Crossovers vs low cut?

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Crossovers vs low cut?

Postby dylanger » Wed Jun 25, 2014 6:28 pm

So I'm in this killer cool new band! Playing bass of all things. We're planing on playing a lot of different kind of gigs, from casinos to original material soft seaters. We need a PA and I'm really tired of renting and piecing together a PA. I'm starting with a mixer. Just ordered the Allen and Heath QU-16. We can save our in ear mixes, effects and all that good stuff. One thing that the mixer doesn't have built in is a crossover and someone told me that it's because most powered speakers have them built in. I know some boxes do have a full range mode and "with subwoofer" mode but a lot lines I've come across just have a low cut. Wouldn't that mean that your still running all the highs through the subwoofer. Would it be better for me to have a crossover?
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Re: Crossovers vs low cut?

Postby Alain Benoit » Wed Jun 25, 2014 6:56 pm

In modern powered PA of the MI ilk, each amplifier to their respective drivers are bandpassed accordingly. This is so that people will little or no knowledge of audio can rent these boxes and whether they be subs, tops, monitors or what have you, the entire rig can be connected together by stringing mic cable from box to box to box so long as the desired mixes are going where you want them, ie: left mix, right mix, US monitors DS monitors.

The full range vs with sub switches are to optimize the tops for use with or without subs. W/o a sub the corner freq might be say 50Hz, with a sub maybe 120Hz.

Get it?

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Re: Crossovers vs low cut?

Postby dylanger » Wed Jun 25, 2014 7:55 pm

100%

So really they would work bad with a crossover because you could potentially send a frequency to the sub and then it would get cut off by the sub....?

So really in "club" audio we'll call it, they are pretty much obsolete.
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Re: Crossovers vs low cut?

Postby Alain Benoit » Wed Jun 25, 2014 8:18 pm

Sure.

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Re: Crossovers vs low cut?

Postby Malcolm Boyce » Fri Jun 27, 2014 3:19 pm

As Al has already said, in "club" type powered systems, the use of an external processor is pretty much overcomplicated and unnecessary. That being said, having a solid understanding of the routing and processing options in the enclosures themselves is as important as understanding crossovers in a traditional active/processed system. I see many different ways of doing the same thing, just depending on manufacturers choices and how things are rigged. I'm talking matched top/sub systems that will need to be set differently depending on whether you cable console-sub-top or console-top-sub, just to achieve the exact same result.
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Re: Crossovers vs low cut?

Postby Malcolm Boyce » Fri Jun 27, 2014 3:46 pm

dylanger wrote:I know some boxes do have a full range mode and "with subwoofer" mode but a lot lines I've come across just have a low cut. Wouldn't that mean that your still running all the highs through the subwoofer. Would it be better for me to have a crossover?
I think you are confusing what the switching is doing depending on the "boxes". It will depend on how a system is patched as to what goes where and why. Unless you are feeding a sub via a processed out, a selection on a top box will not affect what is being fed to a sub at all. As far as a "low cut" setting, it will depend on the freq as to it's function but "with subwoofer" is a high pass or "low cut" with respect to what is happening to the top box itself.

It would be a pretty poorly designed powered subwoofer to not have at least a low pass filter at the cut off frequency of the sub driver itself.
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Re: Crossovers vs low cut?

Postby dylanger » Fri Jun 27, 2014 5:31 pm

Ya sorry wasn't thinking there, the top wouldn't be patched off of a sub if it there was a crossover.

The mixer is ready for me to pick up :) I watched some videos on it last night and it's really capable of a lot. Didn't really think of being able to use it as a DAW controller but it does just that! It also has a button you can hit to turn the faders into a 16 band graphic EQ. Maybe this is a standard feature on a digital desks but I've been using small analog mixers for so long all this is pretty new to me. All in all I'm glad I'm going with this instead of a mix wizard with rack mount EQ's and Compressors. Now I need a couple gigs mixing a band so I can really get into it.
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