Antares ATR1a Hardware user manual

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Pitches are often described relative to one another as intervals, or ratios of
frequency. For example, two pitches are said to be one octave apart if
their frequencies differ by a factor of two. Pitch ratios are measured in
units called cents. There are 1200 cents per octave. For example, two tones
that are 2400 cents apart are two octaves apart.
The traditional twelve-tone Equal Tempered Scale that is used (or rather
approximated) in 99.9% of all Western tonal music consists of tones that
are, by definition, 100 cents apart. This interval of 100 cents is called a
semitone.
How the ATR-1a detects pitch
In order for the ATR-1a to automatically correct pitch, it must first detect
the pitch of the input sound. Calculating the pitch of a periodic waveform
is a straighforward process. Simply measure the time between repetitions
of the waveform. Divide this time into one, and you have the frequency in
Hertz. The ATR-1a does exactly this: It looks for a periodically repeating
waveform and calculates the time interval between repetitions.
The pitch detection algorithm in the ATR-1a is virtually instantaneous. It
can recognize the repetition in a periodic sound within a few cycles. This
usually occurs before the sound has sufficient amplitude to be heard. Used
in combination with a slight processing delay (no greater than 4 millisec-
onds), the output pitch can be detected and corrected without artifacts in
a seamless and continuous fashion.
The ATR-1a was designed to detect and correct pitches up to the pitch C6.
If the input pitch is higher than C6, the ATR-1a will often interpret the
pitch an octave lower. This is because it interprets a two cycle repetition as
a one cycle repetition. On the low end, the ATR-1a will detect pitches as
low as A0 (55Hz) in its normal mode and down to 25Hz when Bass Mode is
selected. This range of pitches allows intonation correction to be per-
formed on all vocals and almost all instruments.
Of course, the ATR-1a will not detect pitch when the input waveform is
not periodic. As demonstrated above, the ATR-1a will fail to tune up even
a unison violin section. But this can also occasionally be a problem with
solo voice and solo instruments as well. Consider, for example, an excep-
tionally breathy voice, or a voice recorded in an unavoidably noisy envi-
ronment. The added signal is non-periodic, and the ATR-1a will have
difficulty determining the pitch of the composite (voice + noise) sound.
Luckily, there is a control (the SENSITIVITY control, discussed in Chapter 4)
that will let the ATR-1a be a bit more casual about what it considers
“periodic.” Experimenting with this setting will often allow the ATR-1a to
track even noisy signals. 
						

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How the ATR-1a corrects pitch
The ATR-1a works by continuously tracking the pitch of an input sound
and comparing it to a user-defined scale. The scale tone closest to the
input is continuously identified. If the input pitch exactly matches the scale
tone, no correction is applied. If the input pitch varies from the desired
scale pitch, an output pitch is generated which is closer to the scale tone
than the input pitch. (The exact amount of correction is controlled by the
Speed parameter, described below and in Chapter 4.)
Scales
The heart of the ATR-1a’s pitch correction is the Scale. The ATR-1a allows
you to program 50 different Scales. For each Scale you can define which
notes will sound and which won’t. And for each note that will sound, you
can decide whether the ATR-1a will apply pitch correction to input pitches
near that note or leave those pitches uncorrected.
Speed
You also have control over how rapidly, in time, the pitch adjustment is
made toward the scale tone. This is set with the SPEED control (see
Chapter 4 for more details).
•Fast SPEED settings are more appropriate for short duration notes and
for mechanical instruments, like an oboe or clarinet, whose pitch
typically changes almost instantly. A fast enough setting will also
minimize or completely remove a vibrato.
•Slow SPEED settings, on the other hand, are appropriate for longer
notes where you want expressive pitch gestures (like vibrato) to come
through at the output and for vocal and instrumental styles that are
typified by gradual slides (portamento) between pitches. An appropri-
ately selected slow setting can leave a vibrato unmodified while the
average pitch is accurately adjusted to be in-tune.
Vibrato
The ATR-1a can also apply a vibrato to the input sound. You can program
the vibrato depth, vibrato rate and the onset delay of the vibrato (or even
control it in real time via MIDI). You can also choose the shape of the pitch
variation in the vibrato (sine, ramp or square). By combining a fast Speed
setting with the ATR-1a Vibrato settings, you can even remove a
performer’s own vibrato and replace it with the ATR-1a’s programmed
vibrato, all in real time. Also, unusual combinations of Vibrato Waveform,
Rate and Depth settings can be used for some interesting special effects. 
						

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An example
As an example, consider this before-and-after graphic representation of
the pitch of a vocal phrase that contains both vibrato and expressive
gestures.
In the original performance, we can see that although the final note
should be centered around D, the vocalist allowed the tail of the note to
fall nearly three semitones flat. The “after” plot is the result of passing
this phrase through the ATR-1a with a Program consisting of a D Major
Scale (with C

 and B set to ”Blank”) and a Speed setting of 10. That Speed
causes the pitch center to be moved to D, while still retaining the vibrato
and expressive gestures. (Setting C

  and B to ”Blank” is necessary to keep
the ATR-1a from trying to correct the seriously flat tail of the last note to
those pitches. See Chapter 4 for more details.)
Program Mode vs. Song Mode
At its top level, the ATR-1a operates in one of two modes, Program Mode
or Song Mode. Which mode you use depends upon your application and,
to some extent, how radical are the required corrections.
Program Mode
In Program Mode, you call up one of the ATR-1a’s 50 individual Programs
to control the correction algorithm. Each Program consists of a Scale, a
Speed setting and Vibrato settings. You can step through Programs with a
foot switch or via MIDI.
Use Program Mode when a single scale (or maybe two) is all that’s required
for a particular correction.
CORRECTED 
BY ATR-1
ORIGINAL
PERFORMANCE 
						

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If a performance is quite close to begin with and only requires minor
correction (i.e., never more that 50 cents), it’s often sufficient to simply
choose the Chromatic scale, set Speed to about 10 and leave it there.
If you are working in the studio to correct an already recorded track, you
might use Program Mode to deal with the track one section at a time,
stoping to change Programs between sections.
Song Mode
Song Mode offers a more elaborate set of controls primarily designed to
facilitate the use of the ATR-1a in a live performance situation, whether in
actual concert or during tracking in the studio.
The ATR-1a provides 20 Songs. For each Song, you can program a series of
up to 15 Song Steps. Each Step can contain a Program (with associated
scale) or one of a number of navigation controls (See Chapter 4 for
details). In performance you move from Song Step to Song Step via the
foot switch or MIDI. You can also call up different Songs via MIDI Program
Change messages.
Each Song also contains its own Speed and Vibrato settings that override
those settings in the individual Programs. In this way, an individual
Program’s scale can be used in any number of songs, each with different
Speed and Vibrato settings. (To accomplish the same thing in Program
Mode would require you to create multiple Programs, each with the
identical scale but with the different Speed and Vibrato settings. Very
inefficient. )
There is of course no hard and fast rule for which mode to use in any
particular situation. Try out both modes and use what feels comfortable
to you. 
						

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Chapter 2:
Setting Up the ATR-1a
Setting up the ATR-1a is a very straightforward.
1. Find a suitable location. The ATR-1a is designed to be mounted in a
standard 19-inch equipment rack.
2. Confirm that the included power supply is correct for the electricity in
your part of the world. If you are not sure, or the power supply has a
plug that is incompatible with your wall sockets, contact your local
Antares dealer for help.
Important!Do not attempt to modify the supply or use any other supply that is not
specifically intended for the ATR-1a.
3. First, connect the power supply’s 7-pin DIN connector to the AC INPUT
jack on the rear of the ATR-1a. Then plug the power supply into an AC
outlet.
4. Connect a balanced or unbalanced audio input to one of the INPUT
jacks (see Chapter 4 for details).
5. Connect a cable to one of the OUTPUT jacks and route the output as
appropriate for your application.
6. If you will be controlling your ATR-1a via MIDI, connect a MIDI cable
from your MIDI source to the ATR-1a’s MIDI IN jack.
An Important Note: Unless you plan to be defining the ATR-1a’s target
pitches via MIDI, be sure that MIDI NOTE MODE is set to OFF in the System
Edit pages (see page 29 for details). If MIDI NOTE MODE is set to ON and
no MIDI note data is present, the ATR-1a will pass through all audio
unprocessed, regardless of the settings of the Program Scale Page —
giving the impression that the ATR-1a is not functioning.
An Important Note About Grounding: The ATR-1a is an extremely quiet piece
of gear. When properly connected and grounded, noise and hum will be
inaudible. However, as you’re no doubt well aware, every studio has its own
unique quirks when it comes to connections, grounding and noise. For the
absolute best sonic performance, ensure that your input and output are fully
balanced. 
						

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An Important Note About Monitoring: If the ATR-1a is used to pitch-
correct an artist’s performance in real time, it is very important that the
performer is able to monitor their original signal, not the pitch-corrected
signal. Trying to react musically to the processed signal will drive them
crazy and, in most cases, drive them farther off pitch. 
						

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Chapter 3:
Panel Controls and Connectors
As you have almost certainly noticed, the ATR-1a has relatively few controls.
We’ll cover them here.
The Front Panel
1 Non-existent Power SwitchThat’s right. There isn’t one. The ATR-1a is
designed to remain on continuously. You can, of course, plug it in to a
switched power strip or power conditioner if you like, but leaving it on
all the time will do it no harm.
2 LCDAn easy-to-read 20 character by 2 line display. You can set the
optimum viewing angle in the System menu (See Chapter 4).
3 Data Entry KnobAs the name implies, turn it to enter data.
4 CURSOR ButtonsThe cursor buttons let you move the cursor in the LCD
display from field to field so that you can change the field’s value using
the knob.
5 PROGRAMS ButtonPress this button to edit a Program or Song. It is
state-sensitive. That is, if you are in Program Mode when you press this
button, you will be taken to the Program Edit pages. If you are in Song
Mode, you will be taken to the Song Edit pages. The accompanying LED
lights to remind you that you are in an edit mode. When the LED is lit,
press the PROGRAMS buttom again to exit the Program Mode.
6 PAGE ButtonWhile in Program, Song or System Edit Mode, press this
button to cycle sequentially through the available edit pages. You can
only move in one direction, but there are so few pages in each mode
that you are never more than a few presses away from where you want
to be.
12
3456789
10 
						

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7 SYSTEM ButtonPress this button to set various parameters that affect
the ATR-1a’s overall functionality (MIDI response, LCD contrast, etc.)
The accompanying LED lights to remind you that you are in System Edit
Mode. When the LED is lit, press the SYSTEM buttom again to exit the
System Edit Mode.
8 BYPASS ButtonPress the Bypass button to pass audio through the
ATR-1a without any pitch correction or other processing. Switching the
Bypass state will not cause any audio artifacts, so it can be used in
performance or in the middle of a recorded track. The ATR-1a can also
be placed into Bypass Mode via a footswitch (see below) or by MIDI.
The accompanying LED lights to remind you that you are in Bypass
Mode, whether the mode was initiated by the Bypass button, the foot
switch, a Song Step Item or MIDI.
9 SIGNAL LEVEL MeterThese six LEDs light to indicate the input signal
level in dBs. Ideally, you should adjust the input to the highest level that
does not consistently cause the top red LED to light. (The red LED lights
at a level of -3dB. Digital clipping, which introduces a particularly nasty-
sounding distortion, will occur if the input exceeds 0dB.)
10 PITCH CHANGE MeterThese LEDs indicate, in real time, the amount of
pitch correction being applied to change the input pitch to the target
pitch. The green LEDs indicate that the input is flat and that positive
correction is being applied. Conversely, the yellow LEDs indicate that
the input is sharp and that negative correction is required. They are
labeled in cents (i.e., 100ths of a semitone). 
						

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The Back Panel
1 AC POWER INPUTPlug the 7-pin DIN connector from the included
power supply in here. Do NOT use a supply which is not expressly
intended for the ATR-1a (even if you could find one with the that
weird plug on it). Bad things could happen.
2 MIDI INConnect the MIDI Out from a MIDI keyboard, sequencer, or
other MIDI source in here.
3 FOOT SWITCHPlug in a foot switch here. A 1/4-inch TS (tip-sleeve)
plug is required. There are two varieties of foot switch: those that are
shorted by default and those that are open by default. You should plug
in your foot switch and then power on the ATR-1a. The ATR-1a will
detect which kind of foot switch you have and behave accordingly.
4 BALANCED LINE INPUTSInputs can be 1/4-inch TRS (tip-ring-sleeve)
Phone, 1/4-inch TS (tip-sleeve) Phone or female XLR.
Note:The XLR input is NOT a microphone input. A line level signal is required.
Also Note:If you use a 1/4-inch TS plug, the input will of course not be balanced.
Yet Another Note:The two inputs will not mix two signals. Plugging in a phone plug will
disconnect the XLR input.
5 LINE OUTPUTsOutputs can be 1/4-inch TS (tip-sleeve) Phone Unbal-
anced or male XLR Balanced.
54321 
						

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Chapter 4:
Display Screens and Menu Pages
Flash Screen
ATR-1a version 1.3
 ATR-1a Processor
The Flash Screen appears for a few moments after the ATR-1a is powered
on. The first line displays the firmware version. The second line can display
any message that will fit in 20 characters. As it comes from the factory, the
ATR-1a displays the rather unimaginative message above. However, you
can create your own (much more clever) message in one of the SYSTEM
pages (see page 36).
Mode Pages
The ATR-1a operates in one of two modes: Program Mode or Song Mode.
When powered on, the ATR-1a reverts to the mode to which it was last
set. (When initially powered on from the factory, the ATR-1a will be
Program Mode.)
Program Mode Main Screen
In Program Mode, this Main Screen (the page visible when the Program
and System LEDs are not lit) appears:
PROGRAM
XX:aaaaaaaaaaaaa
where XX is the program number and aaaaaaaaaaaaa is the program
name. In Program Mode, the parameters of the selected program govern
the pitch correction algorithm.