Re: [Phys-L] Suggestions for audio speakers

[Bernard Cleyet <bernardcleyet@redshift.com>]

old, failed to send (Can't from internet café.)

New after the old

On 2013, Mar 17, , at 22:27, Chuck Britton <britton@ncssm.edu> wrote:

> On another 'Note' - use a single tiny (tinny) speaker to play music and then cup your hands around the speaker.
> The increase in bass respond is VERY dramatic.
> This is keeping the bass waves generated from the BACK of the cone from destructively interfering with those from the front.
>
> A very simple demo that gets GREAT response from the crowd.
>
> Or just hold a sheet of paper with a speaker-sized hole directly in front of the speaker.
> (Amazing)

I add:   sweep the frequency and vary the baffle size(not at the same time)


I've never read of a study of the effect of changing the cone angle of dynamic loud speakers.  None, TIKO, except very small ones, have a zero angle.    I think it has to do with the lack of rigidity of the cone.  Of course, electrostatics are flat.

bc thinks students could make electrostatic speakers -- an engineering exercise.


p.s. I've  never "gotten around to" removing the insulation from BaTiO caps. (many) to make a speaker.

-------------

An inventive guy:


http://en.wikipedia.org/wiki/Winston_E._Kock

not given credit in several of these:

http://blog.modernmechanix.com/neon-lamp-traces-sound-waves-picture/


Much is in his book:

SOUND WAVES and LIGHT WAVES   (The Fundamentals of Wave Motion)

Light being mostly microwaves, which is why I have the book.

AND most interesting is Kock's demonstration of anomalous dispersion using a meta dielectric (resonance at ~ 4 GHz)

Bell Sys. Tech. J.  27  p. 71

bc thinks:  since R. Eisberg says "A wave is a wave is a wave.", one may show anomalous dispersion with longitudinal waves also.