View Full Version : LS f/x xover w/2 LS50's for big surrounds(?)
08-24-2006, 03:56 PM
I have scads of LS50's now, and plenty of parts from LS f/x's. I was thinking that, because the freq response of the f/x is so limited at the low end, that I could link two LS50's, with the f/x dipole/bipole crossover, and angle the LS50's away from each other, with the back corners almost in contact with each other, to achieve a diffuse surround sound. I have enough LS50's to do this 4 times, plus the pair at the front, and a pair to spare. A pair of PSW1200's will take over at the THX recommended 80 Hz, unless there is a good reason to set the sub crossover lower (suggestions?)
I'll have to be careful designing the circuit for the four 6.5" woofers to achieve the same impedance as the two 4" woofers in the LS f/x, but I don't see any other real challenges here. Any warnings/advice/raucous laughter?
08-24-2006, 04:14 PM
Just wire them both in phase, or the rear firing out of phase - and you're bi/di in a flash. Why dick with the F/X crossover at all?
Unless you've got a man-amp to drive the low impedance load of all 4, split the signal at your pre/pro and use two amps, one for each pair.
On the xover, I'd start at 60 and work from there. The LS50's can handle a full range audio signal, you just want to keep the intense LFE track a lot of movies feature out of them.
08-24-2006, 09:48 PM
Good advice. I'm definitely not worried about sending 60 Hz and up to those. What do you mean by wiring them in phase, besides not switching my pos/neg leads, just setting them up as dipole and leaving it? I guess all it would take to go bipole would be to switch the leads, right?
I have no man-amps to drive them, but I was thinking I would use a pair of Adcom 2535's (4 x 60wpc each) on them (for 8 total). The sensitivity of the LS50 is .5 dB higher than the f/x, so I figure it could be a far superior setup by tossing in the second amp.
BTW, I've been using a top and bottom cs350 for centers for a month now, driven by a 2 ch amp. I still haven't figured out what "comb filtering" is, but I like the fact that by using my Yammy M-45, which allows me to attenuate either channel, I can make the sound come right from the center of the screen. My ears used to always be drawn up to the speaker on top of the TV; no more. Neat, huh?
Also, I have yet to try, and will find out soon, but do you think there is an audible improvement in setting the x-over below 80 HZ? I know that above 100 or so, there is.
08-25-2006, 01:03 PM
Switch the leads on the rear firing speaker only to go from bi to dipole.
Bass is directional, and easily localized above 40Hz, imo. If your main speakers can play down BELOW 80 - it helps to mask and blend with a sub playing that high (80Hz). Most people won't notice (or care for that matter) - but we aren't most people, are we?
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