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What does the Clipping Indicator Do?
But in the case of the AirHead, the clipping indicator not only tells you when you’ve got
a hot signal, it also tells you when your batteries are low. Because we’re using some of
those new multi-voltage “rail-to-rail” interated circuit chips, the AirHead will run on a wide
range of voltages. And because “normal listening level” will vary widely due to the varying
impedances of headphones on the market, we can’t really estimate how long the AirHead
“should” run on a set of batteries. (The battery voltage may lower to clipping after 20 hours
of use with a difficult-to-drive pair of AKGs, but you might get 60 or more hours of use at
a comfortable listening level when driving a pair of efficient Grados.) We realized that a
clipping indicator on the ever-diminishing voltage of a set of batteries would be the best
low battery indicator of all. For a given volume level at your headphones, the battery volt-
age will eventually get lower than the signal, and the clipping indicator will start to blink
with the louder bits of the music. If the clipping indicator starts blinking more and more at
your normal listening volume, it’s a sign that your batteries are on their way out and need
to be changed soon.
Next is the clipping indicator, a frosted red LED that lights up every time the amp clips.
“Clipping” is what happens when the signal tries to get bigger than the power supply volt-
age, which it can’t, and the peaks in the signal get “clipped” off. The result is a miserable
crackling sound.
An example of the input signal, and the output signal clipping
