Old faithful
On 16 Oct 2013 19:35:23 GMT, Walt wrote:
On 10/16/2013 1:24 PM, ScottW wrote:
On Wednesday, October 16, 2013 6:58:25 AM UTC-7, Walt wrote:
And there's a lot to that. An unpowered speaker is a passive radiator
that will vibrate in response to the sound field and re-radiate acoustic
energy thereby changing how things sound. It's just like the
sympathetic strings on a sitar or a hardanger fiddle.
I would really like see a report that shows this vibration is of sufficient energy to actually produce an audible sound at the listening position.
And what is the reason that a "powered" speaker won't vibrate as well?
What about other drivers in a multi-driver system? Aren't they stimulated to vibrate as well?
Frankly...you might be able to get a little resonance...but if it's undamped to the point of producing audible sound from the sound field of another speaker...that speakers going to be a mess when powered.
Unfortunately, I am unaware of any technical study that quantitatively
demonstrates this. But a speaker cabinet is basically a resonating
chamber and will vibrate sympathetically. The question is whether the
effect is strong enough to be noticeable. For a single pair of unpowered
extraneous speakers, maybe not. For a wall full of them, most likely.
And if the unpowered speakers are one of those highly resonant "one note
bass" monstrosities one pair is likely to be enough. Agree with your
comment about them being "a mess" when powered up. (c:
By way of analogy, if you play, say, a snare drum in a room with a piano
in it, the sound will be colored by the vibrations from the piano. If
someone presses down on the loud pedal, you will definitely hear the
effect. Why would speakers be immune from this basic physical phenomenon?
A piano has hundreds of undamped resonators (strings) that are easy to
excite.
A (decent) loudspeaker has one or two low q resonances at low
frequencies that are hard to excite. A loudspeaker has much the same
effect on acoustics as the same size box without drive units.
A certain Scottish manufacturer came up with this nonsense to justify
single speaker demos so you couldn't directly compare the competition
and hear just how bad their speakers were.
|