Guides · Translation
Use a diagnostic EQ to hear other speakers
A diagnostic EQ is an equalizer you put on your monitoring, not your mix. It lets you roughly imitate other playback systems and hunt down problem frequencies, without touching what you print.
What a diagnostic EQ is for
Most EQ in a session is part of the mix: it changes what you deliver. A diagnostic EQ sits in the monitoring path and only changes what you hear. It has two jobs:
- Imitation. Shape your monitors or headphones so they lean toward how another system sounds, like a laptop, cheap earbuds or a car.
- Investigation. Boost a narrow band and sweep it to find resonances, harshness or muddiness that are hard to pin down at normal settings.
Neither job is about sounding good. They're about exposing problems quickly.
Imitating other playback systems
These are starting points, not measurements of real devices. Every speaker is different; the idea is to exaggerate a tendency so you can hear what your mix does under it.
| To suggest… | Low shelf | Mid peak | High shelf |
|---|---|---|---|
| Laptop or phone speaker | Cut heavily, around 200–300 Hz | Boost gently around 1–2 kHz, wide Q | Slight cut |
| Cheap earbuds | Cut moderately, around 100–150 Hz | Boost around 3–5 kHz | Boost a little |
| Bass-heavy car or consumer headphones | Boost, around 60–100 Hz | Slight cut around 300–500 Hz | Flat or slight cut |
| Dull, distant playback (next room, TV) | Slight cut | Flat | Cut, from around 4–6 kHz |
For each one, listen for the same things: does the vocal stay intelligible, does the bass line still read, does anything become harsh, boomy or disappear? If a problem shows up under two or three of these curves, it's probably in the mix, not the curve.
Finding resonances by sweeping
This is a classic technique. Resonances, ringing snare frequencies, boomy notes and harsh spots in a vocal are easier to find when you exaggerate them.
- Set a mid peak to a large boost, about +9 dB, with a narrow Q of 6 or more.
- Play the section with the problem and slowly sweep the frequency.
- Stop where the sound gets dramatically worse: a ring, a whistle or a honk.
- Note the frequency, turn the diagnostic EQ off, and fix it in the mix, usually with a smaller, narrower cut on the source track.
Sweeping is loud and tiring, so keep the monitoring level down and take breaks. It's also easy to overdo: not every peak you find needs cutting. If it doesn't bother you with the boost off, leave it.
Don't mix through it
Turn the diagnostic EQ on for a check, then off. Balancing with it on for long will pull the mix toward the opposite of that curve, and the mix will sound wrong everywhere else.
Other quick diagnostic moves
- Low-cut the monitoring. A steep-ish low shelf cut hides the sub and shows you whether the kick and bass still have enough upper content to carry on small speakers.
- Cut the top. A high shelf cut makes it easier to hear the balance of the midrange instruments without cymbals and air distracting you.
- Boost the low mids gently. A wide boost around 200–400 Hz exaggerates mud. If the mix turns to mush quickly, there may already be too much there.
- Boost the presence range. A wide boost around 2–5 kHz shows up harsh vocals, guitars and cymbals before a bright system does it for you.
Combine these with level. Many problems only appear at low volume (thin low end, buried vocal) or high volume (harshness), so try each curve quietly and loud.
Confirm on real devices
An EQ curve can't reproduce everything a small speaker does. Real devices distort when pushed, compress, have limited stereo width and are heard in noisy places. Use the EQ to form a hypothesis quickly, then confirm on the real thing: a phone speaker, earbuds, a laptop, a car. If both agree, fix it.
The diagnostic EQ in MixOutpost
MixOutpost streams your mix from the Mac to your iPhone and has a three-band Diagnostic EQ in the Listen tab. It alters playback on the phone only.
| Band | Frequency | Gain | Other |
|---|---|---|---|
| Low shelf | 30–300 Hz | ±12 dB | |
| Mid peak | 100 Hz–12 kHz | ±12 dB | Width Q 0.4–10 |
| High shelf | 2–16 kHz | ±12 dB |
A curve shows the response, and Reset to flat puts everything back. The app's own hint for resonance hunting matches the method above: boost about +9 dB with a narrow Q (6 or more) and sweep.
Because it's on the phone, you can combine it with the phone's outputs. Put a small-speaker curve on AirPods to approximate cheap earbuds, or add a low shelf boost on the phone speaker to hear whether the bass line gets muddy when a system emphasizes it.
- Never affects measurements. Meters and loudness still show exactly what your Mac sends.
- Never affects recordings. Recordings are made before the EQ.
- Never affects the DAW. The plugin passes your audio through unchanged.
The diagnostic EQ is one of the features proposed for MixOutpost Pro, a one-time purchase.
Questions
Is a diagnostic EQ the same as speaker simulation?
No. A few EQ bands can suggest the tonal balance of a small speaker, but real speakers also have distortion, limited headroom and their own dispersion. Use it as a quick approximation and confirm on real devices.
Why does the EQ not change my meters?
Because it's for listening only. In MixOutpost the EQ changes playback on the phone, while the meters, loudness readings and recordings stay based on exactly what the Mac sends.
What Q should I use to find a resonance?
Narrow. A boost of about +9 dB with a Q of 6 or more, swept slowly across the range, makes resonances jump out. Once you've found one, cut it in the mix with a gentler setting.
Should I leave the diagnostic EQ on while mixing?
No. Turn it on for a check, then turn it off. Mixing through it for long periods would bias your balance toward that curve.
Hear your mix on your phone
Free Mac plugin (AU, VST3) and iPhone app. Lossless, bit-exact and encrypted.