If you are able to connect your phone or the output of a soundcard to your amp, you may trace the resonance down to it's origin and defeat it.
There are various free sound generator apps you can use. Just go up or down in the frequncy range until you nail it. That way you can find the resonating part.
It is no problem to retrofit a brace inside your speaker that stops the resonance. Before you ask, no, there is no negative aspect in stopping the cabinet to resonate. The best box for a woofer is made from concrete.
So please try this, not really complicated, when you have found the exact cause we will find a cure...
There are various free sound generator apps you can use. Just go up or down in the frequncy range until you nail it. That way you can find the resonating part.
It is no problem to retrofit a brace inside your speaker that stops the resonance. Before you ask, no, there is no negative aspect in stopping the cabinet to resonate. The best box for a woofer is made from concrete.
So please try this, not really complicated, when you have found the exact cause we will find a cure...