EQ550b vs GSDSP MMMm
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
EQ550b
This audio effect plugin emulates a classic American equalizer from the late 1960s, offering four bands of equalization with selectable frequencies and proportional Q. It provides a wide range of tonal variations for professional audio manipulation and can be used as a standalone app or an AUv3 plugin.
- Modeled vintage EQ
- Four bands of equalization
- Selectable frequency centers
- Proportional Q filter
- Stereo, Mid, or Side EQ modes
- AUv3 plugin compatibility
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EQ550b 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 EQ550b AUv3 plug-in as many times as you want, thereby you get the Demo period again and again.) Unlimited version of EQ550b AUv3 plug-in comes as In-App Purchase. Based on Classic American EQ from the late '60s, the EQ550b is a continuation of the EQ that played a major role in the history of music recording, but with an additional filter band and several new frequencies. With a surprisingly wide range of tonal variations, the EQ550b is an invaluable and professional audio tool with great flexibility and excellent sonic ability. Features: • Standalone and AUv3 plug-in; • Precise port of Rack Extensions plug-in; • Modeled vintage EQ; • Four bands of classic American equalization; • Each band offers seven selected frequency centers; • 15 dB of boost/cut per band; • EQ band 1 and 4 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. Rather than offer a huge assortment of complex features, the EQ550b provides exactly the right number of controls. Its four EQ bands are overlapped significantly to aid in dual roles as problem solver and sweetening device with each band offering seven switchable filter frequencies that span four-to-five octaves. These frequencies, purposely selected to be musical rather than numeric. 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. The EQ550b 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 EQ550b as a plug-in, you need an AUv3-compatible host app like GarageBand, Auria, AUM, Cubasis and more — EQ550b will appear in the list of Audio Unit extensions for effect plug-ins in the host app.
GSDSP MMMm
This app provides a powerful MIDI modulation engine to control various plugins, hardware, and instruments. It offers a range of modulation sources like LFOs and random generators, and includes a dedicated performance skin for live use. It's a MIDI-only FX version for hosts requiring pure MIDI processing.
- MIDI CC control for plugins and hardware
- LFO, Random, Envelope Follower modulators
- XY pads for modulation
- Dedicated Performance Skin for live use
- AUv3 MIDI FX plugin
- Desktop versions available
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A powerful MIDI modulation engine for controlling plugins, hardware, and instruments using LFOs, random sources, macros, and audio-based modulation. Modulate Everything MMMm is a MIDI controller and modulation workstation designed to control any parameter that accepts MIDI CC — software instruments, plugins, external hardware, or any MIDI-capable device. Create modulation using LFOs, Random Generators, Envelope Followers, XY pads, and more. No more drawing of automation curves, keep your audio dynamic and exciting with ease. Perform Live MMMm includes a dedicated Performance Skin designed for low-light and stage environments. It uses a restrained, red-accented color palette that preserves focus and minimizes visual distraction while performing. The interface remains clear and readable in dark settings, ensuring stable workflow during your live performance. MMM vs MMMm MMM includes audio input, enabling Envelope Followers, audio-reactive modulation, and audio output — ideal when used as an audio plugin. MMMm, by contrast, is a MIDI-only FX version for hosts such as Logic Pro or AUM that require a pure MIDI processor. Both versions support MIDI input and output and provide the same core modulators. MMMm is an AUv3 midi effect plugin compatible with Logic Pro, AUM, Cubasis, GarageBand and many more. A Desktop version is also available for Windows and macOS (VST3 / AU / AAX). More information here: https://gs-dsp.com/products
Screenshots
Verdict
The clearest difference is in-app purchases: GSDSP MMMm at none against EQ550b's 1. EQ550b's advantage is update cadence (every 2 weeks vs every 6 weeks) and iOS requirement (10.0 vs 12.0). On price, rating, review sentiment and ratings volume 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. EQ550b sells 1 one-off in-app purchase. GSDSP MMMm asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 4.8 for EQ550b against 4.9 for GSDSP MMMm. Both are backed by a comparable volume of ratings — 13 and 14 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
EQ550b ships an update every 2 weeks, GSDSP MMMm every 6 weeks. The most recent releases landed on September 1, 2026 and September 11, 2026 respectively.
| Parameter | EQ550b | GSDSP MMMm |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (13 ratings) | 4.9 (14 ratings) — better |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 13 | 14 — better |
| Update frequency | Every 2 weeks — better | Every 6 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 10.0 — better | 12.0 |
| Further details — not scored | ||
| Size | 19 MB | 44 MB |
| Age rating | 4+ | 4+ |
| Developer | RRS, OOO | Gustav Scholda |
Customer experience
EQ550b
GSDSP MMMm
In-app purchases
EQ550b
- RRS EQ550b Unlimited$4.99
GSDSP MMMm
No in-app purchases









