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 Hello from Boston! Quick crossover question 
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Post Hello from Boston! Quick crossover question
Hey there,

Decided I'd make myself a 15" sub with my pops as a cool little father son bonding project. Got all the materials cut out, got my 15" driver, etc. I've got some soldering and electronics skills so I didn't want to buy the prebuilt HPF crossover since I figured I could DIY. Now, since I ONLY have a 15" driver, no horn, tweeter, midrange or anything, I'm wondering just how important that HPF is. The Eminence Kappalite isn't very sensitive way down at 20Hz where it'd get filtered, anyone tried a sub with no HPF at all?


22 Dec 2017 11:51
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Post Re: Hello from Boston! Quick crossover question
Huh? The HPF is for the mid driver, not the 15.

Are you planning on using your sub cab as a standalone, or in conjunction with something else?

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22 Dec 2017 13:59
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Post Re: Hello from Boston! Quick crossover question
I hear people often put a HPF in a sub to cut out sub 20Hz or so rumble. I understand if I had a midrange or tweeter, the sub portion of the crossover would be a LPF. I guess my title is pretty poor, as this isn't really a "crossover", just a filter.

I'm planning to use this 1x15 as a full range cab for bass guitar, with no other cabs at least for now. I have the Kappalite in a different cab right now and it has quite a bit of upper mid range and does ok in the treble, so I figured it'd be enough to start with. I also wanted to keep my first build pretty simple.

Wouldn't the mid driver take a band pass in the crossover, not a HPF? Or is that only if there is also a tweeter?


23 Dec 2017 14:53
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Post Re: Hello from Boston! Quick crossover question
Using passive crossovers as low-cut for [sub]woofers after the power amp really isn't practical -- suitable components beyond first-order (6dB cut per octave) weigh a lot and first-order at a low frequency does little to provide protection in vented cabs used for live bass reproduction. Also: used with some other cab and even if you have big power, any fEARful or FEARLESS does not need protection from overexcursion or unloading. When paired with a typical bass guitar cab, that cab is going to die from low frequency demands well before the fEARful.

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23 Dec 2017 15:07
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Post Re: Hello from Boston! Quick crossover question
shrugs wrote:

Wouldn't the mid driver take a band pass in the crossover, not a HPF? Or is that only if there is also a tweeter?


Right, no tweeter, no need for a LPF leg in the crossover to the mid driver. And even in some 3-way designs, no need for more treble rolloff in the mid driver than what it naturally does on its own.

As greenboy said, a passive HPF at 20Hz (or 40 that matter) and of 2nd order or higher is not really practical or desirable. If you need it then do it on the preamp side.

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24 Dec 2017 10:00
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Post Re: Hello from Boston! Quick crossover question
Ok, so it sounds like the people putting the HPF in their subs might have a mismatched driver/cab and are trying to limit over excursion, in which case I won't need that at all. Great news to me, that's the easier and cheaper route. Thanks for the help!


25 Dec 2017 19:34
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Post Re: Hello from Boston! Quick crossover question
Assuming that the”Kappalite” that you have is a 3015LF,it’s not going to work very well as a single driver cab for bass guitar. When you build your cab, include the mid chamber and cut out for the mid driver so that it (and the crossover) could easily be added later.

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25 Dec 2017 19:58
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