Headphone EQ on a Mac

Q: Is a headphone EQ profile the same as oratory1990's measurements?

Not quite. oratory1990 publishes measurements and his own recommended EQ; AutoEQ derives filters from measurement data across many sources, oratory1990 among them. In BitMuse each profile records which measurement source it came from, so you can see whether the correction for your model is based on oratory1990, crinacle, Rtings or another set, and pick between them when more than one exists.

Measured correction by model, and how it relates to AutoEQ and oratory1990.

The usual way to EQ headphones on a Mac is to find your model on AutoEQ, open the ParametricEQ.txt it publishes, and copy ten filters and a preamp figure into an equalizer by hand — for every pair you own. BitMuse skips that step: the same measurements ship inside the app as selectable profiles. You search for your model, press Apply, and the filters are in the chain.

Why headphones need correction at all

A loudspeaker in a room is judged by whether it measures flat. A headphone cannot be, because there is no room — the driver couples to your ear canal, and the response that arrives at your eardrum is nothing like the response measured in free air. So headphones are designed against a target curve: a measured response that, through that coupling, is perceived as neutral. Every model misses its target somewhere, usually by several decibels in the bass and again around the presence region, and those misses are the audible signature people describe as a headphone being warm or bright or shouty.

Correction means measuring the model on a standardised fixture, comparing it to the target, and computing the filters that flatten the difference. That is exactly what AutoEQ does, at scale, from published measurement data.

What AutoEQ is, and where oratory1990 fits

AutoEQ is an open-source project by Jaakko Pasanen. It collects frequency-response measurements published by reviewers and measurement sites, compares each one to a target, and computes a set of parametric filters plus a preamp value that flattens it. oratory1990 is one of those measurement sources — a well-known contributor who measures on an industry-standard fixture and publishes his data — alongside crinacle, Rtings, Innerfidelity and others. AutoEQ is the machinery; oratory1990 is one of the people whose measurements go into it.

That distinction matters when two sources disagree about your headphones, which happens. BitMuse records the measurement source on every profile and shows it, so when your model has been measured by more than one person you can hear the difference rather than guess which file you downloaded.

What is in the database

The profiles are bundled with the app — there is nothing to download, no account, and it works offline. Measured from the shipped data:

8,666 profiles across 653 brands.
5,656 in-ear, 2,882 over-ear, 128 earbud. The form factor is part of the profile, and the app shows it.
23 measurement sources. The largest are crinacle (1,852 profiles), Innerfidelity (933), Super Review (885), Rtings (795) and oratory1990 (736).
Ten filters per profile, every time: one low shelf, one high shelf and eight peaking filters.

Peaking and shelf filters, in AutoEQ’s own notation

Each filter is one of three kinds, and BitMuse uses AutoEQ’s abbreviations for them so a profile lines up with the text file you would otherwise have typed in: PK peaking, LSC low shelf, HSC high shelf. Each one carries a centre frequency, a gain in decibels and a Q. The app lists them as chips so you can see what the correction is actually doing before you commit to it, and draws the resulting response curve live.

The preamp is part of the profile

Correction that boosts anything needs headroom, or it clips. Every profile stores its own preamp figure — negative in every case in the shipped set, between −9.3 dB and −0.8 dB — and BitMuse applies it as part of loading the profile rather than leaving it as homework. The panel shows it, so you know how much level the correction is costing you.

How it runs

A profile is not a preset for the 31-band graphic EQ. It builds its own biquad bank, one section per filter in the profile, with coefficients computed from the Audio EQ Cookbook formulas and applied through Accelerate’s multichannel biquad. That means the profile and the user EQ are separate effects in the chain and can run at the same time: measured correction underneath, taste on top.

Once a profile is loaded, the chain row stops saying Headphone Profile and starts showing the model name, which is a small thing that saves you opening the panel to remember what is in the path. Searching matches on the model name, and you can browse by brand instead. The window has its own shortcut, ⌥⌘H.

Honest limits

The correction is per model, not per unit. Manufacturing tolerance, pad wear and how the headphone sits on your head all move the real response. A profile is a measured starting point, not a calibration of the pair in front of you.
The same filters go to both ears. The coefficients are duplicated to every channel, so there is no left/right asymmetry correction for a hearing difference or a failing driver.
Ten filters is what the profile is. BitMuse applies the published filter set; it does not re-derive a correction from raw measurement data.
It is EQ, so it is not bit-perfect. Deliberately. See below.

EQ and bit-perfect, in the same app

Correction and bit-perfect playback are opposites, and BitMuse does not pretend otherwise: the chain ships empty of anything switched on, the signal path shows what is in it, and turning integer mode on bypasses the DSP chain outright — the status bar says DSP bypassed in Integer Mode. That makes an honest A/B: one toggle between a corrected path and an untouched one. If you listen on speakers instead, the equivalent tool is room correction from a measured impulse response, and the difference between the two switches is covered in integer mode vs exclusive mode.

FAQ

What is AutoEQ?

An open-source project that turns published headphone measurements into parametric EQ filters. BitMuse ships those filters as profiles instead of asking you to type them in.

Is a headphone EQ profile the same as oratory1990’s measurements?

Not quite. oratory1990 is one of the measurement sources AutoEQ draws on. BitMuse records the source on each profile so you can choose between them.

Do headphone profiles work on any headphones?

If the model has been measured — 8,666 profiles across 653 brands, over-ear, in-ear and earbud. The correction is for the model, not your individual unit.

Does headphone EQ break bit-perfect playback?

Yes, as any EQ does. The signal path shows the active chain, and integer mode bypasses it entirely.

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