For years, guitarists and sound engineers have been
trying to find a way to capture the sound coming
from the amplifier without the challenges of using
a microphone. Although getting a great sound with
a mic can be accomplished, it usually takes a lot
of time and careful mic placement. This can take
hours and even days to get just right.
But in a live situation, this is simply impossible
due to time restrictions and available space on
stage. So for years, a ‘compromise’
has been achieved by placing a mic directly on
the speaker cone. Now if you stop and think about
it, the sound of a guitar changes depending on
where you are standing. This is particularly acute
with guitar amps with two speakers or more. Why?
Because the ‘phase relationship’ between
the speakers and your ears changes depending on
where you stand. This is due to different frequencies
cancelling each other out causing nodes, an effect
commonly known as 'comb filtering'.
To avoid comb filtering the mic is placed right
on the speaker. This way only the sound from one
driver gets into the mic.
Now if you take the time to listen to the guitar
tone that is produced two inches from the speaker,
you will find that the sound is really not that
pleasing. Furthermore, moving the mic ever so
slightly can have a dramatic effect on the tone.
(ex: capturing the sound from the middle of the
speaker sounds very different from the edge.)
But we do it this way because it is quick and
is pretty much the best compromise we have been
able to find so far…
But what sound engineers really want is a way
to capture the sound from the amplifier that is
consistent night after night. This has become
all the more prevalent since the advent of in-ear
monitors as guitarists are no longer listening
to their amps; they are hearing the guitar and
amp through a microphone, mixing console and ear
buds. All of a sudden, they are beginning to realize
that the tone is nowhere near as good as what
they were able to achieve in the studio. This
has augmented the need for a simple audio interface.
We call it the Radial JDX.
The Radial JDX Reactor is designed to ‘capture’
the signal from the complete amplifier by connecting
in between the head and the speaker cabinet. This
is very different from the direct feed coming
from a guitar amp. A direct feed from an amplifier
is completely void of any interaction with the
speaker cabinet which as any guitarist will attest,
plays an integral role in the amp’s tone.
In fact, the amplifier’s ability to control
the speaker – known as the damping factor
– produces effects such as ‘sag’
and the counter-EMF (electro-magnetic field) also
causes the amp’s output stage to constantly
react as the level, impedance and load changes.
It is the relationship between all of these factors
that produces the sound. By capturing the reactive
effect, the JDX comes closer to the original tone
than any other guitar interface ever.
Once connected, the signal is transformer isolated.
The transformer works double duty by both providing
a reactive electro-magnetic interface with the
amp and speaker while also isolating the JDX to
help eliminate ground loops. Then the JDX processes
the signal with via a unique class-A buffering
circuit plus a series of filters to recreate the
typical response curve from a 12” guitar
speaker cabinet. The signal is then electronically
balanced to match a microphone level and sent
along the audio path with the other mics and direct
boxes to the console.
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