2007 Winter Symposium: Technical Papers
Maintaining Quality from Design & Development through Production

Our Call for Papers is now closed. The following papers have been selected:

Sound Quality Improvements in Compression Driver Systems – Earl Geddes, Gedlee

Based on recent studies of the subjective effects of diffraction, internal diffraction type modes in a horn are expected to be highly detrimental to sound quality. With the use of modern polyurethane foams and improved waveguide contours these diffractions can be substantially reduced resulting in compression driver/waveguide systems with superior sound quality. The theory and implementation will be reviewed. This technology is Patent Pending.

Diamond cones for high quality loudspeaker drivers – Adrian Bankewitz, Thiel & Partner GmbH

Sonic quality and acoustical performance of midrange and treble loudspeaker drivers can be significantly improved by the use of CVD diamond membranes. Production of such membranes is described herein. Improvements include usable bandwidth, harmonic and nonlinear distortion, thermal compression and overall stability. Furthermore we demonstrate that by using the right parameters, finite analysis simulations correspond well with measurement results.

A New Method for Measuring Distortion using a Multitone Stimulus and Non-Coherence - Steve Temme, Listen, Inc

A new approach for measuring distortion based on dual-channel analysis of noncoherence between a stimulus and response is presented. This method is easy to implement, provides a continuous distortion curve against frequency, and can be used with a multitone stimulus, noise, or even music. Multitone is a desirable test signal for fast frequency response measurements and also for assessing system non-linearities. However, conventional singlechannel multitone measurements are challenging because the number of intermodulation tones grows exponentially with the number of stimulus tones and makes it extremely difficult to separate harmonics from intermodulation products. By using dual-channel measurement techniques, only well-known, standard signal processing techniques are used, resulting in simplicity, accuracy and repeatability.

Measurement and Visualization of Loudspeaker Cone Vibration – Wolfgang Klippel, Klippel GmbH

Optical measurement of loudspeaker cone vibration (scanning vibrometry) can also be accomplished by using Laser triangulation technique which is a cost effective alternative to Doppler interferometry. Since triangulation sensors provide primarily displacement advanced signal processing is required to measure the break-up modes up to 20 kHz at sufficient signal to noise ratio. In addition to stroboscopic animation of the radiation pattern a new decomposition technique is presented for the visualization of the measured data. Radial and circular modes can be separated and the total vibration can be split into radiating and non-radiating vibration components. This kind of post-processing reveals critical vibration modes, simplifies the interpretation and gives indications for further improvements.