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Path: utzoo!watmath!clyde!floyd!harpo!ihnp4!zehntel!hplabs!hao!seismo!ut-sally!opus!rcd
From: rcd@opus.UUCP
Newsgroups: net.audio
Subject: Re: AR speaker info wanted
Message-ID: <240@opus.UUCP>
Date: Fri, 16-Mar-84 14:25:15 EST
Article-I.D.: opus.240
Posted: Fri Mar 16 14:25:15 1984
Date-Received: Tue, 20-Mar-84 01:55:44 EST
References: <1840@tektronix.UUCP> <352@dual.UUCP>
Organization: NBI, Boulder
Lines: 34

<>
>    I have two notes on the AR-11s.
> 
>    First off, it is very very easy to blow out the mid and high freq drivers.
>    ...
>    2nd, opinion. I myself do not like the sound of the dome tweeters they
> use in the AR-11s. Too harsh for my tastes...

Obviously I don't know the circumstances around this - but I would
conjecture that these two are related and perhaps not the fault of the
speakers.  When an amplifier is overloaded, meaning that it is asked to
deliver more power than it has, it will "clip".  What that means is that
as the amplifier tries to follow a rising signal, it runs into the upper
limit of its power supply's capability.  The top of the waveform gets
chopped off.  In some amplifiers, this cutoff happens very abruptly so that
you get a "corner" in the waveform.  The effect is the same as an impulse
with gobs of high-frequency power.  The sound is extremely harsh, and
letting an amplifier run in clipping mode for very long can put trash into
the higher-end speakers that will fry them.

People tend to overlook this phenomenon because speaker systems are
normally rated in terms of "system capacity" which assumes a reasonable
frequency distribution.  However, in a system regarded as capable of
operating with a 100 W amplifier, it may only take 10 watts to blow out a
tweeter.  Another reason that the phenomenon is overlooked is that an
amplifier in clipping can produce bursts of power which far exceed its
rated power output - yes, a 10 watt amplifier can produce 50 watts of pure
high-frequency crap for short intervals.

So (as he finally returned to the point of the discussion), it could be
that the speakers were being driven by an overworked amplifier driven into
clipping, and they were being killed by the amp.
-- 
{hao,ucbvax,allegra}!nbires!rcd