what is the correct way to set crossover on amp & hu?

[harveywong 0]

What is the best way to set your crossover setting on your amp and headunit? Can you leave your amp a little higher, then adjust from your hu when needed or should they both be set on the same HZ? What would be the best frequency for 2 DD350012e in a trunk setup? Currently I am set at 80 hz on my radio and about 90 hz on the amp. Bass boost is at 0, do you recommend using the bass boost or does this do more harm than help to your subs?

[Sir-Lancelot 216]

use one or the other imo. Both should have a pass through or full range setting. Mine are full range on the HU and set on the amps.

There are thousands of posts advising against bass boost on here.

[Impious 1,476]

You can use one or the other, or both. If you use them both set to the same frequency, and they are both the same "type" of filter, then the slope will increase to that of the two crossovers combined and the signal will be down -6db at the crossover frequency as opposed to -3db (assuming the crossovers are both down -3db @ the crossover frequency). If you use them both but stagger them as you have them now then it's a little trickier to figure up the exact slope(s), but the jist is that the slope again increases where the 2nd filter begins to affect the signal aswell. Using them both either staggered or stacked can be useful in some scenarios. Or you can try using one and then the other and see which you like best. Generally the xover on the amp will provide a greater selection of frequencies as they use a potentiometer to set the xover point which is "infinitely variable" between the minimum and maximum settings, whereas most HU's generally have a few fixed points you have to select from. But differing slopes may make one a better selection than the other in your particular vehicle with your particular setup.

There is no hard and fast rule that can be followed when it comes to setting crossover points in a vehicle as there are too many variables. There is simply no way someone on the internet can tell you the best crossover settings for your stereo. It's simply not possible as there are too many things that need taken into consideration. The best thing to do is simply spend a little time toying around with them on music you are familiar with, and set them to where sounds best.

Bass Boost should generally be avoided as it increases the chances or occurrences of clipping the amplifier.

[sefugi 166]

Great post Impious, gave me a few ideas to check on my setup. Thanks

[harveywong 0]

If my car peaks at 50 hz, does this mean that i should set my crossover at 50 hz also?

[GlassWolf 5]

What is the best way to set your crossover setting on your amp and headunit? Can you leave your amp a little higher, then adjust from your hu when needed or should they both be set on the same HZ? What would be the best frequency for 2 DD350012e in a trunk setup? Currently I am set at 80 hz on my radio and about 90 hz on the amp. Bass boost is at 0, do you recommend using the bass boost or does this do more harm than help to your subs?

no bass boost.

use one or the other, but not both the head unit and amp crossovers.

combining the two causes the slope to be cumulative, and messes with the settings.

I would start with the LPF @ 50Hz, and HPF @ 100Hz. You can adjust from there, but it's a decent starting point.

the 1 octave gap will be filled in by the roll-of from both the mids and the subs.

amplifier crossover settings

The above link illustrates what I mean with the gap between HP and LP filters.

[harveywong 0]

my pioneer hu has the subwoofer outputs but it only let you pick a frequency and does not have a full range setting. So if I were to use the hu crossover where should I set the crossover on the amp (should I turn it all the way up which is 200hz)?

[Impious 1,476]

use one or the other, but not both the head unit and amp crossovers.

There's nothing wrong with using them both. Yes, the crossovers will be cumulative....in some situations this may be beneficial and achieve better results. The goal is to achieve the best sound for the user, how this is achieved is of little consequence. There are far too many factors involved to say that it would be inappropriate to use them both, either cascaded or staggered.

I would start with the LPF @ 50Hz, and HPF @ 100Hz.

the 1 octave gap will be filled in by the roll-of from both the mids and the subs.

amplifier crossover settings

The above link illustrates what I mean with the gap between HP and LP filters.

The recommendation for the 1 octave gap doesn't take into account the acoustic response of either the drivers or the vehicle or the slope of the crossovers. I guess off hand I can't say I've seen a crossover theory that recommends a full octave of separation in crossover points. You are going to have a different interaction if you are using a 2nd order filter compared to a 4th order, or if the vehicle and response of the driver result in steeper acoustic slopes than the electrical slopes used which would result in a lull in the that area of separation.

In regards to the link; The crossover frequency isn't the point where the crossover begins taking effect.....it begins taking effect before the crossover frequency. The crossover frequency would be the -3db point for a Butterworth filter (-6db for a LR crossover, and different points for other less used crossovers). I'm sure you know this, but the wording is misleading as the response will begin to be attenuated before the crossover frequency.

Slope and Q are not the same thing. Slope is expressed in db/octave, Q is a unitless number. The slope is the rolloff of the crossover, the Q describes the shape of the response. If I told you I was using a 4th order filter, you wouldn't be able to tell me the Q of the filter. If I told you I was using a crossover with a Q of .707 or .49, you wouldn't be able to tell me the slope. If they were the same thing, all you would need is one to tell me the other.

There are too many factors to take into account to say do this but not that. For the beginner the best thing to do is simply use some familiar music and listen and set them to where sounds best. If it sounds best using both, so be it. Some users have found that the steeper slope has resulted in better results in their vehicle with their particular system.

[Impious 1,476]

my pioneer hu has the subwoofer outputs but it only let you pick a frequency and does not have a full range setting. So if I were to use the hu crossover where should I set the crossover on the amp (should I turn it all the way up which is 200hz)?

Where ever you find it sounds best.

If you wanted to only use the HU crossover then yes, set the amp to it's maximum setting.

But there's nothing wrong with using them both.

[harveywong 0]

My hu is @18db oct slope and my amp is @24db oct slope. Which is generally better to use the 18 or 24 oct slope?

[Impious 1,476]

Which ever sounds best. I generally prefer to run steeper slopes, but there is no rule that says what works for me will work for you or that what worked in my stereo will be the best for yours. Try them both, see what you like best.

[wutang512 3]

how would you run bandpass on a pair of midbasses with a 3way deck with a amp that can go active as well?

[Impious 1,476]

how would you run bandpass on a pair of midbasses with a 3way deck with a amp that can go active as well?

I'm not sure I completely understand the question since not many details were given.

I'm going to assume this is for a 3-way frontstage (midbass, midrange, tweeter).

You could use the "mid" output on the HU, which is generally bandpassable, to highpass the midbass and lowpass the midrange. Then use the xover built into the amp to lowpass the midbass and highpass the midrange.

Or a better solution would be to use the "mid" output on the HU to bandpass the midbass, and use the highpass output on the HU to highpass the midrange. Then use the amplifier's xover to lowpass the midrange and highpass the tweeter. The reason I say this would probably be better is because then you would have the ability to time align the midbass and midrange independently of each other, which would be beneficial since those two drivers are generally not directly next to each other where they would need identical time alignment applied to both drivers. The midrange and tweeter would then be time aligned together on the same channel, but that's a positive as well since (depending on their location) this could avoid phase issues near the crossover frequency (compared to if they weren't time aligned the same), and the imaging won't really be affected since tweeters well within the IID range.

[wutang512 3]

how would you run bandpass on a pair of midbasses with a 3way deck with a amp that can go active as well?

I'm not sure I completely understand the question since not many details were given.

I'm going to assume this is for a 3-way frontstage (midbass, midrange, tweeter).

You could use the "mid" output on the HU, which is generally bandpassable, to highpass the midbass and lowpass the midrange. Then use the xover built into the amp to lowpass the midbass and highpass the midrange.

Or a better solution would be to use the "mid" output on the HU to bandpass the midbass, and use the highpass output on the HU to highpass the midrange. Then use the amplifier's xover to lowpass the midrange and highpass the tweeter. The reason I say this would probably be better is because then you would have the ability to time align the midbass and midrange independently of each other, which would be beneficial since those two drivers are generally not directly next to each other where they would need identical time alignment applied to both drivers. The midrange and tweeter would then be time aligned together on the same channel, but that's a positive as well since (depending on their location) this could avoid phase issues near the crossover frequency (compared to if they weren't time aligned the same), and the imaging won't really be affected since tweeters well within the IID range.

my bad i should have said how do i bandpass a midbass while doing a 2-way active setup.

[Impious 1,476]

When you say "3-way deck" do you mean the HU has the capability of running a 3-way active setup, or simply that it has 3 sets of preamp outputs (front/rear/sub)?

[wutang512 3]

yeah the deck can do 2-way active plus subwoofer like the 800prs

[Impious 1,476]

yeah the deck can do 2-way active plus subwoofer like the 800prs

Then you can use one or the other. Generally the HU would probably have more flexibility in having adjustable slopes, so that would probably be the better way to go.