Car audio

Many cars which have a graphic equalizer have been observed to have it set as a smiley face curve which emphasizes low and high frequencies.^[8] Graphic equalizer use leading to speaker damage is common — large amounts of bass boost and treble boost can distort music and damage loudspeaker drivers.^[9] Ideally, the equalizer can be set once to compensate for the combination of the response of the speakers and the car's acoustic characteristics.^[10] A smiley face curve can indicate that a car's sound system is lacking both high and low frequency response.^[11]

Bass guitar

Certain styles of electric bass playing, especially slapping, tend to augment the midrange frequencies. Various compensations have been developed to counteract excess midrange response in the instrument, including the use of amplifiers with a built-in smiley face curve and amplifiers that offer a handful of graphic equalizer filters so that the user can make the necessary adjustments when appropriate.

Gallien-Krueger makes an instrument amplifier that produces a classic smiley face curve in its default voicing. However, it includes tone controls that can be adjusted so that the amplifier is within 0.5 dB of a neutral, uncolored frequency response.^[12]

Some bass players decry the attenuation of midrange frequencies, holding that the midrange area centered on 500 Hz will make the bass instrumental line stand out more satisfyingly in the mix.^[13][14] University of Iowa professor and bass player Dan Berkowitz has observed that the smiley face curve as applied to bass played within a blues or R&B band can make it hard for bandmates to play off the bass line. Berkowitz recommends an upside down smile curve: a "frown" curve with its peak centered at 500–800 Hz.^[15]

Guitarists and bassists can choose to equalize their instrument with an effects pedal. Several products exist for this purpose such as a 10-band MXR-branded equalizer offered by Dunlop Manufacturing which includes instructions for a "Metal Distortion" setting that reduces 1,000 Hz, a midrange frequency, down to its maximum reduction point, with nearby frequencies reduced in the form of a mid scoop.^[16]

Live sound reinforcement

Some concert sound mixers employ the smiley face curve as a tool to help them gain initial control of a sound system. Even with recorded sound, the smiley face curve has its backers. Will Shapland of Floating Earth location recorders said in 2004 that his basic mixing technique for the recordings of the Isle of Wight Festival was to use "a bit of a 'smiley-face' EQ curve on the output" until he got a handle on a new band's mix, at which point he said "your balance comes together and you don't really need it."^[17]

Kip Bradford of Expert Village emphasizes that the live sound engineer must not employ smiley face curves when setting up a sound reinforcement system. Bradford advises that the graphic equalizer should instead be used to "tune the system to the room", taking account of the combined frequency response of the room and the sound system to ensure that all audible frequencies have equal presence.^[18]