From
these two curves, the following Thiele & Small Parameters
were generated by LMS (Figure 3). Before we make any comparisons,
I should add that these LMS figures are accurate to within
+/- 10%.
Going
down the list, we can see that my PL18 has a Free Air Resonance
of 48.4Hz whereas the published specs is at 38Hz. Qes is higher
at 0.50 compared to 0.40. Likewise, Qts is higher too at 0.42
compared to 0.34. Lastly, my Vas is smaller, coming in at
20.15 Liters whereas Vifa specs lists 25 Liters.
This
does not imply that Vifa's specs are inaccurate. After all,
my PL18 is not brand new. It has seen many years of use and
it's likely that the compliance has changed slightly over
time. In any event, the differences are not that dramatic
to throw the alignment completely off.
|
Revc
= 5.8 Ohms
Zmax = 34.2 Ohms
Fo = 48.4 Hz
Qms = 2.46
Qes = 0.50
Qts = 0.42
Vas = 20.15 Liters
Cms = 801.99 uM/N
Mms = 13.46 Grams
Sd = 0.0133 sq. Mtr
BL = 6.87 T.M
nO = 0.44 %
SPLo = 88.45 dB |
(Figure
3) T/S of PL18WO09
by LMS
With
these fresh data, we can now confidently proceed with some
Box Modeling for the bass response.
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