I have been experimenting with the Ikea sphere speaker.
To join the 2 bowls tohether I made a wodden ring that goes between them.
All around that ring, I placed 8 small ports calculated with WinIsd.
Now, if I listen to the speaker from above there are some bass (relatively to the small 3" full range I am using).
BUT, if I listen to it with the driver facing me there are much less bass.
I have never came across this kind of bass cancellation.
And, as bass are supposed to be omnidirectional, the cancellation should happen from any listening position.
Is that effect due to the multiple port, to the ports position (in a ring) or what?
And how to calculate the port to have it "playing" in phase with the driver?
I would appreciate your opinion to help me understand what's happening here.
To join the 2 bowls tohether I made a wodden ring that goes between them.
All around that ring, I placed 8 small ports calculated with WinIsd.
Now, if I listen to the speaker from above there are some bass (relatively to the small 3" full range I am using).
BUT, if I listen to it with the driver facing me there are much less bass.
I have never came across this kind of bass cancellation.
And, as bass are supposed to be omnidirectional, the cancellation should happen from any listening position.
Is that effect due to the multiple port, to the ports position (in a ring) or what?
And how to calculate the port to have it "playing" in phase with the driver?
I would appreciate your opinion to help me understand what's happening here.
Assumed that a speaker is aligned within the usual limits i cannot
imagine that.
At fb driver and port are 90 degrees out of phase. The port
contributes the main portion at fb.
Since your speaker is small, there should not be any delay
playing a role for low frequencies.
Maybe you should estimate Qb for your enclosure, possible that
there is more friction in the port than you want.
A friend of mine has a speaker where the port is outside the box
and can be made pointing into different directions.
Bass response is not independent from where it points to, seems
to be a matter of room excitation.
According to the books only the displaced volume should matter
for the radiation of the port.
Thin ice here ... i am not quite shure whether it is in some cases
important where the velocity vector of the port points to, depending
on the speakers position.
Interestingly the velocity vector of your "port-ring" configuration
seems to be zero ...
Kind Regards
imagine that.
At fb driver and port are 90 degrees out of phase. The port
contributes the main portion at fb.
Since your speaker is small, there should not be any delay
playing a role for low frequencies.
Maybe you should estimate Qb for your enclosure, possible that
there is more friction in the port than you want.
A friend of mine has a speaker where the port is outside the box
and can be made pointing into different directions.
Bass response is not independent from where it points to, seems
to be a matter of room excitation.
According to the books only the displaced volume should matter
for the radiation of the port.
Thin ice here ... i am not quite shure whether it is in some cases
important where the velocity vector of the port points to, depending
on the speakers position.
Interestingly the velocity vector of your "port-ring" configuration
seems to be zero ...
Kind Regards
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