That was what I thought until on one occasion I noticed a significantly off-to-the-left stereo image with my system. I then moved the pair of JR149s, that were on the floor to the left of each of my main speakers. This completely fixed the issue.
So based on my own experience and irrespective of the mechanism, I would avoid this situation wherever possible.
My guess would be that the cause was more likely to do with reflections than with the woofers humming along. After all, if woofers can act as passive radiators, they would presumably do it at the woofer/box fundamental resonance, and that would surely be at a frequency that is difficult to localise.
So based on my own experience and irrespective of the mechanism, I would avoid this situation wherever possible.
Seems to be a lot of guessing and presuming in your reply.
Everything that is not (over)damped can resonate. Just depends on the frequency.
When my door rattles due to low bass output, it's very easy to hear where it's coming from... that's how I know it's the door - confirmed by holding the door and the noise stops.
Ever wondered why speaker manufacturers invest so much effort into cabinet design to stop them singing along?
Of course I'm guessing and presuming - I wasn't in your room to hear what you described. I'm just trying to comment on what is more or less likely, and I tried to keep my tone non-dogmatic.
Yes, everything in a room will have a tendency to vibrate. But of all the things in the room, the audio gear, and especially the speaker drivers, are just about the only stuff that is deliberately designed to have a minimal resonant signature in the audible range. Hence my post 78. (And hence why I'm pretty sure that the whole single-speaker dem room thing was just a marketing ploy.)
Of course, there's still the fundamental box/woofer resonance (one frequency for a sealed box, or two for a vented enclosure). But could the resonance(s) of an undriven woofer really be excited sufficiently by another speaker, such that audible sounds are emitted in sufficient quantities to modify the total response of the system? It really seems very unlikely to me. A bass radiator (which has no voice coil to provide damping) moves in response to the pressure inside a loudspeaker enclosure. A room is much bigger than a speaker enclosure (even a Tannoy ) and the pressure variations are correspondingly much lower. Also any movement of an undriven woofer would be damped by its magnetic circuit. All in all, it seems most unlikely that undriven woofers would resonate enough to be audible.
An undriven speaker has no electrical damping (Qes), only some mechanical damping (Qms).
Vented box speakers have 1 resonant frequency, not 2.
The undriven cones are moving/vibrating so it must be possible to measure a voltage at the speaker terminals generated by this vibrational movement....and extrapolate the SPL?
The undriven cones are moving/vibrating so it must be possible to measure a voltage at the speaker terminals generated by this vibrational movement....and extrapolate the SPL?
I still don't think Tony's undriven Tannoys could boost the bass of his LS3/5as. I can't see any mechanism by which this could occur. If you still think otherwise, do you have any thoughts on how it could work?
The Tannoys have a resonant frequency at approx 40Hz. The issue with resonance is that it stores energy and releases it later (think about a ruler twanged on the edge of a table).
The energy released later will change the envelope of the sound, IME this is perceived as fuller bass. It may not be easily measurable as increased SPL.
Yes, I understand that resonance means stored energy, thanks.
The thing is, how much energy is being absorbed by a woofer from the room? And how much of that energy is stored and released later? (Bear in mind that speakers are very inefficient transducers/microphones.) I think the amounts are likely to be very small, and I suspect that the only resonating things in a room that will make an audible contribution to the total sound will be things with very high Q resonances. Speakers are designed to have very modest Q resonances, which is why it seems to me that they are among the least likely things in a room to 'sing along'.
Clearly I'm not going to persuade you, though.
I will ask my pal with a PhD in acoustics, at the weekend.
If he doesn't know...
In the meantime, here's an old Stereophile discussion, with both sides of the argument represented: https://www.stereophile.com/content/controversy-single-speaker-dem-myth
I asked my pal (inventor of the priciple behind the Kef KC62 drive unit control). He said that I am right. He did add that the effect of the passive radiator is unpredictable, it could absorb some frequencies whilst augmenting others.
His overall conclusion was "remove unused speakers from the listening room and then they can't have any effect on the sound". Hard to argue with that logic!