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View Full Version : Headunit VS Amplifier crossover



BlkonBlkFG
11-17-2006, 06:56 PM
So you have crossover settings on your headunit....and you have crossover settings on your amplifier. Which one overrides which? Or do they work together? What exactly happens? If I have my HP on my HU set at 80hz and my amp set at 160hz....how would that work, what would happen? would one override the other or would they just find an average? Thanks guys

BlkonBlkFG
11-17-2006, 10:06 PM
nobody knows ??

heyman421
11-17-2006, 10:08 PM
just use one or the other

choose whichever one has the slope you want, or if the headunit's adjustable, use that

squeak9798
11-17-2006, 10:14 PM
Which one overrides which?

Neither


Or do they work together?

They both will affect the signal according to the xover frequency they are set at and their individual slope and type of filter.


What exactly happens?

Well, if they both were the exact same type of filter and both were set to exactly the same frequency, then essentially their slopes would combine. If they both defined the "crossover frequency" as the point where the signal is attenuated by -3db, and you set them both to 50hz...then the signal the speaker would receive would be -6db down at 50hz. If they were both 12db/oct crossovers, then the signal would be -24db down at 25hz.


You can cascade them, but the final result (the signal the speaker receives) will be the product of both crossovers together. And, depending on the situation...the final result may be more desireable then using either filter independently.




If I have my HP on my HU set at 80hz and my amp set at 160hz....how would that work, what would happen?

See above.


would one override the other or would they just find an average?

Niether. They would both affect the signal in the manor in which they were designed....which means you would need to know specifics (how the xover frequency is defined [generally it's the -3db point, but not always), their slope, the type of filter they are [butterworth, LR, etc]) in order to predict the final outcome.....


This post should help you some aswell;
http://www.caraudio.com/forum/showpost.php?p=1593386&postcount=14

BlkonBlkFG
11-17-2006, 10:30 PM
I guess I have alot of learning to do in order to understand this stuff.

when you guys talk about tones such as 0dB @ 60 hz. I understand that this is a 60hz frequency but what exactly is the 0dB? I thought a dB was a level of noise. So why does it keep going down? -3dB , -6dB, etc....and why the lower it goes does it have a better chance of "clipping" your equipment ? Another thing i dont understand is how or what these octaves and slopes are. So you have a 12dB slope and 18dB slope on your amp. How does this stuff effect the sound and how can i understand it so that i can set my amps and headunit properly to sound good?

heyman421
11-17-2006, 10:39 PM
decibels ARE a measurement of sound energy, correct

people refer to sound levels in recorded music as negative decibels because with any recording media there's a maximum amplitude of the recorded wave, which is referred to as 0db, and then anything less than the absolute loudest recordable amplitude is referred to by it's decreased energy, in negative decibels, any amplitude greater than 0db can't be properly recoded (on the media) or reproduced (by the ampliifer), and so the highest and lowest parts of the wave get cut off, or CLIPPED. Imagine the bouncing visualization meters on a tape deck..... You wanted to get the meters to bounce as close to 0db without going over, into the red.......

and the slope is how quickly the crossover decreases throughput above or below the crossover setting with respect to frequency.................

hit up google, it's hard to understand without visuals, and i'm too tired tonight to draw a picture

BlkonBlkFG
11-17-2006, 10:55 PM
still dont understand it though. i mean which is better for fronts / rears / sub...12/db slope or 18dB slope? will i hear the difference? This is the stuff i dont get. Guess i'll check out google. Thanks man.

heyman421
11-17-2006, 10:59 PM
there's a big difference between a 12db slope, 18db slope, 24db slope, ya, you'll notice.

an 18db slope is the same as if you put the signal through a 12db slope, and then put THAT signal, that had already been through the crossover, through another 12db slope......

and a 24db crossover is the same as putting the signal through 2 18db crossovers, etc.

As long as the speakers are installed correctly, and not terribly overpowered, a steep crossover isn't crucial. the steeper slopes are more critical when people get into active x'overs, or actually crossing their individual speakers from one another, since some speakers are more sensitive than others to playing frequencies that are too high, or too low

squeak9798
11-17-2006, 11:07 PM
still dont understand it though. i mean which is better for fronts / rears / sub...12/db slope or 18dB slope?

Possibly either, possibly neither.

It isn't a "better and worse" type of scenario. It's a what best fits my particular situation type of thing.

All have their advantages and disadvantages, and which is "best" for a particular application will be determined by that specific application.


This is the stuff i dont get. Guess i'll check out google. Thanks man.

Maybe this will help you some ?

http://www.caraudio.com/forum/showpost.php?p=1746548&postcount=2