Frequency balance refers mostly to ground tone, since it is played the most. It can be, but is rarely related to toots.

It depends what we need our didgeridoo for, but for general music purposes, the more the spectrum is covered, the more acoustical information we can get out of the instrument, the more ability for various articulations and finally the more possibilities of expression. In these terms, having FULL sound means having covered as many frequencies as possible. If an instrument has only bass, it does not make a full didgeridoo sound. It gets very boomy.

In order to be able to articulate clearly complex melodic and rhythmic phrases, a lot of the frequency spectrum is needed. Forms of tongue movement, for example, will not be written in the bass, but in mids and some highs. Similary, harmonic changes reach even higher parts of the spectrum. Still, there is another level in observing/knowing didgeridoo sound. It is about fine distinctions of characters and colours. For example, sound is perceived as warm when its spectrum is greater around 200-400Hz or possibly lacks some of 3-5kHz frequencies.

It is also possible to change the spectrum of didgeridoo by changing harmonics in playing. You can add or deduct the number of higher harmonics, but it is difficult to reduce the amount of bass. The reduction of the didgeridoo sound to mere bass is done by maximum relaxation of lips, breath, and opening the mouth. It can be done with every didgeridoo to some extent. It is much more challenging or even impossible to produce mids and highs not present in the drone in the first place.

This is the same principle as in changing particular frequencies through equalization, i.e. equalizers, which are often used during mixing. EQs are more often used to reduce existing frequencies than to add some which are not present.

To conclude; in Duende Didgeridoo we search for instruments with a full sound which is a vessel of abundant acoustic information, and all of which is coloured and characterized in an intriguing, charming, magical manner.