Crossovers

solacedagony · Post by **solacedagony** » Mon Apr 17, 2006 8:34 am

Hey guys, I noticed Jonathan was putting a lot of emphasis on crossovers and whatnot in a couple posts here and there. I was already reading up on them since I was interested in them and I figured I should share whatever information I was coming up with. So for anyone that wants to learn stuff about crossovers, or add additional information (Maybe for the FAQ section if it's complete enough?)

Starter websites:
The individual components, what they do, and some more advanced stuff: http://www.passivecrossovers.com/
Parts Express Crossover FAQ tells why you need them, how they work, etc.: http://www.partsexpress.com/resources/c ... rfaqs.html

Parts Express Crossover Graph Examples: http://www.partsexpress.com/resources/c ... rhelp.html
Parts Express Component Values Chart: http://www.partsexpress.com/resources/xover.html
X-Over 3 Pro Software for designing crossovers: http://www.partsexpress.com/pe/showdetl ... er=500-919

Jonathan · Post by **Jonathan** » Mon Apr 17, 2006 8:40 am

Good stuff, I think this is FAQ or sticky material.

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 8:51 am

I think there should be some emphasis on chossing the right slopes and frequencies. I'm going to be converting my system over to the active crossovers in my deck, (DEH-P940MP), and have been struggling with calculating optimum starting crossover points and slopes. I've found tons of info online regarding calculating caps and coils for crossovers and even how to build active crossovers, but there's not much out there for getting the right slopes and frequencies. So ... if I'm cutting my tweet off at 12db/octive at 4k, at what slope and freq should I start looking at bringing my mid in? and if the Sub is crossed at 63 hz at 24db, what slope and freq. do I cut my mid off there? And how does all of that mess with phasing? Do I invert the phase of the mid or no? I think that sort of info would really help a lot of people out.

Jonathan · Post by **Jonathan** » Mon Apr 17, 2006 9:04 am

You really can't predetermine what will work well in a car (or a home, for that matter). The main thing you need to see is the performance of the individual drivers, particularly their limits. Usually you'll only see tests of raw drivers available to the DIY community. The good thing is that if you have an active crossover, you can get those drivers and shy away from the overpriced garbage that is 90% of the car audio industry.

Once I get the time and software to do it, I may start designing some DIY car audio component systems. Not really for profit, just something to give me something to do in my spare time to help fellow enthusiasts :) . It'll help those that won't have an active crossover and save them tons of money.

Jonathan · Post by **Jonathan** » Mon Apr 17, 2006 9:12 am

Airforceyooper wrote:q should I start looking at bringing my mid in? and if the Sub is crossed at 63 hz at 24db, what slope and freq. do I cut my mid off there? And how does all of that mess with phasing? Do I invert the phase of the mid or no? I think that sort of info would really help a lot of people out.

What type of 2nd order crossover, L-R, Bessel, Butterworth, Elliptic, or other?

You could make ten crossovers at the same frequency and slope and all of them sound very different, it's just so far from cut and dry that you can't nail it. Even in home audio where you have a determined axis, location of the driver, and consistency in the environment, it still takes a long time to design a good crossover. That's why the flexibility of active is so popular.

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 9:23 am

That's where I'm at. I've got my tweets, DLS tweets and Focal mids and am going to set it all using the three way active xover in the hu. I'm looking at new amps and subs yet also. haven't quite decided what they're going to be since my girlfriend isn't liking the size of the price tag on most things. I'm working on her though. Anyway, I know the frequency response of my drivers. But crossing them over correctly is what I'm worried about. I know my tweets can play down to about 1.5k pretty nicely and come with an 12db passive xover at 4k. I know my mids will play very nicely from about 100k or so up to about 2k. My subs suck, I don't even want to talk about them or I'll get made fun of. My amp is just old and needs to be replaced. I've debated getting different mids so I can drop them down lower, but I don't think the girlfriend is going to go for that so I'm stuck with running the sub up higher than I'd like. I've even considered getting a couple 8s or something for midbase and using passive xovers to blend them and the Focals together within the middle active band of the hu. (I hope that made sense) Anyway, I didn't mean to screw up the thread. Sorry if I did. My whole point was this ... If a person has all their graphs and frequency responses of their individual drivers and wanted to set up their actives within the limits of their equipment, how far apart and at what slopes are best to cross them? You don't want to cut your mid of at 2k and your tweet at 2k also. But depending on slopes, the difference between isn't going to be the same either. How should all that be determined? Man I got wordy. Time for bed.

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 9:26 am

See, now I thought L-R, Bessel, Butterworth, etc. were just other names for the orders of Xovers. I didn't reallize you could have a 2nd order Bessel and a 2nd order L-R. Do those not necessary apply to active? And what about the phase issue? Is that a concern with active or only passive since the inductors and capacitors arn't present to tweek the signal?

Jonathan · Post by **Jonathan** » Mon Apr 17, 2006 9:28 am

Noooooooo, don't play those tweets to 1.5k, trust me. Keep them above 3k at least. There are VERY few tweets that can handle 1.5k.

Which Focal drivers are those?

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 9:40 am

I planned to cut them off actively the same as the passives were going to, 12 db at 4k. But at what slope and freq. do I bring the mid in at? The focals are the 6w4311. I've got two for each door to go with the tweet. I thought it would be a pretty decent match. We'll see.

Jonathan · Post by **Jonathan** » Mon Apr 17, 2006 10:27 am

I'm guessing UR1 tweets? I wouldn't focus on running those midbasses as high as possible due to the energy storage issues. Instead, I'd try a steeper slope and lowering the x-over frequency of the tweet to around 2.5-3k or so, and cross those midbasses below that. The exact frequency and slope will be determined by the application, but I'd start with a 4th order L-R x-over for the tweet at 3khz. If it sounds stressed at any point, then you can start raising the x-over freq until they're more composed.