Loudspeaker Grills

The subject of loudspeaker grills comes up right away at the beginning of industrial design (ID). The loudspeaker grill will have a profound effect on the appearance of the product. As a consequence the design of the grill will be a collaboration between ID, mechanical engineering and the acoustics engineer.

From an acoustics perspective the grill choices are ranked as follows:

1. Nothing -- usually not acceptable

2. Knit fabric -- usually stretched over a frame.

3. Loose woven fabric

4. Wire mesh

5. Perforated Metal

6. Plastic slots

7. Plastic holes

In addition, the grill might require a black backing material if the holes are quite visible. This will be discussed below as well.Taking each choice one at a time.

• Nothing -- some diaphragms are physically attractive, so there is a desire to show off a high tech look.  However, diaphragms have to be light so they are not strong, so if there is any chance that the diaphragm will be poked a grill must be chosen.

• Knit Fabric -- A polyester knit can be an excellent choice where sound quality is audiophile level and people will handle the speakers with care. If you can easily breath through the material then sound will go through also, but this is just a very rough indicator. All grill materials need to be tested.

• Loose Woven Fabric -- for appearance purpose a woven fabric might be chosen and it is more resistant to poking. As a first test, try breathing through it. If it is hard to breath through, it might still work, but needs to be tested.

• Wire Mesh -- this can be a really excellent choice with a lot of strength and works almost as well as fabric. The only issue is terminating the edges, a mechanical nuisance.

• Perforated Metal -- This is a very good compromise between cost, performance and strength. The designer should be targeting about 50% open area. Perforated metal is available as stock materials, but a design can also consider a chem etch grill if they would like to make a unique pattern.  If a pattern is chosen it should have a little more open area in the center and can have a little less open area at the edges. A chem etch grill can have very nice termination at the edges and just be glued in place.

• Plastic Slots -- With plastic slots are recommended over holes because slots can be stronger than holes and have a larger open area. The trouble with plastic is that it will be thicker than metal to keep the same strength. This creates a mass of air that makes the holes act as inductors creating additional acoustic impedance.

• Plastic Holes -- The trouble with plastic holes is  that when plastic is injected into the mold it has to flow around the obstacles and then the plastic knits together making microscopic knit lines. As a consequence the mechanical designer has to make the plastic thicker to maintain the strength of the plastic.  This is also an issue with slots, but less-so.