[sdiy] Slightly OT: really loud but light weight speakers

[harrybissell]

There are some experiments using ultrasonic sources and exploiting the
non-linearity of the human ear to demodulate difference tones from
two oscillators separated by the audio frequency.

I have NO idea if this is practical or what power levels are involved...
but
it would use small transducers...

hmmmm.....

H^) harry

Joris wrote:

> John:
>
> > This looks like a driver only. A horn is required. The horn
> > functions as an acoustic transformer. This is how the
> > efficiency is obtained.
>
> Harry:
>
> > a horn driver would be less than useless without a horn... and for
> > a 500Hz cutoff it will have to be a very large horn (just guessing
> > maybe 4" x 10" at the mouth... with no horn it will sound really
> > sick (not in a good way)
>
> Thanks for explaining... I was a bit naive to think I could just leave
> the horn off. And you're right about the size of the horn, it would be
> too large.
>
> > I'd go with several small tweeter horns and live with the 2KHz
> > cutoff.
>
> That sounds like a good idea, some more mid and bass would be great
> but that's probably just impossible for small light weight speakers.
>
> > My initial idea was to suggest you use two horns, and beat
> > two high frequency oscillators... the resulting sum and difference
> > tones would be very loud and very obnoxious... make the other
> > bots wish they were dead...
>
> Tim:
>
> > Use two or even three horns driven by slightly unstable oscillators
> > (about 2 to 2.5 kHz). The beat frequencies combined with the
> > noise from the oscillators as they drift about would be really and
> > truly nasty.
>
> I like the idea a lot, but I don't want to make the
> audience/spectators wish they were dead :)
>
> I'll keep this idea in mind though, the sample player we're using can
> do stereo samples...
>
> Right now we've already got some harsh noises in there btw: revving F1
> engines, distorted industrial loops, sirens etc. Anyway thanks again
> for the help so far, once the new bot is somewhat functional I promise
> I'll post some pics and samples!
>
> Joris