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kingsxman
03-19-2006, 11:32 AM
I'm trying to setup the xover settings on my 8445. I'm running my 2-10" JL 10w6v2 subs off a JL 500/1 and my fronts/rears off a JL 300/4. All connections to amps are from the outputs on the deck.

My question is how to properly set the xover settings on teh 8445. I'm not quite sure how the slope affects the sound. I'm trying to get the bass to be as tight and punchy as possible...while still retaining good SQ. It seems like having the xover settings in "pass" mode seems to sound best..which doesnt make any sense to me. (I hear better upper note definition on the bass guitar that way).

I guess I'm wondering how the slope SHOULD affect the sound and what is the effect of changing from 63hz to 80 hz etc. in the xover setting. Do you get to change settings on EACH of these settings or is it one or the other?

FoxPro5
03-19-2006, 11:55 AM
Well you kind of have a few options. One would be to run the x-over points strictly from the HU like you are talking about, and then run the amps full range (ie not use them). Or you can run the HU "pass" on all frequencies and let the amps take care of it. The dissadvantage here is lack of adjustablility at your finger tips.

If you do both you effectively double the slope. FOr example, if you LP the sub at 63hz at 12db/oct on the HU and 12db/oct on the amp, you now have a 24db/oct at 63hz. At least I think that's correct.

Also remember that the slope is in db per octave....which means higher slopes cut the frequencies at a greater rate than shallower slopes. The best way it was descibed to me would be to imagine two people talking to one another. The end of their sentences would represent the x-over points and how fast they stoped taking would be representitive of the slope. If one person was talking and just slowly faded at the last word of the sentence, that would be a shallow slope....maybe 6db/oct. If that person all of a sudden stopped very quicky that would be a steeper fall off. At the same time you could also think of the next person starting to talk and the rate at which their voice inceases to be the slope of the next speaker, for example. Also, the x-over point is boosted in a way but I can't remember how.

Hope that makes sense. :)

kingsxman
03-19-2006, 12:00 PM
I have to pull the amp off the board and check the settings. The guy did a great job with the install...except I cant see any of the settings! I'm all about mounting the JL stuff upside down so you can see the sh*t! Otherwise..its a pain.

Thats kind of what I thought the pass settings where for..but wasnt sure.

Whats a good xover point for those speakers?

mikegett
03-19-2006, 12:47 PM
You can't add two 12db slopes and get a 24 db slope. A 24 db slope allows more frequencies to pass through the crossover than a 12 db slope. If you pass the frequencies through a 12 db crossover it will loose the frequencies that a 24 db slope would have allowed. The same holds true for two 24 db slopes. Passing frequencies through two 24's will not eliminate the same frequencies that a 12 db would.
Your HU crossovers are called active. Meaning that the frequency is altered prior to the source (in this case your amp). Your amp crossover is passive and altered after the source (your amp). A active crossover uses software to adjust the settings while a passive uses components like resistors and caps. Some people prefer the sound of active while others prefer passive. I would suggest using both seperately and see what you like more. I doubt you will notice much of a difference on your subs. It becomes more noticable between mids and highs.
Every sub will very on how it should be crossed over. Even the sub enclosure will affect how well it will reproduce frequencies. The sealed enclosure will allow the sub to reproduce wider ranges without distortion. The only real way to know is by setting your crossover high and play test sounds. You did say that bandpassing sounded better. Most likely this was due to the sub playing frequencies that were too low for it. Set the sub high pass slightly above the manufacturers rated low end. I would suggest using a 12 db slope on all subs. The 24 will allow too many frequencies. Place your low pass close to 200 htz. Most mid bass like quitars are in this range. Play a good rock cd paying special note to the mid bass. A sub has a very difficult time producing mid bass and bass affectively. If the guitar strings sound muddy opposed to short and snappy, lower the low pass setting. You won't be able to improve how the sub reproduces the mid bass, but you will be able to tone down its volume. Allowing your fronts to control the mid bass.
If you are new to crossovers, I suggest you search for charts on frequency ranges. It will help you to know what sounds are played in what ranges.

thch
03-19-2006, 01:13 PM
If you do both you effectively double the slope. FOr example, if you LP the sub at 63hz at 12db/oct on the HU and 12db/oct on the amp, you now have a 24db/oct at 63hz. At least I think that's correct.

well, it'll be 24db/oct, but with a response that is not quite the same as a true 24dB/oct fillter. and the cutoff point will no longer be 63hz.



A active crossover uses software to adjust the settings while a passive uses components like resistors and caps. Some people prefer the sound of active while others prefer passive.

digital crossovers = software based. active = any crossover that uses external energy (not from the signal). passive = anything that uses no external energy.


as for the crossovers and slopes. you should expiriment. some things to try:
both shallow slopes. (6db/oct or 12db/oct) --good if the subwoofer is turned up very loud compared to the midwoofers)
both steep slopes (24db/oct) -- good if the midwoofer and subwoofer have sound issues (sub sounds bad on vocals, mid sounds bad on bass)
staggard slopes (24db/oct on subwoofer, 12dB/oct on midwoofer). -- the idea is that the midwoofer will have an acoustic 12dB/oct rolloff, so it makes sense to conbine it with a 12dB/oct rolloff for a 24dB/oct rolloff.
try each for a few frequency settings. make sure to try the woofer "reverse phase" option, as turning it on or off my improve the sound.

kingsxman
03-19-2006, 08:45 PM
Good advice all.

I should point out that my "mid woofers" are my 6x9's in the rear and my 5 1/4's in the front. So...not much for mid woofers....

I ended up setting up my sub amp to run "full range" and did the xover at the deck. I found that with the 8445 I got better "punch" by crossing it over at 63 hz. I also found that I could retain the best "note definition" by keeping the slope relativly small. The more I made the slope (i.e. in the deck xover the more db's I made the cutoff) the more of a break there seemed to be in the xover but for some reason their just didnt seem to be as good of flow between the sub and the mid woofers.

I played with the reverse phase and found that it did seem to make a difference..although very slight. I didnt play with the 24db slope setting on the amp yet. I did see that JL Audio recommends 12db if the subs are in a trunk and not firing directly into the cab. ...so thats what I did.

Just havent been able to get the punch out of this system compared to my old system that was stolen. But I think the biggest thing might have been that my old system had a sealed enclosure built specifically for my JL's by Mr. Marv...who does great work. This setup was built for the speakers but seems to be physically bigger than Marvs box. The bass doesnt have the punch or definition of the Marv cabinet and is a bit boomy...