the weighting filter 8121FT-1 (IEC-268-1) 1 8121FT-1 is the weighting filter made by IEC-268-1 requirement, it must linked with either Model-8121C, to enable it to generate a weighting noise filter that complies with IEC-268-1 requirements, for undergoing the life testing of the loudspeaker and defining the rated power of the loudspeaker 2 When using please take note that: The input signal adopts the Pink Noise, and not other signal of noise sources. 3 Furthermore, the noise generated from this weighting filter also complies with the filter noise required by the JIS C5532. SUNLIGHT AUDIO SWEEPER 7116C Loudspeaker Polarity Tester 139B NOISE GENERATOR 8121C GAUSS METER 138 IMPEDANCE METER 152A DIGITAL HIGH-SPEED Fo METER 7117 C.