Both consumer- and audiophile-grade speakers often ship with speaker grilles that can be kept on or removed, but which is best for sound quality? Truthfully, it depends. Some speakers are designed to be used with their included grilles, and have been tuned to compensate for their impact on frequency response. Other speakers, like subwoofers, only produce low-frequency sound waves that aren’t affected by speaker grilles at all.
However, the most common speaker types — full-range drivers, bookshelf speakers, and loudspeakers — are tasked with producing mid- and high-frequency sounds that can be negatively affected by a speaker grille. After investing in a 5.1.2 home theater system with Dolby Atmos, I considered whether to use the magnetic speaker grilles that came with each speaker.
The speaker grille mesh isn’t the problem
And you don’t have to worry about a subwoofer’s speaker grille
For starters, the thin mesh that covers the woofers and tweeters on your speakers isn’t affecting their sound quality. The mesh itself can be described as acoustically transparent, meaning the material has no impact on frequency response. The sound waves produced by your speaker drivers pass through them without issue. The frame that attaches that mesh covering to your speaker cabinet is a different story.
The frame can cause diffraction, which is when sound waves bend or scatter around the frame’s edge. The sound passes cleanly through the mesh fabric without obstruction, but it can’t pass through the frame holding the mesh together and attaching it to the speaker cabinet. This sends certain parts of a sound wave in different directions, scattering throughout the room. In the prime listening position, a listener hears the soundwaves coming directly from the speakers mixed with the scattered waves, which arrive at different times.
But not every sound wave will be impacted by the frame of a mesh speaker grille. Speakers that produce low-frequency sound waves, like subwoofers, are not impacted by a speaker grille’s frame. This is because low-frequency sound waves have a long wavelength. Sounds with a 20Hz frequency, sitting at the low end of the human hearing range, have a wavelength of about 56 feet. For comparison, consider that a 20,000Hz sound at the high end of the human hearing range has a wavelength shorter than an inch.
The long wavelength of low-frequency sounds allow them to bend around the edge of a speaker grille’s frame without diffraction. Meanwhile, sounds produced by midrange woofers or high-frequency tweeters diffract when they reach the grille frame, impacting the speaker’s frequency response.
The grille’s frame impacts frequency response
It’s all about edge diffraction and frequency scattering
So, how does grille frame diffraction actually affect the listening experience? It starts with diffraction’s impact on stereo imaging. In order to correctly perceive a sound’s position in the soundstage, the sound wave needs to reach the prime listening position at exactly the right moment. The human brain can interpret auditory timing variances as small as 10 to 20 microseconds, even though we don’t realize our brains are doing it. These miniscule differences tell us where sounds are coming from, and are critical to accurate stereo imaging.
This is why speaker placement is extremely important — optimal positioning and audio receiver configuration go hand-in-hand in making sure sounds reach the listener at the right time. Tying these concepts back to grille frames and diffraction, when a sound wave diffracts as it hits the edge of a speaker grille frame, its timing is impacted. The sound waves coming straight from the drivers get mixed with the ones slowed down and scattered by frame-edge diffraction.
These mixed sound waves can interfere with each other, canceling some sounds out. In a broad sense, it’s like how active noise-cancelation works — opposite sound waves attenuate each other. This results in dips and peaks along a speaker’s frequency response curve, because diffraction is canceling certain frequencies out. Specifically, there can be variances of plus or minus 1–3 dB in the upper midrange and high frequency range, between 2kHz to 15kHz.
Are speaker grilles worth the trouble?
Use them when you’re not listening, take them off when you are
The big question is whether you’ll actually be able to hear a difference between how your speakers sound with the grilles on or off. Unfortunately, this also depends on a variety of factors, including your speaker model, grille frame material, and grille frame thickness. Check the manual for your speakers for any manufacturer guidance on whether the speakers were tuned and measured with the grilles on or off. When in doubt, trust your ears.
The other consideration is the intended purpose of a speaker grille: protection. If you have kids or pets, it may be worth keeping the grilles on your speakers despite their marginal frequency response impact. A crushed cone will have a bigger impact on sound quality than a mesh grille, and sometimes, the decision is as simple as that.
I went with the hybrid option — I take the grilles off for critical listening sessions, and keep them on for everything else. As my JBL loudspeakers have magnetic grilles, taking them off and putting them back on takes seconds. If there’s a scientific impact on frequency response, why not temporarily pull them off?