# 5ths Machine — The circle never stops...

> Music theory app for understanding key signatures and equal temperament. (iPhone/iPad app by Lucy Hudson.)

- Source: https://appshunter.io/ios/app/5ths-machine/id1582877284 (this page in markdown: same URL + `.md`)
- Developer: [Lucy Hudson](https://appshunter.io/developer/1179157812)
- Category: Music, Education
- Price: $1.99
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 4+
- Requires: iOS 12.0 · 18 MB
- Languages: American English
- Released: 2022-01-27
- Data updated: 2026-06-04
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/5ths-machine/id1582877284/reviews.md

## What is 5ths Machine?

Think you know your key signatures cold?  Answer this: which key has 41 sharps? 

The equal temperament system is a circle with 12 positions, just like a clock. And, just like on a clock, the hands keep going around and around forever. The key signature of 41 sharps is theoretically consistent with the Western diatonic system ― learn why, and learn how to find out what key it is. The Background Information and the Quiz Tips explain the system in detail, and Chronology puts it all in perspective.

Enjoy the “Perpetual 5ths Machine Boogie” while key signatures you’ve never seen before pass by on parade. Then, buckle down and solve the Quiz questions. NOW you understand music theory the 5ths Machine way!

## Key features

- Key signature quiz
- Equal temperament system explanation
- Theoretical key signature exploration
- Background information on music theory
- Quiz tips and strategies
- Chronology of music theory concepts


## Frequently asked questions about 5ths Machine

### What is the price of 5ths Machine?

5ths Machine is a paid application, available for $1.99. This one-time purchase grants you full access to all its features without any additional costs or subscriptions.

### Does 5ths Machine have ads?

No, 5ths Machine is completely ad-free. You can enjoy the music theory content and interactive quiz without any interruptions from advertisements.

### What devices is 5ths Machine compatible with?

5ths Machine is designed for iOS devices, including iPhone, iPad, and iPod. It leverages the touch interface for an engaging learning experience.

### How often is 5ths Machine updated?

The latest version of 5ths Machine is 2.0.1, last updated on January 2, 2026. While specific update frequency isn't detailed, the app has seen updates since its release on January 27, 2022.

### What is the age rating for 5ths Machine?

5ths Machine has an age rating of 4+. This indicates that the content is generally suitable for all ages, with no mature themes present.

### What makes 5ths Machine unique compared to other music theory apps?

5ths Machine focuses specifically on the theoretical exploration of key signatures and the equal temperament system, offering a unique quiz format to test understanding. It delves into concepts like keys with 41 sharps, which is not commonly found in other music theory applications.

### Can I use 5ths Machine offline?

The provided information does not specify offline functionality. However, as it is a quiz and educational tool, it is likely designed to function without a constant internet connection after initial download.

## Version history (last 3 releases)

### 2.0.1 — 2026-01-02

answered new age rating questions

### 2.0.0 — 2024-10-18

-Added iPad capability
-Screen redesigns for clarity
-Small bug fixes

### 1.0 — 2022-01-27

No release notes.

## Apps similar to 5ths Machine

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Two Handed Touch Arpeggios](https://appshunter.io/ios/app/two-handed-touch-arpeggios/id647622881) | 5.0 (2) | $12.99 | Music |
| [mTonal](https://appshunter.io/ios/app/mtonal/id1433790768) | — | $4.99 | Music |
| [Circle Of Fifths Pro](https://appshunter.io/ios/app/circle-of-fifths-pro/id1330706579) | 5.0 (2) | $0.99 | Music |
| [Smartleggio](https://appshunter.io/ios/app/smartleggio/id6476707166) | 1.5 (2) | Free | Music |
| [Solo Guitar Lessons](https://appshunter.io/ios/app/solo-guitar-lessons/id434081139) | 3.3 (7) | Free | Music |

## More apps by Lucy Hudson

- [MeanTones](https://appshunter.io/ios/app/meantones/id1582880428)
- [PentaMonochord](https://appshunter.io/ios/app/pentamonochord/id1582880506)

All apps by Lucy Hudson: https://appshunter.io/developer/1179157812

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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 2026-06-04.*