EQ550 4+

Classic American EQ


    • 4.4 • 10 Ratings
    • Free
    • Offers In-App Purchases



The EQ550 faithfully captures the punch, low-frequency transparency, and ultra-tight imaging of iconic American EQs of the late 1960’s.

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.


• 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;
• 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.

What’s New

Version 2.5.0

- Implemented Saturation adjust knob;
- Implemented GUI Scale on Pinch feature;
- Implemented Presets Drop-down Menu;
- Fixed parameters tweaking crash bug in some DAWs.

Ratings and Reviews

4.4 out of 5
10 Ratings

10 Ratings

anickt ,


These guys kill it with every app they make. IMHO they are underpriced. Sound great, easy to use, get them all! New synth kicks!

ZSS Enterprise ,

Needs a MacOS release to be realistically usable

Title says it all. I like this as a 550A emulator, especially for the price. Pretty nice features and interface, although I don’t love the curve in the saturation knob. Basically goes from no audible difference to total fuzz in like one notch. Feels like they used a virtual “linear pot” where a log would have been the ticket. I also would like an option to use stepped gain values like on an actual 550. All that said, the sound of this thing is pretty nice.

BUT. The lack of a version for MacOS cripples this plugin. Using more than a few instances on a project quickly overloads my iPad, forcing me to try to port it to my laptop in order to keep moving forwards. Then I find out all my plugins are disabled with no hope of using them. This, imo, is a major oversight and it relegates this from tool to toy status. Yes, I know it’s just GarageBand, but come on.


Sounds amazing until..

Loading this breaks my whole garageband session now. There’s just a high pitched click and then everything goes silent. The only way to fix it is to start a new project without loading this eq.. so it’s kinda useless

App Privacy

The developer, RRS, OOO, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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