Possible use for unused loudspeakers

[rgpit]

Has anyone tried using speakers in cabinets to tame low frequency resonances in a listening room? I have several unused speakers in cabinets and I was thinking of shorting their inputs and placing them in various places in my listening room to act as "acoustic shock absorbers" to help tame room resonances. Any thoughts or ideas?

 

[Blumlein 88]

My immediate thought is the area of the speaker cones is such a small fraction of the total sound in the room it wouldn't make much difference. I suppose if placed in high level places like corners it might do something. You could measure the voltage coming from the speaker being driven by in room sound waves. Say short it with 8 ohms or something like that. I believe you'll find the total power generated is not even a rounding error.

 

[Doodski]

Does 40 pair of speakers in a sound room without the terminals shorted count as a example? When I retailed gear the small room had 40 pair and we tested it with and without speakers and the sound difference was not detectable with human ears and with no blind testing method available it was a bit of a crap shoot but it all sounded pretty good before and after.

 

[Inner Space]

In principle it's a good idea. They would be the equivalent of tuned membrane absorbers. But instinct tells me you'd want a variety of at least 15" woofers, and a huge number of them - enough to stack into probably eight door-sized assemblies. Possibly better in theory than practice.

 

[egellings]

If the speakers were powered and had a mic that picked up LF sound and then had the speaker generate sounds in antiphase to cancel out a resonant boom, then the speaker could be useful. Simply leaving a passive speaker just sitting there will get you nearly nothing, and what are the chances that the speaker's natural resonant frequency coincides with the one you are trying to attenuate?

 

[Chrispy]

I'd rather play music thru them....

 

[egellings]

That would be the optimal use for them, since that's what speakers are for in the first place.

 

[ryanosaur]

I hear they make great paperweights and door stops.

 

[Doodski]

I hear they make great paperweights and door stops.

I like to take my Estwing hammer and separate the magnets from the basket and use the magnets for screwdriver magnetizing and other magnet stuff. It's refreshing bashing them.

 

[egellings]

I 'spoze.

 

[restorer-john]

Does 40 pair of speakers in a sound room without the terminals shorted count as a example? When I retailed gear the small room had 40 pair and we tested it with and without speakers and the sound difference was not detectable with human ears and with no blind testing method available it was a bit of a crap shoot but it all sounded pretty good before and after.

I did the same in our speaker room back in the day too. No doubt the large 12" 3 ways made a difference when they were in the room or out of the room, but I reckon that was just the volume (volumetric) changing and a whole bunch of refective surfaces removed. Shorting the speakers did nothing. But, like your 'experiment'- it was hardly scientific as it took half an hour to short each speaker and crawl behind them all to un-short them.

 

[Doodski]

I did the same in our speaker room back in the day too. No doubt the large 12" 3 ways made a difference when they were in the room or out of the room, but I reckon that was just the volume (volumetric) changing and a whole bunch of refective surfaces removed. Shorting the speakers did nothing. But, like your 'experiment'- it was hardly scientific as it took half an hour to short each speaker and crawl behind them all to un-short them.

I estimate 2/3 of the peeps thre where subjectivists and could hear a duck fart in the parking lot. There was some ideas floating around in group speak. Like heyyy why not keep all the speakers out of the sound rooms and pull in just the ones you want to sell etc etc... I'm selling $20K on the best day of the year and I do not have time to haul speakers around. I vetoed against that idea real fast! big fat N O ! lol...

 

[Blumlein 88]

If the speakers were powered and had a mic that picked up LF sound and then had the speaker generate sounds in antiphase to cancel out a resonant boom, then the speaker could be useful. Simply leaving a passive speaker just sitting there will get you nearly nothing, and what are the chances that the speaker's natural resonant frequency coincides with the one you are trying to attenuate?

There have been a product or two that worked that way. Have been tempted to try it myself. Pretty easy, cheap recording interface and cheap omni microphone connected to powered subs. Plug them together. Main problem I see is you'd also be working against low frequency noise which isn't part of a room mode.

 

[G|force]

If a dynamic cone driver is enclosed, it can make a handy kick drum microphone. It's not my idea, been done.

 

[rgpit]

Well, at least it seemed interesting. I guess if it was effective some company would be selling it.

 

[FeddyLost]

I was thinking of shorting their inputs and placing them in various places in my listening room to act as "acoustic shock absorbers" to help tame room resonances. Any thoughts or ideas?

If you need something less complicated than AVAA or K+H ARAM, you'll need to make a lot of huge subwoofers with resonance frequencies tuned exactly to your modal frequencies.

Commercially available speakers are made to be "resonanceless" as possible and typically have too small area of woofers.
Just compare your available Sd and area of your walls.

 

[alex-z]

It is possible, but hilariously inefficient.

When doing measurements of my room, if I play the front subs with the rear subs disconnected, I can see a tiny resonance about 40Hz. Only about .5dB, and extremely narrow. As soon as the rear subs are the connected to an amplifier, the damping factor makes that resonance go away.

Each sub is a sealed 12" driver in a .7 QTC enclosure, not an insubstantial amount of surface area. Doing a purpose built helmholtz resonator would be more efficient, but still not practical, as you can only treat 1 room mode effectively. If you try and broaden the Q of the absorber, it loses efficiency.