online calculators aren't remotely close in the real world..
good luck-
Follow Ups:
I'm afraid I wouldn't know how to determine the actual impedance at any given frequency. Before reading your post, however, I bought a few caps and chokes for a 1200Hz crossover. I used, ahem, one of those online calculators.I hooked it all up tonight and it ain't half bad, really, but there seems to be a dip in the midrange somewhere and, at least on some tracks, the sound is a bit aggressive. Some better quality caps may take care of that. Overall, though, the sound is already better than the stock JBL 4312. It's definitely more detailed and dynamic.
no 'ahems' are even remotely necessary.. you're alright- man.. everybody goes through the process!most times you end up with a midrange hump 'cause your woof's impedance (at these values.. i use a similar setup) is a good deal higher than nominal, and so's the comp drivers'-- e.g. @ 1300hz, my comp drivers running about 9.3ohms, and the woof's at about 12.5-- which are pretty big errors with 8 ohms dialed in! to me-- that manifests itself as not a bit agressive.. but shreekin'-- not to mention distorting pretty bad!
your message had me thinking-- so i went back and did the math on the online calculators, and they seem ok after all-- but that's entirely contingent on having the right ACTUAL impedance (don't forget to add for you inductors, too.. low DCR ones get you a little closer to your actual values..)
don't forget-- them comp drivers are FAST critters.. so detail and dynamics'll fool ya.. i made TONS of mistakes (am still making mistakes?!) tweaking my own crossover coming from regular speaker drivers... horns really do throw a huge wrench in the works- but its still negotiable with enough patience..
Yeah, I'm beginning to see what you mean about horns throwing a wrench in the works. I think I'm going to switch to Plan B, which is active biamping through a Behringer DCX. Otherwise, I think it'll take a lot of time and money to get everything dialed in right just by experimenting with different crossover values.Ultimately, I do plan to get different woofers because the ones from the 4312 aren't the last word in bass. I was just fooling around with what I had on hand.
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