BitCrusher BC3 Combinator

Saturday, September 4th, 2010 | 8:23 pm and filed in Reason, Combinator, Tutorials.


The combinator (version 3) in Reason 5 / Record 1.5 has a few notable improvements. Programming is easier with hierarchical destination menus - you no longer need to scroll down long lists of destination parameters. Another welcome improvement is the addition of direct CV inputs. In combinator 2 (Reason 4), a CV source such as an envelope generator, LFO, or step sequencer curve could only be routed through a rotary which subsequently modulated parameters on nested devices. Now in combinator 3, any CV modulation source can be routed directly to a parameter or group of parameters on devices in the combi sub rack.


I put together a bitcrusher patch based around the Scream 4 ‘Digital’ algorithm. In this patch, an MClass compressor not only processes the dynamics, it’s provides a variable cv source from the compressor’s gain reduction value. The gain reduction cv is routed through the combinator CV input which then alters the DAMAGE CONTROL parameter of the Scream 4. As the input signal increases in intensity, the cv routing causes the DAMAGE CONTROL value to increase. The actively changing damage value adds a different character compared to a static setting of the Digital algorithm.

Combinator TS8450 v3 patch require Reason 5 or Record 1.5+Reason 5 duo

BC3 BitCrusher Controls

wordlength - adjusts the RESOLUTION parameter of the digital algorithm

bitrate - adjusts the RATE parameter of the digital algorithm

gain - adjusts the OUTPUT GAIN amount of the MClass Compressor to drive the signal harder into the Scream 4. This parameter also offsets the gain reduction CV value causing a DAMAGE CONTROL offset.

intermodulation - controls the compression THRESHOLD and RATIO and increases the gain reduction as the rotary is turned clockwise. Increased compression causes the DAMAGE CONTROL to increase in intensity.

response - controls the compressor time constants. The ON state sets long values for the ATTACK and RELEASE parameters.

variable bitrate - When this button is enabled, the gain reduction control voltage is tapped and routed to the bitrate rotary. This causes the bitrate to decrease as the input signal increases. Thor is used as a CV on/off switch.

max - This sets the Scream 4 MASTER level to max. Enabling this button can make the signal very loud, but limits around -4dB FS.

emphasis - toggles the compressor SOFT KNEE value which changes the gain reduction curve. In turn this causes starker DAMAGE CONTROL modulation.

BC3 BitCrusher Modifications

One recommended modification is to tap the gain reduction signal and route it to the Scream 4 parameter 2 CV input to establish a variable wordlength modulation. The following steps describe how to implement this feature:

1. On Thor Mod Bus 3, set the source to CV In1.

2. Set the Amount to 80, and set the Destination to CV Output 3.

3. Tab to the rear view and connect the Thor Modulation Output CV3 to the Scream 4 P1 CV input.

4. On the BC3 panel, set wordlength to zero, bitrate to 101, gain to 56, and intermodulation to 95.

5. Disable response, variable bitrate, and max.

6. Enable the emphasis button.

7. Run a drum loop signal through the BC3 BitCrusher to to hear the distortion created by modulating wordlength.

Another suggested mod is to adjust the variable bitrate switching amount. The modulation signal starts with the MClass Compressor gain reduction CV. This CV out is connected to Thor CV 1 input and distributed via the Thor Modulation Busses. The Mod Bus 2 amount value is determined by the min/max values of combi button 2. The minimum value is set to zero, and maximum is set to -50. Changing these values will alter the dynamic modulation characteristics. The following steps describe how to establish this modification:

1. Click on the BC3 Combi Show Programmer Button.

2. Click on “Thor 1″ in the combi programmer device list.

3. On the Modulation Routing section, locate the “Button 2 | Mod 2 Dest Amount” row and set the Min value to 70 and the Max value to -100.

4. Toggle the ‘variable bitrate’ button. This sends the revised values to the Thor modulation bus.

5. Process a signal through the combi patch and toggle button 2 to hear how the values change the distortion characteristics.

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