Reason 13.1 Operation Manual
DAW | Rack Plugin
Dr. Octo Rex Loop Player
The Dr. Octo Rex Loop Player is the successor to the trusty Dr. Rex Loop Player, introduced in Reason Version 1. The Dr. Octo Rex can hold up to eight different REX loops at once, in eight pattern memories, and allows you to switch between loops and slices in very flexible ways. The Dr. Octo Rex Loop Player is fully backwards compatible with the discontinued Dr. Rex device. This means that all REX loops that previously used Dr. Rex devices in your songs will now open and play back in Dr. Octo Rex devices instead. The loops will sound exactly the same as they did in Dr. Rex.
The Dr. Octo Rex Loop Player is capable of playing back and manipulating files created in ReCycle, another product created by Reason Studios, or bounced from open Single Take audio clips in Reason (see “Bounce Clip to REX Loop”). ReCycle is a program designed especially for working with sampled loops. By “slicing” an audio loop and making separate samples of each beat, ReCycle makes it possible to change the tempo of loops without affecting the pitch and to edit the loop as if it was built up of individual sounds.
#ReCycled Loops
To fully understand Dr. Octo Rex you need to understand what it means to ReCycle a drum loop. Imagine that you have a sample of a drum loop that you want to use in a track you are working on. The loop is 144 BPM and your track is 118 BPM. What do you do? You can of course lower the pitch of the loop, but that will make the loop sound very different, and if the loop contains pitched elements they will no longer match your song. You can also time stretch it. This won’t alter the pitch, but will make the loop sound different. Usually it means that you loose some “punch” in the loop.
Instead of stretching the sample, ReCycle slices the loop into little pieces so that each drum hit (or whatever sound you are working with) gets its own slice. These slices can be exported to an external hardware sampler or saved as a REX file to be used in Reason. When the loop has been sliced you are free to change the tempo any way you want. You can also create fills and variations since the slices can be moved around in the sequencer.
Dr. Octo Rex can read REX files in the following formats:
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REX (.rex)
This is the file format generated by previous versions of ReCycle (Mac platform).
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RCY (.rcy)
This is the file format generated by previous versions of ReCycle (PC platform).
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REX 2 (.rx2)
This is the ReCycle file format for both Mac and PC platforms generated internally in Reason (see “Bounce Clip to REX Loop”) or by ReCycle version 2.0. One of the differences between the original REX format and REX2, is that the REX2 format supports stereo files.
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Unlike the Dr. Rex device, Dr. Octo Rex can also load and save the device panel settings in a special Patch format (.drex). The REX file(s) and the Dr. Octo Rex panel settings are also saved in the Song file just like every other patch in the song.
Loading and saving Dr. Octo Rex patches is done in the same way as in other patch based devices - see “Loading patches” and “Saving patches”.
Dr. Octo Rex patches can consist of up to eight separate REX loops. When you load an Dr. Octo Rex patch, the REX loop(s) will be automatically loaded in the Loop Slots with their names shown in the display(s) below each button.
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You can also load Dr. Octo Rex patches by dragging them from the Browser and dropping on the device panel.
#About the Dr. Octo Rex patch format
Dr. Octo Rex patches (.drex) contains all panel and synth parameter settings as well as references to all (up to eight) REX loops. The actual REX files are not contained in the patch but must be available separately on the computer.
#About opening songs that previously used Dr. Rex devices
Songs created in earlier versions of Reason that used Dr. Rex devices will open just fine in this version of Reason. Any Dr. Rex devices will be replaced by Dr. Octo Rex devices and the corresponding REX loop will load in Loop Slot 1. The original Dr. Rex device settings will be translated as follows:
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The panel parameter settings are automatically applied to the Dr. Octo Rex device.
This makes the loop play back and sound exactly like it did when you created it in Dr. Rex.
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The Enable Loop Playback button on Dr. Octo Rex will be set to Off.
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Any automation for Level and Transpose are converted to Master Level and Global Transpose.
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Routing to CV Mod Input Level is routed to Master Volume.
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The Dr. Octo Rex is set to “Master Keyboard Input to Slices” Mode, so that it behaves exactly like the old Dr. Rex.
1.
Make sure the Enable Loop Playback button is on (lit).
2.
Click the desired Loop Slot button.
3.
Play back the loop by clicking the Run button.
The loop in the selected Loop Slot will play back repeatedly in the tempo set on the Transport Panel. If you change the tempo, the loop tempo will follow.
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You can also play the loop once via MIDI, by using the D0 key.
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To check out the loop(s) together with other device sequencer data and patterns already recorded, click the sequencer Play button.
The loops will automatically play back in perfect sync with the sequencer.
#Switching playback between Loop Slots
Switching playback between loops in different Loop Slots is just like switching a Pattern in a Redrum device, for example.
1.
Activate the Enable Loop Playback button on the Dr. Octo Rex device.
2.
Click the Run button - or start sequencer playback.
3.
Click another Loop Slot button to switch loop.
Selecting Loop Slots that have no loops loaded will result in silence.
#The Trig Next Loop function
The Trig Next Loop function determines how long Dr. Octo Rex waits after a Loop Slot button (or a key) is pressed before it actually “gates in” or triggers the loop. This allows for different “precision” when switching between running loops:
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Activate the Bar button to make the loops switch at the next bar of the current loop.
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Activate the Beat button to make the loops switch at the next beat of the current loop.
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Activate the 1/16 button to make the loops switch at the next 1/16th note of the current loop.
#Switching Loops using Pattern Automation in the sequencer
Switching between Loop Slots can be automated, by using Pattern Automation in the main sequencer.
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When using Pattern Automation, the Trig Next Loop function described above is disregarded - the switching between Loop Slots is instantaneous.
Refer to “Pattern automation recording details” for details about Pattern Automation.
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When you use the Pencil tool to draw Pattern Automation clips and select Pattern in the Inspector, the Bank selection is of no importance since Dr. Octo Rex doesn’t make use of Banks.
#Triggering playback and selecting Loop Slots from a MIDI keyboard
It’s also possible to control playback, stop and Loop Slot selection in real-time by pressing different keys on a MIDI keyboard. By pressing the keys E0 to B0 you select Loop Slot 1-8 and start playback of the corresponding loop. The loop(s) will play back continuously, one loop at a time, until you press the D#0 key to stop playback, or click the Run button or Stop in the main sequencer. The time between key press and Loop Slot switching is determined by the Trig Next Loop function, see “The Trig Next Loop function”.
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Note that the Enable Loop Playback button must be on.
The picture shows what keys should be pressed to select and play Loop Slot and to stop loop playback:
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To maintain backwards compatibility with Dr. Rex, the D0 key can be used to play back the REX loop in the Loop Slot that currently has Note To Slot focus (see “Note To Slot”).
The loop is played back once (single-shot) and cannot be stopped during this time.
To add one or several (max 8) loops into the Dr. Octo Rex Loop Player, proceed as follows:
1.
Unfold the Loop Editor panel.
2.
Select the Loop Slot you wish to add the (first) REX loop into.
3.
Open the REX Loop browser by clicking the folder button to the left of the Loop Slot buttons.
Alternatively, select “Browse Loops...” from the Edit menu or the device context menu.
4.
In the Browser, locate and select the desired loop(s).
You can listen to the loops before loading by using the Preview function in the Browser.
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To select several loops, hold down [Ctrl](Win)/[Cmd](Mac) and click.
To select a range of loops, hold down [Shift] while clicking the last file.
5.
Click the Load button in the Browser to load the selected file(s) in the Loop Slot(s).
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If you have selected and opened several loops, the first loop will load in the selected Loop Slot and the rest will load in consecutive Loop Slots.
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Loading new REX files will replace any files currently in the slots.
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Alternatively, select the REX loop(s) in the Browser and drag and drop it/them on the Loop Editor panel section, or on a Loop Slot button on the Controller Panel.
If you have selected several loops, the first loop will load in the selected Loop Slot and the rest will load in consecutive Loop Slots.
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If you drag a single REX loop from the Browser and drop on the Controller Panel (not on a Loop Slot button), the REX loop will load into Slot 1 and all other Slots will be cleared.
#Loading Loops “On the Fly”
Another practical method for checking out loops, is to load them “on the fly”, i.e. during playback. This is especially useful if you want to check out a number of loops against other sequencer data and patterns previously recorded. Proceed as follows:
1.
Activate the Enable Loop Playback button on the Dr. Octo Rex device and start sequencer playback.
The REX loops and the sequencer are synced.
2.
Now load a new REX file by using the Browser in one of the usual ways.
After a brief silence, the new file is loaded, and sync is maintained.
3.
Repeat step 2 as necessary until you have found a suitable loop.
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If you are trying out loops within the same folder, the quickest ways to select and load a new loop is to use the arrow buttons next to the loop name display.
Or, you can click in the loop name display and select a new loop from the pop-up menu that appears.
#Removing Loops
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To remove a loop from a Loop Slot, select “Remove Loop” from the Edit menu or device panel context menu.
#Cut/Copy and Paste Loops between Loop Slots
To cut or copy a loop from one Loop Slot and paste into another, proceed as follows:
1.
Click the button of the Loop Slot that contains the loop you want to cut or copy.
2.
Select “Cut Loop” or “Copy Loop” from the Edit menu or panel context menu.
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You have to context-click on the panel (not any button or knob) to access the correct context menu.
3.
Click the destination Loop Slot button and select “Paste Loop” from the Edit menu or panel context menu.
Now, you can edit the slices of the pasted loop as desired, see “Slice handling”.
The individual slices in a REX loop can be transferred as separate MIDI notes to tracks in the sequencer. This makes it possible to have detailed control over every single sample in a REX loop. Proceed as follows to create sequencer notes from the slices:
1.
Select the sequencer track associated with the Dr. Octo Rex device.
2.
Set the left and right locators to encompass the section you want to fill with REX notes.
3.
Select the Loop Slot that contains the REX loop you want to copy to the sequencer track.
4.
Click the Copy Loop To Track button.
Now, the program will create clips containing a note for each slice of the REX loop in the selected Loop Slot, positioned according to the timing of the slices. The notes will be distributed in semitone steps, with the first note on C1, the second on C#1 and so on, with one note for each slice.
In addition to the created notes, the Note To Slot parameter (see “Note To Slot”) is copied into the clips as a Performance Controller. This way, Dr. Octo Rex will always know which Note Slot the generated notes originated from and will thus automatically play back the loop slices from the correct Loop Slot.
The loop clips in the Arrange Area...
...and in the Edit Area.
5.
Disable the Enable Loop Playback parameter.
This is because you probably don’t want the loop playback to be controlled by the regular Run function but from note playback in the sequencer. If the Enable Loop Playback parameter is on, there will be double notes during playback from the sequencer.
Activating playback in the sequencer will now play back the notes on the sequencer track. These in turn will play back the slices of the REX loop in the Loop Slot defined by the Note To Slot parameter, in the correct order and with the original timing maintained. Now the fun begins!
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If the space between the Left and Right locators is greater than the length of the REX loop, the clips will be repeated on the note lane.
The REX loop is 1 bar long and the space between the locators is 4 bars, thus the clip is repeated four times on the note lane.
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The Copy Loop To Track function always creates an exact number of complete clips, meaning that the last clip may “stick out” after the right locator.
Here, the REX loop is 4 bars long. Since there are only two bars between the locators, the clip will stick out after the right locator.
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If you are using the Alt function for slices in the REX loop, these slices will output different note numbers each time you use the Copy Notes To Track function. See “About the Alt parameter” for details.
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If you like, you can manually resize the clip to two bars by clicking and dragging the right clip handle. The last two bars of the clip will then be masked and won’t play (see “Resizing (masking) clips”).
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You can change the groove in the loop by quantizing or moving notes.
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You can transpose notes to change the order of the slices on playback.
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You can use the Alter Notes function (see “Alter (Note pitches)”) to scramble the loop notes - without destroying the original loop timing.
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You can remove and draw new notes, creating any kind of variation.
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You can use the User Groove function to apply the rhythmic feel of the loop to notes on other sequencer tracks.
For details about editing in the sequencer, see the “Note and Automation Editing” chapter.
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Note that if you have created sequencer notes from a REX file in one Loop Slot, selecting another Loop Slot with another REX loop could make the playback sound awkward. This is because the notes generated from the original REX loop will in most situations not correspond to the slices in the other REX loops. However, in some situations this could produce really interesting results so don’t be afraid to experiment.
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You can automate Loop Slot selection using the Notes To Slot function, see “Note To Slot”.
You can also export the REX file as a MIDI file, as described in “Export REX as MIDI File...”.
#Selecting Slices
A selected slice is indicated by being highlighted in the waveform display. To select a slice, use one of the following methods:
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By clicking in the waveform display.
If you hold down [Alt](Win) or [Option](Mac) and click on a slice in the waveform display, it will be played back. The pointer takes on the shape of a speaker symbol to indicate this.
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By using the “Slice” knob below the waveform display.
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Via MIDI.
If you activate “Select Slice Via MIDI”, you can select and “play” slices using your MIDI keyboard. Slices are always mapped to consecutive semitone steps, with the first slice always being on the “C1” key.
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If you play back a loop with “Select Slice via MIDI” option activated, each consecutive slice is selected in the waveform display as you play the keys.
You can edit parameters during playback.
#Editing individual Slices
There are two basic methods you can use to edit individual slices in Reason:
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In the Waveform display of the Dr. Octo Rex device.
This is used for making playback settings for a slice.
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In the Sequencer.
Here you can edit the notes that play the slices. There is a special REX edit lane for editing REX slice notes, with the notes indicated by the slice numbers instead of by pitches. Editing notes in the sequencer is described in the “Note and Automation Editing” chapter.
#Editing in the Waveform Display
Here you are able to edit several parameters for each slice, by first selecting the slice and then using the knobs below the waveform display. If you want to edit a single parameter for several slices at once, a more convenient way would be to use the Slice Edit Mode, see “The Slice Edit Mode”. The following slice parameters can be set:
| Parameter
| Description
Pitch
Allows you to transpose each individual slice in semitone steps, over a range of more than eight octaves.
Pan
The stereo position of each slice.
Level
The volume of each slice. The default level is 100.
Decay
Allows you to shorten individual slices.
Rev
Allows you to play back individual slices reversed (backwards)
F.Freq
Allows you to modify the Filter (cutoff) Frequency of individual slices. This value is added to, or subtracted (if negative) from the FREQ value of the synth panel, see “Filter Frequency”.
Alt
Allows you to assign slices to an Alternate group (1-4). Slices assigned to any of these four Alt groups will be played pack in a random fashion within each group, see “About the Alt parameter”.
Output
Allows you to assign individual slices to separate audio output pairs (1-2, 3-4, 5-6 or 7-8). If you want the slices routed to individual outputs (1-8), select the appropriate output pair and then pan the slice hard Left/Right using the Pan parameter described above.
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If you have made settings to any of the parameters listed above, these will be lost if you load a new REX file into that Loop Slot.
#About the Alt parameter
The Alt parameter in the waveform display can be used to create a more “live” feel to your Rex loops by alternating samples within each individual Alt group. For example, if you assign all snare hit slices in the loop to the Alt 1 group, the snare samples will be selected and played back randomly each time these slices appear in the loop. Then, you could assign all hi-hat slices to the Alt 2 group and so on. The result will be a loop that plays back differently every cycle.
In the example below, slices 3 and 6 have been assigned to the same Alt group. Here, we have used the Copy Loop To Track function five times to generate notes from the loop slices, just so you can see the note distribution. As you can see, slices 3 and 6 have been distributed randomly for each loop cycle:
This randomization within each Alt group also occurs when you play back the REX loop using the Run function - and when you use Pattern Automation in the main sequencer.
#The Slice Edit Mode
A very convenient way of editing several slices at once is to work in Slice Edit Mode. In Slice Edit Mode, you can edit one parameter at a time for all slices in the loop.
1.
Click the Slice Edit Mode button.
The waveform display switches to show the REX loop in Slice Edit Mode.
2.
Select the parameter you want to edit by clicking on its name below the REX loop.
The parameters that can be selected are: Pitch, Pan, Level, Decay, Reverse, Filter Frequency, Alt Group and Output.
Here, we have selected the Pitch parameter.
3.
Edit the Pitch value for each individual slice by clicking, or drawing across several slices, in the display.
Now, the Pitch parameter can be edited for all slices in a single sweep.
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To reset the selected parameter to its default value for one or several slices, hold down [Ctrl](Win) or [Cmd](Mac) and click on the desired slice(s), or draw across the slices in the waveform display.
4.
When you are finished with one parameter, select another parameter and repeat the procedure by drawing values for the slices in the waveform display.
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If you have made settings to any of the parameters listed above, these will be lost if you load a new REX file into that Loop Slot.
#Pitch and Mod wheels
The Pitch wheel to the left is used for “bending” the pitch up or down. The Mod wheel can be used to apply various modulation while you are playing the loop(s). Virtually all MIDI keyboards have Pitch Bend and Modulation controls. Dr. Octo Rex also has two “wheels” on the panel that could be used to apply real time modulation and pitch bend should you not have these controllers on your keyboard, or if you aren’t using a keyboard at all. The wheels mirror the movements of the corresponding MIDI keyboard controllers.
The Pitch bend range and Mod destination parameters are set on the synth parameter panel, see “Pitch Bend Range” and “Mod. Wheel”.
#Trig Next Loop
The Trig Next Loop parameter determines the timing when switching between Loop Slots See “The Trig Next Loop function”.
#Note To Slot
The Notes To Slot knob set to Slot 1
The Note To Slot knob controls which Loop Slot is currently controlled from the MIDI master keyboard, or by any recorded sequencer notes. The Loop Slot which currently has “note input” is indicated with a lit LED.
The Note To Slot parameter can also be automated. This means you could switch between Loop Slots for every single sequencer note if you like. This opens up for very interesting “beat mangling” experiments. In the example below the Note To Slot parameter has been automated to switch between the REX loops in the seven first Loop Slots:
Automation of the Note To Slot parameter to automatically switch between Loop Slots
In the picture above slice 1 is played from Loop Slot 1, slices 2 and 3 from Loop Slot 2, slice 4 and 5 from Loop Slot 3, slice 6 from Loop Slot 2 and so on.
#Loop Slot buttons
The eight Loop Slot buttons are located in the center of the front panel. You can load one REX loop per Slot. Loading REX loops are done from the Loop Editor panel, see “Select Loop & Load Slot”.
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Click a Loop Slot button to select its REX loop for playback.
Play back the REX loop in the selected Loop Slot by clicking the Run button (or Play in the main sequencer).
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Note that selecting a Loop Slot only selects the corresponding REX loop for playback using the Run function (see “Enable Loop Playback and Run”) or Play from the main sequencer. Which Loop Slot the master keyboard or sequencer notes control is defined with the Note To Slot button, see “Note To Slot”.
#Enable Loop Playback and Run
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Click the Enable Loop Playback button to make it possible to play back the REX loops using the Run button or Play function in the main sequencer.
If the Enable Loop Playback button is off, clicking Run or Play in the sequencer won’t play back the loops. This can be useful if you only want to control the individual slices of the REX loops from a master keyboard or from recorded notes in the main sequencer.
#Volume
The Master Volume parameter acts as a general volume control for the loops in all Loop Slots.
#Global Transpose
Set the global transposition of the loops in all Loop Slots by using the Global Transpose spin control. You can raise or lower the pitch in 12 semitone steps (+/– 1 octave).
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The Global Transpose value can also be controlled via MIDI Notes, by pressing a key between C-2 and C0 (with C-1 resetting the transpose value to zero).
This way you can also record transposition changes in the sequencer.
The Dr. Octo Rex synth parameters are used for shaping and modulating the sound of the REX loops. These parameters are familiar synth parameters, similar to the ones in the synthesizers; The Subtractor and the Malström, and in the samplers; the NN-19 and the NN-XT. It is important to remember that these parameters do not alter the REX files in any way, only the way they will play back.
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Most of the synth parameters are global, in the sense that they will affect all slices in the REX files as well as all REX loops in all eight Loop Slots.
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All Dr. Octo Rex synth panel settings are stored in the Song (and in the Dr. Octo Rex patch file if you choose to save the settings as a patch).
#Select Loop & Load Slot
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Click any of the eight Select Loop & Load Slot buttons to select a loaded REX loop for editing, or to load a new REX file to.
If no loop is already present in the selected Loop Slot, the Waveform Display will be blank. Otherwise, the display shows a graphical readout of the REX loop and info (name, original loop tempo, number of bars and signature).
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Click the Follow Loop Playback button to “synchronize” the Select Loop & Load Slot buttons to the Loop Slot buttons on the front panel.
This way, the currently playing loop will always be displayed in the Waveform Display. If you’re using Pattern Automation in the sequencer, where the Slots are switched during playback, you might want to deactivate the Follow Loop Playback function to make it easier to edit a specific loop.
Refer to “Adding Loops” for info on how to load REX files and to “Editing in the Waveform Display” for info about editing the REX loop.
#Loop Transpose
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Set the transposition of individual loops in the Dr. Octo Rex by using the Loop Transpose knob to the bottom left on the panel, or by clicking on the keyboard display below the knob.
You can raise or lower the pitch in 12 semitone steps (+/–1 octave).
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It’s also possible to set a global transpose value that affects all REX loops equally, see “Global Transpose”.
#Loop Level
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Set the individual levels for the loops in the Loop Slots with the Loop Level knob.
This lets you match the levels of the loops in the 8 Loop Slots.
#Oscillator section
For a REX file, the audio contained in the slices are what oscillators are for a synthesizer, the main sound source. The following settings can be made in the Osc Pitch section of the Dr. Octo Rex:
#Env. A
This parameter determines to what degree the overall pitch of all the REX files will be affected by the Filter Envelope (see “Filter Envelope”). You can set negative or positive values here, which determines whether the envelope curve should raise or lower the pitch.
#Oct and Fine - Setting the overall Pitch
You can change the overall pitch of all REX files in the 8 Loop Slots in three ways:
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In octave steps.
This is done using the Oct knob. The range is 0 - 8, with “4” as default.
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In semitone steps.
This is done by using Global Transpose controls, see “Global Transpose”.
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In cents (hundredths of a semitone).
The range is -50 to 50 (down or up half a semitone).
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To transpose individual REX loops, use the Loop Transpose parameter, see “Loop Transpose”.
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To tune an individual slice in a REX loop, select it and use the Pitch parameter below the waveform display, see “Editing in the Waveform Display”.
#Mod. Wheel
The Modulation wheel can be set to simultaneously control a number of parameters. You can set positive or negative values, just like in the Velocity Control section. The following parameters can be affected by the modulation wheel:
| Parameter
| Description
F. Freq
This sets modulation wheel control of the filter frequency parameter. A positive value will raise the frequency if the wheel is pushed forward. Negative values invert this relationship.
F. Res
This sets modulation wheel control of the filter resonance parameter. A positive value will increase the resonance if the wheel is pushed forward. Negative values invert this relationship.
F. Decay
This sets modulation wheel control for the Filter Envelope Decay parameter. A positive value will increase the decay if the wheel is pushed forward. Negative values invert this relationship.
#Velocity section
Velocity is usually used to control various parameters according to how hard or soft you play notes on your keyboard. A REX file does not contain velocity values on its own. And when you create sequencer track data by applying the “Copy Loop To Track” function, all velocities are set to a default value of “64”. As velocity information is meant to reflect variation, having them all set to the same value is not meaningful if you wish to velocity control Dr. Octo Rex parameters.
There are basically two ways you can apply “meaningful” velocity values to REX files:
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After creating track data, you can edit velocity values in the Velocity Lane in the sequencer.
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You can play slices in real time on your keyboard. The resulting data will have velocity values reflecting how the notes were struck when you played.
When velocity values have been adjusted, you can control how much the various parameters will be affected by velocity. The velocity sensitivity amount can be set to either positive or negative values, with the center position representing no velocity control.
The following parameters can be velocity controlled:
| Parameter
| Description
F. Env
This sets velocity control for the Filter Envelope Amount parameter. A positive value will increase the envelope amount with higher velocity values. Negative values invert this relationship.
F. Decay
This sets velocity control for the Filter Envelope Decay parameter. A positive value will increase the Decay time with higher velocity values. Negative values invert this relationship.
Amp
This let’s you velocity control the overall volume of the file. If a positive value is set, the volume will increase with higher velocity values.
#The Filter Section
Filters are used for shaping the overall timbre of all REX files in all 8 Loop Slots. The filter in Dr. Octo Rex is a multimode filter with five filter modes.
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Activate or deactivate the filter completely by clicking the Filter On button.
The filter is active when the button is lit.
#Mode
With this selector you can set the filter to operate as one of five different types of filter. These are as follows:
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Notch
A notch filter (or band reject filter) could be described as the opposite of a bandpass filter. It cuts off frequencies in a narrow midrange band, letting the frequencies below and above through.
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High-Pass (HP12)
A highpass filter is the opposite of a lowpass filter, cutting out lower frequencies and letting high frequencies pass. The HP filter slope has a 12 dB/Octave roll-off.
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Bandpass (BP 12)
A bandpass filter cuts both high and low frequencies, while midrange frequencies are not affected. Each slope in this filter type has a 12 dB/Octave roll-off.
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12 dB Lowpass (LP 12)
This type of lowpass filter is also widely used in classic analog synthesizers (Oberheim, early Korg synths, etc.). It has a gentler slope (12 dB/Octave), leaving more of the harmonics in the filtered sound compared to the LP 24 filter.
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24 dB Lowpass (LP 24)
Lowpass filters lets low frequencies pass and cuts out the high frequencies. This filter type has a fairly steep roll-off curve (24dB/Octave). Many classic synthesizers (Minimoog/Prophet 5 etc.) used this filter type.
#Filter Frequency
The Filter Frequency parameter (often referred to as “cutoff”) determines which area of the frequency spectrum the filter will operate in. For a lowpass filter, the frequency parameter could be described as governing the “opening” and “closing” of the filter. If the Filter Freq is set to zero, none or only the very lowest frequencies are heard, if set to maximum, all frequencies in the waveform are heard. Gradually changing the Filter Frequency produces the classic synthesizer filter “sweep” sound.
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Note that the Filter Frequency parameter is usually controlled by the Filter Envelope (see “Filter Envelope”) as well. Changing the Filter Frequency with the Freq slider may therefore not produce the expected result.
#Resonance
The filter resonance parameter affects the character of the filter sound. For lowpass filters, raising the resonance will emphasize the frequencies around the set filter frequency. This produces a generally thinner sound, but with a sharper, more pronounced filter frequency “sweep”. The higher the resonance value, the more resonant the sound becomes until it produces a whistling or ringing sound. If you set a high value for the resonance parameter and then vary the filter frequency, this will produce a very distinct sweep, with the ringing sound being very evident at certain frequencies.
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For the highpass filter, the resonance parameter operates just like for the lowpass filters.
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When you use the Bandpass or Notch filter, the resonance setting adjusts the width of the band.
When you raise the resonance, the band where frequencies are let through (Bandpass), or cut (Notch) will become narrower. Generally, the Notch filter produces more musical results using low resonance settings.
#Envelope section
Envelope generators are used to control several important sound parameters in analog synthesizers, such as pitch, volume, filter frequency etc. In a conventional synthesizer, envelopes govern how these parameters should respond over time - from the moment a note is struck to the moment it is released. In the Dr. Octo Rex device however, the envelopes are triggered each time a slice is played back.
There are two envelope generators in the Dr. Octo Rex, one for volume, and one for the filter frequency (and/or pitch). Both have the standard four parameters; Attack, Decay, Sustain and Release
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Please refer to “Envelopes - General” in the Subtractor chapter for a description of the basic envelope parameters.
#Amplitude Envelope
The Amp Envelope governs how the volume of each slice should change over time, from the time it is triggered (the slice note starts) until the slice note ends. This can be used to make a loop more distinct (by having a snappy attack and a short decay time) or more spaced-out (by raising the attack time).
#Filter Envelope
The Filter Envelope can be used to control two parameters for all REX loops in the 8 Loop Slots; filter frequency and overall loop pitch. By setting up a filter envelope you control how the filter frequency and/or the pitch should change over time for each slice.
The Amount parameter determines to what degree the filter frequency will be affected by the Filter Envelope. The higher the Amount setting, the more pronounced the effect of the envelope on the filter.
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Try lowering the Frequency slider and raising Resonance and Envelope Amount to get the most effect of the filter envelope!
#LFO section
LFO stands for Low Frequency Oscillator. LFOs are oscillators in the sense that they generate a waveform and a frequency. However, there are two significant differences compared to normal sound generating oscillators:
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LFOs only generate waveforms with low frequencies.
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The output of the two LFOs are never actually heard. Instead they are used for modulating various parameters.
The most typical application of an LFO is to modulate the pitch of a (sound generating) oscillator or sample, to produce vibrato. In the Dr. Octo Rex device, you can also use the LFO to modulate the filter frequency or panning.
#Waveform
LFO 1 allows you to select different waveforms for modulating parameters. These are, from top to bottom:
| Waveform
| Description
Triangle
This is a smooth waveform, suitable for normal vibrato.
Inverted
Sawtooth
This produces a “ramp up” cycle. If set to control pitch (frequency), the pitch would sweep up to a set point (governed by the Amount setting), after which the cycle immediately starts over.
Sawtooth
This produces a “ramp down” cycle, the same as above but inverted.
Square
This produces cycles that abruptly changes between two values, usable for trills etc.
Random
Produces random stepped modulation to the destination. Some vintage analog synths called this feature “sample & hold”.
Soft Random
The same as above, but with smooth modulation.
#Destination
The available LFO Destinations are as follows:
| Destination
| Description
Osc
Selecting this makes LFO control the pitch (frequency) of the REX file.
Filter
Selecting this makes the LFO control the filter frequency.
Pan
Selecting this makes the LFO modulate the pan position of the REX file, i.e. it will move the sound from left to right in the stereo field.
#Sync
By clicking the SYNC button you activate/deactivate LFO sync. The frequency of the LFO will then be synchronized to the song tempo, in one of 16 possible time divisions. When sync is activated, the Rate knob (see below) is used for setting the desired time division.
Turn the knob and check the tooltip for an indication of the time division.
#Rate
The Rate knob controls the LFO’s frequency. Turn clockwise for a faster modulation rate.
#Amount
This parameter determines to what degree the selected parameter destination will be affected by the LFO 1, i.e. the amount of vibrato, filter wah or auto-panning.
#Pitch Bend Range
The Pitch Bend Range parameter sets the amount of pitch bend when the wheel is turned fully up or down. The maximum range is 24 semitones (=up/down 2 Octaves).
#Setting number of voices - polyphony
This determines the polyphony, i.e. the number of voices, or slices, Dr. Octo Rex can play simultaneously. For normal loop playback, it is worth noting that slices sometimes “overlap”. Therefore, it is recommended that you use a polyphony setting of about 3-4 voices when playing REX files. If you are “playing” slices via MIDI, the polyphony setting should be set according to how many overlapping slices you want to have.
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Note that the Polyphony setting does not “hog” voices. For example, if you are playing a file that has a polyphony setting of ten voices, but the file only uses four voices, this doesn’t mean that you are “wasting” six voices. In other words, the polyphony setting is not something you need to consider if you want to conserve CPU power - it is only the number of voices actually used that counts.
#Audio Quality settings
Dr. Octo Rex features two parameters that provide ways of balancing audio quality vs. conservation of computer power. The parameters are called “High Quality Interpolation” and “Low Bandwidth” and are located to the right on the rear panel:
#High Quality Interpolation
When High Quality Interpolation is active, the loop file playback is calculated using a more advanced interpolation algorithm. This results in better audio quality, especially for loops with a lot of high frequency content.
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High Quality Interpolation uses more computer power - if you don’t need it, it’s a good idea to turn it off.
Listen to the loop in a context and determine whether you think this setting makes any difference.
#Low Bandwidth
This will remove some high frequency content from the sound, but often this is not noticeable (this is especially true if you have “filtered down” your loop). Activating this mode will save you some extra computer power, if needed.
On the rear panel of Dr. Octo Rex you will find the connectors. The left part of the panel houses a number of CV/Gate inputs and outputs. Using CV/Gate is described in “Routing Audio and CV”.
#Modulation Inputs
These control voltage (CV) inputs (with trim pots), allow you to modulate various Dr. Octo Rex parameters from other devices (or from the modulation outputs of the Dr. Octo Rex device itself). The following CV inputs are available:
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Master Volume
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Mod Wheel
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Pitch Wheel
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Filter Cutoff
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Filter Resonance
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Osc Pitch
#Modulation Outputs
The Modulation outputs can be used to voltage control other devices, or other parameters in the Dr. Octo Rex device itself. The Modulation Outputs are:
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Filter Envelope
The Filter Envelopes in Dr. Octo Rex are polyphonic (one per voice). Only the filter envelope of voice 1 is output here.
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LFO
#Gate Inputs
These inputs can receive a CV/gate signal to trigger the two envelopes. Note that connecting to these inputs will override the “normal” triggering of the envelopes. For example, if you connected an LFO CV output on another device to the Gate Amp input on the Dr. Octo Rex, the amplitude envelope would not be triggered by the incoming MIDI notes to the Dr. Octo Rex device, but by the LFO CV signal. In addition you would only hear the LFO triggering the envelope for the slices that were playing at the moment of the trigger.
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Amp Envelope
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Filter Envelope
#Gate Output
This outputs a gate signal for each triggered slice in the loop.
#Slice Outputs
To the right of the modulation inputs and outputs are the eight individual slice audio outputs. You can assign individual slices to any of these outputs as described in “Editing in the Waveform Display”.
#Main Outputs
To the right are the main left and right audio outputs. When you create a new Dr. Octo Rex device, these are auto-routed to the first available channel on the audio mixer.