2 Way Passive Crossover for PA

[jaya000]

Want to design passive crossover for PA 2 way speaker system.
I will measure the thiel small parameters of the 12" woofer. For Compression Driver, thinking of testing it with horn for thiel-small parameters. Then to use xover pro( bass box pro) to design the passive crossover.

want to design based on actual driver parameters instead of text book crossover. is this ok? or any other method will be better.

[norman bates]

it won't be easy. The 12" has an increasing Impedance curve. It is not a simple 8 ohm resistor. And you are probably going to have to really pad down the compression driver.

I'd use a 24db Linkwitz Riley active crossover.

Even then, you are going to need a bunch of hf boost to get high end out of the compression driver, unless you are using a horn with a very narrow dispersion, and if you do that narrow dispersion horn, you will not have highs off to the sides.

The only tip I can give you is to cross at 1,200hz.

Norman

[jaya000]

Thanks Norman,,
The 12" speaker is having linear frequency response upto 4 khz. I checked this with LMS. It has copper cap inside. So i was thinking just to crossover above 3 khz.

[norman bates]

Well, a 12" loses directivity above 1.2khz, however, that doesn't stop manufacturers from crossing above that. And by crossing above 1,200hz, it allows more power to go to the compression driver without blowing.

Hey, it's your ears, you may like crossing that high depending on preferences and goals.

Norman

[jaya000]

Originally Posted by norman bates

Well, a 12" loses directivity above 1.2khz, however, that doesn't stop manufacturers from crossing above that. And by crossing above 1,200hz, it allows more power to go to the compression driver without blowing.

Norman

Nice explanation. If i crossover at 1200 hz, i need to use 2" CD for it. right?
But people say it blows quickly.

[Charles Darwin]

BMS make four 1" compression drivers (2 neos & 2 ferrites) with 1.75" voice coils which are ok to use down to 1200Hz.

[djk]

A typical 12" woofer has about 60° dispersion at 1.6Khz, that is what I would use for PA.

The JBL 4425 studio monitor crosses over at 1.2Khz to a 100° x 100° horn, the 12" woofer is about 100° at 950hz.

It will sound the best to match the pattern on the horn (and Di figure) with the pattern on the woofer (and Di figure) at the crossover point.

What pattern were you considering for the horn?

An interesting horn for PA use might be the P-Audio PH-180

http://www.loudspeakersplus.com/pdfs/PH-180.pdf

It has 100°H below its center axis, and 50°H above its center axis, the total vertical dispersion is 60°V. With the speaker cabinet mounted on a stand it has wide coverage for those up close and narrower coverage for the back of the room, ideal for a typical rectangular room. It would work well crossed at 1.6Khz (I own a pair of these horns, less than $10 from Parts Express as #292-2576).