New Energy: Audio Vibrations Create Movement Energy

[sophiecentaur]

If you put the '100W speaker' into a concrete box and had a vibrating diaphragm across a hole in the box, you could probably get a watt of kinetic energy (more, if the system were tuned / matched well. But you would be better to cut out the middle man and connect the speaker leads directly to a load.

If you are just talking about using the 'wasted' sound power in a room then you have to accept that most of it will be absorbed by walls and furnishings (or, if you're outside at Glastonbury, the rest of the world) and there's precious little available for your 'sound energy collector', which will intercept a small fraction of what was produced by the speakers. If it were a worthwhile project, don't you think that they'd have something of the sort on every airfield runway, to get the power from the jet engines and inside every big noisy piece of machinery?

And, yes, speakers can get hot enough to melt the speech coil, if you drive them too hard.

 

[turbo]

It's been a while since I've put my hand on one, but I think the coils do get hot!

Note that a lot of the heat is also dissipated at the amplifier.

I have put my hands on the speaker housings and spiders, especially in applications in which I thought I was over-loading the speakers. When I built guitar amps, I almost always built open-back designs, and when I was running inverted-chassis designs (so that the tubes were head-down in the same enclosure as the speaker) and really pushing them I sometimes ran external fans to cool stuff. Probably the most iconic tones are produced Fender 5E3 tweeds and smaller Vox amps, which can run hot if pushed.

 

[sophiecentaur]

Did you ever actually measure the current and volts applied to the speech coils, though? Did you ever run 1kHz tone at a measured 100W into them? 'Loud' music is seldom equivalent to the max power single tone situation. Even with a lot of compression, the peak to mean ratio of 'interesting' guitar sounds will be a lot less than unity - you need peaks for an edgy sound.

 

[turbo]

I rarely ever benched amps with an O-scope or with a multi-meter. My concentration was on replicating tones of iconic amps. As long as the amps were performing well, and I could tweak them to get the right tones, I didn't concern myself with minutia. I built some head-only amps, and combined them with speaker enclosures that were open-backed, partial open-backed, and closed. The closed enclosures got more of my attention WRT to waste heat. Velcro a thermocouple to the the housing surrounding the voice coil (the motor of a speaker) and watch what happens when you crank the amp. I'm a pragmatist when it comes to amp-building.