SP395 SoundPro Audio Integrator Form7492 Operation Manual
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4. Select the averaging time constant. Longer times provide a more stable display, while
slower times respond more quickly to changing sounds and noise. Use 6 second (or
longer) averaging when performing low frequency equalization.
5. Select the desired weighting. Use Flat (no weighting) for most applications.
6. Turn on the pink noise. If you are using the SP395 as the signal source, turn on both the
FFT function and the generator. ("Gen on" field).
7. Adjust the Graph Range and Graph Resolution. Adjust the range and resolution so
that the entire graph display fits on the vertical axis. Depending on the SPL difference
between the highest and lowest levels, you may need to use 35 dB resolution to see the
entire graph.
8. Use the measurement cursor to read the exact frequency and dB level of any
frequency band on the graph. Pause the FFT if desired, to freeze the display.
Storing an FFT graph to memory:
FFT graphs can be stored in any of the 40 non-volatile memories, using the memory control
icons in the center of the bottom toolbar. Use the memory number field to select a memory
number. See the Bottom Toolbar section of this manual for details on the memory toolbar
section. When the memory number field is selected, the type of memory stored (or “---” if
empty) appears on the bottom of the graph. The memory type for the FFT is labeled “FFT”.
To store an FFT measurement screen to memory:
1. Select a memory number in the memory number field. Note: The display indicates if a
previous test screen is stored or “- -” if empty.
2. Store to memory - Click on the S (Store) icon to store the function data to the current
memory number.
3. Recall from memory - Click on the R (Recall) icon to recall function data from a
selected memory number. If the data type does not match the current function, a “Wrong
type” error message will appear momentarily. A recalled graph can be analyzed exactly
the same as a live graph - by changing the octave band filter size, graph amplitude range,
and using the cursor to read individual band frequencies and dB levels. Memory data can
also be transferred to a PC using the Transmit Data function.
4. To Clear memory. Click on the C (Clear) icon to clear function data from the current
memory number.
FFT - Difference Mode
You can operate the FFT Analyzer in a “Diff” or Difference mode. This allows you to see how
current conditions differ from a stored memory. This allows you to see how current conditions
differ from a stored memory FFT. It is especially useful to compare seating position FFTs or to
judge how changes to the room affected the acoustic performance
To use the Difference mode, first either recall or save a memory. Then, change the overlay field
to ‘Diff’ and the display will switch to Difference mode. The center of the screen will be set to 0
dB, with a ±15 or ±7.5 dB scale, depending on the graph resolution selected (top left corner of
FFT Analyzer graph). To exit Difference mode, change the ‘Diff’ in the overlay field to “Flat.”
Real-time Interface
The FFT function can be used with the TerraLink computer software program to provide real
time measurements on a PC screen. See the TerraLink Control – Real Time Computer Interface
section of this manual for more information.
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