Make a ukulele sound like a guitar (almost)

Those of us who have attempted (rather unsuccessfully) to learn guitar and ended up learning the ukulele sometimes miss the “fuller” sound of the guitar, which makes it appropriate for sadder songs, just to mention one possibility. The re-entrant high-G tuning of most ukuleles doesn’t help much in this regard, but if you are, say, in a gig situation where you are going to amp the instrument anyway, there’s an inexpensive solution that will supply the “missing strings” without having to change your uke or your playing style at all. It’s called an “octaver pedal.”

Now, “pedals” get their name from the fact that most commonly they are placed on the floor so performers can switch them on and off or change the settings with their feet so they can keep their hands on their instrument, which is typically an electric guitar. They comprise some electronic components inside a sturdy box (so it can be stepped on), plus 1/4 inch input and output jacks. You feed the raw sound on the right, and get the processed sound on the left, from where it can go into another pedal or chain of pedals, and eventually into an amplifier. For an acoustic ukulele that doesn’t have its own output jack, you’ll need to add a stick-on piezo transducer, which will get the sound from the vibrations of the soundboard.

There is a huge variety of pedals available, most of which are designed for electric guitars: chorus, flangers, phasers, equalizers, compressors, overdrive, distortion, loopers, you name it. Some are cheap and some are more expensive than the guitars plugged into them. The particular kind mentioned in this article is the “polyphonic octaver,” which people often call “POG pedal” after a popular brand name. An octaver takes the input sound and shifts it one of more octaves up or down, then it mixes the result with the original. Say you play an open C string on the ukulele, which is more accurately a C4 because it’s the start of the “4th octave”. An octaver pedal set for lower octave will output that sound at half frequency, that is, a C3, mixed with the original C4. It will do the same with any sound you throw at it: it would produce a wave that is identical in duration but at half the frequency of the original. This is easier said than done, because the duration must still be the same so it’s not just a matter of recording the original and playing it back at half speed. Sophisticated digital signal processing (DSP) algorithms must be used.

So let’s say you do just that: add the original sound taken one octave down. Then if you play a C major chord on the ukulele, which comprises these pitches from lowest to highest: C4, E4, G4, C5, then the octaver adds C3, E3, G3, and C4, so the combined chord coming out contains C3, E3, G3, C4, E4, G4, C5 from lowest to highest pitch. As a comparison, a C major chord on a 6-string guitar with standard tuning (6th string muted) comprises these pitches: C3, E3, G3, C4, E4. We see that the octaved ukulele chord goes down as low as the guitar chord, with some additional pitches on top. An octaved G major chord on a standard ukulele will comprise D3, G3, B3, D4, G4, B4 (two strings give the same G pitch), while a standard guitar would give G2, B2, D3, G3, B3, G4, which should sound deeper. Of course, if the uke has a low-G 4th string, then the result will contain a G2, matching the guitar a lot better.

Octaver pedals used to be expensive (at least, the original POG and its derivatives are in the $200 range), but there are some alternatives that are much more economical. To do this test, I got an “Ammoon Octa” pedal through aliexpress.com for $38, shipping included from China. I only needed to add an extra cable for $2 and a power supply (because I didn’t have one with the right polarity) for $10. You can get this one, or another brand, but be warned that the pedal should be of the more recent “polyphonic” type. Old-style “monophonic” octavers expect sounds to contain a dominant pitch, and as a consequence don’t handle chords well.

Does it sound like a guitar, or at least sound good enough? You be the judge. Below are two sound samples. The first contains some chords played on a tenor ukulele with standard tuning, though an amp. The second is the same chords and the same uke, but this time the Octa pedal with some low octave mixed in is between the uke and the amp.

Straight sound:

With octaver:

 

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