Vibrating speakers

Enter speaker isolation. Hel-loo speaker isolation!

Imagine making a speaker attempting to get the same sonic behavior as a violin. Well, that's great, but how do you deal with a drum, a sax, the human voice, bells?  Yes, some instruments are made of wood, but many are not.

The speakers should not add any unintended sonic signature. I say "unintended" because some speakers have a house sound which is achieved through a variety of means, and I imagine cabinet construction is one of them.

Ideally, these vibration controls occur:

• The cabinet does not vibrate
• The cabinet does not transmit vibration to the floor, which then re-radiates into the room
• The speaker itself is fixed in all three dimensions

The last one is why adding mass to the top of a monitor can help.


Having said this, there is some research related to controlling, instead of eliminating, vibration altogether. I don't remember much about it, but it's a compromise brought on by the need to create affordable and relatively small and lightweight systems.

All box speakers vibrate. No way around it. ’Ye cannae change the laws of physics Jim.’


So what to do?

Well, with existing speakers, if you really feel there’s an audible problem - there might not be if the designer has factored in cabinet vibration/ output into the desired sonic signature they wanted - you can try to stand them on something which might attenuate some of their cabinet vibrations. Sorbothane, springs or footers etc. Townshend Audio have a long history of looking at isolation but they are not the only ones. In my experience these products can help where the sound can tend to get slightly ’muddy’ with certain recordings.

With cabinet design there are usually two approaches. Make it either extremely rigid to try to force these resonances up the frequency range (hopefully out of the listening range) or alternatively make the cabinet lossy (BBC style) so they disappear beneath the bass floor where our ears are the least sensitive.

Or alternatively you can opt for planar types and open baffles where the box resonances are naturally less of a problem.

There is a third approach, quite rare nowadays, akin to transmission lines, is to try to carefully use the unavoidable resonances (why fight the impossible?) in the same way as musical instruments do, ie to actually enhance the sound.

I think Russell K loudspeakers employ this strategy and they certainly have their fans. The piano firm Bosendorfer used a similar approach for their loudspeakers, but I don’t know if they still do. In any case I would always prefer a speaker with slightly too much life, and maybe not measure absolutely ruler flat than one that does but has too little life.

None of the current solutions are perfect but hey it’s only 2020 and we still await the next major engineering breakthrough.

It could be closer than we think if AI keeps evolving at its predicted rate.

I broke two laws of physics today and it’s not even time for breakfast. Don’t let some stuffy old physics dudes tell you what you can or cannot do. Faint heart ne’er won fair maiden. 💃