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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: richrumble on August 11, 2004, 08:43:58 pm

Title: Cross-overs
Post by: richrumble on August 11, 2004, 08:43:58 pm
I'm sure there is a lot of variation on which way to go, or what each person has... but my Lab's are nearly complete, and I'd like to know what everyone uses as their crossover point, do you use the suggested 35hz as Eminence has posted in the specs of the sub? Who uses passive x-overs, active or even both... does anyone use any impedience correction... anyone care to share their design specs of thier x-overs?
Personally, I'm going to try a few different ones, but they will be passive as the amp I currently have has no real filter to speak of, plenty of power, but not much else Smile
Title: Re: Cross-overs
Post by: Al Limberg on August 11, 2004, 10:01:33 pm
Hi Rich,
First off, let's clear up one thing.  That 35Hz is NOT a crossover point - it's a high pass filter, and when using my Labs one or two per side or with two in center mono format, I typically run a 24db/octave hi pass at 35hz.  In groups of four (and if the style of music warrants it) I will lower that to 28 or 32Hz.  On the high end, I've settled in at 80hz as my low pass.
Regarding the use of passive crossovers,  you might want to reconsider that long and hard.  As a rule of thumb, the lower the crossover point, the larger and more expensive the components become.  In the fine print on that same thumb you'll discover that those components also have to handle a great deal more power.  I suspect that by time you manage to build two passive crossovers and two passive high pass filters, you will probably be approaching the price of a good used digital speaker controller and even some of the lower priced new ones.
Good luck and welcome to the sawdust club!!

Title: Re: Cross-overs
Post by: richrumble on August 15, 2004, 09:52:22 pm
Your right, a little over-generalization in my head-  Smile Thank you for the correction, and your feedback- that's precisely what I was hoping for. I think I'm going to try both- passive and active I've finished my first box, and I'm pretty happy with it- I've got the pic's on another pc- and will post them tomorrow-

I've not RTA'd them yet, but I want to get my crossovers first, naturally. I've also found 80hz to around the point I like I'm sure it will be around there, thanks again-
Title: Re: Cross-overs
Post by: richrumble on August 19, 2004, 09:55:31 am
It needs to be finished... not decided on paint or carpet.. other... and I'm still messing with the x-overs- but here she is:

Title: Re: Cross-overs
Post by: Dave Rickard on August 23, 2004, 03:38:01 pm

Another issue to consider is that a passive crossover cannot delay the tops to match the LABsub horn length.