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From: schley@mmm.UUCP (Steve Schley)
Newsgroups: net.audio
Subject: Re: source of data on transient response in receivers
Message-ID: <192@mmm.UUCP>
Date: Tue, 24-Sep-85 09:45:34 EDT
Article-I.D.: mmm.192
Posted: Tue Sep 24 09:45:34 1985
Date-Received: Mon, 30-Sep-85 01:10:30 EDT
References: <126@ur-tut.UUCP>
Reply-To: schley@mmm.UUCP (Steve Schley)
Distribution: net
Organization: 3M Company, St. Paul, Minn.
Lines: 34
Summary: 

In article <126@ur-tut.UUCP> tuba@ur-tut.UUCP (Jon Krueger) writes:
>I'm looking to buy (upgrade) a receiver in the 150-300 range.  I
>don't need more than 35 watts for my tastes and speakers.  But I've
>heard that buying more power than that may also buy me more headroom
>for sudden but brief peaks in music.  These "transients" may zip up
>to 100 watts, although not often or for long.  I can't seem to find
>any vendor specs on their product's performance in this area.  Can
>anyone give any pointers to technical writeups or lab test data?

You are onto something here, and it's a topic that is generating more
interest lately.

The accepted terminology is "dynamic headroom", and it indicates (in
positive deciBels) how much power an amplifier is capable of putting
into a load for brief (~20 milliseconds, I think) musical peaks.  Many
articles have appeared in the popular press (Stereo Review, Audio), but
I can't point you anywhere specifically.

Among the manufacturers that were earliest to design in significant
dynamic headroom is NAD.  Check the latest Stereo Review (October?) for
a review of the latest and biggest NAD amplifier.  The reader will
probably learn something about dynamic headroom from the review as well.

Another less common attribute of amplifiers is "output current".  This
helps when driving real loads like speakers, which often look to the
amp like a very complex impedance whose real value can drop very low,
and whose imaginary component can be large.  Output current drive
capability and dynamic headroom often, though not always, are found in
the same products.

-- 
	Steve Schley

	ihnp4!mmm!schley