D'Amore engine'ring SMD IM-SG, Руководство пользователя

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Finding the Thiele / Small (T/S) parameters of
a driver - continued
15. To measure the V
AS
we need to add some mass to the
cone and re-measure the f
S
with the mass on the cone.
We found that play dough or modeling clay works well
because it is easy to make various weights and it molds
easily onto the cone. It is important that the mass
doesn't rattle on the cone or vibrate independently from
the cone, so press it into the cone and distribute it
evenly. If it rattles it will be difficult to measure because
the impedance reading on the IM-SG won't be stable.
Select an appropriate mass from the chart below. Use
the postage scale to measure the mass in grams.
Speaker Diameter Approx. Mass to Add to
Cone
5.25 inches 30 grams
6.5 inches 50 grams
8 inches 80 grams
10 inches 150 grams
12 inches 200 grams
15 inches 300 grams
18 inches 500 grams
16. Find and record f
MA
: Once the mass is firmly on the
cone, use the IM-SG to find the new resonant
frequency with the mass added. This is where the
impedance peaks. We will call this frequency f
MA
. This
number should be at least 25% lower than f
S
. If not,
add more mass and repeat.
17. Record the weight of the mass used in step 16 as MA,
in grams.