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doyall
09-22-2006, 10:15 AM
What practical significance is there to the particular capacitor, resistor and inductor configuration used to achieve a specific crossover frequency? In other words do crossover points of, say, 800 or 3,000 Hz result in the same electronic end results by any method achieved? As a more narrowly focused question, I am wondering about the desirability, or more appropriately the lack thereof, of using a NLXE990 network (XO at 800, 3200 Hz http://manuals.harman.com/JBL/HOM/Technical%20Sheet/LXE990%20ts.pdf (http://manuals.harman.com/JBL/HOM/Technical%20Sheet/LXE990%20ts.pdf) ) in conjunction with L50 transducers (127A, LE5-10 & LE26 - spec XO at 800, 3000 Hz http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L50%20ts.pdf (http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L50%20ts.pdf) ) in an off-model vintage, but pristine, JBL box similar to the L50 until I can either acquire or build a proper N50 network.

soundboy
09-22-2006, 10:27 AM
Don't go down the road of plug and play with X drivers, Y crossovers, etc. Without going in to detail, if you want flat response, and drivers that blend, you need to have the system drivers plotted and crossovers done with a LEAP or similar program. Grabbing a "800 hz" crossover, and using it with whatever drivers ain't gonna work..Period. Been there done that 25 years ago:banghead:. JBL designed specific filters for specific systems. Stick with a complete system done that way, or have someone do the crossovers with a program and actual impedence plots and responses....otherwise, you will end up with a group of drivers that make noise, but won't blend. Trust me , the crossover is 90% of any system. Read some past posts on this, there are many. A speaker engineer smarter than me said a long time ago..."It's not the drivers you use, it's what you do with them"...ie how you blend them together. I would rather have Audax, or what ever drivers, together with a killer network, than state of the art JBL, and off the shelf "textbook" crossovers. Don't waste a decent set of drivers by throwing a random crossover at them, that wasn't specifically designed for them. Especially a 3 way... If you can afford these drivers, you can afford a good filter network. Just trying to save you a headache....stick with the schematic for the L50, and use the best caps and air coils you can afford. The box volume and porting is just as critical. Stick with the origonal box and porting...Copy the origonal engineering, don't just guess, you will be sorry. Solens are pretty decent caps for the money, just don't bypass them, been there done that too. Use better caps, intead, if you don't like them. Stay away from electrolytics, solens are cheap enough. Hope it helps, Pete

Robh3606
09-22-2006, 05:06 PM
Hello doyall

This auction might help you out.

Good Luck Rob:)

http://cgi.ebay.com/JBL-L50-SPEAKER-CROSS-OVERS_W0QQitemZ270032448163QQihZ017QQcategoryZ5059 7QQrdZ1QQcmdZViewItem

doyall
09-22-2006, 05:20 PM
Appreciate the advise and the link!

Thom
09-22-2006, 09:55 PM
For sure there is quite a bit of truth to that, except when sliderules (ask your parents) were a real bitch there was quite a bit of trial and error and must be still if we're to believe (being nice is just no fun) the stuff about this cap and that cap because where do you plug that in your formula? And can you really make your room right for more than one seat, really right/ depends on the room but maybe not. If you like it and nothing is getting lower freq than it can handle. Anyway the first time I opened up a jbl crossover I was shocked. I had built several by then (good or bad is to subjective) and I'd read how theirs cost so much be cause of all the care and expensive materials and what I opened was damn near empty.

duaneage
09-23-2006, 06:40 AM
Voicing a crossover takes time. Designing the network is only the start. I have a crossover box that features different values on rotary switches I can use to try different values and plug in any value I choose.

http://www.vidsonix.com/vx3/vx_aud4ind.html

I don't work for them or anything, although Charlie the founder is a nice man to talk to on the phone. It'sa little pricey but invaluable for design work

Thom
09-23-2006, 02:51 PM
That's trick, and certainly not a fortune, unless,of course, you believe that when you change types of cap you'll have to start all over. Damn, I really shouldn't do that.