Fletcher Munson 'Loudness Control' Video

Hello Lewm,  For $100 you can do that on a Schitt EQ. Just adjust the 1st and last controls up slightly or a bit more. Or, per Gdaddy1, adjust the middle controls down slightly or a bit more. 80% of the time I have it out of circuit. 20% of the time the improvement is much better than the slight degradation. It makes some rock and classical listenable.  -JAS in Phila. 

Ideally, you want it to be automatically and progressively implemented as you lower the volume below your ’normal’.

That is how the Yamaha and some others work.

Even better: remote volume control.

The Chase RLC-1 works like that, however it only progressively boosts the bass, no treble involvement. Raise the volume, the boost is progressively reduced, raise it above normal, no boost at all.

We old dogs are not hearing ’real’ highs at normal volumes, as they say, most people adjust the bass.

How can a receiver, particularly a vintage one, sense the SPLs in your room across the audio spectrum and then compare the responses at key frequencies, in order to introduce the proper loudness compensation? Answers: it can’t. You have to do it by ear which is why ideally you want a potentiometer in order to adjust by ear or by in room measurement. 

Lewm's argument seems irrefutable.  There are two uncontrollable factors that make it impossible for a manufacturer to design the perfect loudness compensation into their control circuitry.  First, no two people hear the same way and for that matter our hearing changes over time too.  Second, every room is different and every speaker system will interact differently with boundaries of the room it is placed in differently in consequence.  As lewm correctly argues there is only one way to address what is in essence an infinite puzzle.  It all starts with two ears and a brain.

Fletcher Munson adjustment was poorly named, and no doubt poorly implemented. The Animal’s song ’Don’t Let Me Be Misunderstood’ was never accomplished, to this day!!!!!

It cannot be perfect, however it can make low volume listening more enjoyable. For me by progressively boosting the bass as the volume lessens, maintaining involvement with the music rather than letting it drift into inattentive background music. 

Others, for various reasons, listen at low volumes most or all of the time, and they need some adjustment applied most or all of the time.

They ask, what speakers sound good at low volumes?. Absurd, if a speaker, by itself, sounds good at low volumes, it has exaggerated bass, and perhaps exaggerated highs. Turn it up to ’normal’ or higher, it would sound both bloated and screechy; and test results would show a very poor frequency response. 

As the video mentioned, and as I have said many times, it is

1st necessary to make a ’normal’ volume listening setting with a primary control, no boosts, and leave that alone. (different ears, different rooms, thus ’different normals’).

2nd a separate attenuator, most often labeled ’loudness’, that both raises and lowers the volume from the pre-set ’normal’. No boost is applied as the volume is raised. Boost is progressively added when that separate attenuator is lowered below ’normal.

The Chase works this way, remote volume, automatically and progressively applied as you go below ’default’ volume (except it does not effect the highs, only the lows). Nothing altered as you raise the volume above ’default’.

The Yamaha Receiver’s work this way, applying Fletcher Munson boost progressively to both lows and highs as you go below ’your normal’.

Other receivers did this ’two attenuator’ solution.

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Many simply had a single attenuator and a ’loudness’ button or rocker, engaging ???? These, including my McIntosh mx110z and Fisher 500C.

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What was/is not understood, is it changes the action of the primary attenuator. 

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Un-engaged, lower the volume and it does not boost anything

Or, use it like this: 

a. set the primary (only) attenuator to ’normal’. 

b. engage the ’loudness’ rocker

c. NOW, as you lower the volume, it progressively engages Fletcher Munson boost to bass and highs.

Thus, you might leave the ’loudness’ rocker engaged ALL THE TIME, as it only does anything when the volume is lowered below ’your normal’.

Or, as you go up above ’your normal’ some designs require you to disengage the loudness control.