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Loudness controls

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When you first turn the volume down there may be a perceived reduction in bass, do you not adjust though and after a while it sounds right again?
I once worked in a lab with a powerful infra-red laser. You couldn't see the dangerous laser beam, which made it extremely dangerous - you could easily be blinded accidentally. To prevent this, it was mandatory that you put on special infrared-blocking goggles before you entered the lab, and wore them until you left the lab.

The googles not only removed IR, they also removed a huge chunk of the visible spectrum in the red and orange areas. When you put first put them on, everything you could see was tinted a hideous blue.

But after you'd been wearing them for a while, your brain compensated to a considerable degree, presumably through some sort of internal white-balance adjustment. Your co-workers in the lab appeared to have normal flesh tones to their skin again, instead of a blue tint. But if you looked at the room lights, they still looked blue; apparently your brain knows what white skin should look like, but isn't so sure about light-bulbs.

When you finally left the lab at the end of the day, and took the googles off, now everything looked hideously too red. Once again, it took some time before your brain compensated, and you started to see normal colours again.

So your brain can compensate, to some degree, for lighting with an abnormal spectrum. But surely this is not an argument supporting the idea that everyone visiting an art gallery should wear spectacles that block out most of the red end of the spectrum? You cannot possibly see the art as the artist intended if you do this.

In much the same way, your brain can compensate to some degree for a severe lack of bass and treble in low-volume music - you can get used to hearing only the midrange, as everyone did in the golden age of AM radio. But surely this is not an argument supporting the idea that hearing only the midrange is the right thing to do? You cannot possibly hear the music the way the composer and performers intended if you do this.

Personally I find loudness compensation beneficial at the extreme case of very quiet bedroom listening levels. At normal living-room SPL, I don't feel a need for it, even though this is much lower than the original performance of whatever music I'm listening to.

-Gnobuddy
 
Totally agree with above post.

But then as Wavebourn intimated, the idea of directly relating F-M compensation to distance from the performance is also wrong.

The intensity of music right at the ear is of importance. If a perfect microphone is placed there, the intensity when playing your music in a living room may not be all that different from what said microphone would indicate with Von Karajan conducting the 1812 full blast, to a listener somewhere toward the rear of the concert hall - although few of us are probably in such a favourable situation that we are remote from any neighbours.

Thus one is probably not playing with concert hall energy right at your ear; I would imagine that some compensation is in order (this seems to correspond with what listeners perceive). Yes, the conventional tone controls might suffice - only the contours are different.
 
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I used the existing loudness circuit in SX-780 as well as the tone stack. Works fantastic with 2 stage 6922 driver biased at 7ma.
pushing AM response up to 7khz certainly makes it better. HA1197 will support this if you widen the IF passband at the expense of selectivity.
 
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