IEC PAS 62459:2006 pdf download Sound system equipment – Electroacoustical transducers – Dynamic measurement of suspension parts
Scope
This PAS applies to the suspension parts of electroacoustical transducers (for exampleloudspeakers). lt defines the parameters and measurement method to determine the stiffnessof suspension parts like spiders, surrounds, diaphragms or cones before being assembled inthe transducer, The measurement results are needed for engineering design purposes and forquality control. Furthermore, this method is intended to improve the correlation ofmeasurements between suspension-part manufacturers and loudspeaker manufacturers.
The measurement method provides the effective stiffness, Kafr, based on a linear model andthe variation of the stiffness, K(x), versus displacement x using a non-linear model. Bothparameters are measured dynamically by exciting the suspension part to mechanicalvibrations.
Terms and definitions
For the purposes of this document, the following terms and definitions apply
2.1
inner clamp dimension,D
diameter at the neck of the suspension part which is clamped by inner clamping parts (forexample,cone and cup)
2.2
outer clamp dimension.D.
inner diameter of the outer rim of the suspension part which is clamped by the outer clampingparts (for example, the upper and lower clamping rings)
2.3
displacement,xdisplacement measured in the perpendicular direction at the inner rim of the suspension part
2.4
driving force，F
force representing the total effect of the restoring force, friction and inertia of both thesuspension part and the inner clamping parts at the neck of the suspension
2.5
transfer function, H(f)function defined as the amplitude response
X(jo)H(f)=F(jo)
between the displacement spectrum X(jw) = FTx(t)) and the force spectrum F(jw) = FT(F(t))
2.6
resonance frequency，JR
frequency at which the restoring force, Fk = K(x)x, equals the inertia at the moving mass, m
3 Test equipment
The essential elements of the test equipment needed are as follows:
– a sine wave generator and frequency counter;
– means for exciting the suspension part (for example, pneumatically);
– outer clamping parts (for example, a pair of matched clamping rings);
– inner clamping parts (for example, a cone and a cup);
4 Test method Both the effective stiffness, K eff, and the displacement varying stiffness, K(x), of the suspension part are measured dynamically by performing the following steps.
a) The neck of the suspension part is clamped at the inner dimension, D I , by using inner clamping parts (for example, a cup and a cone).
b) The total mass of the suspension + inner clamping parts is measured by using a precision weigh. c) The outer rim of the suspension part is clamped at the outer dimension, D o, by using the top and bottom clamp rings. The cup is mounted on the upper side while the cone is on the lower side. It is recommended that the upper side of the suspension part which points to positive displacement be marked.
IEC PAS 62459:2006 pdf download
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