SP395 SoundPro Audio Integrator Form7492 Operation Manual
56
How to Use TDA to Measure Microphone Response
1. Connect the output. Connect the output of the SP395 to an amplifier and to the speaker.
It is advisable to have a gain control at or before the amplifier, since the only other way to
control 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.
Determine the speaker to microphone distance, either by measuring, or by running the
Energy Time Graph. Enter this number in the Initial Delay field in the TDA setup menu.
3. Set the sweep time. Start with 20 seconds. Use a longer time for the most accurate results,
or a shorter time for a quick reading.
4. Set the filter Q. Set this field to 50.
5. Set the number of sweeps. Set this field to 1.
6. Run the test. Click on the generator On/Off icon on the bottom toolbar to begin the tests
7. Read the results. Check the graph for level. If you get the word “Overload”, reduce the
speaker volume. If you get “Low input” or the level is below 60dB or so, raise the speaker
volume. You can read the results directly on the screen using the cursor.
Storing TDA Sweeps into Memories
The TDA function can run up to 20 sweeps in
a group and store them to the internal SP395
non-volatile memory locations. Stored sweeps
can then be recalled and viewed.
After running one or more sweeps, you can
store them to memory. To do this, select the
starting memory location on the bottom
toolbar, and click S (Store). Note that when the
memory location is selected, the type of
memory stored (or “---” if empty) appears on
the bottom of the graph. As many sweeps as
are part of this set are stored in consecutive
memory locations. Note that if you leave the
TDA function without storing the sweeps to
memory, the measurement data is lost.
Recalling TDA Sweeps from Memories
To recall a set of TDA sweeps from memory,
to view them on the SP395, select the first
memory location in the series and click the R
(Recall) icon. If the memory number selected
is the first (or only) memory in a TDA series,
the series will be read into working memory
and you can then click on the Sweep number
field (Information Field) to scroll through the
sweeps.
Note that when the memory number field is
selected, the type of memory stored (or “---” if
empty) will appear on the bottom of the graph.
Only “TDA” type memories can be recalled to
the TDA function. If you see “Tm,” that means
that the selected memory is not the first sweep,
but one of the later sweeps, in a TDA set of
sweeps.
TDA – TerraLink Software
The SP395’s TDA function is designed to
work hand-in-hand with TerraLink PC
software. On the SP395 screen, you can see
only one sweep graph at a time. To view a set
of room response sweeps, you page back and
forth through the sweeps and watch the decay
pattern, to see how the decay varies by
frequency as you move through time.
Although this works, seeing multiple graphs in
3D gives a much more intuitive and quicker
understanding.
To use TerraLink for TDA analysis, just
perform the sweeps in the SP395, store them
to non-volatile memory, and transfer them to
TerraLink. From TerraLink, you can bring up
a set of TDA sweeps as a three-dimensional
graph. The surface of the graph represents the
decay curve for the room. You can rotate this
graph and view it from the top, or look at in
perspective. You can also switch between
wire-frame view and solid view.
As with other TerraLink graphs, you can store
TDA sweeps in project files on the computer
hard drive, to keep an archive of TDA
information, and to print or share with others.
You can also define a reference curve in
TerraLink, and compare a TDA curve against
the reference. This is particularly useful for
doing production line testing of transducers,
such as speakers and microphones.
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