Smiley face curve

Last updated
An idealized and extreme smiley face curve shown using a 29-band graphic equalizer Smiley Face EQ.png
An idealized and extreme smiley face curve shown using a 29-band graphic equalizer

A smiley face curve or mid scoop [1] in audio signal processing is a target frequency response curve characterized by boosted low and high frequencies coupled with reduced midrange frequency power. This curve is often attained by users employing a graphic equalizer, which shows a graphic representation of a "smile" using its frequency band faders to form a curve that sweeps upwards at each end of the frequency spectrum. Smiley face curves have been popular with some car audio enthusiasts, disc jockeys, electric bass players, home stereo owners and sound reinforcement operators. [2] [3] Though the graphic equalizer was intended to tailor a system's response to compensate for venue and performance conditions, the smiley face curve is sometimes applied as a purely stylistic effect. [4] [5]

Contents

Equal-loudness contour

Lindos1.svg

The smiley face curve is roughly analogous to the frequency response of human hearing as charted in the equal-loudness contour, and has been compared to loudness compensation circuitry in that it increases the relative power of high and low frequencies without increasing the midrange power. In order for a sound system to be heard properly by humans, it should have an equal-loudness contour applied to it when it is performing at low sound pressure levels, then the curve should gradually flatten out as it gets louder. [6]

Usage

The origin of the smiley face curve has been attributed to the search for more bass and treble response from loudspeakers that did not extend as low or as high as desired, especially in the 1970s and 1980s. [7] It has also been seen as either a useful or a detrimental tool for shaping the sound of a bass guitar.

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

A stereo 15-band equalizer showing modest smiley face curves Graphic equalizer.jpg
A stereo 15-band equalizer showing modest smiley face curves

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]

Manufacturer presets

Some audio equipment manufacturers have accommodated the user by engineering a smiley face curve into a product. dbx, Inc. offers several smiley face curve presets in their digital graphic equalizer product line called DriveRack. [19] Jim Dunlop offers a direct box intended for bass players that includes a preset labeled "color" which engages a smiley face curve. [20] Neither of these products prevent the user from adjusting the equalizer based on the sound that is actually heard rather than relying on a predetermined visual image.

Alpine Electronics has offered for sale a product for car audio systems that works to counteract any smiley face curve that was applied to a car's factory OEM sound system, along with an analysis feature that adjusts for road and vehicle noise. [21] Empeg Car, a digital media player, includes a "Loudness Control" feature that is described as adding a "smiley face" curve automatically" at low sound levels but which is used to lesser and lesser degrees as the car sound system's volume is increased. This describes an equal-loudness contour circuit. [22]

See also

Related Research Articles

Effects unit Electronic device that alters audio

An effects unit or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing.

Subwoofer Loudspeaker for low-pitched audio frequencies

A subwoofer is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-certified systems. Subwoofers are never used alone, as they are intended to augment the low-frequency range of loudspeakers that cover the higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker enclosure (cabinet), often with a built-in amplifier.

A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, "woof". The most common design for a woofer is the electrodynamic driver, which typically uses a stiff paper cone, driven by a voice coil surrounded by a magnetic field.

Instrument amplifier

An instrument amplifier is an electronic device that converts the often barely audible or purely electronic signal of a musical instrument into a larger electronic signal to feed to a loudspeaker. An instrument amplifier is used with musical instruments such as an electric guitar, an electric bass, electric organ, synthesizers and drum machine to convert the signal from the pickup or other sound source into an electronic signal that has enough power, due to being routed through a power amplifier, capable of driving one or more loudspeaker that can be heard by the performers and audience.

Guitar amplifier Electronic amplifier for musical instruments

A guitar amplifier is an electronic device or system that strengthens the weak electrical signal from a pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce sound through one or more loudspeakers, which are typically housed in a wooden cabinet. A guitar amplifier may be a standalone wood or metal cabinet that contains only the power amplifier circuits, requiring the use of a separate speaker cabinet–or it may be a "combo" amplifier, which contains both the amplifier and one or more speakers in a wooden cabinet. There is a wide range of sizes and power ratings for guitar amplifiers, from small, lightweight "practice amplifiers" with a single 6" speaker and a 10 watt amp to heavy combo amps with four 10” or four 12" speakers and a powerful 100 watt amplifier, which are loud enough to use in a nightclub or bar performance.

Audio filter

An audio filter is a frequency dependent circuit, working in the audio frequency range, 0 Hz to 20 kHz. Audio filters can amplify (boost), pass or attenuate (cut) some frequency ranges. Many types of filters exist for different audio applications including hi-fi stereo systems, musical synthesizers, effects units, sound reinforcement systems, instrument amplifiers and virtual reality systems.

Sound reinforcement system Amplified sound system for public events

A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience. In many situations, a sound reinforcement system is also used to enhance or alter the sound of the sources on the stage, typically by using electronic effects, such as reverb, as opposed to simply amplifying the sources unaltered.

Horn loudspeaker

A horn loudspeaker is a loudspeaker or loudspeaker element which uses an acoustic horn to increase the overall efficiency of the driving element(s). A common form (right) consists of a compression driver which produces sound waves with a small metal diaphragm vibrated by an electromagnet, attached to a horn, a flaring duct to conduct the sound waves to the open air. Another type is a woofer driver mounted in a loudspeaker enclosure which is divided by internal partitions to form a zigzag flaring duct which functions as a horn; this type is called a folded horn speaker. The horn serves to improve the coupling efficiency between the speaker driver and the air. The horn can be thought of as an "acoustic transformer" that provides impedance matching between the relatively dense diaphragm material and the less-dense air. The result is greater acoustic output power from a given driver.

Equal-loudness contour Frequency characteristics of hearing and perceived volume

An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness contours. By definition, two sine waves of differing frequencies are said to have equal-loudness level measured in phons if they are perceived as equally loud by the average young person without significant hearing impairment.

Klipsch Audio Technologies is an American loudspeaker company based in Indianapolis, Indiana. Founded in Hope, Arkansas, in 1946 as 'Klipsch and Associates' by Paul W. Klipsch, the company produces loudspeaker drivers and enclosures, as well as complete loudspeakers for high end, high fidelity sound systems, public address applications, and personal computers.

Scholz Research & Development, Inc. Music technology company

Scholz Research & Development, Inc. was the name of the company founded by musician and engineer Tom Scholz to design and manufacture music technology products.

Tone control is a type of equalization used to make specific pitches or "frequencies" in an audio signal softer or louder. It allows a listener to adjust the tone of the sound produced by an audio system to their liking, for example to compensate for inadequate bass response of loudspeakers or earphones, tonal qualities of the room, or hearing impairment. A tone control circuit is an electronic circuit that consists of a network of filters which modify the signal before it is fed to speakers, headphones or recording devices by way of an amplifier. Tone controls are found on many sound systems: radios, portable music players, boomboxes, public address systems, and musical instrument amplifiers.

RIAA equalization Specification for the recording and playback of phonograph records

RIAA equalization is a specification for the recording and playback of phonograph records, established by the Recording Industry Association of America (RIAA). The purposes of the equalization are to permit greater recording times, to improve sound quality, and to reduce the groove damage that would otherwise arise during playback.

Loudspeaker enclosure Acoustical component

A loudspeaker enclosure or loudspeaker cabinet is an enclosure in which speaker drivers and associated electronic hardware, such as crossover circuits and, in some cases, power amplifiers, are mounted. Enclosures may range in design from simple, homemade DIY rectangular particleboard boxes to very complex, expensive computer-designed hi-fi cabinets that incorporate composite materials, internal baffles, horns, bass reflex ports and acoustic insulation. Loudspeaker enclosures range in size from small "bookshelf" speaker cabinets with 4-inch (10 cm) woofers and small tweeters designed for listening to music with a hi-fi system in a private home to huge, heavy subwoofer enclosures with multiple 18-inch (46 cm) or even 21-inch (53 cm) speakers in huge enclosures which are designed for use in stadium concert sound reinforcement systems for rock music concerts.

Bass amplifier Electronic amplifier for musical instruments

A bass amplifier or "bass amp" is a musical instrument electronic device that uses electrical power to make lower-pitched instruments such as the bass guitar or double bass loud enough to be heard by the performers and audience. Bass amps typically consist of a preamplifier, tone controls, a power amplifier and one or more loudspeakers ("drivers") in a cabinet.

Loudness compensation

Loudness compensation, or simply loudness, is a setting found on some hi-fi equipment that increases the level of the high and low frequencies. This is intended to be used while listening at low-volume levels, to compensate for the fact that as the loudness of audio decreases, the ear's lower sensitivity to extreme high and low frequencies may cause these signals to fall below the threshold of hearing. As a result audio material may become thin sounding at low volumes, losing bass and treble. The loudness compensation feature applies equalization and is intended to rectify this situation.

Stage monitor system Speakers for live music performances

A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a performance for the audience. The monitor system allows musicians to hear themselves and fellow band members clearly.

Equalization (audio) Changing the balance of frequency components in an audio signal

Equalization in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer.

Keyboard amplifier

A keyboard amplifier is a powered electronic amplifier and loudspeaker in a wooden speaker cabinet used for amplification of electronic keyboard instruments. Keyboard amplifiers are distinct from other types of amplification systems such as guitar amplifiers due to the particular challenges associated with making keyboards sound louder on stage; namely, to provide solid low-frequency sound reproduction for the deep basslines which keyboards can play and crisp high-frequency sound for the high-register notes. Another difference between keyboard amplifiers and guitar/bass amplifiers is that keyboard amps are usually designed with a relatively flat frequency response and low distortion. In contrast, many guitar and bass amp designers purposely make their amplifiers modify the frequency response, typically to "roll off" very high frequencies, and most rock and blues guitar amps, and since the 1980s and 1990s, even many bass amps are designed to add distortion or overdrive to the instrument tone.

Linn Isobarik Loudspeaker designed and manufactured by Linn Products

The Linn Isobarik, nicknamed "Bariks" or "Briks", is a loudspeaker designed and manufactured by Linn Products. The Isobarik is known for both its reproduction of low bass frequencies and being very demanding on amplifiers.

References

  1. Diverse Devices. Video and Audio Abbreviations and specialised terms
  2. Harmony Central Musician Community Forums. Recording Forum. "Smiley face" EQ curve... feelings? Posted by Elements6259 on March 18, 2004. Archived May 21, 2011, at the Wayback Machine "I see (non-recording) people do it on their cars and stereos all the time..."
  3. Media College. Audio Forum. Getting Rid of Feedback. Post by fstfwd74 on September 8, 2007. "My biased perception ...is much the same as seeing a soundman's eq set to "smiley face" setup... it's an indicator of inexperience or maybe last resort..."
  4. ActiveBass: The Online Bass Community. November 7, 2002. Kelly Marsh. How to EQ Your PA
  5. Ampage.com. Tube Amps / Music Electronics. Archive of vintage threads from the first ten years. Re: Settings for Peavey XR600F. Posted by Enzo on October 15, 2004. "Some folks even tell you to set the smiley face before you even turn it on."
  6. Slashdot.org. Why Music Really Is Getting Louder: Not always true – the Fletcher-Munson curve. Post by Andy R on June 9, 2007. "The 'smiley face' EQ curve is actually desirable if you are listening at lower than usual volume levels."
  7. Audioholics: Online A/V Magazine. Home Theater Forums. EQ Horse Hockey?. Post by Rob Babcock, Moderator, on June 6, 2004. "Pretty much everyone tried to boost the lows to get some decent bass and boost the treble to try to coax something resembling highs out of the 2" paper tweeter!"
  8. Car Audio Book. Car Audio Basics. What Is Sound?
  9. Electronic Musician. December 1, 2007. Brian Smithers. Square One: The Sculptor's Tool: How to use EQ to shape your music Archived September 30, 2008, at the Wayback Machine
  10. Car Audio Book. Car Audio Basics. Car Audio Signal Processors – Crossover, Equalizers and More
  11. Basic Car Audio Electronics. Graphic Equalizers
  12. Francis Deck. December 22, 2005. GK Backline 600 Review
  13. Ernie Ball. Forums. Music Man Basses. Need Some Effects For My New Bongo Post by adouglas on September 26, 2008. "Keep it pure, keep it clean, EQ it right (mids are your friend, avoid "smiley face" EQ curves) and let your fingers do the talking."
  14. Premier Guitar. September 2008. Mike Visceglia. Zen & the Art of Bass Tone "...Ivan Bodley, bassist for soul legend Sam Moore... said that if you invert the normal smiley-face EQ curve to a frown-face curve with 500Hz as the high point, you generally will have a tone that cuts through most live band performances."
  15. Premier Guitar. March 2008. Dan Berkowitz. Bass EQ Basics: A frown for the smiley face. "It sounds big and powerful, but lacks the note definition that helps your bandmates play off of what you’ve done on bass."
  16. Jim Dunlop. MXR M-108 Ten Band Graphic EQ (PDF image manual)
  17. Sound On Sound. December 2004. Daniel James. Live Sound. The Isle Of Wight Festival Sound: Behind The Scenes
  18. Expert Village Presents. Music series. Kip Bradford. How to Set Up PA Systems: 11. How to Set Up a Graphic Equalizer. (online video)
  19. dbx, Inc. Studio DriveRack Manual. pp. 38. Presets 9, 13 and 17.
  20. Sputnik Music. Forums. MXR M-80 Bass DI+. Post by edgebass5 on September 19, 2005. "Essentially all the color switch does is engage a preset "smiley face" EQ curve."
  21. engadget.com. Darren Murph. January 14, 2008. Alpine adds brains to in-car equalization with IMPRINT architecture
  22. Persiconi Construction. WRX. Downloads. Empeg Sound Archived 2008-10-01 at the Wayback Machine