🚀 go-pugleaf

In article <1992Dec29.134904.350@ncrcae.ColumbiaSC.NCR.COM> 
chris@lightnin.Columbia.NCR.COM writes:

>  Can someone enlighten me as to what is meant by "Headroom"?  Technical
>descriptions as well as figurative descriptions would be helpful.

The term "headroom" is used to describe both technical and esoteric
aspects of audio.  The proper definition is:

Headroom= The difference between a nominal and maximum signal level
that an audio device is designed to function.  The signal is described
in dB.

Example:  An audio mixer designed to operate at (one) +4dBm will
usually have a headroom of 20 dB.  In other words the maximum output
will be +24dBm. 

Maximum output= the point just below cliping of the signalin question.

Power amp discussion:

For power amplifiers used in audio the term headroom _usually_ defines
the difference in the rated output and the maximum output when the
amplifier is stimulated by a signal that is increased above the level
that generated the rated output.  Usually a gated signal.  I would
have to dig up the specs on this kind of measurement (I am sure that
others will be able to supply these test methods from memory, and or
correct my ststements  :-).

The figures that I have seen on consumer amplifiers is on the order of
a couple of dB.

Keep in mind that with crest factors of 12-20 dB audio can eat up
power and you won't know it until you are out of power!

There has been a lot of discussion on "do I really need a 200 watt amp"
I have seen responses like " a (""better sounding") 100 watt amp can
sound better than a 200 watt amp.

All of this is true but for different reasons.  My basic observation
is that lotsa a power is good.  Caculate it for yourself!  How much
power does it take to reproduce the 12-20 dB crest factor of an audio
signal using a speaker who's midband output is 90 dB, 1 watt, 1 meter?
What is the power rating requirement for the speaker that is to
produce this sound?  For this problem only, ignore the thermal
compression of the speaker!

Gee I sure got off the topic!

-- 
Chris Christensen                  The opinions I express are my own,
chrisc@gold.gvg.tek.com            and sometimes they are wrong!
916-478-3419 FAX 916-478-3887      After all, I *AM* only human.