Note: Last update 27.07.2023

Configure microphone and setting speaker levels for measurements in Dirac Live v2 & v3

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 making it so loud it could potentially damage 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, 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. The "Master output" slider adjusts the master volume of your AVR/AVP and therefore the overall test signal level later on.
  2. Move "Mic gain" slider up as long as background noise level stays below the -50dB mark or is barely peaking above. The "Mic gain" slider adjusts the signal level coming from the mic. 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 at your subwoofer all the way down. This is just a precaution. We'll adjust subwoofer levels later. 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 (speaker meter showing roughly -20 to -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 (speaker meter showing roughly -20 to -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" at -6.8dB, "Surround Right" is the loudest speaker as it had to be lowered the most).
  6. Click "Play" button for the subwoofer.
  7. Turn level/gain knob at your subwoofer (NOT within Dirac Live) up until the level is also at least 20dB above noise floor (speaker meter showing roughly -20 to -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 shows the largest positive trim value (in most AVRs this is the "0" mark) check how much negative trim has been applied to the loudest speaker. If the value is within a couple of decibels no additional adjustments are necessary. If the difference is 10dB or even larger then increase gain at the sub plate amp and rerun Dirac Live. Ideally the sub should end up being amongst the loudest speakers, i.e. have the largest negative trim setting in the AVR. This approach ensures a good signal-to-noise ratio in the main speaker channels and increases digital headroom in the subwoofer channel so it doesn't clip early.