Measurement Toolbox

DEQX Calibrated™ measurement toolbox

Calibrated microphone ensures a true measurement of the speaker

Time domain based measurement shows impulse response, phase & magnitude response

Per-driver measurement to allow a unique analysis and correction of each driver

Pseudo-anechoic measurement separates speaker from room response with a user-controllable window

Logarithmic cepstrum based smoothing removes unwanted artefacts and makes complex speakers easier to measure.

Lower frequency limits can be applied to each driver to protect tweeters from bass during measurement

Speakers can be measured after correction to verify correct operation of filters

Uses log swept sine test signals to maximize SNR. User can modify sweep length and number of averages to optimize for their measurement environment

Optimal measurement method eliminates noise from the measurement that is not correlated to the measurement signal

Confidence level is reported for each measurement, giving immediate feedback as to the quality of a measurement - picking up errors such as noise or aliasing

A test signal is run through each loudspeaker driver in turn, and the behaviour measured using a DEQX CalibratedTM microphone. When doing room measurements, or if a passive speaker is used, all drivers are measured simultaneously.

DEQX uses multiple swept sine waves for measurements to provide the best possible signal to noise ratio. The user can specify the length of each sweep, and the number of sweeps to average for each measurement. This allows the user to choose fast measurement times when quiet room conditions are available, and longer measurement times for measurement in large or noisy rooms.

When setting up to perform the pseudo-anechoic measurement, care is taken to maximise the distance of the first reflected sound wave (from the floor or a piece of furniture for example) to the microphone, compared to the direct sound from the loudspeaker, which is measured on-axis to the speaker baffle, at up to one metre.

The DEQX software provides a logarithmic cepstrum based smoothing method which can be employed to remove any unwanted measurement artefacts, in the case of difficult to measure speakers.