A funny thing about “Loudness” compensation

[AJM1981]

In the 30's Fletcher and Munson discovered that our hearing is not linear. To make matters worse, the dis-linearity increases the lower the SPL. Basically our ears are the worst microfoon ever.
Loudness as implemented in amps compensate for it. Unfortunately the amp doesn't know the sensitivity of the speakers hence doesn't know the SPL generated. Therefore the loudness compensation is wrong most of the time.

I assume modern amps measure the response so they do know the SPL generated.

Maybe there were some intended combinations or set-like setups. Sansui for example produced some loudspeakers in the 70s along with some amps in time periods. Would surprise me a bit if they did not fit in their own ecosystem.

 

[Snarfie]

In my highly reflective living room i can't live without my Bose Wave Music System III
loudness setting it uplift/correct the room acoustics considerbly.

 

[popej]

I assume modern amps measure the response so they do know the SPL generated.

Yes, loudness (YPAO Volume, Audyssey Dynamic EQ) is active after performing speaker measurements by AVR.

 

[Reed]

Back in the late 70’s I had a Yamaha integrated amp with a variable loudness scheme. You set the loudness knob to flat and increase the volume until the sound was at the level that the sound was balanced to the ear across the spectrum. Then you turned the loudness down to the listening level you wanted. Worked great. Was it accurate? Who knows but it seemed a better solution than on/off.

 

[AJM1981]

Back in the late 70’s I had a Yamaha integrated amp with a variable loudness scheme. You set the loudness knob to flat and increase the volume until the sound was at the level that the sound was balanced to the ear across the spectrum. Then you turned the loudness down to the listening level you wanted. Worked great. Was it accurate? Who knows but it seemed a better solution than on/off.

Part of this range in the CR series probably, fourth knob from the left on the picture.

 

[mhardy6647]

In the 1950s and 1960s, variable loudness was quite common, at least in the US. Eico, for example, offered separate VOLUME and LOUDNESS controls. It was used like the Yamaha model of the 1970s and beyond. Sherwood, e.g., also offered this scheme on some of their integrated amplifiers. There were others; those are the ones I have the most experience with.

DSC_6480 by Mark Hardy, on Flickr
On this Sherwood, the "gain" control sets a "flat" maximum volume, then the LOUDNESS control is used to set the desire output sound level.

As to Yamaha's scheme - one (more) picture's easily worth 10^3 words, as they say.

YamahaCR-2020loudnesscurves by Mark Hardy, on Flickr

OK, two pictures
The relevant sector of a Yamaha R-1000 control panel (sorry it was so grubby when I photographed it!)

DSC_7247 (2) by Mark Hardy, on Flickr

Set the loudness to "minimum cut" (labeled FLAT), turn the volume to the loudest listening level "ever" desired, then use the loudness (cut) to adjust the desired... well... loudness of the program material in the room at the time.

 

[mhardy6647]

Here's a more aesthetic example: CA-610II integrated amplifier (purchased new in 1978 and still goin' strong ).
CA610II and T550 by Mark Hardy, on Flickr