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Can you have one inverted and one normal subwoofer in one box? Answered

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Hello. I'm thinking of building a 4x4 subwoofer box with one inverted subwoofer on top and one regular vertical subwoofer to save space. Is it possible? I'm thinking it will be weird since one subwoofer will pull and one will push, will it work and do i need to change the polarity?

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Marcus BjörnR (author)2015-12-01

I found a picture of someone doing this!

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iceng (author)Marcus BjörnR2015-12-15

Ever throw a rock into a pond and observe the waves. Maybe you saw reflected wave fronts.. If you put a 3 sided wall to intercept the waves you will see higher frequency corner wave forms.

There are corners in your box that will create a possibly annoying frequency shift.

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Quercus austrina (author)2015-12-15

Short answer, YES.

Long answer, yes, it is called Isobaric mounting where one is on the front of a baffle and the other is on the back of the baffle ( just like you drew in response to Steveastrouk's comment)(Hi Steve!) and they are wired anti-phase so that when one pulls, the other pushes - the cones are moving in the in the same relative direction not pulling or pushing against each other.

This configuration changes the woofer specs in several ways.

1. The power ratings add up. For example, if each woofer is rated 100 watts, that combo is now 200 watts.

2. The impedance is reduced. If they are rated 4 ohms, the combo is 2 ohms.

3. The driver specs, such as Qes and Qms are changed, I forget exactly how (it's been probably over 15 years since I studied on this and wrote a Q basic program for it), which changes the Qts of the system, while the Vas and Fo stay the same. If these are foreign terms to you, I suggest you find some speaker building books or one of the many online sites that can demystify them.

Once you understand all this, use one of the many websites available to design a sealed box that is right for your configuration.

Have fun!

Qa

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Marcus BjörnR (author)2015-12-04

Would this work better? I love the idea of a down facing subwoofer.

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Marcus BjörnR (author)2015-12-01

What do you guys feel about this subwoofer? It's 100 euros per subwoofer. http://www.ljudfokus.se/produkt/~reservdel-stratego-215-sa-15-tums-baselement/3712/ The specs are listed under and it's called Proson Stratego 215 SAH.

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It looks OK, at the frequencies subs work at, its not a hi-fi thing really....

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iceng (author)2015-12-02

As Steve says... that is why baffle design software is available to phase delay sound in the desired frequency range...

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Marcus BjörnR (author)iceng2015-12-02

In english please. You have no idea how hard this is to understand for a guy that has never owned a custom built sound system :)

So there's software that controls the phase delay? I'm guessing on an amp or do i need special equipment?

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iceng (author)iceng2015-12-02

If you get into audio design one day you might understand ballistic voice coil compensation.

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steveastrouk (author)2015-12-01

In my sub, I have two 15 inch speakers on a common baffle, facing each other, they are configured in anti-phase. It works very well.

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user

Would that mean that i could make the box really thin?

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Mine is about 400mm deep, overall. There is a port from the inside of the box to the outside.

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I really want a sealed box though.

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No, you need a certain volume in the box so the speaker can operate properly.
This means the speakers go in the box the way they are supposed and not like in your image.
If you want it smaller use smaller speaker, you can get very good bass speakers with just 10cm in diameter and they would not need an oversized box.

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