Note: This guide also applies to Dirac Live 3. Last update 14.07.2021

Configure microphone and setting speaker levels for measurements in Dirac Live 2/3

This tutorial shows how to configure microphone and speaker levels for measurements.

The goal of this procedure is to get the test signal level as far away from the room's noise floor as possible without damaging speakers or ears. A 20dB difference between noise floor and test signal level is good, higher is better. In a quiet room this can be achieved with a high mic gain and a low test signal level. In a noisy room mic gain needs to be reduced but test signal level needs to be louder.

Requirements

AVR with Dirac Live 2/3 room correction (e.g. NAD T758v3), Mac or PC capable of running Dirac Live 2.5 or later.

Getting started

  1. Connect the measurement microphone to your computer or AVR/AVP (if supported).
  2. Place microphone at the main listening position using a mic stand. Never put the mic directly on a surface. Make sure the mic cable is not dangling around. Mic pointing up towards the ceiling. Mic tip exactly at ear height in the center where your head would be.
  3. Start Dirac Live
  4. Select your AVR/AVP

Select Recording Device

  1. Load the calibration file for the microphone.
  2. Make sure the correct microphone is selected.
  3. Proceed to the "Volume Calibration" tab.

Volume Calibration

Preparation

  1. Move "Master output" slider all the way down.
  2. Move mic gain slider up as long as background noise level stays below the -50dB mark. Make sure devices that are known to generate a lot of inaudible low frequency noise are switched off, e.g. HVAC, refrigerator, washer, dryer, people walking around (they sometimes don't have an off switch though), etc. Such noise can invalidate measurements.
  3. Move all speaker/subwoofer channel sliders all the way up.
  4. Turn level/gain knob on your subwoofer all the way down. If your sub has a low pass filter, make sure it is switched off or set to the highest value.

Find softest speaker

  1. Click "Play" button for the left speaker.
  2. Slowly increase "Master output" slider until left speaker plays the noise signal at a comfortable level.
  3. Click "Play" button for each speaker successively. Omit subwoofer.
  4. Note the softest speaker (in this example "Height 1 Left").

Level speakers

  1. Click "Play" button of the softest speaker.
  2. Move "Master output" slider up until level of the softest speaker (in this example "Height 1 Left") is at least 20dB above noise floor (roughly -30dB, green or blue zone in older app versions).
  3. Click "Play" button for the left speaker and reduce its level so it also measures at least 20dB above noise floor (roughly -30dB, green or blue zone in older app versions).
  4. Repeat step 3 for all other speakers except the subwoofer.
  5. Move subwoofer channel slider roughly to the same value as the loudest speaker (in this example "Surround Right").
  6. Click "Play" button for the subwoofer.
  7. Turn level/gain knob on your subwoofer up until the level is also at least 20dB above noise floor (roughly -30dB, green or blue zone in older app versions).

You're now ready to proceed to the "Select Arrangement" tab and do the actual measurements.

Tips and Tricks

After successfully running a Dirac Live calibration check the trim values in the AVR (unfortunately some devices do not offer this option). If the sub is 0 check how much negative trim has been applied to the loudest speaker. If the value is within a couple of decibels there are no additional steps necessary. If the value is closer to -10dB or even larger then increase gain at the sub plate amp and rerun Dirac Live. The sub trim value in the AVR should end up being amongst the loudest speakers (largest negative trim).