SP395 SoundPro Audio Integrator
Form7492
Operation Manual
55
How to Use TDA to Measure Speaker Response
1.
Connect the output.
Connect the output of the SP395 to an amplifier and to the speaker
that you wish to test. It is advisable to have a gain control at or before the amplifier, since
the only other way to change the speaker level during the TDA testing is to switch to the
signal generator function and set the level from there.
2.
Set up the speaker.
Set the speaker at least 4 feet from any surface.
3.
Set up the microphone.
Mount the microphone on a mic stand and point it at the speaker.
The microphone should be as far as possible from any solid surface, to minimize
reflections. The TDA filters will help eliminate reflections, but they will work better given
better input.
4.
Set the Initial Delay.
Set this field to the speaker to microphone distance. Determine the
speaker to microphone distance either by measuring, or by running the Energy Time
Graph.
5.
Set the Sweep Time.
Start with 8 seconds. This is a good trade-off between shorter SEB
and more low frequency energy.
6.
Set the Sweep Delta.
This field has no effect since we are running only one sweep.
7.
Set the number of sweeps.
Set this field to 1.
8.
Set the Filter Q.
Set this field to 36.
9.
Run the test.
Click on the generator On/Off icon on the bottom toolbar to begin the test.
10.
Read the finished graph.
Check the graph for level. You can read the results directly on
the screen using the cursor. If the warning “Overload” appears, reduce the speaker volume
and run the test again. If you get “Low input” or the level is below 60 dB or so, increase
the speaker volume and run the test again.
How to Use TDA to Measure Room Response
1.
Connect the output.
Connect the output of the SP395 to an amplifier and speaker. It is
advisable to have a gain control at or before the amplifier, since the only other way to
change the speaker level is to switch to the signal generator function and set the level from
there.
2.
Set up the microphone.
Mount the microphone on a mic stand and point it at the speaker.
3.
Set the Initial Delay.
Set this field to the speaker to microphone distance. Determine the
speaker to microphone distance either by measuring, or by running the Energy Time
Graph.
4.
Set the Sweep Time.
Start with 10 seconds.
5.
Set the Sweep Delta.
Choose the Sweep Delta and the number of sweeps to cover the
room time decay period that you wish to examine. For example, if the room decay time is
just under one second, and you would like to see that decay time split into ten sweeps,
choose a Sweep Delta of 1/10
th
second (100 mS).
6.
Set the number of sweeps.
Set this field to the number of sweeps that you want to run, as
determined in the step above.
7.
Set the Filter Q.
Set this field to 17. This will result in a smoother set of graphs.
8.
Run the test.
Click on the generator On/Off icon on the bottom toolbar to begin the test.
9.
Read the results.
Check the graph for level. You can read the results directly on the
screen using the cursor. If the warning “Overload” appears, stop the test, reduce the
speaker volume, and run the test again. If you get “Low input” or the level is below 60dB
or so after one sweep, stop the test, increase the speaker volume, and run the test again.
When the test is complete, you can use the sweep number field to page through the stored
graphs, to observe the pattern of sound decay in the room.
