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-   -   How does this crossover work? (pics) (http://www.diyaudio.com/forums/multi-way/227055-how-does-crossover-work-pics.html)

brandontw 4th January 2013 10:38 PM

How does this crossover work? (pics)
 
This is a crossover from a set of JBL GTO607C car component speakers. I was originally considering using it for a boombox project, but I think I've figured out it wont work, now I'm trying to figure out why.

The specs for the set say that it is a 12db/octave 4000hz crossover (for 2 ohm speakers)

But it only has 1 cap and inductor each, and is set up oddly.

I don't know what i'm doing! Here is pictures of the front and back, and a sketch i made for myself to try to figure out how its laid out. Any help would be greatly appreciated.

http://i232.photobucket.com/albums/e...psf6cbb36b.jpg
http://i232.photobucket.com/albums/e...psfd3cf46f.jpg
http://i232.photobucket.com/albums/e...pse66da9e7.jpg

tuxedocivic 4th January 2013 10:50 PM

It's a single order electrical high pass on the tweeter and low pass on the woofer with an optional series resistor on the tweeter. The tweeter is wired out of phase with the woofer.

Looks like a crappy cross over.

brandontw 4th January 2013 11:02 PM

Quote:

Originally Posted by tuxedocivic (Post 3311400)
It's a single order electrical high pass on the tweeter and low pass on the woofer with an optional series resistor on the tweeter. The tweeter is wired out of phase with the woofer.

Looks like a crappy cross over.

Cool! That's what i thought, but i couldn't figure out how they got 12db/octave with that setup, and why the tweeter would be out of phase.

Would it be safe to rob the capacitor out of them if I decide i could use them?

Looks like I could use the 4.7 uF Cap for a simple high pass for an 8 ohm tweeter (about 4220 hz) if i wanted to. If the inductor was marked i could consider using that also, but i don't know how to tell what it is.

wintermute 4th January 2013 11:22 PM

Probably the marketing dept got involved ;)

Depending on the drivers used, it *may* result in a 2nd order rolloff when combined with the drivers natural rolloff (my original MTM crossover I used 1st order electrical on my tweeter to get 2nd order accoustic rolloff), however it is much more likely to result in a 3rd order acoustic rolloff (at least on the bass side).

With a 3rd order rolloff, in theory it should not matter which way around the tweeter is mounted, in practice however one orientation will likely give better results than the other.

In all instances I would be VERY surprised if it results in an optimal crossover regardless what drivers it is connected to ;)

Tony.

brandontw 4th January 2013 11:51 PM

Thanks! I think ill go ahead and attempt to build my own... Is parts express the best place for cheapish caps/inductors?

cT equals piD 6th January 2013 12:14 AM

Quote:

Originally Posted by brandontw (Post 3311480)
Thanks! I think ill go ahead and attempt to build my own... Is parts express the best place for cheapish caps/inductors?

If you are looking to save money, Parts Express I think is generally much more expensive than other vendors. I think that most likely you would find much better prices on the least expensive capacitors (bipolar or non-polar electrolytic) and inductors at MCM Electronics, Mouser Electronics, and/ or Digi-key. As far as I know, though, Mouser and Digi-key don't sell inductors suitable for use in cross-over networks.

Regards,
Pete

brandontw 6th January 2013 03:43 AM

Thanks! I was looking for another source... How do I tell if they are decent audio quality components?

balerit 6th January 2013 05:40 AM

That's a 6 dB sloped filter and the tweeter is incorrectly wired.

Pano 6th January 2013 05:56 AM

Parts-Express or Madisound for crossover parts. I don't think you'll find what you need at Mouser or Digikey. Great for other stuff, tho.

wintermute 6th January 2013 07:26 AM

Parts connexion is also not a bad place for at least crossover caps (if you want low cost good quality) I use their very inexpensive axon caps AXON True Cap Metallized Polypropylene Capacitors Note that they also have "boutique" stuff some of which will cost more than expensive drivers!!!

They have inductors as well, but I'm not sure how they compare price wise as I made my own ;)

Tony.


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