“扬声器单元在线测试的一些思考”一文的补充
杨定军 (写于2014-7-24)
一个年青朋友告知我,当年我在声学楼聚会5周年的报告已在这个微信平台上再次发表.事隔四年,这篇文章受到关注,我很高兴,因为我当年提出这个问题,而且文中有”迷思”这两个字.足见我那时并没找到操作性较高的解决问题的办法.
关键是TS参数及单元在测试箱里的低频响应曲线的测量.我的观点是,电动式纸盆扬声器的低频响应曲线和测试箱的大小有紧密关联,在线测试用的测试箱的容积受场地所限,不可能足够大,于是其低频响应曲线的测试结果存在疑问.
最好是测量单元的TS参数,并作管控.但是TS参数的完整结果需要两次测量,不论是附加质量法或是偏置电压法,在生产线上耗时较多,而不是那么具备可操作性.
于是感到迷惑.
2013年,在ISEAT国际电声研讨会前夕,我读到一个有名公司的一个报告,说他们的测试系统可以在生产线上快速地(一秒的数量级)测定单元的特性.我的看法是,就TS参数而言,那个系统只能测出大部分TS参数,而不是全部.
所以.我没解开疑惑.
感谢ISEAT2013,研讨会正式开始,.我在这个会上见到了Geoff Hill先生(Hill Acoustics Limited).知道他有个报告,而且带来一个测试系统.
看来一个可能的解决方案仍然是采用测试箱来测量低频频率响应曲线.Geoff Hill先生的测试系统能不能解决我的疑惑?请这儿的有条件作研究的年青同行们作进一步研究.
关于Geoff Hill先生及他的文章的要点,可浏览下列网页.
http://www.iseat.org/showagenda.asp?id=607&BigClass=%C2%DB%CE%C4%D5%AA%D2%AA
Consistent and Reliable Loudspeaker Measurements using a Tetrahedral Enclosure |
Geoff Hill Hill Acoustics Limited ABSTRACT One of the biggest problems this industry faces is that we do not trust each other especially when it comes to Acoustic performance issues. Many consequences spring from this situation, ranging from minor quibbling over specifications through to outright rejection of Loudspeakers and Transducers that have been built and supplied often under tight deadlines and other constraints. Neither the supplier nor the customer wins from this situation. What is the cause of this situation and what can we do about it? I believe this situation has occurred because we are largely using outdated techniques not easily replicated upon the World Scale our industry now serves. However rather than look back to how tests have been conducted in the past I believe we should decide how to make measurements now and in the future, so we avoid the problems caused by the existing methods.I propose an updated test methodology, based around a Tetrahedral Structure rather than a conventional box, fitted with an Internal Microphone and a series of fully interchangeable baffles.
These should be built specifying: (1) Major dimensions (2) Overall sub baffle design (3) Microphone position and distance (4) Overall Geometry (5) Calibration Methodology
It is my belief that it is only through the application of a known and widely accepted methodology throughout the entire supply chain that will resolve these types of issues...
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这里是声学楼
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