TC Electronic SYSTEM 6000 MKII Algorithm Manual - Backdrop - Tutorial

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bACkDrOP - TuTOrIAl

BackDrop does this using the current Trim Start and Trim 

End settings.

Play

The Play button starts and stops playback of the captured 

audio buffer. The audio buffer plays repeatedly until Play is 

turned off. 

Trim Start and Trim End

The Trim Start and Trim End controls allow you to zoom 

in on a specific range of the captured audio buffer. These 

controls are used to make sure that the audio contained 

between the start and end points contains only noise and 

no signal.

When calculating the noise print information or when using 

the Play feature, only the audio contained between the 

start and end points is used. Therefore, in order to update 

the noise print information, you should press Calculate 

whenever the Trim Start or Trim End controls have been 

altered. It should be noted that whenever the Trim Start 

or Trim End controls are adjusted, BackDrop restarts 

playback of the capture buffer from the Trim Start point.

Getting Started

This section is intended to give you a simple guide to get 

started using BackDrop. BackDrop has a rather unique 

set of controls and you may require some time to get the 

optimal performance from BackDrop. 

If possible, in order to help you to become familiar with 

BackDrop’s controls, use a piece of music that has a fairly 

audible (although not too high) level of hiss.

The first step when removing noise from a signal is to 

capture a noise print so that BackDrop can learn the 

characteristics of the noise and dissect it into its various 

components. Start by going to the Print screen. 

When you press the Capture button on the Print screen, 

BackDrop automatically records 1.5 seconds of audio. 

It then automatically calculates all of the noise print 

information that is required for the 3 algorithm models 

(Basic, MultiBand and MultiType).

In order to get the best possible performance from 

BackDrop, it is important to capture a sample of just the 

noise without any of the signal. Therefore, it is a good idea 

to use the Play feature to listen to the buffer of audio that 

has been used to calculate the noise print information. To 

do this, go to the Print screen and press Play. This will play 

the captured buffer. If you hear any signal within the buffer, 

use the Trim Start and Trim End controls so that only noise 

is heard. Once you are satisfied that there is only noise 

between the Trim Start and End points press the Calculate 

button to update the noise print information using the new 

buffer start and end points. You are now ready go to the 

Model screen and apply the noise reduction.

When listening to the capture buffer using the Play 

feature, BackDrop may already be performing 

noise reduction depending on the present settings 

of the controls. To hear the unprocessed capture buffer, 

simply press Bypass.

Go to the Model screen and select the Basic algorithm 

using the Algorithm Model control. In order to get an 

initial feel for BackDrop’s controls we will use some 

rather extreme settings. Do not take these settings as an 

indication of typical settings for BackDrop’s controls!

Start by linking BackDrop’s controls using the Link button. 

Set Basilar Dispersion and Transient Recovery to 0%. This 

effectively turns off BackDrop’s model of the ear. Now set 

the Aggression control to 100% and Max Reduction to 0 

dB. Because Max Reduction is set to 0 dB BackDrop will 

not yet reduce the noise at all.

Slowly increase the level of Max Reduction. As you do this 

you should hear the level of the noise go down accordingly. 

Set Max Reduction to about 10 dB and listen as you turn 

the processing on and off using the Bypass button. The 

noise reduction should be obvious. If not, something is not 

quite right and you should re-trace the above steps.

Continue to increase the level of Max Reduction beyond 10 

dB. If the level of the noise in your input signal is relatively 

high, you will likely begin to hear strange low-level random 

chirping sounds. These low-level artifacts are usually 

referred to as “musical noise” or sometimes as “Mars-men”, 

or “space monkeys”. These artifacts are commonly found 

in other noise reduction products and can seriously limit 

the usability of the noise reduction system. Fortunately, 

BackDrop provides you with a means of eliminating these 

artifacts.

Slowly increase the level of the Basilar Dispersion 

parameter. You should hear the musical noise artifacts 

disappear. This is exactly the purpose of the Basilar 

Dispersion parameter. By taking advantage of the masking 

properties of the ear, Basilar Dispersion eliminates low 

level artifacts that can occur as a result of the noise 

reduction process.

To further investigate BackDrop’s controls, set Aggression 

and Basilar Dispersion to 100% and set Max Reduction 

to 100dB. You are now applying the maximum amount of 

noise reduction available from BackDrop. With this amount 

of noise reduction you will very likely hear distortions to the 

desired signal. 

For example, you may hear a smearing of the transient 

portions of the signal. BackDrop’s Transient Recovery 

parameter was specifically designed to maintain sharp 

attacks and to prevent transients from being smeared. 

Increase the Transient Recovery control and listen to how 

the transients are restored to their original sound.

Hopefully, you now have a feel for the four primary controls 

for BackDrop’s Basic algorithm. The controls for the other 

two algorithms (MultiBand and MultiType) are similar in 

functionality. Remember that the settings for BackDrop’s 

controls described in this tutorial are by no means the 

recommended settings. They were simply intended to help 

you become familiar with their effect.

It is instructive to play some more with the various