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From: firstname.lastname@example.org (carltons)
Subject: Re: Loudspeaker and microcontroller
References: <email@example.com> <3DB65042.66FB6FCB@scazon.com> <firstname.lastname@example.org> <email@example.com>
User-Agent: NewsWatcher-X 2.2.3b2
NNTP-Posting-Date: Sat, 26 Oct 2002 01:45:44 GMT
Date: Sat, 26 Oct 2002 01:45:44 GMT
In article <firstname.lastname@example.org>,
email@example.com (john jardine) wrote:
> firstname.lastname@example.org (jools) wrote in message
> > very helpful guys thanks, just could some one tell me the relevance of
> > the speaker impedance, I know higher impedance less current through it
> > etc. But which one do I want for the biggest sound output.
> > Also the sound is just going to be a two tones, perhaps some wave
> > shaping to make it slightly nicer to listen too.
> A higher audio voltage ups the watts. A higher audio current ups the
> The max audio voltage you can get is set by the power supply voltage.
> The max audio current you can get is set by the speaker resistance.
> You have choice of control over both. Double the audio voltage and you
> get 4 times the watts. Halve the speaker resistance and get only twice
> the watts. The magic formula ...
> Speaker power is (audiovolts*audiovolts) / SpeakerResistance.
> As you are probably stuck with (say) a 9V dc power supply, then this
> sets the maximum audio voltage that can be pumped out to the speaker
> (using an audio amp)at about 2.5V ac rms. A bigger audio power
> therefore can only come from upping the speaker current, which means a
> finding a speaker with the least resistance eg, 8 or 4 ohms. Which
> would give in turn a max of about 3/4watt and 1.5watts, which is still
> not a lot.
> The best way to up the power is to go for increasing the amp supply
> voltage to say 24V, use a standard 8ohm speaker and feed the audio
> amp from the PIC, via a volume control (max 8watts).
> Sounds complicated? ... It is!. There is *nothing* simple in
> electronics design. Get this Watts/volts/ohms thing, sorted out in
> your mind though and (honest!) you are well on you way to designing
> 100kWatt crowd pleasers.
Why not go for better speaker efficiency? You don't have to buy speakers
with Alnico magnets when there are all kinds of super magnet speakers
around. Look up the specs, they are now available via the stupid 1's and
0's machine in front of you. Screw a bunch of 1Kw amps driving a
0.000001% efficiency speaker. Lousy speakers are lousy speakers, driving
the bejeepers out of them doesn't change this fact.
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