Inverted Subs? Subs Facing each other? Why?

[sungwei 10+ year member]

I've scene custom installs where the subs are facing the inside of the enclosure. I've also scene designs where the subs face each other. What does this do? When can you do it and why?

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[tomd 10+ year member]

facing the inside just is for looks, you reverse the polarity, works just the same, but some baskets just look sweet.

where they are faced together, its called isobaric, don't really know anything about it though... sorry

 

[78nova 10+ year member]

if i only invert 1 sub, which sub do i reverse the polarity on, i saw in another thread that the guy inverted his and he reversed the polarity on the inverted one and it ****** the other one in, also would it be good to invert one of them in a ported box

 

[fv04as 10+ year member]

I heard/read somewhere that you get better sq if you invert. Is that true?

 

[LostCause 10+ year member]

if i only invert 1 sub, which sub do i reverse the polarity on, i saw in another thread that the guy inverted his and he reversed the polarity on the inverted one and it ****** the other one in, also would it be good to invert one of them in a ported box

The only time you'll invert the polarity of a sub is either when you have an isobaric system going on or you have just flipped a single sub in a normal box...In the isobaric enclosure scenario you only reverse the polarity of one of the subs (usually the inverted one) so it works in conjunction with its partnered sub...Isobaric enclosures are usually a waste of money and wattage unless you are really strict on space...I've also never seen a ported isobaric enclosure...so don't flip the polarity on your subs because you don't have an isobaric setup...

In a normal box with one sub or two (both facing their faces out or in...) you can reverse the polarities by flipping BOTH subs so their baskets face out...don't invert just one sub in a normal enclosure because you'll probably cause damage...

I heard/read somewhere that you get better sq if you invert. Is that true?

Don't quote me on this but it seems that the practical reason for inverting a basket (beyond it looking nice) is to maximize the space inside of a sub box...without the basket and motor unit taking up space inside the box you could build it a bit smaller...I think they sound the same though...

 

[sungwei 10+ year member]

Oh ok. I always thought this was for louder sound. It certainly does look wild. It would take up more space though and you'd have to have a secure mounting on the box as all the weight would be on one side.

Would inverting the sub cause less vibration since the air wouldn't be pushing outward onto everything inside the trunk/cabin?

 

[helotaxi 5,000+ posts]

All inverting the sub does is show off the basket. I am using inverted subs in the design I am currently working on because the enlosure is only 2" deep. By inverting the subs I can use a really shallow enclosure. The air moves around the ribs of the basket the same way it moves out from the cone in a conventional mounting setup; if it didn't you wouldn't be able to hear it. Also remember that there are two halves of a sine wave. The positive side of the wave moves the cone of the speaker out from the neutral position and the negative side moves it in from the neutral position. As for reversing the polartiy of subs when they are inverted, it is only necessary to do anything different with the wiring if you have multiple subs mounted different ways (some mounted normally and some mounted inverted). All the polarity determines is relative phase. As long as they are all wired correctly in relation to each other then you are OK. You really should try the subs with the total phase reversed anyway to see what gives you better a midbass transition.

Bottom line. If all the subs are inverted: wire them all the same way.

If no subs are inverted: wire them all the same way.

If some are inverted and some are not: wire the inverted ones with opposite polarity to the normal ones.

Subs mounted facing each other is, as mentioned already, called an isobaric setup. The idea is that the two subs act as one single driver with double the moving mass and half the Vas. Basically it gives you the response of a single sub in an enclosure half as big as a single sub of the same model as the pair in the iso-group. This was made popular in the early 90's before the advent of the small box sub. You need twice the amount of power going to the pair to get the same volume as with the single driver. Basically you are trading efficieny for the ability to use a smaller box. With most current subs, you really don't have much to gain from this as they already work well in really small boxes.

 

[sungwei 10+ year member]

Thanks helotaxi, that helped. I"m still a little confused on the inverted part. Are you saying that the sound is coming from the back side of the sub? Or is it from the air inside the enclosure? That is cool that you can use a shallower box. You still need the same amount of volume (sq/ft) for the enclosure though right?