Re: [Phys-l] [tap-l] speakers

[Brian Huang <huang.brian.c@gmail.com>]

The impendance of the speakers has to do with matching the amplifier
output.  If the impedance is different from that of the amp, you get
reflections.  The power output of the speaker is reduced by the power
reflected.  So...  sometimes  you will see an imepedance matching circuit at
the output of an amplifier so that it is matched at 8 ohms.  If you look at
the output of your stereo receiver, for example, it usually has a stated
output impedance.

For 100% power transmission, you want a perfect match.  Unfortunately, the
match is frequency dependent - so, you try to get it as close as possible in
the mid-band and build a broadband matching circuit to account for the rest.

On Tue, Apr 26, 2011 at 8:30 AM, Anthony Lapinski
<Anthony_Lapinski@pds.org>wrote:

> I have an old Fisher speaker system. Remove the grill and it shows a
> woofer, midrange, and a tweeter. Red/black connectors in back. Works well
> with a Radio Shack amp.
>
> On the back is a sticker with information about this unit:
>
> impedance = 8 ohms
> input power = 5 - 50 watts
> crossover = 1.5/6 kHz
>
> I have a few questions.
>
> 1. Does the impedance of a speaker affect the sound quality/loudness? So
> for a given power, you need a certain "ideal" impedance (resistance). And
> if you use a speaker with a higher impedance, the power output will
> decrease (P = V2/R)?
>
> 2. Are the crossover frequencies the lower limits of the midrange and
> tweeter, respectively?