PSA: Short Unused Speakers and Subs in the Listening Room

I think most people know this, but it’s important to electrically short speakers and/or subwoofers in the listening room that aren’t being used. This can be accomplished by connecting the terminals together with a spare speaker cable or jumpers.

I had a pair of passive, sealed subwoofers I didn’t have hooked up in the listening room. I could tap on the subwoofer cone and the room would energize with bass at the resonance frequency of the subwoofer. When I shorted the terminals with a copper wire and tapped on the cone, there was silence. It was quite remarkable actually.

Has anyone else experienced this? One question I have is if I should short a subwoofer that is not in any sort of box or enclosure. When I tap on it, it doesn’t seem to energize the room with sound.


Rooms are more similar than most think. Geddes paper, the gold standard study and paper on this, is linked below. The one thing I would add, we didn't know enough back then (this was more than 30 years ago) about the importance of isolating speakers in order to avoid them mechanically exciting room resonances. Without isolation, vibrations generated by speakers and subs flows right into the floor, walls and ceiling, with the result the whole room structure is mechanically set to vibrating. Walls in effect become radiators of sound, speakers, themselves. 

As with so many other things that happen so often we've probably never heard anything else, it is difficult to even know this is what's happening, and even harder to appreciate the extent to which this is going on- until it's gone!

Most typical solutions involve lots of monstrously large bass traps. The best room I've been in, faux walls were incorporated that hid bass traps the size of a large walk-in closet! Wonderful sound, but who has the room and construction budget for that? When my subs were isolated on Nobsound springs the improvement was greater than a large tube trap that had been used. When they were moved to Townshend Pods the improvement was profound! The extent of this was hard to appreciate until another visit to the best room, and this time when coming home was no longer disappointed in my awful bottom end. This experience was repeated at a friends, when we moved his Pendragons onto Townshend Podiums. He was shocked, it was like a whole different room! 




Here’s my question: If you only care about one listening position, are multiple subs really better? I just can’t shake the thought that multiple subs (4 or more) spread throughout the room wouldn’t integrate that well with each other. Would the bass be smooth and full? Good lord, yes. But true to the original signal? I am not sure on that. Perhaps it’s the best we can do though.