# Plectrum Theory — Music Theory for Guitar

> Music Theory for Guitar (iPhone/iPad app by DAVID TRION OTT.)

- Source: https://appshunter.io/ios/app/plectrum-theory/id6765868991 (this page in markdown: same URL + `.md`)
- Developer: [DAVID TRION OTT](https://appshunter.io/developer/1885019442)
- Category: Education, Music
- Price: $9.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-08-17
- Data updated: 2026-08-19
- User reviews in markdown: https://appshunter.io/ios/app/plectrum-theory/id6765868991/reviews.md

## What is Plectrum Theory?

Music theory for guitarists, taught on the fretboard.

Most music theory is written with the piano in mind, leaving guitarists to translate every concept to the neck. Plectrum Theory starts with the guitar. Every idea is shown as something you can see, hear, and play, directly on the fretboard—so you understand how it connects, not just what it is.

THE CURRICULUM

Seventy-three lessons across thirteen modules, arranged to build naturally from the fundamentals to improvisation.

Foundations — notes on the fretboard, intervals, and the building blocks of music
Scales & Keys — scale construction, key signatures, and the modes
Chords — triads, open chords, the CAGED system, and seventh chords
Harmony — diatonic harmony and chord progressions
Improvisation — applying theory to create music

Lessons are short and focused. Each ends with a review question to reinforce what you've learned, while progress tracking and bookmarks make it easy to stop and pick up where you left off.

THE REFERENCE

A practical reference you'll keep returning to long after you've finished the lessons.

Intervals — every interval with formulas and fretboard diagrams
Scales — construction, formulas, and fretboard positions
Chords — nineteen chord qualities from triads to thirteenths, each with formulas and diagrams
CAGED — the five interconnected shapes across the neck
Progressions — the essential progressions and the harmony behind them
Fretboard Notes — every note across the neck in every key

BUILT FOR LEARNING

Every diagram is drawn on a real guitar fretboard.
Interval labels appear on every shape, making patterns understandable instead of something to memorize.
Portrait and landscape layouts.
A distraction-free dark interface designed for long study sessions.

Works entirely offline.


## Version history (last 1 release)

### 0.1.0 — 2026-08-17

No release notes.

## More apps by DAVID TRION OTT

- [Branch Daily](https://appshunter.io/ios/app/branch-daily/id6760566285)
- [Plectrum Practice](https://appshunter.io/ios/app/plectrum-practice/id6764858285)

All apps by DAVID TRION OTT: https://appshunter.io/developer/1885019442

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-19.*