Making Your own Passive Crossover.

[TimmyB]

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]

http://www.parts-express.com/resources/building-a-crossover.cfm

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

http://www.parts-express.com/projectshowcase/projectindex.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]

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]

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]

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]

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.

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.

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]

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]

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]

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.

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]

H4Y1OGalDUo


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]

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]

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:)

[White WK Swagga]

What is a crossover? I'm a newb to this audio stuff. I used to just buy it and have it installed but now I'd like to try to install it myself.

[Matt]

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:)

I think design is where he is lost (as I am).... but I'm learning/reading.

Construction is easy :p

What is a crossover? I'm a newb to this audio stuff. I used to just buy it and have it installed but now I'd like to try to install it myself.

Simple explanation.

A crossover basically takes a full-range signal that your headunit pumps out and filters out the higher frequencies to be delivered to a tweeter, or smaller speaker and sends the lower frequencies to a mid woofer, or larger speaker.

http://i168.photobucket.com/albums/u197/ucf52/Untitled-32.jpg

[White WK Swagga]

Ok so for the money you're saying I should install one also? or is that only for serious systems?

[Matt]

Ok so for the money you're saying I should install one also? or is that only for serious systems?

It totally depends on what kind of speakers you're going to be using.

For a sub... the amp should have a crossover built-in.

For coaxials... they have built-in inline crossovers.

For components... they come with passive crossovers

For... raw drivers (like what I used), I have active crossovers in my processor.

Building your own passives is really meant for home use.


In a car you can usually match up raw drivers with a set of passives from a component set and be just fine.

[B.P.O.D]

matt/timmy if you guys want crossover designs let me know what specs you need and i will try to get the diagrams to you... crossovers are easy to assemble. just getting the right parts can be tricky.. also they can get large:(

[White WK Swagga]

*&^@*%@#@&*(@!*@$)(*&^)$&@^)!@&*)


^^^ That's what I understood out of what you just said. LOL But I think I understand what you're saying.....

[Matt]

matt/timmy if you guys want crossover designs let me know what specs you need and i will try to get the diagrams to you... crossovers are easy to assemble. just getting the right parts can be tricky.. also they can get large:(

Yeah, I think I'm going to pick up a loudspeaker cookbook. Learn the basics/fundamentals. I'd like to get to the point I am now with car audio and be able to recognize what drivers do well when paired together, interpreting t/s parameters and how they correspond with in-home acoustics, etc, etc.

I definitely need to figure what I can and can't do with my receiver. Filters, EQ, time alignment, etc.


*&^@*%@#@&*(@!*@$)(*&^)$&@^)!@&*)


^^^ That's what I understood out of what you just said. LOL But I think I understand what you're saying.....


:lol::lol::lol::lol:

[TimmyB]

Great info above. Basically I look at my JL XR crossovers and know I can def make an exact copy of them if one ever failed on me because all the components are labeled. But I want to try out drivers im seeing on partsexpress, tweeter and 6.5 mids, to put a nice little system in my friends VW. What is an "L-Pad"? The reason I ask is I just read this in an article on building a speaker "Incorporating an L-Pad into the tweeter design reduces the output by approximately 6db, aligning it with that of the Tang Band woofer". Im also wondering like i brought up before, just getting a decent midwoofer and then a tweeter with a cap soldered inline with it, would that work? Because thats how my JL TR's are right now, there is no crossover per say, just a woofer, and tweeter with a cap in believe on the positive lead.

But now im wondering why when I look up the JL XR tweeters being sold just by themselves they are spec'd at 8ohm's. I wonder if the resistors in the crossovers bring it down to 4 ohms like the complete system is spec'd at.

[Matt]

But I want to try out drivers im seeing on partsexpress, tweeter and 6.5 mids, to put a nice little system in my friends VW.

Dude, go active if you want to try out raw drivers... NO-ONE does that passively. No one.

Or buy a packaged component set.

Search Amazon.com for PG RSd65cs or 60cs - that set will blow away those JL's you have at a fraction of the cost :thumbsup:

What is an "L-Pad"? The reason I ask is I just read this in an article on building a speaker "Incorporating an L-Pad into the tweeter design reduces the output by approximately 6db, aligning it with that of the Tang Band woofer".

http://en.wikipedia.org/wiki/L_pad

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

Looks to be an inline level control for passive systems.

Im also wondering like i brought up before, just getting a decent midwoofer and then a tweeter with a cap soldered inline with it, would that work? Because thats how my JL TR's are right now, there is no crossover per say, just a woofer, and tweeter with a cap in believe on the positive lead.

Wouldn't then your mid woofer be sent a full range signal?

You'll have gobs of frequency overlap. In a stereo configuration you want like frequencies being reproduced from two drivers; one on the left and one on the right (left mid, right mid), or (left tweeter, right tweeter) - not (left mid, left tweeter, right mid, right tweeter).

But now im wondering why when I look up the JL XR tweeters being sold just by themselves they are spec'd at 8ohm's. I wonder if the resistors in the crossovers bring it down to 4 ohms like the complete system is spec'd at.

Likely. Crossover components + multiple drivers can change the final impedance that the amplifier sees.

[TimmyB]

Nope, the TR set I have only have a 6.5 woofer, a tweeter, and came with speaker wires for the tweeters that have what looks like a cap soldered onto the positive line. So the woofer is in the door, the leads on the woofers have 2 connectors on them, one for the speaker wires coming from the amp, then one going to the tweet. There is nothing but speaker wire between the woofer and amp.

I dont want to go active in her car, I want to buy raw drivers and find out how to make a simple crossovers for them. Im doing this because I want to upgrade her gear since she has dont alot for me, and I want to learn entry level speaker building. Im about to take apart my home tower speakers that I never use and use some of the components in there. Im not looking to make a competion system, just something better than her stock speakers. I have a nice older model precision power 100x2 amp for her fronts and an MTX amp for subs. I'll just keep the rear stock speakers in prob.

[Matt]

Nope, the TR set I have only have a 6.5 woofer, a tweeter, and came with speaker wires for the tweeters that have what looks like a cap soldered onto the positive line. So the woofer is in the door, the leads on the woofers have 2 connectors on them, one for the speaker wires coming from the amp, then one going to the tweet. There is nothing but speaker wire between the woofer and amp.

Right, so the amps is sending a full-range signal to your woofer, then the woofer is sending that same signal to your tweeter, but the inline cap on your wiring removes the lower frequencies.

I dont want to go active in her car, I want to buy raw drivers and find out how to make a simple crossovers for them. Im doing this because I want to upgrade her gear since she has dont alot for me, and I want to learn entry level speaker building. Im about to take apart my home tower speakers that I never use and use some of the components in there. Im not looking to make a competion system, just something better than her stock speakers. I have a nice older model precision power 100x2 amp for her fronts and an MTX amp for subs. I'll just keep the rear stock speakers in prob.

Yeah, but you really can't just start throwing random crossovers with random drivers. The passive crossover needs to be designed to work with the drivers you're using.

I'd use a passive crossover from a car audio component set before I used one from a home audio tower set.

[TimmyB]

Right, so the amps is sending a full-range signal to your woofer, then the woofer is sending that same signal to your tweeter, but the inline cap on your wiring removes the lower frequencies.

That is what it seems, odd to me but I guess it works???



Yeah, but you really can't just start throwing random crossovers with random drivers. The passive crossover needs to be designed to work with the drivers you're using.

Thats what I want to learn, how to make a crossover for the speakers I am eyeing on PE.

I'd use a passive crossover from a car audio component set before I used one from a home audio tower set.

I do have two extra JL XR crossovers and the tweeters I bought in a set where I only needed the woofer. I can use those, but then I would have to pick out raw drivers that would work with them. Any ideas? Keep in mind I want to do this sytem cheap, thats why I want to buy raw drivers and do everything myself. Partsexpress has Dayton SDS 6.5's for 10 bucks each on sale that has good reviews. Thats what im looking to do, nothing fancy or expensive and using all the spare wires and amps I have. Im about to just rip out my TR's from the rear doors and give them to her. I want to do something nice for her, but I have limited money to do it.

[Matt]

I do have two extra JL XR crossovers and the tweeters I bought in a set where I only needed the woofer. I can use those, but then I would have to pick out raw drivers that would work with them. Any ideas? Keep in mind I want to do this sytem cheap, thats why I want to buy raw drivers and do everything myself. Partsexpress has Dayton SDS 6.5's for 10 bucks each on sale that has good reviews. Thats what im looking to do, nothing fancy or expensive and using all the spare wires and amps I have. Im about to just rip out my TR's from the rear doors and give them to her. I want to do something nice for her, but I have limited money to do it.

Hmm, I'd email JL and get the specs for the crossover.

Try to get;

Tweeter x-over point, slope and if there's any attenuation)
Woofer x-over point, slope

Then go from there.

The Peerless SLS (on buyout) (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-250) aren't a good match for a door. They have a pretty high inductance (Le), very low QTS and not a whole lot of Xmax - definitely stay away from those unless you're going to use an enclosure for them.

[TimmyB]

Good info, and good starting point. What is a good Xmax for a 6.5 woofer? I am seeing about 5mm on average. The other references you mentioned I have no idea about or what they even mean, the Le and QTS, so im going to research some more.

I just tested my extra XR crossovers and tweeters and they work great. So now I just need to get a set of 6.5's that will work with them. Im emailing JL right now to see if I can get some detailed specs on the XR's.

[TimmyB]

Now im completely confused. The JL XR tweeters are 8 ohm but the 6.5 mids are 4 ohms. So the only thing I can think of is the resistors in the crossover make the amp see a 4 ohm load for the tweets? My amp is not stable at an 8 ohm load, so I would be getting an overload light on if the tweets were trying to run off 8 ohms.

[Matt]

Good info, and good starting point. What is a good Xmax for a 6.5 woofer? I am seeing about 5mm on average. The other references you mentioned I have no idea about or what they even mean, the Le and QTS, so im going to research some more.

5mm is about the minimum I would go. It may not seem like much but going from a woofer that has 4mm xmax to 5mm xmax is a 25% increase.

Le (inductance) is tough to explain, especially since I don't fully understand it. The lower it is, generally the better a driver will perform in a door (properites like: faster response, snappier punchier, etc). Definitely shoot for something under 1mH.

Qts is also tough to explain, especially since I don't fully understand it. :p But the higher the Qts, the better it is for a door application. Shoot for something over .5 Qts.

Now im completely confused. The JL XR tweeters are 8 ohm but the 6.5 mids are 4 ohms. So the only thing I can think of is the resistors in the crossover make the amp see a 4 ohm load for the tweets? My amp is not stable at an 8 ohm load, so I would be getting an overload light on if the tweets were trying to run off 8 ohms.

Amp stability is only a floor (not a ceiling), so if your amp is stable down to 2 ohm, or 4ohm, then it will be fine for anything above that ohm load (i.e. 16ohm). Power output will be reduced though.

[TimmyB]

Ok, thats what I was under the impression of. That if per say I have an amp rated for 100 watts per channel at 4 ohms, if I were to hook up an 8 ohm speaker it would still "work" but the output of the amp would be cut in half? And it only works when using a higher ohm speaker, as in if an amp is rated at 100 watts per channel at 4 ohms I would not be able to use a speaker rated below 3.9 ohms because it would overdraw that amp? I am still really unclear to all this, but trying to at least grasp the concepts.

So if what I am thinking is correct, I can buy a 12 ohm 6.5 woofer rated at 30 watts RMS and safely run it off my JL amp fronts that are spec'd out at producing 150 watts per channel at 1.5-4 ohms. Because the higher ohms would drop the watts to a "safe" level?

[Matt]

Ok, thats what I was under the impression of. That if per say I have an amp rated for 100 watts per channel at 4 ohms, if I were to hook up an 8 ohm speaker it would still "work" but the output of the amp would be cut in half?

Pretty much yep!

And it only works when using a higher ohm speaker, as in if an amp is rated at 100 watts per channel at 4 ohms I would not be able to use a speaker rated below 3.9 ohms because it would overdraw that amp? I am still really unclear to all this, but trying to at least grasp the concepts.

Correct. Some amps that are 4ohm stable (and that's their lowest rated ohm load) can still dip below that, but it's always best to stick within the manufacturers limits.


So if what I am thinking is correct, I can buy a 12 ohm 6.5 woofer rated at 30 watts RMS and safely run it off my JL amp fronts that are spec'd out at producing 150 watts per channel at 1.5-4 ohms. Because the higher ohms would drop the watts to a "safe" level?

You could also buy a woofer that's rated for 4ohm and be just as safe, well actually safer; It's all about gain control. Headroom is a good thing... the lower you can keep your gain, the less chance you'll have at clipping, the lower you can keep your noise floor.

If I could I would have 500w amp channels driving my dash drivers (rated at 15 watts) and my mid woofers (rated at like 80 watts). Remember, your speakers don't ever see those rated numbers - those are the absolute peak! So it's not like your speakers will see 150 watts ever from your amp... even at 1.5ohm. Music is dynamic.

[TimmyB]

I swear, the more I try to research speakers and crossovers the more confused I am. I am now wondering why the need for going "active" and having crossovers. I know both will filter out frequiencies that the dedicated speaker is not rated for. But here is why I am confused, or why my mind is now thinking.

I have been researching two way speakers and it appears that the woofer receives a full signal from the amp or headunit and there is only a capacitor on the positive going to the tweeter. I was just looking at my stock speakers, and they appear to have nothing to filter out any highs or lows. I keep going back referring to my JL TR components, because there is only the 6.5 woofer and a capacitor soldered onto the poistive wire going to the tweeter. So going with this, I can safely make a component set by getting a woofer and soldering a cap onto the tweeter for it? That is what is basically in a 2 way car audio speaker.

[TimmyB]

Here is a simple two way speaker, it only has a capacitor on the tweeter positive wire.

http://i276.photobucket.com/albums/kk37/tdiglar78/299-275_sI.jpg


I was also looking up 2 way speaker pattens.

http://i276.photobucket.com/albums/kk37/tdiglar78/6963650-0-display.jpg

[Matt]

I swear, the more I try to research speakers and crossovers the more confused I am. I am now wondering why the need for going "active" and having crossovers. I know both will filter out frequiencies that the dedicated speaker is not rated for.

It also, more importantly, gives you the flexibility to try out as many different drivers as you'd like. With a passive, you're stuck with those settings. Also, pretty much all active decks give you the ability to level set, time align, and very good equalizers. All that you don't get with a passive crossover.


But here is why I am confused, or why my mind is now thinking.

I have been researching two way speakers and it appears that the woofer receives a full signal from the amp or headunit and there is only a capacitor on the positive going to the tweeter. I was just looking at my stock speakers, and they appear to have nothing to filter out any highs or lows.

Your stock speakers are being sent a filtered signal from the amp. The factory Boston Acoustic amp has built-in filters.

I keep going back referring to my JL TR components, because there is only the 6.5 woofer and a capacitor soldered onto the poistive wire going to the tweeter. So going with this, I can safely make a component set by getting a woofer and soldering a cap onto the tweeter for it? That is what is basically in a 2 way car audio speaker.

Yes you could. Here's the difference between a separate, external passive crossover and an inline capacitor wired between the mid woofer and tweeter.

The separate passive crossover will designate/filter frequencies for BOTH mid-woofer and tweeter. This ensures a smooth transition between drivers when playback occurs. (assuming the passive crossover is in fact meant/built for the the mid-woofer and tweeter).

The full-range signal sent to the woofer, inline capacitor system relies on the natural roll-off of the mid-woofer instead of an actual filtered (crossover) signal. So, with this method, you are leaving a lot of overlapping frequencies - being covered by both the tweeter and mid woofer. This causes confusion for the listener/ear.

It's much cheaper for manufacturers to build a simple inline cap for a mid/tweeter 2-way speaker, and most people don't know the difference anyways, so why would they even bother with an external crossover.