17
Calibrating Scratch
LIVE
The TTM 57SL interprets the signal on record and communi-
cates with the software. The signal needs to be clear for Scratch
LIVE
to perform well. This section describes how to calibrate
Scratch
LIVE
to optimize reading the control signal from your
turntables or CD players.
For best results, re-calibrate Scratch
LIVE
each time you move
or make changes to your DJ equipment. To calibrate Scratch
LIVE
, go to the
setup
screen by pressing the button at the top of
the main screen, to the right of the Scratch
LIVE
logo.
Signal threshold
The first step is to set signal threshold. There is always a certain
amount of background noise, particularly when using turntables
in a club environment. With a normal turntable setup, this back
-
ground noise is transmitted through the body of the turntable
and platter to the stylus, and can cause stylus feedback. In Scratch
LIVE
, this can cause errors on the reading of the position and
velocity of the control record, resulting in a garbled digital noise
and/or poor tracking.
Place the needle on the record
with the record stopped
.
Click the
estimate
button to measure the background noise and
estimate the appropriate threshold. Moving the threshold slider
to the left will make Scratch
LIVE
more sensitive to slow record
movement, but also more sensitive to background noise.
Tip: If the slider jumps to the far right, then you have a prob-
lem with noise in your turntables/CD players/mixer. Check all your
connections and make sure your equipment is well earthed. In some
situations you will not be able to improve the signal quality, and
you will have to play on regardless. In this situation, stick to
relative
mode. (See page 23 for details)
Scope view
Once you have set the threshold, start both turntables. You will
see green rings appear in the scope view, as shown below.
For optimal performance the inner ring should be as close
to circular as possible. Use the scope zoom slider (
1x
to
16x
) to
zoom in or out as necessary. Use the scope
L/R balance
and
P/A
balance
controls to adjust the shape of the inner ring.
The number in the top left corner of the scope view gives the
current absolute position within the control record or CD. The
number in the top right corner is the current speed in RPM. In
the bottom left is the current threshold setting, and the number
in the bottom right shows the percentage of readable signal – this
number should be at least 85% when your system is calibrated
properly.
Tip: If you have trouble getting the rings circular, you probably
need to clean or change your needles. If the image appears as a line,
then one of the channels of the turntable is not working. See examples
of potential problems and fixes on pages 42-43.
