What happened to the loudness control?

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.

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.

Eldarford: In the example I gave you, I used 100% of the volume control simply because there wasn't enough gain in the system. During that period, my volume control would be at max most of the time, not at 90% or any other setting.

Tell me how your loudness control compenstates for the roll off of your subwoofers? They certainly aren't flat nor do they have uniform output as the volume drops.

However, you have piqued my interest in loudness control circuits. I think I will revisit the current thinking of circuit topology and see if anything new has been done in the last few years.

Eldarford: Really? You have consistent efficiency in your subs across the entire voltage input range? I would be most interested in your studies. Many, if not most, subs or speakers for that matter, have consistent efficiency across their entire voltage input range.

My comment above was spoken in the context of linearity, rather than efficiency. It seems in general these days, if your speakers efficiency is off across the input range, it is acceptable for the amplifier to make up for it. There is an arguement that consistent efficiency, as well as higher efficiency, results in better sound but I don't take a side on that one as I have heard bad and good systems at both extremes.

I am still very interested in seeing your test results. If you don't want to publish your results here, please email me directly.

Thanks,

Eldartford: Thanks for publishing the data again. I have been offline for the past week or so due to some reconstruction of my home network.

Your data is very interesting. Who made your subs and what drivers are you using?