What happened to the loudness control?

IIRC the old Fletcher-Munson curves were superceded decades ago by a study by Robinson and Dadson (spelling may be wrong) which provides more accurate correction for changes in hearing sensitivity at lower sound levels. Of course, these are data averaged over lots of listeners, and your level-specific sensitivity is likely to be a bit different. You could have a simple audiogram to get an idea of your sensitivity across the spectrum, but that wouldn't tell you about your relative growth of loudness across the spectrum at various sound levels.

An equalizer set the way you like it seems more appropriate. I fear the god of audio purity may strike me for writing that.

db

That is what a loudness compensation control is, an equalizer, but variable with the volume. One hopes that it complementary to the frequency response variability of the ear according to volume.
I use the variable loudness compensation control on my Nak 630 pre-amp by setting the compensation at 0 and the main volume control for a natural sounding volume of about 80db or flat frequency response. When I want to reduce the volume to more background levels, I use the loudness compensation control. The main volume setting remains the same.
Works great! I think that the loudness controls on the old Macs worked in the same fashion.
One button loudness compensation is next to useless because it is fixed.
Bob P.

The reason the loudness control was dumped is simply that no one has ever come up with a circuit that worked 100% of the time at 100% of the volume settings. Consumers eventually figured this out and preferred not to own it.

Spatialking...No one uses 100% of the volume control range! The twin control scheme described by [email protected] works very well.

Eldartford: What you wrote isn't exactly correct. Although few folks will turn their volume up to max, there are ocassions when that becomes neccessary. I have experiemented with amplifiers with sensitivities so low that my volume control was at max with some recordings.

But, the reason I stated 100% of the range is that the loudness control is a relative to the volume setting. By design, if it can't function properly over 100% of the range, the circuit is flawed by definition.

Secondly, all preamps have a dual knob loudness control if they have a bass control. Simply turn the bass up slightly to your preferece when you turn the volume down. At least you will get the proper amount of bass. Please understand the loudness control is simply nothing more than an attempt to eliminate one additional tone adjustment. It isn't much effort to tweak the bass control a smidge.

Lastly, the Fletcher Munson curves are an average, they aren't correct for all humans. Consequently, even if the loudness control followed the curves perfectly, it would still be wrong for many, if not most, of us.