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-   -   Making Your own Passive Crossover. (http://www.jeepgarage.org/f50/making-your-own-passive-crossover-8038.html)

TimmyB 03-30-2010 04:50 PM

Making Your own Passive Crossover.
 
I have been researching making passive crossovers for a set of front speaker components. The reason is im finding really good prices on speakers on partsexpress.com and want to install a decent system in one of my friends VW Passats. From blowing some of my speakers and buying replacement sets I have speakers left over also. I know i should prob be posting this on DIYMobile, but I dont like that site for some reason. Looking at my JL XR crossover, it looks like I can make it myself with radioshack parts, if I learn a little more about ohms and values of capacitors. Im not to that level yet, but getting there.

Has anyone ever made a working passive crossover system, either for home or car audio? I have been researching online for the past two hours now and there is so much info around, seeing if anyone from here has done it. I found this informative site that im still trying to grasp.

http://www.bcae1.com/passxovr.htm

Matt 03-30-2010 05:13 PM

Re: Making Your own Passive Crossover.
 
http://www.parts-express.com/resourc...-crossover.cfm

http://www.parts-express.com/resourc...-a-speaker.cfm

http://www.parts-express.com/project...ojectindex.cfm

http://www.parts-express.com/resources.cfm

Get your reading glasses out! :p

BCAE1 is an excellent resource!

DIYMA has some VERY knowledgeable folks when it comes to building passive crossovers... 'MiniVanMan' - he's a great resource.


I'm just getting myself into Home Theater and I'll be taking on building my own speakers in the near future. Should be fun!

TimmyB 03-30-2010 05:53 PM

Re: Making Your own Passive Crossover.
 
Great info. But here is my thing, I have JL Audio TR 650 components in the rear doors of my car right now, and all they consist of is running the speaker wire from the amp directly to the 6.5 mid, then there are speaker wire connections at the mid terminals to run the tweeter speaker wires to the tweeter, and on the positive wire there is "something" encased in heatshrink. But thats it, no seperate crossover boxes or anything else. So im thinking my TR mids are running directly off the amp and the tweeters are being "highpassed" by that "something" heatshrinked with in the wiring. So why do my XR's have this elaborate big crossover when the TR's have only a capacitor it seems to the tweets?

TimmyB 03-30-2010 05:59 PM

Re: Making Your own Passive Crossover.
 
I will never buy JL Audio speakers ever again. Their amp, YES. But what im finding on partsexpress appear to be the same if not better speakers for much less money. Am I wrong?

TimmyB 03-30-2010 06:03 PM

Re: Making Your own Passive Crossover.
 
I have a set of JL XR crossovers and tweeters sitting here, I want to install them in my friends car. I know the tweeters are 8ohms, so does that mean the mids would be 8ohms also to make a 4 ohm load? And in the JL spec sheet is says to never use the crossover without the XR components, is that a bunch of junk and I can use different brand speakers off that crossover?

Matt 03-30-2010 06:22 PM

Re: Making Your own Passive Crossover.
 
Quote:

Originally Posted by TimmyB (Post 179287)
Great info. But here is my thing, I have JL Audio TR 650 components in the rear doors of my car right now, and all they consist of is running the speaker wire from the amp directly to the 6.5 mid, then there are speaker wire connections at the mid terminals to run the tweeter speaker wires to the tweeter, and on the positive wire there is "something" encased in heatshrink. But thats it, no seperate crossover boxes or anything else. So im thinking my TR mids are running directly off the amp and the tweeters are being "highpassed" by that "something" heatshrinked with in the wiring. So why do my XR's have this elaborate big crossover when the TR's have only a capacitor it seems to the tweets?

The XR passives are better (obviously). The inline passives aren't up to par.

Quote:

Originally Posted by TimmyB (Post 179290)
I will never buy JL Audio speakers ever again. Their amp, YES. But what im finding on partsexpress appear to be the same if not better speakers for much less money. Am I wrong?

:thumbsup:

Many brand name speakers are just badged raw drivers. JL's home audio speakers are re-badged ScanSpeak drivers, Alpines Type-X speakers are re-badged ScanSpeak drivers, the list goes on.

Quote:

Originally Posted by TimmyB (Post 179293)
I have a set of JL XR crossovers and tweeters sitting here, I want to install them in my friends car. I know the tweeters are 8ohms, so does that mean the mids would be 8ohms also to make a 4 ohm load? And in the JL spec sheet is says to never use the crossover without the XR components, is that a bunch of junk and I can use different brand speakers off that crossover?

ehh, I'm not sure. You may want to do a search over on DIYMA.

TimmyB 03-30-2010 06:35 PM

Re: Making Your own Passive Crossover.
 
Matt, im really shocked you do not know that answer. Does a mid and tweeter running off the same crossover act like its wired in parallel. I really have been trying to find out, so im not just trying to take the easy way out. Do you know how I can test my JL 6.5 mid to see what rated ohm it is? Until recently I was under the impression a passice crossover just splits the signal and does not effect the ohm's, but after seeing the tweeters are 8ohm I am thinking different now, thinking the mids must be 8 ohm also to have a final value of 4 ohms.

TimmyB 03-30-2010 06:47 PM

Re: Making Your own Passive Crossover.
 
Great info Matt. I am now going another route, trying some of the brands you recommended insted of the "name' brand high priced stuff.

Matt 03-30-2010 06:56 PM

Re: Making Your own Passive Crossover.
 
Quote:

Originally Posted by TimmyB (Post 179330)
Matt, im really shocked you do not know that answer. Does a mid and tweeter running off the same crossover act like its wired in parallel. I really have been trying to find out, so im not just trying to take the easy way out. Do you know how I can test my JL 6.5 mid to see what rated ohm it is? Until recently I was under the impression a passice crossover just splits the signal and does not effect the ohm's, but after seeing the tweeters are 8ohm I am thinking different now, thinking the mids must be 8 ohm also to have a final value of 4 ohms.

Actually, I do know (and I should have remembered, lol). I've used a mid woofer from a component set before, and my research showed that the mid and tweeter in a 4-ohm component set are each 4ohm as well.

So;

Mid = 4ohm
Tweeter = 4ohm

That was based on the set I was using.

I don't think it's wired in a parallel. The power is split, then filtered, then sent to the appropriate driver (if I had to guess). Honestly, I have always stuck with active crossovers, as that's what got me started on that site, so my knowledge base for passive systems isn't any where near what it is for active.

Quote:

Originally Posted by TimmyB (Post 179353)
Great info Matt. I am now going another route, trying some of the brands you recommended insted of the "name' brand high priced stuff.

If you want a good mid wofer that performs well in the door, try the Dayton RS180. You really need a flexible active crossover though, especially if you're going to start getting into drivers that need to be high passed (tweeter, wide-band).

Matt 03-31-2010 08:52 PM

Re: Making Your own Passive Crossover.
 



Thought you may find this helpful. I'm debating with myself about purchasing this DIY speaker kit and noticed it had a video showing how easy it was to assemble the crossover network.

I don't think assembly was ever an issue with you, rather what exactly to use and where, but I figure it may intrigue you to continue your search.

:)

05wkguy 04-01-2010 01:50 AM

Re: Making Your own Passive Crossover.
 
I've worked with and built a few (5-10) passive systems. The link you posted does the hard part for you and figure out what values you need for the impedence and frequency. Best advice i can offer is to use the best quality components you can get (Solen comes to mind) as the cheap stuff will not have the tight tolerances you need to accurately cut the frequencies. Also you will lose some power through a passive,the better parts will lose less than the cheap stuff (2-4% loss versus 10-15%).

For your guys' own info,the way a crossover works is not actually by "dividing" the sound as that's not physically possible. What happens is that full range is sent to each device but the cap or coil filters out the unwanted frequencies,so the driver only receives the intended range. As for impedence load,the amp will see only one driver in each frequency range so it "sees" just a standard 4 ohm load, assuming you're using 4 ohm drivers.

Timmy, you should also consider using a Zobel impedence equalization circuit within the crossover. I'll see if i can dig up my Mobile Dynamics books with the design calculations for you. It's a relatively easy add-on but helps smooth out the freq response.

B.P.O.D 04-01-2010 11:01 AM

Re: Making Your own Passive Crossover.
 
crossovers are really easy to make timmy!!! matt gave you some good reading, i've made crossovers for cars and home audio with my dad... you know how to solder so you're good to go:)


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