G-tune Features
G-tune is more than a guitar tuner. With its advanced frequency measurement algorithm, oscilloscope and spectrum analysis displays, strobe-tuner and noise filter, it is equally at home
in a
laboratory as in a home-studio. What's more if you do lots of
direct-to-disc recording on the PC, G-tune is the ideal tool to use to
monitor levels (especially to watch for clipping) and to select input
sources. And because you can "power" it off, you don't have to close it
when your finished. It can even output MIDI so you can use your guitar
as a MIDI
controller.
Record From Any Input
For maximum ease-of-use, G-tune allows you to record from any input,
and from any sound card installed on your computer. You can select
"MIC",
"LINE", or "CD" if your sound card supports these, and you can control
the input level too. What's more is that G-tune will remember these
settings
so that whenever you restart G-tune, the settings will be restored too,
regardless of Windows' own settings. If your sound card does not
support
these options (typically because it is old and it doesn't have new
drivers)
then you simply use the "DEFAULT" setting and use your sound card's own
mixer utility to control which sound source is selected. If your sound
card
has a DC-offset, G-tune can also compensate for this.
From here you can also calibrate your input device, lock the sample
rate, compensate for DC offsets and set the Auto-Power-Off option.
Frequency Display
G-tune is essentially a frequency meter, and can be used to accurately
measure the main frequency in any input signal. The measured frequency
is displayed with a resolution of 0.01Hz. An the cents deviation from
the nearest semitone is also shown with a resolution of 0.01cents. Note
that the actual accuracy will depend on the sound card used. See G-tune performance for more
information.
CPU Meter
This neat little meter lets you know how much CPU time G-tune is using.
It also lets you know how much CPU power is left for other applications
which are also running.
Reference Frequency
By default, G-tune tunes all notes such that A is tuned to 440Hz
(concert pitch) but you can change this in steps of 0.1Hz. In this way
G-tune allows you to tune to any reference pitch; useful for tuning to
existing recordings which are not referenced to 440Hz.
Tuning Needle
The tuning needle in G-tune lets you instantly see how in-tune, or
out-of-tune, your instrument is. When tuned precicely, the needle will
be in its central position. If the tuning is out, the needle will move
to the left or right. The scale is calibrated in cents (there are 100
cents per semitone) and
the central region gives a measure of what is good enough for
most
occasions.
The needle also has a damping facility, which can be turned on or off,
so that small but fast-moving fluctuations do not stop you tuning
accurately (i.e., the average value is shown).
Note Indicator
G-tune works in a hands-off mode so that you do not need to
select any notes (or string values) before you tune. Instead, G-tune
always automatically detects the correct note and illuminates the note
indicator so that you
always know which note is being tuned. This display is used in
conjunction
with the tuning needle (above).
Above
each note, an indication of the current temperament
is shown.
Strobe-tuner
This displays an alternative way to
tune that
can be used instead of, or in conjunction with, the Needle Scale. The
display
and operation is similar to a traditional electro-mechanical
strobe-tuner,
providing instant response and unparalleled accuracy. Clicking on the
display
cycles through the following display options (the first one disables
the
strobe-tune display).
Although it initially seems complex,
once you
have used the Strobe-tuner, you will notice how effective it is at
providing an
instant-response with highly accurate tuning with bettern than
0.1 cents
accuracy.
Any of the above three displays can
be used, and
it is often personal which is preferred.
When a note is tuned to pitch, the strobe-tune
display will stop moving. The direction of movement indicates if the
note is flat or sharp. The “line” and “wedge” displays move upwards
when the note is sharp, and downwards when the note is flat. The
display with two dots rotates clockwise when the note is sharp, and
anti-clockwise when the note is flat.
The more out-of-tune the note is, the faster the display will move. When the Strobe-tuner isn’t measuring a note, this will
fade out to avoid confusion.
Strobe Note Indicator
This displays the current note (including octave) for the measurement
being displayed in the Strobe-tuner display. This note may be different
to that displayed on the traditional “Notes Display” because the
response is instant, and is not affected by Needle Damping. When the
Strobe-tuner isn’t measuring a note, this will fade out to avoid
confusion.
Oscilloscope
The oscilloscope in G-tune features an auto-trigger mechanism
which ensures that the display is always stable. Using the "scope", you
can analyse the waveform of your instrument, and quickly assess how bad
the background noise is; an essential step in setting up your inputs
for
optimal performance. The display updates in real-time, at around 21.5
times
per second.
Spectrum (Frequency) Analyser
Like the oscilloscope display, the frequency display shows the measured
signal in real-time (updating at 21.5 frames per second). This not only
allows you to see the frequency components of the incoming signal, but
also
gives you much more information on the background noise. It is also
lots
of fun to watch: try whistling into a microphone, or playing a CD into
G-tune.
The frequency scale is marked of in Hz (from 20Hz to just over
5000Hz). The vertical scale is marked off in 10dB steps.
Small Window
A compact version of G-tune when you don't want to see everything.
Useful when G-tune is set to "TOP" and you don't want to use too much
screen space.
Sensitivity
This adjusts how sensitive the measurement will be. If a signal is very
weak, setting the sensitivity high (moving the slider to the right)
will allow G-tune to measure what it determines to be the most dominant
frequency.
However, this can lead to false-triggering, where noise is measured
instead of the real signal.
Normally, you will set the Sensitivity to a position where nothing is
measured when you are not playing any notes (i.e., noise is ignored),
and the note is measured when it is played. This is particularly useful
when using the Strobe-tune display to ensure that only real signals are
measured, and when outputting MIDI to avoid triggering of false notes.
Advanced Noise Filter
G-tune contains an advanced noise filter so than unwanted noise can be
removed to allow easier, or more accurate frequency measurement. For
example, the frequency plot below shows the signal taken directly from
a microphone. Note that there is lots of 50Hz noise (interference from
mains electricity) and that the background noise is rather high.
If we want to tune, say, an acoustic guitar using this set-up we would
have to ensure that the sound from the guitar is loud enough to be
larger than the 50Hz peak (otherwise G-tune will think that the 50Hz
peak is to
be measured instead, as indicated by the red cross on the above
diagram).
However, using G-tune's noise filter, we can measure the background
noise and effectively remove it. The resultant frequency spectrum when
this noise is removed is shown below.
As you can clearly see, the background noise has almost completely been
eliminated. Note also that the 50 Hz peak has been reduced in size by
around 60dB.
If we try and tune our acoustic guitar now, we obtain the following
plot.
Note that the peak at around 110Hz is now clearly visible and is the
peak being measured by G-tune (indicated the red cross). This this
method
has allowed our guitar string (the A string) to be tuned easily and
accurately even although there was a lot of background noise. Note also
that the peak in the bottom graph is almost 30dB quieter than the 50Hz
peak which we had in the first graph; if we has not used the noise
filter, we could not have tuned our guitar string at all.
It is worth pointing out that the noise filter is usually not
required if, for example, an electric guitar is connected directly to
the line-in of a sound card because in this case the background noise
is usually insignificant.
Pitch Graph
G-tune measures the pitch in real-time and displays the results on the
needle meter and illuminates the note indicators. However, if you are
using G-tune to measure your performance on an instrument or whilst
singing it can be difficult to gauge how good you are performing. The
pitch graph display presents you with a much easier overview of this.
The pitch graph window displays the notes on the vertical axis and
time on the horizontal axis. The current note is plotted as a red line,
and
is continually updated, scrolling as required. The bottom of the window
indicates of the amplitude. The window can be resized, and zoomed in
all
directions using the “+” and “-“ buttons.
On the graph, the horizontal lines indicate the position of in-tune
notes. The example above shows a simple guitar part being played: note
changes, string bends and vibrato are clearly seen.
Real-time MIDI Output
A logical extension of the pitch graph, allows G-tune to output MIDI
notes. These notes can be sent to a synthesizer for play-back. This
allows, for example, a guitar to be used as a MIDI controller, sending
MIDI data to a synthesizer in real-time. G-tune is capable of measuring
every nuance of a
performance including pitch bend and vibrato. This can also be sent as
MIDI
if required by enabling the “Send Pitch Bend” button. Notes can be
transposed, and the bend range adjusted to match your synthesiser or
sound module.
Temperaments
When tuning most instruments we often think in terms of an
“even-tempered” scale. This means that each of the notes are evenly
spaced, and are all exactly 100 cents apart. However, this is only true
of certain instruments; guitars and pianos being the most common
examples. Indeed the even-tempered instrument is a relatively modern
invention; in the past, no instruments were even-tempered but followed
other “temperaments”. This subject is steeped in history and
mathematics, initiated by Pythagoras whose tunings were the norm for
almost 2000 years.
G-tune allows the selection of several common, and many lesser known
temperaments. In addition, a “user” setting is available where the you
can set any temperament you desire.
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