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description: Audio advice and discussions with audiophiles and professionals. Free discussion forums, open to all and frequented by industry experts. Ask questions and get advice on stereos, speakers, hi-end amplifiers, pre-amps, home theater, tube hi-fi, turntables, vinyl, tweaks, music, films, video, DVDs and more.
items: Spring projects...
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items: Re: Discrete resistors vs. variable L-Pad
items: Re: Discrete resistors vs. variable L-Pad - Thanks!

Spring projects...
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description: 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
creator: themilford
date: 2007-03-30T15:28:02-00:00

You've got mail!
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description: 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.
creator: Wayne Parham
date: 2007-03-31T15:35:15-00:00

Re: You've got mail!
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description: 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?
creator: themilford
date: 2007-04-02T02:48:54-00:00

Re: You've got mail!
type: item
description: 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.
creator: Wayne Parham
date: 2007-04-02T13:37:13-00:00

Re: You've got mail!
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description: 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!
creator: themilford
date: 2007-04-04T04:43:47-00:00

Re: You've got mail!
type: item
description: 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.
creator: Wayne Parham
date: 2007-04-04T13:33:50-00:00

Re: Discrete resistors vs. variable L-Pad
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description: 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.
creator: dB
date: 2007-04-06T09:58:29-00:00

Re: Discrete resistors vs. variable L-Pad
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description: 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.
creator: Wayne Parham
date: 2007-04-06T16:34:20-00:00

Re: Discrete resistors vs. variable L-Pad - Thanks!
type: item
description: Thanks Wayne. I was afraid that they were inductive, like in resistors. I tried to measure one but is kind of difficult.
creator: dB
date: 2007-04-06T18:23:51-00:00