This is a toughie. To a lot of people, speaker grilles serve two minor purposes: one, to appease those that don't like the look of those beautiful drivers, and two, to keep nosey guests from touching them. And while these can be pretty important factors, there's a whole lot more to it than that.
Imagine you're speaking to an audience. You want to speak clearly and project. Now imagine you're doing all that with a hand in front of your mouth. It has a serious effect on how you're heard. Sound radiates outward in a wave, and placing something in the field of that wave causes diffraction, interfering with the wave forms, changing the quality of your voice.
What we're saying is, sound bumps into things on its way to your ears. Bumping sound waves can smear sound or create ghost images and echoes, much like white light diffracting through a prism splits into colours. The fewer things a sound bumps into, the less diffraction will distort the sound.
Maybe it didn’t occur to you, but there's something right in front of your speaker drivers that could potentially cause lots of diffraction distortion: your speaker grilles! A lot of cheaper manufacturers don't put much thought into the design of grilles, which leads to disastrous results. This kind of obvious thing occurs to us, though, because we’re skilled audio engineering professionals. It's our job. If you don't consider the way the grille interacts with the sound being generated right next to it, you risk incurring diffraction distortion before your sound gets even a few centimetres from its source.
So we changed the way our grilles are designed. In our traditional loudspeakers, we limited the grille structure, and used stronger materials, so that our grilles are lighter and more durable. We designed a special mesh that floats in front of the drivers. The mesh appears solid, but actually allows over 75% pass-through. Sound waves have virtually no impediment, and so diffraction distortion is minimised. In our built-in, in-wall, and in-ceiling speaker models, our grilles have no edge, floating over the driver, and virtually disappearing into your decor. We enhanced our innovative, zero diffraction mesh design to insure moisture resistance in built-in environments.
After all is said and done, grilles are made detachable for a reason, and they do affect the sound of your speaker. Depending on the speakers you listen to, the changes grilles can present vary greatly, sometimes negatively and sometimes positively. If you've got Polk speakers, we've negated as much of the bad effects as possible, and you may find that you have a wider soundstage when they are attached. But at the end of the day, the decision is yours to make, and requires a good bit of critical comparative listening.
Ready to learn some more about speakers? Check out our guide to getting started in hi-fi.