ALMA International Symposium & Expo 2019
Dates: June 9th - 10th, 2019
Location: Double Tree Hilton Universal, Orlando, FL (USA)
We will be exhibiting together with our US representative Warkwyn.
Ultra-fast EoL-Testing with Maximum Sensitivity for Loudspeaker Defects
Measurement time is a crucial factor for the total cost and feasibility of end-of-line quality control. This paper discusses new strategies minimizing the test time for transducers and audio systems while ensuring high sensitivity of defect detection, extracting comprehensive diagnostics information and using available resources in the best possible way. Modern production lines are fully automated and benefit highly from high speed testing. Optimal test stimuli and sophisticated processing in combination with multi-channel test design are the key factors for smart testing. Finally, typical concerns and pitfalls when testing at high speed are addressed and illustrated by measurement results.
Minimizing Costs in Audio Devices through Efficient End-of-Line Testing
Variances in the parts and uncertainties in the assembling process degrade the performance and the reliability of the manufactured devices. Defective units increase the manufacturing cost if detected during end-of-line testing or increase the after-sales cost if an undetected failure occurs in the field. This paper addresses the role of end-of-line testing in reducing both kinds of failures and maximizing the performance/cost ratio as seen by the end-user. The selection of sensitive and fast measurements, which can be performed under manufacturing condition, is the basis for the PASS/FAIL classification. The paper shows that optimal production limits used in EoL-testing minimize the overall cost by considering a clear product definition, information from the particular design, statistical data from manufacturing process and traceability of the field rejects. The general concept presented here is illustrated using practical examples from automotive and other applications.
SPLmax - Using Standards to Maximize the Loudspeaker Output
The new standard IEC 60268-21 defines acoustical measurements for assessing the sound pressure output of active and passive loudspeaker systems. It introduces a powerful characteristic SPLmax that corresponds to the maximum sound pressure level generated by a broadband stimulus (e.g. noise), on-axis at a specified distance (e.g. 1 m). The manufacturer rates this value for specified measurement conditions and a defined stimulus considering the requirements in the particular application and verifying that the device under test can handle this amplitude over 100 h. This presentation discusses and shows in practical experiments various test methods (e.g. as proposed by CEA 2034) applied to find the thermal and mechanical limits of SPLmax and addresses the practical use of the rated SPLmax for gain adjustment in active system testing.
Green Speaker Design Part 2: Optimal Use of System Resources
Increasing the efficiency and voltage sensitivity of the electro-acoustical conversion is the key to modern audio devices generating the required sound output with minimum size, weight, cost and energy. Traditional loudspeaker design sacrifices efficiency for sound quality. Green speaker design is a new concept that exploits digital signal processing in order to use hardware resources more effectively. A first seminar presented at the AISE 2018 showed the potential of transducers maximized for efficiency by using a short voice coil overhang and soft suspension and operated by nonlinear adaptive control to cancel the nonlinear distortion and to actively stabilize and protect the voice coil. This second seminar applies the new paradigm to the overall system design and shows the consequences for enclosure, panels, passive resonator, amplifier, cables and DSP.