G-sential Theory of Music

Welcome to G-sential Theory of Music! If you are looking for excellent, affordable, up to date and easy-to-use theory books, YOU’RE AT THE RIGHT PLACE!

Whether you love theory or dread it, our books have been written for people like you! It contains short and easy-to-follow explanations with just enough exercises.

Our Story

G-sential was founded in 2007 by Dr Tronél Hellberg who loves theory of music… seriously!

The name “G-sential” is a coinage between “G clef” and “essential”. The G clef is one of the first concepts taught in theory which is essential for understanding other concepts and the basics of reading music (well, for most musicians)!

G-sential is preferred by hundreds of music teachers, schools, colleges and universities across South Africa and abroad. Since its establishment, it has become a leading theory of music brand in South Africa. Why? We understand the needs of our clients. Teachers and learners alike want to get the job done in the shortest, easiest and most enjoyable way!


Our Books

We believe theory of music books should be versatile, up to date and easy-to-use:

VERSATILE – drawing from a variety of syllabi. Our Grade 1-6 theory of music books cover the content of the latest ABRSM, UNISA and Trinity Guildhall syllabi. The Grade 10-12 books were written for the theory component known as “Music Literacy” (Topic 2) of Music CAPS. These books are also used in many private schools that follow, for example the IEB curriculum.

UP TO DATE – an important commitments to our clients. To achieve this, the series is regularly updated to meet the demands of changing syllabi – all in one book. A syllabus changes, we update our books. Period. No addenda or add-in exercised because a syllabus changed. The only time this happens is when a syllabus changes and there is old stock (max 20 books) that need to be sold.

EASY-TO-USE – A great benefit and point of sales! G-sential Theory of Music is known for its outstanding balance between explanation and exercises. We get it, music teachers and learners don’t have time to read through lengthy explanations and battle through an excess of exercises – information overload is definitely not the way to go! We want learners to achieve excellent marks without drowning them in work. G-sential believes in explanation that are concise, yet efficient. At the same time, exercises are structured in such a way to allow learners to gradually master and apply their theoretical knowledge without making them feel overwhelmed by the amount of work. The ideal balance between explanation and exercises makes G-sential’s theory of music books great for using in the classroom, as well as self-study.


Dr Tronél Hellberg and Mrs Marianne Feenstra, January 2020.

Expanding our range: new home of Feenstra Books

One of the people who had a significant impact on Dr Hellberg’s music career is Mrs Marianne Feenstra, a phenomenal person who had a major impact on music education in South Africa, particularly in terms of her contribution as harmony and music history teacher, author, curriculum developer and custodian for music education. Sadly and very unexpectedly, Mrs Feenstra passed away in November 2020, leaving a tremendous hole in music education in South Africa. As former student and later colleague, co-author and friend of Mrs Feenstra, it’s an honour to have taken over Feenstra Books to ensure that her legacy lives on through her outstanding publications.

Select From Our Range Of Books