[JoshK]

To simulate dipole bass one can take, for instance, two sealed subs in cubic enclosures (front firing) and put one facing the listener and the other behind it facing backwards.  However, the one facing backwards, is it suppose to be wired in or out of phase with the front firing sub?

[sonicboom]

They are supposed to be wired out of phase.  Think of it this way:  if you have a bass driver in an open baffle (thus a dipole) the front of the driver's diaphragm (which you' re looking at) would be moving towards you during the initial transient as would the back face of the diaphragm - kinda logical since we' re talking about the same unit.  To have the same effect using two sealed subs, the woof facing you would have to be moving towards you or away from the enclosed volume of the cabinet (again at the initial transient) and at the same time the rear facing driver would also have to be moving towards you or going into the enclosed volume of the cabinet.

Hence, one driver's motion is into the cab and the other's is out of the cab and the way to make this happen is to wire them out of phase.

Hope this helps.

[John Casler]

To simulate dipole bass one can take, for instance, two sealed subs in cubic enclosures (front firing) and put one facing the listener and the other behind it facing backwards.  However, the one facing backwards, is it suppose to be wired in or out of phase with the front firing sub?

Hi Josh,

I too have this on my list to try with my 4 LARGERs.

To get dipolar youwould want the woofers to move "in unison" so the rear should be out of phase.

I am also looking at using the same config in the BIPOLAR, which might also prove interesting.  For this, both subs would be "in phase".

[JoshK]

They are supposed to be wired out of phase.  Think of it this way:  if you have a bass driver in an open baffle (thus a dipole) the front of the driver's diaphragm (which you' re looking at) would be moving towards you during the initial transient as would the back face of the diaphragm - kinda logical since we' re talking about the same unit.  To have the same effect using two sealed subs, the woof facing you would have to be moving towards you or away from the enclosed volume of the cabinet (again at the  ...

Thanks!

Then if one were to build a sub with a passive radiator on the back side then this should simulate a dipole.  A interesting application of this would be to take the tower subs that RAW just made using GR Research subs and turn the PRs towards the back instead of the side to gain dipole radiation patterns.

[Occam]

Thanks!Then if one were to build a sub with a passive radiator on the back side then this should simulate a dipole.....

But the passive radiator(PR) is not moving in phase with driver, or 180o out of phase....
And and that phase angle varies with frequency as does relative excursions of the actual driver and the PR. It should'nt function as a dipole.
Which is a good thing as it is what make ported(bass reflex) speakers work. And a passive radiator is in reality a port(duct).

[EDIT But I do see why you made that leap. An enclosure with a passive radiatior is obviously sealed. Just look at the dang thing. But from a 'physics' perspective its not sealed (acousitic suspension/infinite baffle), its ported ]

[JoshK]

Sonicboom said the subs should be out of phase that is why i thought it, because the PR would be 180º out of phase with the front sub.  I wasn't aware that subs had to be sealed to simulate a dipole sub.  I was just simplifying the assumptions in my example so we didn't have to worry about the port radiation.

[jeffreybehr]

One other thing necessary to simulate a real dipole woofer* would be to have both drivers in the same front-back position--else the 2 wavefronts would indeed be out of time (phase) with each other, but to differing degrees depending on frequency AND physical displacement.

*  See http://community.webshots.com/album/238619181WkZSKm for my real dipole woofer prototype added to an Eminent Technology LFT-12.