How-to: Calibrate Scratch Live

Why is it important to calibrate Scratch Live?

In the standard configuration of Scratch Live an analogue audio source (turnable / CDJ) sends the Scratch Live control signal into a Rane Scratch Live hardware device, where it is digitized, sent to the Scratch Live software and used to control playback of a digital audio file. It is important to calibrate your set up so the software can distinguish between what is heard as the control signal and what is recognized as background noise and ignored. 

If you have not correctly calibrated Scratch Live for your system and environment you may run into a number of playback issues including glitchy/skipping playback and your tracks not playing at all.

To calibrate Scratch Live click here.

How Scratch Live tracks the control vinyl

There are two parts to the Scratch Live control signal: The directional tone, and the noise map. These two parts of the control signal perform two different functions in controlling Scratch Live:

- The directional tone provides the current speed and direction of the record

- The noise map tells the software precisely where on the record the needle is currently.

The noise threshold

The noise threshold in Scratch Live is the limit below which the input signal will not be interpreted as a control signal. In other words, if it's below the threshold, it is considered noise and ignored by the software. This setting is necessary because a turntable stylus is very sensitive and will inevitably pick up noise from the environment as well as the signal on the record. This especially noticeable in the noisy environment of a live show or busy club.

Noise threshold slider
Noise threshold slider

The scopes

The scope views on the setup screen in Scratch Live display the input signal as a phase diagram. The key factors to look at on the scope display are crisp clean lines, round shape, and the tracking percentage in the lower right corner. This view shows how well Scratch Live is tracking the control signal.

Scope view
Scope view

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