Do people here experiment with active basstraps?
An active basstrap is a subwoofer placed in a corner. A microphone a bit before the woofer records incoming bass frequencies, these get send to the woofer with a time delay equal to the distance mic - woofer and played back in anti phase. Result is that the low frequencies get absorbed.
How does it compare to multi sub ala gedlee?
An active basstrap is a subwoofer placed in a corner. A microphone a bit before the woofer records incoming bass frequencies, these get send to the woofer with a time delay equal to the distance mic - woofer and played back in anti phase. Result is that the low frequencies get absorbed.
How does it compare to multi sub ala gedlee?
Wouldn't the OP's bass trap only work in the corner in which it's placed? Multiple subs spread/even out the modes around the room
Interested in building one myself.
Anyone tried? I'm assuming some simple circuit and low quality amplifier should do the trick.
Anyone tried? I'm assuming some simple circuit and low quality amplifier should do the trick.
Actually, (good) multisub solutions are no more than multiple sources that, in an enclosed space, prevent the existence of standing waves in that space. They are no antisound devices. You don’t need antisound.
There is no single correct entry point into the space of a room which has reflective walls. As scottjoplin implies, multiple sources average with each other, both trim and fill, both in space and as seen in measurements.
It is somewhat more complicated than that. Toole, amongst others, has pointed out that strategically placed multiple sources attenuate the standing waves in the sound field. That is not the same as averaging. The sound field itself consists of direct, reflected and modal components. The last are of a very resonant nature, whereas the other two are not. But modal patterns are highly disrupted with more than a few spatially apart coherent sources. That is the fun with the multisub approach.
Why is a reflection not a resonance, and why does a standing wave not include a reflection?
In order to attenuate the energy in a standing wave you engage that mode, to that extent not affecting things in a way contrary to that mode, and to that extent removing energy from but not changing the structure of the mode. Say this means higher than expected output in some locations, and nothing in others. The goal becomes to attenuate the modal energy to the desired level (not eliminate it), and to fill in the spatial gaps.
In order to attenuate the energy in a standing wave you engage that mode, to that extent not affecting things in a way contrary to that mode, and to that extent removing energy from but not changing the structure of the mode. Say this means higher than expected output in some locations, and nothing in others. The goal becomes to attenuate the modal energy to the desired level (not eliminate it), and to fill in the spatial gaps.
Earl Geddes has seen fit in the past to refer to reflections as resonances, due to their behaviour, though some may prefer to be more specific.
I don't mind breaking it down, to preserve terms. It doesn't change the way the room works.
I don't mind breaking it down, to preserve terms. It doesn't change the way the room works.
OK. Effective theory in acoustics defines eigentonen as a function of the dimensions and shape of the room. ‘Reflections’ are, of course, the cause, but they lead in a broader way to a more or less diffuse sound field.
The other way around is solving the wave equation for every point of interest in a given room with given sources. Fun if you’re into math but tedious if one wants to describe sound field characteristics of a room in general.
So, what to discuss?
The other way around is solving the wave equation for every point of interest in a given room with given sources. Fun if you’re into math but tedious if one wants to describe sound field characteristics of a room in general.
So, what to discuss?
How would you describe eigentonen in a room where all boundaries are covered with coherent sources?
If you have sources covering all walls at once, they will access all of the room assuming reflections are a part of all applied energy, but the locations of the walls themselves are otherwise insignificant. Of course when done right, it should be as though no walls are there.
Are you sure this isn't a matter of semantics? If my coffee cup doesn't fill because it has a hole in it, am I not pouring coffee?
Are you sure this isn't a matter of semantics? If my coffee cup doesn't fill because it has a hole in it, am I not pouring coffee?
Of course it is semantics. You did not show your understanding of the physical qualities of room modes and postulated it only was a matter of filling gaps in the frequency spectrum, whereas reducing the standing wave would be less relevant. Multiple sources change the time/distance related aspects of the sound field and standing waves turn into propagating waves. Not 100 percent, sure, but quite effectively so.