A loudspeaker without an enclosure would naturally be vulnerable to damage, but that’s not the only reason an enclosure is necessary. Without an enclosure, even the best-designed loudspeaker will lose a significant amount of its ability to produce sound.
It’s More than Protection
For a speaker to generate the soundwaves we perceive, it has to create positive air pressure. In any speaker, the front side creates positive air pressure while the back creates negative air pressure. Interactions between these two pressure fields can cause sound to be canceled out.
That’s the main reason why, when loudspeakers are tested with no enclosure, they produce very little or no bass response. In fact, there is no way to truly gauge all the acoustic properties of a given loudspeaker until the right enclosure is provided. It is central to the design and product performance.
The Two Key Engineering Considerations for Any Speaker Enclosure
In addition to their protective qualities, enclosures must do two things well:
- Properly separate the front and back of the speaker to prevent sound cancellation
- Manage the resonant frequency of the speaker relative to the intended application.
Once the loudspeaker is placed inside the enclosure, the shape, size, type, and materials of the enclosure will change the speaker’s bass response.
Loudspeaker Materials, Shape, and Size Transform Results
The design of an enclosure can dramatically impact the end results of the speaker.
To give just one example, ported enclosure designs (also called vented or bass reflex ported enclosure designs) are able to assist a speaker in low frequency performance. A vent or port tube (which can be of any shape) is tuned by changing the surface area and volume to interact with the volume of air inside the enclosure and the speaker.
The trapped air within the vent acts as an air piston, or secondary speaker, utilizing the Helmholtz resonance effect. This is the same effect you notice when blowing across the opening of a glass soda bottle. The volume of available air in the soda bottle impacts the resonant frequency (the tone you hear when blowing across the opening), which changes to lower tones as you drink the soda.
Speaker Enclosures Are Limited Only by Your Imagination
Everyone has seen a loudspeaker enclosure. You can probably picture one in your mind, seeing the overall shape as square or rectangular. However, just like the loudspeaker’s permanent magnets or other components, enclosures are evolving thanks to an increasing variety of materials and manufacturing processes.
Today, loudspeaker enclosures can be made to nearly any shape or size imaginable. A big part of this change is the introduction of FDM and SLA 3D printers. Now a unique enclosure design can be quickly prototyped, tested, and measured before committing to the expensive process of tooling up for a plastic injection molded enclosure for production.
One reason so many organizations are embracing 3D printed enclosures for prototyping is that an enclosure design can be optimized or changed rather quickly in a modeling environment such as SolidWorks or Inventor.
Additionally, different materials can be used with 3D printers according to the application. PLA, made from all-natural or fully recycled materials, and ABS plastics are the two most prevalent types of materials used. ABS is more durable than PLA, but can be more difficult to use. (MISCO typically uses a carbon fiber reinforced PLA for their prototypes, which offers the strength of ABS but the consistency of PLA).
3D printing greatly expands the options for enclosures, improving both what can be conceptualized to improve brand awareness, as well figuring out how an enclosure contributes to sound quality. Experienced sound engineers like the team at MISCO Speakers can design enclosure prototypes to your exact specifications, even if it would not be possible with conventional materials.
Contact MISCO to find out more about optimizing your custom audio project.
