Micro & Mini Loudspeaker Selection
Modern loudspeaker design and driver technology has come a long way over the past few years, with small portable micro and mini loudspeakers now able to deliver exceptional audio quality.
In this article, we look at some of the technologies and consider some of the questions that help in the decision-making process for the selection of an appropriate loudspeaker solution.
One of the first steps is to understand the limitations in terms of dimensions and volumes for the loudspeaker enclosure design since the amount of space and volume available is typically the most significant factor for the selection of the loudspeaker. If you are using the device enclosure as your loudspeaker enclosure you will need to make sure there is nothing that can vibrate internally with the higher pressure levels produced.
The next most important question, is what type of source material will the loudspeaker normally handle? Perhaps it will be used for warning or audio tones for example as part of the user interface, or maybe voice and/or music. These factors can help to define what resonant frequency can be most appropriate for the source material.
The power available for the application is also highly relevant to the selection process as this influences both the loudspeaker technology used as well as driver sensitivity. Finally, the operating environment and water resistance level required are also important to the selection process. With an understanding of these factors, we have the starting point for making decisions for what loudspeaker can be best suited to the application.
The main technologies available for micro/mini loudspeakers include: aluminium driver cone with polymer surround, acrylic-treated cloth or polyester (or mylar) cone and surround.
The physics of acoustics defines that larger enclosures are more suited to rendering of low frequencies. At audio frequencies, the volume of the enclosure can be viewed as acting as a ‘spring’ from a pneumatic standpoint. Smaller enclosures result in the equivalent ‘spring’ being stiffer in nature. If the volume is too small this raises the resonant frequency with a higher roll-off frequency thus preventing the loudspeaker from delivering the maximum possible frequency range. Fortunately, however, modern DSP-equipped amplifier driver chips include parametric equalization allowing challenging loudspeaker volumes to be tuned to reduce the resonant frequency and boost bottom-end bass. Nevertheless, when boosting bass, the physical displacement of the cone can rapidly reach its maximum (xmax) value. Luckily modern chips can estimate this as well as voice-coil temperature, with audio effects such as limiting or compression applied dynamically when the xmax starts to reach its maximum value.
Are you designing a loudspeaker solution for your product? Reach out to us today to discuss the available options.
