OT Fletcher-Munson curve

[joyspring]

THe Sub woofer fills the room with ambiant bass. If you have a more sophisticated system with active compononets you can RTA the sound perfectly.

A subwoofer does assist at low frequency but so will any large system that has sufficient volume displacement and proper tuning.

You can RTA the sound perfectly at a single listening level. When you turn your volume knob down, a preamp/receiver/amplifier will not compensate for equal loudness...

But you then mention active components - by which I assume you're referring to DSP - and yes, the better implementations (i.e. - Audyssey XT, etc.) do have equal loudness compensation based upon its room test measurements. This has nothing to do with subwoofers or RTAs as mentioned in your OP.

Classic Loudness control is automatic in that it is directly tied to the volume control of the amp. As the volume control is turned up/down, the frequency curve is also changed, per the Fletcher-Munson curve, so the human ear perceives consistency

The "Classic Loudness Control" is tied to the volume control of an amp by using a tapped potentiometer (usu. at 40%) to implement a facsimile of equal loudness curves at lower listening levels with the volume control below the tap. This never was standardised because it would be impossible to do so.

As I mentioned before, proper implementation depends on loudspeaker sensitivity, amplifier gain, room acoustical loading.

The self powered sub woofer output on all new recivers is directly linked to volume control also.

I would hope so.

BTW, the term `Fletcher-Munson' has been deprecated as subsequent research resulted in an international standard (ISO 226) referred to as `Equal Loudness Contour'.

BobR