Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watcgl.UUCP
Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.audio
Subject: Re: Fletcher-Munson curves obsolete?
Message-ID: <2303@watcgl.UUCP>
Date: Sun, 25-Mar-84 05:16:03 EST
Article-I.D.: watcgl.2303
Posted: Sun Mar 25 05:16:03 1984
Date-Received: Sun, 25-Mar-84 14:00:01 EST
References: <273@opus.UUCP>
Organization: U of Waterloo, Ontario
Lines: 22

Typical "loudness" controls introduce some amount of bass and treble boost
in the lower 1/3 or 1/2 of the volume control setting - above that there
is no effect.  So, even if the compensation is ideal over the range
in which it operates, it is compensating to make the sound appear to have
the same tonal balance at lower volumes as it does at some specific
higher volume where the compensation reduces to zero.  This may be at quite
a range of sound pressure levels at the listener, depending on sensitivity
of the power amp, speakers, and the room.  So it can't be more than
a very approximate compensation anyway.

I've seen one brand of receiver (Yamaha?) which had both volume and
loudness pots.  You set the loudness controll full clockwise (which
was "no effect"), then set the volume control to what you considered
a realistic full-volume listening level, and then you turned the
loudness control counterclockwise to reduce the perceived loudness to
where you wanted it.  This reduced the midrange more than high or low
frequencies; the intended effect was that the low-volume sound should
seem to sound the same as at the full-volume level you picked.

It seems to me that this sort of two-control system at least has a
chance of working the way that loudness compensation is supposed to work.
If so, why is it so rare?