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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
natural, and you brain becomes fatigued trying to fi gure out where sound is
coming 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 amplifi ers 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 processor switch. The usefulness of the circuit varies depending
on what type of recording you are listening to; mono and binaural record-
ings need no processor at all. Old studio recordings that have instruments
panned hard left or right, benefi t greatly from the processor. Live and classi-
cal recordings miked from a distance benefi t somewhat less, and can often
be listened to without the processor quite comfortably.
Plain
Headphones
With
HeadRoom
The crossfeed switch in
HeadRoom amplifi ers
allow you to cross-feed
a little of the left and
right channels across
to eachother through a
short time delay.
Far ear
hears
slight delay.
Near ear
hears sound
fi rst.
30 degrees
off axis
Filter/Brightness Switch
The fi lter/brightness switch is used to compen-
sate for the slight warming action of the cross-
feed circuit. In the center position, there is no
fi lter present in the circuit. This is generally the
preferred setting. But if you feel that the cross-
feed is causing too much bass response in the
source material or a faint blurring of the central
soundstage image, a mild high frequency boost
can be turned on. The “fi lter 1” setting accentu-
ates the highs at around 3kHz; with the “fi lter 2” setting, the fi lter starts an
octave earlier and catches some of the upper mids while providing an ad-
ditional boost in the amplitude of the frequency range. The best setting is
whatever sounds good to you!
Volume Control Upgrades
stepped attenuator
The Home amp comes standard with an
extremely good quality Nobel volume
potentiometer that is continuously vari-
able. The upgraded volume pot option is
the Stepped Attenuator.
The Stepped Attenuator is a 24 position
multi-pole switch is a shunt-design at-
tenuator which greatly minimizes the number of contacts the signal has to
pass through during this fi nal output stage before it gets to your headphones.
The shunt stepped attenuator has the voltage divided between a single fi xed
resistor on the circuit board and the resistor selected by the stepped attenu-
ator. The parts we use to hand-build this pot include the well-regarded Elma
Type 04 24-position switch for which we manufacture our own Electroless
Nickel / Immersion Gold (ENIG) switch contact circuit boards. This is just a
fancy way of saying that these boards are highly corrosion resistant and have
a very heavy gold plating -- signifi cantly heavier than normal circuit board
gold coatings. This is important to the increased lifetime of the switch. You
can choose the stepped attenuator option upon intial purchase of you Home
amp or have it upgraded at a later date. Visit our webiste or call us at 800-
828-8184 for more details.
About the Filter Switch & Volume Control Upgrades
