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Long time no post... sorry I haven't contributed more. but, maybe you can help me with a few questions. I think I'm going to move the Delta 12LFs from my Karlsons into some proper Theater 3 Pi boxes. (So Wayne I'll need some plans). I have the crossovers and comp/drivers but I have the H295 horns and wonder if I should get the H290s? Also, I was thinking of putting the Beta-12LTs into the Karlsons... I'd like to try them with some sort of "super tweeter" like the Fostex FT17H (or the T-90A if I can get some cash together). My last question is: can anybody here figure out what sorta crossover I'll need for this? If I just want to run the 12LT wide-open and put a cap in front of the tweet what value? Does anybody have any experience with this set up? Thanks guys, David
Stick with the H290 on the three π's. As for your other speaker, generally I've found that a simple first-order works best on something like that. First-order crossovers have such wide overlap that the choice of components isn't all that critical. You have about +/-2x window there. So I'd probably suggest something like a 1.0μF to 4.7μF capacitor with a shunt damping resistor of about 12Ω to 20Ω.
Thanks Waye. I'll let you know how it goes... Will I need to pad the tweeter? should I just get a cheap L-pad?
If you're asking about the Fostex tweeter and the Beta 12 midwoofer, then yes, I'm sure you'll want to pad the tweeter. I prefer fixed voltage dividers made with discrete resistors, but you could also use a variable L-Pad.
Wayne, Actually I'm gonna try running the Beta 12 LT which has the whizzer cone... I think it goes up to about 8 or 9k. Would you recommed a smaller cap value then? I was figuring I would get a cheap L-pad. Find the best setting. Then measure and replace with resistors. thanks again!
A 1.0μF capacitor should work just fine. If you want a little less tweeter, you might try a 0.68μF or 0.47μF cap.
Re: Discrete resistors vs. variable L-Pad
Hi, Wayne, is the variable L-Pad frequency dependent, showing a different L/R "behaviour" with frequency, or just a "neutral" component more like (variable impedance) non inductive discrete resistors? Or is it necessary to measure L-pad inductance "L" also? Cheers. note: I am using L-Pad's in addiction to discrete resistors to achieve a plus/minus output control that you mention earlier in your definitions of a perfect L-Pad xover design.
Some L-Pads are made to hold their impedance constant, but others are really just potentiometers. The latter will cause crossover characteristics to shift as the slider is moved.
Re: Discrete resistors vs. variable L-Pad - Thanks!
Thanks Wayne. I was afraid that they were inductive, like in resistors. I tried to measure one but is kind of difficult.