25
Finding the Volume
of a Subwoofer Enclosure
(V
b
)
By taking some measurements with the IM-SG and knowing
two of the T/S parameters of the driver, it is possible to find
the exact volume of a subwoofer enclosure. For this
method to work, the enclosure has to be completely sealed.
As such it may not be possible to use this method on a
ported enclosure unless it is possible to seal off the port
completely.
1. Find the V
AS
and the f
S
of the raw driver (see page 33 to
measure these or use manufacturer's specs).
2. To measure the volume of a enclosure, V
b
, make sure
the room or area around the subwoofer is quiet and free
from moving air.
3. Connect the test leads to the speaker system, if it has
multiple voice coils they all need to be connected. A
parallel connection will work fine.
Make sure there is
no amplifier connected or damage to the IM-SG
could occur!
4. Turn on the IM-SG by holding the
On
button for 1
second.
5. After the unit is operating, turn the frequency down as far
as it goes. Then slowly raise the frequency until a
first
peak in impedance is found. If you go too far and pass
the peak, just back down the frequency until the peak in
impedance is found. This frequency peak is
f
C
, the
resonant frequency of the sealed box subwoofer system.
This is the same measurement as the procedure on
page 21. We found the f
C
of our test driver mounted in
the test box to be 40 Hz.
Содержание SMD IM-SG
Страница 1: ...IM SG Impedance Meter Signal Generator Owner s Manual ...
Страница 17: ...17 Figure 1 Impedance curve of a single 4 ohm voice coil 15 inch subwoofer Notice the fS at 24 Hz ...
Страница 20: ...20 Figure 2 Impedance curve of a typical 4 ohm 1 tweeter Notice the fS at 1 59 kHz ...
Страница 22: ...22 Figure 3 fC of a single 4 ohm 15 inch subwoofer in a 2 cubic feet sealed box ...
Страница 44: ...44 Notes ...
Страница 45: ...45 Notes ...
