Axiom Home Page Forums General Discussion Technical Questions Speaker sensitivities / calibration question

Yay, someone with a real answer!

Thanks, JohnK. So the receiver basically figures out the speaker's sensitivity by the trim coupled with the distance settings? Is that right? Otherwise, I don't see how it works. Calibrating at one volume level wouldn't really show the receiver the speaker's sensitivity, since distance would be a factor in the volume, right? So does it, in fact, use both trim and distance figures to create a curve for the speaker's sensitivity, or am I still missing the boat?

Charles, the volume levels of the various speakers are equalized. It doesn't matter whether the correction is due to a difference in sensitivities, a difference in speaker location, or whatever. The receiver doesn't specifically care what the sensitivities are; it just wants the speakers to be equally loud at the listening position.

Yes, and that's why I'm at a loss as to how it can accurately predict how much juice to send a speaker at any volume other than reference, if it doesn't know the speakers's sensitivity. Is it really a straight line in output, not a curve?

As was mentioned in my first reply, the difference in sensitivities doesn't change with changes in volume levels. There's no need to "predict" anything. Whatever the incoming voltage from the source material is at a given instant in time, it's subjected to the same gain(around 14dB for the preamplification and 28dB for the amplification, increasing the voltage about 120 times)and results in the speaker being audible.

The difference in sensitivities doesn't change. You're right. But if not every speaker in the system has the same sensitivity, then how is the output matched correctly at volumes other than what you calibrated at? I realize I'm probably just being super-thick, so I appreciate your patience.

The trim settings in the receiver vary how much of the voltage coming in from the source material is let through to be preamplified and amplified to each speaker(the receiver "volume" control varies this uniformly to all speakers). For a more sensitive speaker, or one closer to the listening position, or whatever else might make it louder, the trim reduces the incoming voltage in its channel enough so that after the uniform gain that applies to all channels takes effect, it's no longer louder than the other speakers. This takes place at all "volumes", i.e., all levels of voltages coming in from the source material. Since the difference in sensitivities doesn't change with volume, there's no "matching" problem at different volumes.

It just seems like sensitivity and distance should act on a speaker's output to different degrees. The way you explain it makes it seem like the sensitivity and distance affect the volume the exact same amount. Is that right?

CV, it is magic.


That is all.

Finally, someone put it in layman's terms. Ha ha.