In Search of the Missing Fundamental: by Richard K. Jones
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Electronic Tuners

Tune-bot by Overtone Labs

The Tune-bot, although not designed for use with timpani, can produce satisfactory results for isolating and measuring the frequency at each lug point. It has some very interesting functions like pitch/note mode, which switches between frequency and note name. Filter mode, which acts as a high pass/low pass filter. Difference mode, which displays the difference in pitch between the lug hit and a target value; an analog dial showing the relative difference, is also displayed.

The Tune-bot is designed to clip on the counterhoop (of a smaller diameter drum) and remain stationary when tuning. When doing that with timpani, in order to get it to trigger, you need a high SPL, which produces way too many unwanted partials. A simple work around is to take the clip off and move the bot to each lug point to measure the frequency. It then will trigger at a low SPL.

The Tune-bot does a very adequate job of measuring what it is designed to measure; however, it was primarily designed to isolate and measure only a single note/frequency at a time, not a note with a harmonic series. Your heads have to already be relatively clear or evenly tensioned with a Drum-Dial in order to get consistent and stable readings. You can then use it to get each lug to correspond to a single frequency, which is certainly musically functional, but that doesn’t necessarily guarantee that the upper partials will line up harmonically. When using this device, fine tuning/tempering may still need to be done in order to coax the upper partials into a semblance of “harmonicity.”

What about the Protune Tuner?

In theory, the mechanics of how the Protune tuner works makes complete sense since it measures the vibrational modes of the head and then represents that as a pitch. Unfortunately, the principal tone of a timpano’s spectrum (mode 1,1) decays much quicker than the subsequent overtones often leaving the fifth (mode 2,1) to dominate the spectrum. Users report that the Protune often picks up the fifth (the second mode) more than the first. This happens simply because the second mode is baffled less by the bowl and consequently sustains longer than the principal tone. The manufacturer of the Protune tuner states that repeated striking of the head is necessary for the Protune tuner to function properly. Repeated striking of a timpano in a professional situation, no matter how soft, is not practical. The Protune may in fact function best as a supplemental aid in the ear-training of the young timpanist rather than as tuning device.

When the author lectures on timpani acoustics, he uses a Protune tuner to demonstrate the strength of the second mode or the fifth because it works very well for that. With a Protune tune, if you strike the drum once with a soft mallet, it will/may briefly register the principal tone but it inevitably it reads the fifth within a few milliseconds. The User Tips page on the product website details the shortcomings of the device.

Finding the Missing Fundamental

Electronic tuners that display the octave register as well as the frequency are most useful if you want to measure timpani pitch just for the sake of measuring timpani pitch. This type of tuner is usually able to detect the missing fundamental. Since the harmonic spectrum of a well adjusted timpano can be compared to a harmonic series with a missing fundamental, if you can get the tuner to register the actual pitch as the one being an octave lower than the one you are actually playing, then you know you have clear, balanced or tempered heads. i.e., when you are playing a C3 @130 Hz on your 29” drum but tuner is registering C2 @65 Hz this means that your partials are lined up well. Please see the section on Virtual Pitch and Timpani for more information.

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