Getting Started with Room EQ Wizard

The Room EQ Wizard can work with data you have already acquired by manual measurement or using another program (see Importing Measurement Data), or it can act as a complete signal generation, data capture/analysis and filter tuning tool. This section gives an overview of getting the Wizard running as a complete solution for room response measurement and equalisation filter tuning, if you already have some data you want to tune filters against you can import it and skip to Filter Adjustment.

When using the Wizard to make measurements it is best to exit any other applications and disconnect from the internet. High processor demand from other applications, automatic anti-virus updates and the like can cause gaps in the generated or captured audio signals leading to incorrect measurement results.

The steps required to make room measurements are:

  1. Configure the audio input and output
  2. Set the measurement level
  3. Set the input volume
  4. Calibrate the SPL reading
  5. Make a soundcard calibration measurement

If running the Wizard for the first time it is best to read through these initial help chapters in sequence rather than jumping directly to the individual setup steps.

Equipment Needed


Soundcard Connections


System Connections

Measurements may be made by connecting directly to an equaliser or by connecting to an AV processor input. If your aim is solely to configure an equaliser (such as BFD Pro DSP1124P or FBQ2496) to optimise your subwoofer's response, connect one of the soundcard's line outputs directly to the equaliser input in place of the Sub connection from your AV processor. For a BFD Pro the operating level switches on the rear panel should be pressed in to select the -10dBV range. To make measurements that will show the response of main speakers as well as the subwoofer, and to view the integration between subwoofer and main speakers, connect to an AV processor input.

If connecting to an AV processor input, the input used should ideally be one that the processor can route to any speaker output. AV32R DP and AV192R provide this ability in the Test Signal entry within the TMREQ filter menus for each speaker. If the processor does not have such a signal routing facility it may have 5.1 or 7.1 analog inputs that can be used, but in some cases bass management will not be applied to such inputs, limiting the ability to check sub/main speaker integration. Connecting to the left or right channel of an analog input will allow the corresponding main speaker and the subwoofer responses to be measured - turn off or disconnect the relevant main speaker or the sub to exclude them from a measurement.

If the AV processor input being used offers an anti-clipping feature (automatically reducing its sensitivity if it detects large signals) this should be turned off, as it could shift the measurement levels. The sensitivity of the input should ideally be set to 0.5V, though this is not critical.

To measure the responses of individual speakers and subwoofer in the absence of 5.1 or 7.1 inputs it may be possible to connect the soundcard's line output directly to the line level input of the amplifier driving the corresponding speaker, in place of the connection from the AV processor - however if connecting directly to the amplifiers great care must be taken to ensure that high signal levels are not inadvertently presented as this could damage loudspeaker drive units.

SPL Meter Range

Your SPL meter's range should be set to the value normally used for speaker level calibration and must not be altered while using the Wizard. If you are using the Radio Shack meter, select the 80dB range if you calibrate your system at 75dB (this is the standard level recommended by DolbyTM).

Set your meter to C weighting. If you are using a microphone and preamplifier for measurement, turn off the Wizard's C weighting compensation in the Meter menu. There have been reports that the digital display version of the RS meter does not require C weighting compensation for its line output, but other reports that it does. The schematics of the meter (at least one version of it) show that the C weighting compensation should be required.

Configuring Audio Input and Output

The wizard needs to be told what it should use for audio input and output. These selections are made at the bottom of the SPL Meter and Signal Generator panels. The device lists show all soundcards that the Wizard has detected, when a soundcard has been selected the input and output lists show the available inputs/outputs on that soundcard. Note that if a USB soundcard is plugged in after the Wizard has been started it may take up to 1 minute for it to appear in the list of devices - this is a feature of the Java Runtime Environment.

Audio input selection

Audio output selection

The lists include both internal and external devices and default drivers offered by the operating system.

Audio input devices

Where possible, select the soundcard itself rather than the OS drivers "Primary Sound Capture Driver", "Primary Sound Driver", "Java Sound Audio Engine" or similar. The Wizard needs direct access to the controls on the soundcard if it is to automatically adjust levels, this may not be possible if the OS drivers are selected.

Once the devices have been chosen, the input and output can be selected. Typically the input will be called "LINE_IN" and the output will be "SPEAKER" or "LINE_OUT", however these names may be different for USB soundcards - for example, the input may be labelled "Digital Audio Interface".

Trouble-shooting tip: To prevent the Wizard from attempting to access soundcard controls, select the input and output devices but do not select the input and output, i.e. leave those selectors set to "Choose input..." and "Choose output...". The actual input and output used and any level control settings will then need to be made using the Windows volume control or the soundcard's mixer.

Note that on the Mac it is necessary to set the Sample Rate to 44.1k in the Soundcard menu, it will then be possible to choose "Mac OS X Core Audio" as the input device and "Java Sound Audio Engine" as the output device. There is no programmatic access to soundcard controls on the Mac.

After the inputs and outputs have been selected the next task is to Set the Measurement Level

Help Index

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