future features like mods and patches to its musical
instrument digital interface (MIDI) and multi-note
polyphony (e.g., more than two-note).
MIDI of the Road
Speaking of MIDI, while the Macchiato kit is currently
able to respond to Note and Velocity information via an
attached MIDI controller, Marshall Taylor at SparkFun
Electronics has created a GitHub repository that contains
Arduino code for MIDI splitting, testing, and bending that
could be used for experimenting with the Synth kit. You
can locate his code at github.com/marshalltaylorSFE/
ArduinoSynthMidiFilter.
Can Touch This
Meanwhile, back at the kit ... there are two additional
features that make the Macchiato Mini Synth more than
just a sum of its parts. For one, what good is a synthesizer
without a keyboard, right? Well, Teenage Engineering has
made a formidable product line of “pocket-sized”
synthesizers as shown in Figure 5 with nary a keyboard in
sight. Ranging from $50-$90, these calculator-looking
devices claim a “wall of sound,” but this ain’t Phil Spector,
baby. Sure, they might be fun to fiddle around with, but
two-note polyphony, U Can’t Touch This.
The Mini Synth comes with a one octave keyboard
and it’s hiding right in plain sight. Unlike a conventional
keyboard with ebonies and ivories that you can tickle, this
dirigible kit has a “wunder-weapon” capacitive
touch keyboard that is built smack dab into the
PCB (see Figure 6). It works great, but there are
a couple of caveats.
Straight from the Zeppelin Design Works
Quick-Start Guide, you can play a low note
“drone” along with an accompanying melody
by tapping on the lower note key and then
playing the melody as a staccato. This playing tip can be
enhanced by adding a long decay.
The second caveat continues along this drone action
by setting a similar low octave drone, but then switching
to a higher octave and playing a melody. We mention
these points as “caveats” because we were unable to
achieve satisfactory results during our testing.
Naturally, practice makes perfect and these two
keyboard tricks could be added to your playing arsenal
with apt application of deft digit dexterity.
Dial-A-Song
While the capacitive touch keyboard might be a giant
feature of the Macchiato Mini Synth, the nine adjustable
potentiometers just might steal the show. As you can see
in Figure 7, lined up in an easily accessible row above the
keyboard, these nine pots are anything but stock current
adjusters.
First off, these fancy pots don’t require knobs for
operation — the knob is built right into the shaft. How
often is “getting the shaft” such a good thing, right? Well,
uglying up the design aesthetic with a bunch of “chicken
head” knobs would certainly make this synth less
appealing.
Second of all, these pots control the generation of the
circuit’s waveforms and its low frequency oscillator (LFO)
and low pass filter (LPF). There are nine controls that you
can apply to the Macchiato Mini: (from left to right) wave
shape (sine, triangle, sawtooth, and square); octave (1-4);
52 September 2017
FIGURE 5. The Teenage
Engineering “Robot”
synthesizer.
FIGURE 6. The capacitive
touch/one octave keyboard is
along the right-hand edge of the
PCB in this photo.
FIGURE 7. The first three potentiometers
have been soldered into place.
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www.nutsvolts.com/magazine/issue/2017/09.