35
Finding the Thiele / Small (T/S) parameters of
a driver - continued
R
O
represents an impedance that we are going to try to find
with the IM-SG. This impedance will happen twice, once at
a frequency lower than the f
S
and once at a frequency higher
than the f
S
. We are going to call these f
L
and f
H
respectively.
See figure 8 for a graphical representation. Plugging in our
numbers from our test woofer we get:
= 3.4 X
Solving for R
O
we get 11.41 ohms. This is the impedance we
are going to search for, below the f
S
frequency to find f
L
and
above the f
S
frequency to find f
H
.
10. Slowly sweep the frequency down to find f
L
. It will be
lower in frequency than f
S
was and will occur at R
O
ohms. See figure 8. Record the frequency you found
as f
L
. We measured f
L
to be 15.3 Hz on our 12 inch
woofer.
11. Now slowly sweep the frequency up, higher than the f
S
frequency. We are looking for the frequency that is at
R
O
ohms on the other side of the peak now. We call
this frequency f
H
. Record the frequency you found as
f
H
. We measured f
H
to be 43.6 Hz on our 12 inch
woofer. Refer to figure 8.
Congratulations, at this point you have found and
recorded f
S
, f
L
, f
H
, R
ES
, R
E
and R
O
! Now with a little
math we can find Q
MS
, Q
ES
, and Q
TS
.
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 ...
