INFLUENCE OF THE PERFOMANCE PARAMETERS IN TRANSMISSION LINE LOUDSPEAKER SYSTEM PACS number: 43.38.Ja Basilio Pueo, José Escolano, and Miguel Romá Department of Physics, System Engineering and Signal Theory, University of Alicante E-03080 Alicante, Spain e-mail: basilio@disc.ua.es, jescolano@disc.ua.es, mroma@disc.ua.es ABSTRACT Various different Transmission Line (TL) prototypes were fabricated to characterise the influence of the main performance parameters of a TL. In this paper it has been demostrated that low frequency response and electric input impedance changes due to several parameters are presents line length, cross sectional areas and stuffing density are the main perfomance parameters. Not also these known parameters perfomance but also some other unexplored ones are tested on several TL prototypes. Finally, a set of non affecting parameters are presented. INTRODUCTION Acoustic Labyrinth loudspeaker enclosure has been studied since 1936 by Olney [1]. In a classic model, the sound wave from the back of the woofer is channelled down a long pathway filled with an absorbent material. The total response is achieved by adding front and back radiation. Theorically, this extends the low frequency response up to one-third octave below the fundamental resonance of the driver. Unlike classical enclosures, Transmission Lines cannot be analyzed by using Thiele-Small parameters [2]. Since a valid model is not developed, a first approach is to know the influence of some parameters and how they operate on the system response. Objective information is seldom provided and it is confined mostly to a few designs frequency response measurement. A deep study of electroacoustic device must consider two sides: the electric input impedance, in terms of electric coupling, and the pressure response. Length and shape of the pipe, stuffing density and cross sectional area are the main parameters to change the response. An optimum Transmission Line enclosure for a given loudspeaker is not the purpose of this paper. On the contrary, the influence of the known parameters are reconsidered in a more general view. This means to consider other tested parameters that has not been performed before. PROTOTYPE DESCRIPTION An acoustic Transmission Line is a low frequency radiation system comprising a loudspeaker in a damped pipe. Its length is the quarter wavelength of alignment frequency, and generally, this is the loudspeaker resonance frequency. As vented boxes [3], the total response is adding the two responses. Notwithstanding, the Transmission Line has an open-back so the acoustic load