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Re: Limited Power?

To: BobMGT@aol.com
Subject: Re: Limited Power?
From: Trevor Boicey <tboicey@brit.ca>
Date: Fri, 14 Nov 1997 03:49:29 -0500
BobMGT@aol.com wrote:
> The radio itself would draw no more that 2 amp at sane volume levels or
> 6 amps at insane levels. 

  Well, not really to be honest. I'm not too into car stereo,
but if you have a few subwoofers it's amazing how many watts
a system can have and still not be excessively loud.

  Often the sensation of "loud" is actually the brain noticing
the extreme distortion that a small system has at full
volume. When audio quality is maintained, the threshold of
loud can be MUCH higher.

> I am not familiar with this particular model, but
> most designs today draw power from the battery line (constant-power
> circuit) rather than the ignition line.

  This I heartily disagree with, at least for common
installs (being defined as not totally rewiring everything
in the car for audio).

  In most cars, the "battery" line is a very thin wire intended
mostly for radio presets. Because of it's high resistance
compared to real cable, you get too much ground bounce if you
attempt to draw serious current through it. (evidenced by
stereo lights dimming on loud notes)

  Only the ignition line can comfortably carry the current
without too much voltage drop. Often because that same wire
powers the cigarette lighter and other big draws.

-- 
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/

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