Before measuring, Dirac plays a test signal through each speaker so you can set levels. The aim is simple: every speaker loud enough to be heard clearly above the room’s background noise, but nowhere near loud enough to strain anything.
Set up the room
Beginner
- Switch off anything that hums or blows: air conditioning, fans, dehumidifiers, a fridge in the same room.
- Close doors and windows.
- Put the microphone at your main seat, on a stand, at seated ear height (Step 2).
Set the levels
- Set Mic Gain to 100% as long as the background noise reading stays below about −50 dB.
- Start with the Master Output low. Around −55 dB is a common starting point in receiver manuals.
- Click Play for the front left speaker and watch the level meter.
- Adjust that speaker’s own level slider until the meter reads between −15 and −30 dB. As a rule of thumb, aim for about 30 dB above the background noise reading.
- Repeat for every speaker, leaving the subwoofers until last.
- If a speaker can’t reach the target even with its slider at maximum, raise the Master Output a little and go back through the others.
The test signal should sound a bit louder than you’d normally listen, but not uncomfortable. The coloured bar is a guide, not a rule.
Subwoofer level matching
This is the question that comes up most in the Dirac groups. The best practice is to set the subwoofer a little louder than the speakers using the gain (volume) knob on the subwoofer itself, not the slider in Dirac.
- Before measuring, set each subwoofer’s own controls: phase to 0°, low-pass filter off or at its highest setting (or LFE mode), and any room EQ or bass boost in the sub’s app switched off.
- Leave the subwoofer slider in Dirac at 0 dB.
- Click Play for the subwoofer and turn up the gain knob on the sub until it reads a few dB louder than your speakers did. Dirac’s own advice is roughly 0 to 3 dB above the speakers. Many experienced calibrators go 5 to 10 dB above.
- With two or more subs, do this for each one separately, so each sub on its own reads about the same level at the seat.
Why louder? Dirac will then turn the sub down in the receiver (a negative trim) rather than up. That keeps digital headroom in the receiver for loud bass in films, and it lets the subwoofer’s amplifier do the work.
If a subwoofer shows a red lock or can’t be adjusted high enough, raise the gain on the sub itself rather than pushing the Master Output up.
Common questions
The questions people ask most at this step, collected from a year of posts in Dirac user groups.
Do I need to change the phase knob on my subwoofer?
No. Dirac says you can leave it at 0° because Dirac corrects the phase where it needs to. The same goes for Bass Control.
The background noise reading is too high
Switch off anything that hums or blows, close doors and windows, and measure at a quieter time of day. If the noise can’t be removed, raise the speaker levels so each one still sits well above the noise, as described above.
This is standard measurement practice rather than a quoted Dirac instruction.
I have two subs. Do they share one level?
Only if they share one output. Two subs on a Y-splitter look like one sub to Dirac, so it sets one level for both. On separate outputs, set each sub’s level separately as described above. See Multiple Subwoofers with Dirac.
Do I need to set speaker distances and levels before Dirac?
No. Dirac measures them. With Bass Management or Bass Control, Dirac calculates the distances, levels and crossovers itself, and many receivers then lock those settings while the filter is on (Denon and Marantz do). Seeing different values, or zeros, afterwards is expected.
Source: Denon: Dirac Live manual.
Can I change the volume partway through measuring?
Yes. Dirac says it’s safe to change the master gain or a speaker’s gain on the Measurement Levels screen between positions. It compensates, so you don’t need to redo the positions already measured.
Source: Dirac Help Centre (official): adjusting volume calibration.
What should I set on the amp before measuring?
Tone controls flat, and loudness, dynamic EQ and any sound enhancement off, so Dirac measures the system you’ll actually listen to. Community practice rather than a Dirac instruction.
What the level screen is really doing
Advanced
Each measurement is a sweep recorded by the microphone. Its accuracy depends on signal-to-noise ratio: how far the sweep sits above the room’s background noise. Around 30 dB of clearance gives Dirac clean data down into the deep bass, where room noise is highest. Too quiet and low frequency readings get noisy. Too loud and you risk compressing the speaker or clipping the mic, which gives Dirac distorted data to correct.
The levels you set here are not your final channel levels. Dirac calculates those itself when it designs the filter. This screen only sets how loud the measurement sweeps are.
Subwoofer gain and headroom
Receivers have a fixed maximum digital output. If Dirac needs to boost a subwoofer channel to match the speakers, that boost comes out of the headroom available for LFE peaks. Setting the sub’s own amplifier gain higher means Dirac trims the channel down instead, so the full digital range is available for content. The trade-off is that a very high sub gain raises any hiss or hum from the sub, so don’t go further than you need to.
Multiple subwoofers
Setting each sub to a similar level on its own gives Bass Control an even starting point. If one sub is far from the seat or in a corner, its gain setting will be quite different from the others for the same reading at the seat, which is normal. Dirac treats subs on separate outputs individually. If your receiver sends one output to several subs, level-match them to each other first, as Dirac will see them as one.
Dirac Live 3.11 changed the Mic Gain scale: +18 dB in 3.11 and later equals 0 dB in earlier versions. Older forum advice on mic gain numbers may not match what you see.
Sources
- Denon: Dirac Live web manual (Configuring AVR settings, Measuring with Dirac Live software)
- Dirac Help Centre FAQ
- Dirac Live Guide (community, 2025), including StormAudio calibration advice