Gammajo, here's the deal on speaker placement over joists:
Assuming the joists are running the short way across the room (and that you have your speakers facing the long way) take care to place the front and rear spikes of the speaker(s) as close to adjoining joists as possible. In other words, if the front and rear spikes were actually 12" apart, then the front spikes should be right on top of one joist and the rear spike on top of the next joist to the rear.
Or another example, if the F and R spikes are 16" apart, then the fronts should be 2" in front of one joist and the rear 2" behind the next joist to the rear.
You can locate the joists pretty easily with an electronic stud finder if you can't actually get under the floor and see them.
That is what I meant by "cunning" speaker placement relative to the joists.
Assuming the joists are running the short way across the room (and that you have your speakers facing the long way) take care to place the front and rear spikes of the speaker(s) as close to adjoining joists as possible. In other words, if the front and rear spikes were actually 12" apart, then the front spikes should be right on top of one joist and the rear spike on top of the next joist to the rear.
Or another example, if the F and R spikes are 16" apart, then the fronts should be 2" in front of one joist and the rear 2" behind the next joist to the rear.
You can locate the joists pretty easily with an electronic stud finder if you can't actually get under the floor and see them.
That is what I meant by "cunning" speaker placement relative to the joists.