DelayTool vs Solo
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
DelayTool
This application helps musicians and sound engineers calculate precise timing values for musical subdivisions. It automatically updates a table of milliseconds and Hertz based on the entered tempo, ideal for setting up delays and oscillators.
- BPM calculator
- Tempo input and tap tempo
- Automatic table updates
- Calculates milliseconds and Hertz
- Supports common musical subdivisions
- Precise delay and oscillator setup
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DelayTool is a simple BPM calculator for producers, engineers, and musicians. Enter or tap the tempo and watch the table of values update automagically. For each common musical subdivision, you will see times (in milliseconds and Hertz) for the current tempo. Just what you need to precisely set up delays and oscillators!
Solo
Master your guitar fretboard with this interactive trainer. Learn note names, intervals, chord changes, and scales through guided exercises. Designed by professional guitarists, it offers customizable workouts for all skill levels.
- Fretboard visualization
- Note name trainer
- Interval shape memorization
- Chord change outlining
- Scale practice
- Interactive fretboards
- Customizable workouts
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Solo is the ultimate practice App for mastering fretboard visualization, designed by world renowned guitarists Tom Quayle and David Beebee. Four powerful fretboard trainers allow you to work intuitively on each aspect of the visualization process; learning note names, memorising interval shapes, outlining chord changes, and practicing scales. Solo asks you to find intervallic functions against one root note, chord symbol or scale at a time, listens to the notes you play, and doesn’t move on until you’ve correctly found each note by its intervallic function in the specified order. Practice with Solo and finally learn your note names, master interval shapes, confidently play through chord changes and break out of scale boxes with intervallic functions. Start transforming your playing and confidence on the fretboard today! NOTE TRAINER The Note Trainer is perfect for beginner and intermediate players getting to grips with note names on the neck - the foundation of solid fretboard knowledge. ‣ Solo shows you random root notes to find and listens, waiting for you to get it correct. ‣ Slide on the interactive fretboards for helpful diagrams and to study alternative options. Choose from 6 string guitar (standard and 4ths tuning), 7 string guitar, 4 string bass & 5 string bass. ‣ Optional practice suggestions offer challenging ways to limit and test yourself. ‣ Duration based workouts allow you to craft the perfect practice session. INTERVAL TRAINER The Interval Trainer will help players at all levels work on interval shapes with intervallic functions - the key to unlocking true freedom on the fretboard. ‣ Choose any combination of intervallic functions to practice. ‣ Create custom interval groups or choose the intervals for ANY chord type or scale. ‣ The Interval Trainer will randomise your chosen intervals and ask you to find them against either a fixed or random root note. ‣ Slide on the interactive fretboards for helpful diagrams, showing you where all of the interval shapes are across the neck, and to study alternative options. Choose from 6 string guitar (standard and 4ths tuning), 7 string guitar, 4 string bass & 5 string bass. ‣ Duration based workouts allow you to craft the perfect practice session. CHANGES TRAINER In the Changes Trainer you find intervallic functions, using single notes to outline different chord types or sets of chord changes, a key skill for learning to improvise through chord changes. ‣ Practice outlining intervallic functions through over 100 common chord progressions and single chord exercises. ‣ 50 intervallic function levels. Go from simple chord tones to complex melodic structures and scales. ‣ Solo intelligently maps out the correct intervals over each chord and listens for you to play each intervallic function in the specified order. ‣ Powerful workout options provide almost limitless ways to challenge yourself. ‣ Transpose the key of any progression or exercise. ‣ Choose to randomly transpose the progression (or single chord exercise) each time it repeats. ‣ Work on voice leading chord tones through single note lines. SCALE TRAINER The Scale Trainer contains a vast array of scales and powerful workout options, allowing you to finally break out of the box and develop a much deeper understanding of how scales are constructed on the fretboard. ‣ Practice finding scales on the fretboard using intervallic functions. ‣ Over 50+ Scales and modes. ‣ Powerful workout options provide almost limitless ways to challenge yourself. ‣ Melodic sequence options let you focus on starting from any chord tone within the scale. ‣ Duration based workouts allow you to craft the perfect practice session.
Screenshots
Verdict
The clearest difference is price: DelayTool at $0.99 against Solo's $17.99. DelayTool also leads on in-app purchases (none vs 2) and rating (5.0 vs 4.7). Solo's advantage is update cadence (monthly vs every 23 months) and ratings volume (657 vs 5). On ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
DelayTool costs $0.99 and Solo $17.99 up front. Solo sells 2 one-off in-app purchases. DelayTool asks for nothing beyond the download.
DelayTool holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Solo has 657 ratings behind it against 5, so its average is the more settled of the two. Written reviews complicate that: 67% of DelayTool's written reviews are positive against 83% of Solo's, so the app with the better star average is not the one people write more warmly about.
DelayTool ships an update every 23 months, Solo monthly. The most recent releases landed on October 24, 2026 and October 27, 2026 respectively.
| Parameter | DelayTool | Solo |
|---|---|---|
| Price | $0.99 — better | $17.99 |
| Rating | 5.0 (5 ratings) — better | 4.7 (657 ratings) |
| Positive reviews | 66.7% of reviews | 83.3% of reviews — better |
| Number of ratings | 5 | 657 — better |
| Update frequency | Every 23 months | Monthly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Best chart rank | — | #79 — better |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 26.0 | 16.0 — better |
| Further details — not scored | ||
| Size | 5 MB | 231 MB |
| Age rating | 4+ | 4+ |
| Developer | Joel Perry | Trio Software Ltd |
Customer experience
DelayTool
Solo
Bugs and requests
DelayTool
Not enough reviews yet to summarise bugs or requests.
Solo
Reported bugs
3 issues- Crashes when launching the app
- Inconsistent note detection
- Inability to save progress or settings
Requested features
8 requests- Add ability to create custom chord progressions
- Integrate metronome functionality
- Provide visual representation of intervals on staff
- Add option to practice natural notes only
- Implement option to hear chord tones in the background
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- Allow randomization of scale order
- Add support for non-standard tunings
- Implement sound feedback when finding the correct note
In-app purchases
DelayTool
No in-app purchases
Solo
- Custom Tunings$1.99
- Custom Chord Progressions$5.99









