Beat Repeater Combinator Tutorial

Sunday, December 28th, 2008 | 10:55 am and filed in Combinator, Tutorials.


For quite some time, I’ve been trying to perfect a beat repeater combinator. You may have seen it in one of my song files or in James Bernard’s demo reason song “Age of Technology”. The quandry that I’ve faced is that there’s no way to make a universally useful version of the patch, so I’ve decided to post a PTR style tutorial so that people can build it themselves and further develop their own modifications.

The beat repeat effect uses DDL-1 Digital Delay Lines as loopers - a real-time sampler. When the delay feedback is set to maximum, the DDL-1 will indefinitely echo the audio in the delay buffer. Incoming signals are merged with looping audio, so a “gating” mechanism must also be put into place that will mute incoming signals while the delay is looping. This is easily set up with a few combinator modulation routings.

Basic Beat Repeater Combi

Devices and Audio Routing
1. In a Reason Song File, create a Combinator. Verify that it’s been connected to a mixer input channel or some other way of monitoring the output signal.

2. Open the Combi Programmer, and then click on the empty space in the Combi Device sub-rack. You will see a red line appear in the sub-rack.

3. Hold down the [Shift] key to bypass auto-routing, and create a Line Mixer 6:2.

4. Hit the [Tab] key to access the cabling on the rear of the rack. Connect the Combinator’s ‘To Devices’ outputs to the Channel 1 inputs on the Mixer.

5. Bypass auto-routing and create two DDL-1 Digital Delay lines. Double click on the labels and rename these devices to “Delay L” and “Delay R”.

6. Bypass auto-routing and connect the Line Mixer Master Out Left to the ‘Delay L’ Left Input.

7. Connect the Line Mixer Master Out Right to the ‘Delay R’ Right input.

8. Bypass auto-routing and connect the ‘Delay L’ Left Output to the Combinator ‘From Devices’ Left input.

9. Connect the ‘Delay R’ Left Output to the Combinator ‘From Devices’ Right input socket.

Combinator Modulation Routings
10. In the programmer window, select “Line Mixer 1″ from the device list. In the Button 1 row, click on the Target Column, and select the item, “Channel 1 Mute”. Leave the default minimum and maximum values.

11. Select “Delay L” in the device list, and in the source column click on “Rotary 2″ and reassign the source to “Rotary 1″. Also, reassign “Rotary 4″ to “Button 1″. Both Rotary 1 and Button 1 will perform multiple operations so it is necessary to have a couple of settings for each. In the target column make the following modulation routings:

Source: Target: Min: Max:
Rotary 1 DelayTime (steps) 1 4
Rotary 1 DelayTime (ms) 1 80
Button 1 Feedback 0 127
Button 1 Dry/Wet Balance 0 127
Button 2 Unit 0 1

12. The routings are duplicated for “Delay R”. After selecting “Delay R” in the device list, assign the source column settings and target modulation routings as indicated in step 11.

13. On the Combinator’s main panel, rename “Rotary 1″ to “Delay Time” and set the rotary value to 0.

14. Rename “Button 1″ to “Repeat” and “Button 2″ to “Unit”. Optionally, you can clear the labels on the other unused rotaries and buttons. Reset the settings by clicking twice on the “Repeat” button. Enable the “Unit” Button, so that the default setting is the delays’ Steps mode.

15. Save the combinator patch as “Basic Beat Repeater.cmb” by clicking on the floppy disk icon. You can also simply save the song file to archive your work up to this point.

Adding a Signal Source
This patch is an insert effect and should be placed in series between a sound module and a mixer channel. You can also insert the beat repeater after a main mixer output in order to apply the effect on the entire mix. Continue with the following to incorporate a ReCycle loop into the song file:

16. Click on the empty rack below the combinator and add a Dr.REX loop player to the rack to use as a signal source.

17. From the Reason Factory Sound Bank, load the REX file, “Acs03_SureGroove_070.rx2″, located in the Acoustic / Shuffle / 070 Sure Groove / Directory. Click on the “To Track” button to export the slice data to the Dr.REX 1 Sequencer Track.

Run the Sequence and as the loop plays, click on “Repeat” Button to engage the beat repeat effect. While the combi is repeating a step, adjust the “Delay Time” control to induce pitch artifacts as the delay cycles with modified values. You can get some really cool effects.

Millisecond Unit Mode
In step mode, the patch is limited to 16th note segments. The main workaround for this issue is to double the tempo of a track, if you want precise 32nd note repeats. Alternatively you can switch off the unit button and adjust the delay time to segments shorter than a 16th. You will need to rely on a delay time/bpm calculator to find the durations for 32nd note or shorter intervals. For example, at 120 BPM, a 32nd note is 62.5 ms, so set the delay time to 63 ms. It’s not precise, but you probably wont notice the half-a-millisecond difference.

Beat Repeater Modifications

Because this effect is highly sensitive to timing, one of the basic modifications is to have the effect triggered by a Matrix Pattern Sequencer. Instead of assigning “Button 1″ as the trigger, change the source settings in all three devices to “Rotary 4″.

Set the default value of Rotary 4 to 0, connect a Matrix Curve CV to the Rotary 4 CV input, and set the Rotary 4 CV scaling to maximum. Now you can program repeat events on the Matrix Curve editor. This is designed to work in unipolar mode with maximum values in the curve editor.

Another very interesting modification is to have a second Matrix Pattern Sequencer modulate the Delay Time rotary. The pitch shifting/artifacting effect can then be controlled with a bit more regularity since you can store the automation with the patch and quickly recall it. This can also be automated with sequencer clips, but it’s a little more convenient to save the patterns within the combinator for use in other projects.

Have fun with this!

5 Responses to “Beat Repeater Combinator Tutorial”

  1. mark tarlton Says:

    Thanks for making this tutorial Peff. It was a little confusing at first to build the Repeater in Reason 3 because of step 11 since you can’t reassign buttons and rotaries like you can in R4, once I remembered how to do it the old way it was a piece of cake. Also step 17… that Rex file isn’t in the R3 factory sound bank.

    This is one of my favorite EFX combinators at the moment :)

  2. hanssm Says:

    Terrific tutorial - very very helpful in understanding the mechanics of beat repetition - thanks for that. I now predict for myself a period of terrible audio experiments before hopefully emerging on the other side a bit wiser. :)

  3. meowsqueak Says:

    Great little tutorial - a similar style to your excellent “Power Tools” book.

    A simple improvement on your “second matrix” idea is to use the Gate CV to modulate the Combinator “Feedback/Wet/Dry” rotary (use 0 or 100%) and use the Curve CV to modulate the “Delay Time” rotary. This way you can trigger the repeat and change the delay within the same Matrix.

  4. Peff Says:

    mark: Thanks for the correction. You could use the spare routing slots at the bottom of the routing list in Reason 3.0. I also forgot those acoustic loops were new in Reason 4.0

    meow : theoretically using the Gate CV should work, however there’s an issue with the Matrix Gate CV which doesn’t fully work in this case. The maximum value of a Matrix Gate CV signal is 126, and when you modulate a the mute button with a rotary, the mute will not engage until the rotary value is 127. That’s why I suggested the dual matrix configuration rather than a single. If you want to make the single matrix version work in the way you recommended, double the gate cv value by merging it with itself. Split the signal, then merge two of the split CV signals and route it to the rotary controlling the gate and delay feedback.

  5. blacktiger Says:

    Fantastic beat-mangling going on here! I’m still getting used to some of the unpredictable curves, but that’s what makes this project fun. Either that or I’ll have Mark give me drum lessons if we want to scare everybody: “Look out! Rick’s got a drum!”