"Dr. Slick" wrote:

(Richard Harrison) wrote in message ...
Ian, G3SEK wrote:
"Examples include a loudspeaker---."

Good transducer example. Its problem is abysmal efficiency, even if
better than the usual incandescent lamp.

The loudspeaker`s efficiency can be improved by a better match to its
medium. The usual loudspeaker is small in terms of wavelength. A result
is that it is capable of exerting much force on a small area of a very
compliant medium, air. Air could better accept power exerted over a much
larger area, especially at low frequencies, with less force required to
make the air move..

We have a high-Z source and a low-Z sink in the loudspeaker and air.
Conversion from electric power to mechanical power can be more efficient
through better impedance matching. Two solutions are often used for a
better match, a larger loudspeaker or a horn between the loudspeaker and
its air load. The larger speaker is directly a better match. The horn is
an acoustic transformer. They both improve energy conversion efficiency.


But a speaker is designed for broadbanded operation, 20-22kHz, not
just one frequency like many antennas.

I'm sure a speaker optimized for one frequency alone will be much
different than a broadband one.


You can be just as sure that the speaker presents its rated impedance only
at one frequency, too.

Dick Carroll wrote:
You can be just as sure that the speaker presents its rated impedance only
at one frequency, too.

Is it still 1000 Hz?
--
73, Cecil, W5DXP

On Fri, 18 Jul 2003 09:51:35 -0700, W5DXP
wrote:

Dick Carroll wrote:
You can be just as sure that the speaker presents its rated impedance only
at one frequency, too.

Is it still 1000 Hz?

Hi All,

Such easy things to confirm.....

I have a pair of Pioneer speakers, looked at their spec.s pasted to
the back, rated flat from 10Hz to 25KHz (flat being order of two from
nominal 10 Ohms) with a small (BW) peak at 80Hz.

Years ago in my metrology lab, we abandoned laboratory grade
amplifiers and speakers for commercial ones as the market offered far
better product at much cheaper rates.

Sound, like light, makes virtual experts of everyone through their
misperception of its common features. Eyes and ears are fine
instruments clouded by the brain.

73's
Richard Clark, KB7QHC