KDJ vs EQ550
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
KDJ
Create music on your smartphone with a portable audio workstation. Compose original songs or mix existing tracks using over 400 instruments and 200 preset samples. Ideal for beginners and on-the-go musicians.
- Compose music in 5 minutes
- Over 200 preset tracks
- Over 400 instruments
- Sequencer, Synthesizer, Sampler modes
- Song Mode for arrangement
- Personal DJ machine functionality
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Introducing the smartphone app of the world’s first portable audio workstation, the “KDJ-ONE”! Compose a song in just 5 minutes on your smartphone device! Compose your own music, or mix existing tracks and use it as your own personal “DJ Machine”. Utilize your imagination and ideas to create your own music as if you were in a professional studio. Boasting a selection of more than 200 preset tracks and over 400 instruments to choose from, you can compose your own music without a musical background. Create a short melody in 5 minutes, or use the mute function and song mode to mix and easily play music like a DJ. ◆Recommended For:◆ Beginners looking to create their own music! People who want to create music on the go! On tour, vacation… and more! People creating music for games and performances! People who want to experience the hardware version of the KDJ-ONE! ◆Functions: Preset Samples: Over 200 tracks! Preset Instruments & Sounds: Over 400 varieties! Modes: Sequencer (Insert different instruments and sounds into your composition) Synthesizer (Synthesize waveforms to form a timbre) Sampler (Record and modify sounds from external audio inputs) Song Mode (Arrange and playback your composition) ◆Languages: Japanese, English ◆Compatibility iOS 10.0 or later ◆URL KDJ-ONE Official Site: http://www.kdj-one.com This app is based on the hardware version of the “KDJ-ONE” and may differ with regards to development and functions.
EQ550
This audio effect plugin emulates classic American EQs from the late 1960s, offering precise control over equalization with unique Proportional Q technology. It functions as a standalone app or an AUv3 plugin for compatible hosts, providing a flexible and characterful sound shaping experience.
- Standalone and AUv3 plugin
- 3 bands of classic American equalization
- Proportional Q filter bandwidth
- Stereo, Mid, or Side EQ modes
- Undo/Redo and A/B comparison
- Scalable GUI
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EQ550 AUv3 plug-in — comes as time-limited Demo-version for you to try. It gives you 5 minutes of Free play time. (You can reload the EQ550 AUv3 plug-in as many times as you want, thereby you get the Demo period again and again.) Unlimited version of EQ550 AUv3 plug-in comes as In-App Purchase. The EQ550 faithfully captures the punch, low-frequency transparency, and ultra-tight imaging of iconic American EQs of the late 1960’s. Making use of Proportional Q intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings without the need for additional bandwidth controls. This unique feature minimizes the «phase-shift» sound found in many equalizers. Features: • Standalone and AUv3 plug-in; • 3 bands of classic American equalization; • Each band offers 7 selected frequency centers; • Maximum 15dB of boost/cut per band; • EQ Band 1 and 3 offer shelf/peak switching; • Proportional Q narrows filter Q at extremes; • Stereo (Mono), Mid or Side EQ modes; • Undo/Redo; • A/B comparison; • 2x/4x/8x Upsampling; • Macro controllers; • Built-in Gain Match; • Scalable GUI. The EQ550 provides reciprocal equalization at 21 points in 5 steps of boost to a maximum of 15dB of gain at each point. The twenty one equalization points are divided into three overlapping ranges. The high and low frequency ranges are individually selectable as either peaking or shelving, and a band-pass filter may be inserted independently of all other selected equalization settings. Frequency ranges and boost/cut are selected by switches, and a pushbutton «IN» switch allows the EQ to be silently introduced to the signal path. A small toggle switch is used to insert the band-pass filter into the EQ550. The EQ550 extends the features of the original hardware and joins the flexibility of the digital world to the character of the analog processing. Allows you to choose between equalizer modes (Stereo, Mid, Side) and remove analogue saturation from the processing circuit to deliver pure digital sound. To use EQ550 as a plug-in, you need an AUv3-compatible host app like GarageBand, Auria, AUM, Cubasis and more — EQ550 will appear in the list of Audio Unit extensions for effect plug-ins in the host app.
Screenshots
Verdict
The clearest difference is in-app purchases: KDJ at none against EQ550's 1. KDJ also leads on review sentiment (67% vs 33%) and rating (4.8 vs 4.5). EQ550's advantage is update cadence (monthly vs every 3 months). On price, 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
Both are free to download. EQ550 sells 1 one-off in-app purchase. KDJ asks for nothing beyond the download.
KDJ holds the better App Store score, 4.8 against 4.5. Both are backed by a comparable volume of ratings — 17 and 11 respectively. Written reviews point the same way: 67% of KDJ's written reviews are positive against 33% of EQ550's.
KDJ ships an update every 3 months, EQ550 monthly. The most recent releases landed on October 25, 2026 and October 24, 2026 respectively.
| Parameter | KDJ | EQ550 |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (17 ratings) — better | 4.5 (11 ratings) |
| Positive reviews | 66.7% of reviews — better | 33.3% of reviews |
| Number of ratings | 17 — better | 11 |
| Update frequency | Every 3 months | Monthly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 10.0 | 10.0 |
| Further details — not scored | ||
| Size | 82 MB | 20 MB |
| Age rating | 4+ | 4+ |
| Developer | CyberStep, Inc. | RRS, OOO |
Customer experience
KDJ
EQ550
In-app purchases
KDJ
No in-app purchases
EQ550
- RRS EQ550 Unlimited$4.99









