Crossover Points

[amr952 10+ year member]

I have a quick question for some of you pros out there.

I bought a set of CDT CL-62s a while back thinking I was just going to stick to passive, but I recently picked up a CD8455 so I am hoping to try out an active setup. What I wanted to know is how do you pick what crossover points you use and what slopes to use.

What I have seen by reading around is ppl usually go about 100hz up to somewhere between 2.5 and 4khz on the mid, and then from 2.5 to 4k up on the tweet. So how do you pick between 2.5 and 4 or in between and do you overlap the tweet and mid.

If the speakers that I have now wiill not sound being used in an active setup, than I will buy something better. I just wanted to try this out with what I had first. If I need better speakers feel free to post your opinions.

I would really like some good info about this stuff, so feel free to post up some links to sites where I can learn more or just give me your opinion. Thanks for your help in advance.

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[alphakenny1 10+ year member]

http://www.caraudio.com/forum/showthread.php?t=146726

but to quickly answer your question:

Just a quick note on how to choose crossover points and slopes, just simply look at a speaker’s frequency response graph and it can give you a rough idea where to cross everything. Every manufacture has these graphs, so look at them and it can give you a rough idea on where to choose your points and slopes.

but some of it is trial and error if you don't have access to an FR graph. just basically set xover pts/slopes to your liking as staging and imaging goes as well.

 

[loserpunk 10+ year member]

you'll want to set the xover points for the tweets and mids at the same....you won't need to overlap say...2.5 and 2.7 or something like that, they will both be set at 2.5 or whatever freq you decides sounds best in your car to you

 

[amr952 10+ year member]

The problem is, I have never really heard a good system. I live in a small country town where everyone runs wal-mart crap. I am used to hearing crap so I just really was not sure what to listen for. Anyways I will start tuning though in that range and see what I come up with. Thanks for the help.

I am also going to contact CDT and see if they would give me a FR graph, not sure if they give those out but I will try.

Thanks Again.

 

[FoxPro5 5,000+ posts]

A good place to start would be at double the free air resistence (Fs) of the tweet. You may or may not need to cross them at the same frequency depending on your install.

 

[amr952 10+ year member]

I will try that, thanks.

I contacted CDT earlier this morning to see if they could get me an FR curve for the speakers. Hopefully I can get that and if not I will just ask for the specs.

 

[alteraudiousa 10+ year member]

well alot of it depends on your slopes you use. I currently am using a 8454 and running an hybrid active/passive setup. My HIGH RCA is used for the kick mid(5.25) and tweet which is run off the passive crossover and one of the MK 2.70. I run it pass at 200hz and up, the passive cross's the tweet over at 4khz IIRC. The MID RCA runs my larger 6.5 woofer in the door off the other MK2.70. For the crossover point I used 800hz and a 12db slope. I've found that the steeper the slope the higher crossover point I had to use to keep a full sounding stage. If i used the 6db slope I could go down to 500hz or so and it be fine. You definitely need some overlap as the crossover slopes slowly phase out/in the frequencies the closer they get to the crossover point. Its a lot of trial and error so get a few CDs that are musically diverse in the frequency range. Have fun i've spent 1 week finding the setup I like. Also first I'd suggest getting your time alignment right, use the formula in the manual and you'll have a good base to start with.

 

[amr952 10+ year member]

well alot of it depends on your slopes you use. I currently am using a 8454 and running an hybrid active/passive setup. My HIGH RCA is used for the kick mid(5.25) and tweet which is run off the passive crossover and one of the MK 2.70. I run it pass at 200hz and up, the passive cross's the tweet over at 4khz IIRC. The MID RCA runs my larger 6.5 woofer in the door off the other MK2.70. For the crossover point I used 800hz and a 12db slope. I've found that the steeper the slope the higher crossover point I had to use to keep a full sounding stage. If i used the 6db slope I could go down to 500hz or so and it be fine. You definitely need some overlap as the crossover slopes slowly phase out/in the frequencies the closer they get to the crossover point. Its a lot of trial and error so get a few CDs that are musically diverse in the frequency range. Have fun i've spent 1 week finding the setup I like. Also first I'd suggest getting your time alignment right, use the formula in the manual and you'll have a good base to start with.

Yeah looks like that is what I am going to be doing, CDT does not have the FR graph for my set of speakers. I am now hoping that they will give me the TS parameters but we will see.

Thanks.

 

[amr952 10+ year member]

Well, CDT gave me a spec sheet for the mid, but they did not have any specs for the tweeters so I guess I will be doing all of this by ear.

They did tell me this though:

"Xover is an elliptic design with a 24dB slope feeding into a 6dB design at the knee between the mid/twtr creating an “acoustic” 60dB slope. This is happening at around 4.2kHz"

So maybe I can start around there and see what I come up with.

 

[amr952 10+ year member]

Well I went outside today, and adjusted some things. I kind of like the sound of crossing them over at 3.15khz on a 18db slope. I would like to put it even lower, but I dont want to mess up the tweets, CDT crosses them over at around 4. I also played with the PEQ alot, that really does work really well to smooth them out.

I do really like the sound of an active setup though. Now I just need some more Mid-bass. But I am sure that will be fixed when my Sound deadener arrives. I am going to order a roll of RAAMmat BXT, that looks like the best bang for the buck.

Thanks for all of the help. If you have any more advice to add feel free to throw it out there, I am not finished by far. Thank for all of the help so far.