Simple crossover question

[Aurelios 0]

If my crossover has a low pass filter that ranges from 40-400 hz, does that mean whatever I set it too is the highest frequency it will play? Also, does that mean that 40 hz is the lowest it will play?

[sefugi 166]

My understanding of the low pass filter is: the filter will pass everything that is below your low pass set point. set point would be if the filter is adjustable from 40-400 if it was set to 200 then everything from 200 down will pass (all freq. below 200 will play) Make sence?? hope that helps

[jcarter1885 995]

If your Low Pass Filter is set at 40Hz, it will play frequencies unattenuated from 40hz on down. From 40hz on up it will start dropping off significantly.

The opposite for High Pass Filter, if it is set at 40hz then it will play from 40hz on up.

[Aurelios 0]

But no matter what it's set to it will still drop below 40 right?

Edited September 9, 2010 by Aurelios

[PHATBOi 38]

You have to find the frequency range of the amp, most decent amps start at 10-15Hz. That's the lowest it will produce. But you also have to figure in the frequency range of the sub, if it starts at say 23Hz, then that's the lowest it will produce.

[jcarter1885 995]

But no matter what it's set to it will still drop below 40 right?

It much more complicated then what I wrote, not to be a smart ass but here is what I learned and then expanded from it. Use what Im about to type until you read up on crossovers/slopes and how all that works, then what I wrote earlier will make more sense.

If your low pass filter is set at 60hz, it will play frequencies from 60hz on down to wherever it cuts out. If your high pass filter is set at 60hz, it will play frequencies from 60hz on up to wherever it cuts out.

The sub sonic filter is a high pass filter used to set a bandwidth crossover setup. So for example if you want your sub to play from 30-60hz. You will set your low pass filter at 60hz and your sub sonic filter at 30hz, this way it wont play above 60hz or below 30hz. You can do the same thing for your mids if you were running active. You could set your mids to play from 65/80hz to 3000hz, low pass at 3000hz and the sub sonic at 65/80hz.

Just an example and hope it helps.

[KU40 173]

The crossover range is just that, it's for the crossover. Not for all the frequencies the amp plays. Technically an amplifier will play all frequencies, it's just that depending on how it's built it will play some better than others. Some don't have the power supply to play very low frequencies (<15 hz) with the same amplitude as higher bass frequencies, others can't reproduce tweeter-level frequencies with enough accuracy to be used (generally why Class D amps are for subs only). The crossover itself has limitations based on the components used for it within the amplifier. Certain components can only filter between certain frequencies, hence the 40-400 hz range.

If you read a crossover's specs, it will say something like 12 db/octave. This means that it will attenuate the signal by 12 decibels for each octave below or above the crossover point, depending on if it's a high or low pass crossover. So for example, if you set a 12 db/octave low pass crossover at 100 hz, 200 hz will have 12 db less output than 100 hz. 400 hz will have 24 db less, 800 hz will be 36 db less, 1,600 hz will be 48 db less, etc. It's not a brick wall. It's an attenuation point.

[Aurelios 0]

Cool, thank you everyone for all the useful information.

[///M5 2,833]

Crossover point is referenced at the point in the slope where the signal is 3dB down, not at where it starts to drop.

[KU40 173]

Crossover point is referenced at the point in the slope where the signal is 3dB down, not at where it starts to drop.

I thought about referencing that in my post, but wanted to keep it simple to start off with.

[Impious 1,476]

Crossover point is referenced at the point in the slope where the signal is 3dB down,

....for a Butterworth filter

[Duran 387]

Crossover point is referenced at the point in the slope where the signal is 3dB down,

....for a Butterworth filter

I've never seen her in a crossover?