Specifications

EAW Smaart 6 Operation Manual Applications

The additional energy shown in the impulse response after the arrival of direct sound is

due to room reflections and the noise floor, which has a relatively constant average level.

The accuracy of the measurement depends on an adequate S/N between the direct sound

and noise level.

Impulse response measurements are used extensively in room acoustics work. IR

Analysis mode can also help identify problematic reflections that may cause comb

filtering and other real-time measurement anomalies. It is more common to use the auto

delay locator (Auto Sm or Auto Lg) to find the delay time for real-time frequency response

measurements. However, it is important to understand how this measurement is made

because the underlying process is the same and IR Analysis mode can be very useful

for troubleshooting problems making automatic delay measurements in the field.

4.3.3 Frequency Response Measurement of the Loudspeaker

1. Close the IR Analysis menu and return to the main real-time window. Click the

Freq. Response Phase (top) and Magnitude (bottom) displays.

2. Click the Auto Sm button to set Smaart 6’s internal delay to compensate for

the propagation time between the speaker and mic. Smaart 6 runs an impulse

response measurement in the background to automatically measure the delay

time. The Delay Found field displays the measured delay time.

3. Click Insert Delay to accept that time to compensate for the propagation delay

during Frequency Response measurements.

4. Delay presets can store several delay times for quick recall. This is useful for

switching between mics in different locations, or a measurement mic and an

equalizer. To assign the current delay time value to a preset, click the Delay

button to open the Delay tab of the Options dialog. Click one of the A-E buttons

to assign the Delay Time field to that key. Recall this preset by pressing the cor-

responding function key on your keyboard.

5. Click the Start button to begin real-time measurement. The frequency response

of the speaker (energy vs. frequency) is displayed. If the display is somewhat

erratic, select a larger number of averages from the Avg list under the Freq.

Resp. button to stabilize the trace.

Capturing and Loading Measurement Traces

Reference Traces are snapshots of the active live trace that can be captured, stored, and

recalled for later analysis. See Capturing and Loading Measurement Data on page 60.

NOTE: The Delay Locator requires the FFT Time Constant (time window) to be large

relative to the decay time of the device or SUT. For an electronic device or

small/medium sized room, a time window in the range 0.3-1.0 s is adequate.