Timer 555 Calculator Pro vs SPL
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Timer 555 Calculator Pro
Calculate parameters for monostable and astable circuits. Find component combinations for desired pulse width or frequency. Share circuit files via iCloud Drive or AirDrop.
- Calculate monostable pulse width
- Calculate astable frequency
- Find component combinations
- Adjust component tolerance
- Unlimited combinations (Pro)
- Share circuit files
Read full descriptionHide full description
This app is used to calculate monostable and astable circuit. Features * Calculate pulse width of monostable circuit * Calculate frequency of astable circuit * Find out combination of components making a desire pulse width in monostable circuit * Find out combination of components making a desire frequency in astable circuit * Share file to iCloud Drive (For iOS8 or later) * Share file via AirDrop Additional Features in the Professional Edition * Unlimited number of combinations * Allow to change tolerance * No ads
SPL
This utility app serves as a companion for the E-mu SP-12 drum machine, enabling users to save and load sequencer and sound memory data via MIDI. It includes a manual and sample banks for connection verification, with an upgrade option for custom sound loading.
- Save and load sequencer data
- Save and load sound memory data
- MIDI connection support
- Built-in manual
- Sample banks for connection verification
- Upgrade for custom sound loading
Read full descriptionHide full description
The SPL-12 Sampling Percussion Librarian is a companion app for the E-mu SP-12 Sampling Percussion drum machine. The application makes no sound on it's own. It's purpuse is to provide a convenient way to save and load sequencer and sound memory data via a MIDI connection. A built-in manual will guide you through the process of connecting your unit. A provided set of sample banks help you to verify your MIDI connection first and you can upgrade to the full version with a one-time in-app purchase to load your own sounds and sequences. We hope enthusiasts will find this utility useful and keep the spirit of 12-bit sampling alive for many years to come. Enjoy!
Screenshots
Verdict
The clearest difference is price: SPL at Free against Timer 555 Calculator Pro's $0.99. SPL also leads on update cadence (every 6 days vs every 3 months) and iOS requirement (9.3 vs 13.2). Timer 555 Calculator Pro's advantage is rating (4.7 vs 3.8) and in-app purchases (none vs 1). On review sentiment, ratings volume, 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
SPL is free to download; Timer 555 Calculator Pro costs $0.99 up front. SPL sells 1 one-off in-app purchase. Timer 555 Calculator Pro asks for nothing beyond the download.
Timer 555 Calculator Pro holds the better App Store score, 4.7 against 3.8. Both are backed by a comparable volume of ratings — 3 and 4 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
Timer 555 Calculator Pro ships an update every 3 months, SPL every 6 days. Both last shipped on October 23, 2026.
| Parameter | Timer 555 Calculator Pro | SPL |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 4.7 (3 ratings) — better | 3.8 (4 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 3 | 4 — better |
| Update frequency | Every 3 months | Every 6 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.2 | 9.3 — better |
| Further details — not scored | ||
| Size | 3 MB | 19 MB |
| Age rating | 4+ | 4+ |
| Developer | Siu Yuen Ho | Delta Seven Kft. |
Customer experience
Timer 555 Calculator Pro
SPL
In-app purchases
Timer 555 Calculator Pro
No in-app purchases
SPL
- Full Functionality$29.99
Questions
Is Timer 555 Calculator Pro free?
Is SPL free?
Which has better reviews, Timer 555 Calculator Pro or SPL?
Do Timer 555 Calculator Pro or SPL have ads?
Which is updated more often, Timer 555 Calculator Pro or SPL?
Other comparisons
