7
What is the HeadRoom Crossfeed?
Imagine you are listening to a pair of speakers. If you turn off the left speaker,
both ears hear the sound from the right speaker. But because the left ear is
slight farther away than the right ear, it hears the speaker’s sound slightly
after the right ear; about 300 microSeconds. This time difference is called the
“inter-aural time difference” and it is the main thing your brain listens for in
order to tell where to place sound left-to-right.
But in headphones if you turn off the left channel, only the right ear hears the
sound. In headphones, if there is any sound that is only in the left channel, or
only in the right channel, then only that ear hears the sound. This is not natu-
ral, and you brain becomes fatigued trying to figure out where sound is com-
ing from when only one ear is hearing it. This tends to create an audio image
that is a blob on the left, blob on the right and a blob in the middle.
HeadRoom amplifiers cure the problem by allowing you to cross-feed a little
of the left and right channels across to each other through a short time delay
using the crossfeed switch. The usefulness of the circuit varies depending on
what type of recording you are listening to; mono and binaural recordings
need no processor at all. Old studio recordings that have instruments panned
hard left or right, benefit greatly from the processor. Live and classical record-
ings miked from a distance benefit somewhat less, and can often be listened
to without the processor quite comfortably.
Plain
Headphones
With
HeadRoom
The crossfeed switch in
HeadRoom amplifiers al-
low you to cross-feed a
little of the left and right
channels across to eacho-
ther through a short time
delay.
Far ear
hears
slight delay.
Near ear
hears sound
first.
30 degrees
off axis
