Arpulator — a “smart” arpeggiator

With just a few stompswitches, Arpulator lets you quickly and easily change an arpeggio. Then, you can run it in forward, in reverse, or at random, over one octave, two octaves, either up or down, or transpose it up an octave entirely.

Additional features include portamento between notes, an envelope mode that allows you to shape the amplitude of each pitch shifted note, and a delay for giving the arpeggiated notes “space.”

HOW DOES IT WORK? (Functional explanation. Deep breath, then read if you want this patch to do things. Once you know the controls, I think it works pretty easily, but if you don’t know them, this patch is a digital paperweight.)

Set a root note by playing the note, then TAPPING the RIGHT stompswitch (SW) (you will see four blue lights across the top of the front page blink). TAP the MIDDLE SW to move to the next note, which will cause the blue pixel to move to the next position. Let’s say your next note is a fifth above the root note (although it can be below, too). Play the note, tap the right stompswitch again, then tap the middle stompswitch to move to the next note. You must select four notes (including the root), but the same note played in succession will “tie” together.

When you are done selecting your arpeggio, HOLD down the MIDDLE SW TWICE, until the white light on the front page’s left hand side becomes bright. Now you are “safe” mode or “performance” mode, and your arpeggio is locked in. HOLDING down the MIDDLE SW AGAIN will bring you back to record mode, and you can change your enter arpeggio or just a single note by scrolling through the options.

Now, depress the LEFT SW. The yellow pixel on the left hand side of the page will begin to get brighter, as the LFO increases in speed. Release the footswitch and tap it to lock the value in place. (This takes a little practice, but once you get the hang of it it’s pretty easy.)

Now your arpeggio will track across the fretboard.

When in “performance” mode, the MIDDLE SW and RIGHT SW take on new functions.

The MIDDLE SW allows you to select range: one octave, two octaves up, two octaves down, and one octave above the note you play.

The RIGHT SW changes the order of the arpeggio: forward, reverse, and random.

FRONT PAGE:

The front page is broken into two sides: indicators (left) and controls (right).

Going down the left side of the page:
Blue pixel(s)–indicate arpeggio scroll during record mode, i.e. what note you are recording. They flash to indicate a note value has been locked.
White pixel–dim indicates you are in record mode, bright indicates you are in performance mode.
Yellow pixel–indicates arpeggio speeds. Dimmer is lower speeds, brighter is faster speeds.
Magenta pixel(s)–indicate arpeggio order, forward, reverse, random. They dim and grow brighter as they move through the arpeggio, depending on the order.
Green pixel(s)–range. Left is one octave, then two octaves up, two octaves down, and finally one octave up.

Going down the right side:
Blue pushbutton–momentary, delay tap tempo. Blue value control–delay mix.
White value control–“tone” control. This controls a low-pass filter that follows the pitchshifter. I would suggest subtle changes, centered around the .600-.700 range.
Yellow value control–mix. This mixes between the dry signal and arpeggiated signal before the delay.
Magenta value control–glide or portamento.
Green pushbutton–toggles between regular pitchshifting (continuous) and envelope mode.**

**Some notes about envelope mode: most of the pertinent controls are on the front page or accessed via the stompswitches, but buried deep in the patch are some controls you may want to adjust relating to the envelope. In its default condition, the envelope is a fast decaying pluck, with almost no attack or release. I have *starred* the attack and release controls. I would avoid sustain, except in very slow-moving arpeggios.

Additionally, there is a switch on this page, its channel select is also *starred*, and you can adjust it by turning the rotary knob. This selects the gate source of the envelope. By default, it receives a constant gate from the sequencer that drives the arpeggio (channel 1). But you can also change it to other sources. Channel two uses the CV values of the forward arpeggio, so the envelope increases in volume as the arpeggio progresses. Channel three uses the reverse arpeggio, so notes start loud and become quieter. Channel four uses a random module clocked to the arpeggio but different from the random module used for the random mode.

How does it work? (Structural explanation.)

Essentially, in record mode, the root note provides a point of comparison for subsequent notes, in order to determine intervals. It does this by sampling and holding the note (triggered by the tap of the right stompswitch). Each subsequent note is also sampled and held by the same method. Then the held values are added to the inverted value of the root, which yields their intervals. Once the intervals are established, the root can change as you move across the fretboard.

The rest of it is mostly brute force sequencing and switching. The pages are all labeled, although figuring out what to call a block was often difficult and inevitably idiosyncratic, so proceed with caution.

There is a way to do this without all the footswitching. Play a few notes and determine the arpeggio, but it’s glitchy and unreliable. For now, I would prefer this slightly more cumbersome version, but since, for me, really the purpose of this patch was to explore this interval technique in order to employ it elsewhere, if I perfect/refine the footswitchless option in the future, I will issue a revision.

Sound clip:

I usually have fairly detailed notes, but honestly, I played some notes, changed some settings, played some more guitar, changed some arpeggios. Toward the end of the guitar section, I use my favorite setting, which is a fast speed, with the octave up and the envelope mode. Call it the “pixie” setting. At the end, I play a little bass and a little electric piano. There are a lot of interesting sounds in this patch (and admittedly some not interesting ones). Play around.

I didn’t think to document it, but the patch does interesting things with chords. Most of the time, better than I expected.