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Below are some multi-band graphic equalizers that can be used for optimizing room audio and making adjustments to audio systems so they will be fine tuned for your specific unique hearing and preferences.

These equalizers are suggested, but not necessarily recommended, since they’ve not been fully tested by us. They all seem to have fairly good ratings on Amazon.

  • ART EQ355 Dual Channel 31-Band Equalizer ($190) “The Model 355 Dual 31-Band 1/3 Octave Graphic Equalizer may be used in a variety of applications such as live sound, recording studios, instrument racks, DJ sound systems and fixed equipment installations. Designed to interface into any audio system, the Model 355 is a powerful tool for solving audio problems and creating interesting sound textures. The Model 355 possesses a long list of impressive features including: constant Q circuitry, 20mm center detent sliders (with a selectable boost/cut range of 6dB or 12dB), balanced XLR and 1/4? and unbalanced RCA input and output connections, adjustable high pass and low pass filters, variable input level controls, signal clip level indicators, ground lift switch, internal power supply and selectable line voltage switch. The rugged, all-steel constructed chassis occupies 2U rack spaces and is intended for installation into standard 19? equipment racks. The 355 Dual Channel 31 Band EQ has the features and performance you need for any of your audio applications requiring precise equalization.”
    • 94% 4-5 star reviews, 0% 1-2 star reviews.
  • Behring MiniFBQ FBQ800 ($70 to $105) “Revolutionary FBQ Feedback Detection system instantly reveals critical frequencies and can also be used as Audio Analyzer. Additional Low-cut filter removes unwanted frequencies, e. g. floor rumble. Accurate 6-segment LED input/output meters and Level control for precise level indication. High-quality illuminated faders, potentiometers and illuminated switches for long-term reliability”
    • 80% 4-5 star reviews, 7% 1-star reviews.
  • Behring Ultragraph Pro FBQ3102HD ($150) “Professional 31-band stereo graphic equalizer for live and studio applications. Revolutionary FBQ Feedback Detection system instantly reveals critical frequencies and can also be used as audio analyzer. Ultra-low noise 4580 operational amplifiers for highest signal integrity. Dedicated mono subwoofer output with adjustable crossover frequency. Additional sweepable high and low-cut filters for each channel remove unwanted frequencies, e.g. floor rumble, hiss etc.”
    • 82% 4-5 star reviews, 0% 1-star reviews.
  • EMB EB831EQ Graphic Equalizer ($200) “Gain / attenuation value can be chosen as + /-6dB or + /-l5dB. Input gain control is a block of step 41 rotary potentiometers. With EQ selection key. you can EQ bypass. 40Hz low-frequency cut filter on the live performances of non- Often used. Ill with the latest type of noise reduction circuit, the improvement of SNR 20 dB. 8uilt-in limiter, threshold adjustment range from 0 to +24 dBu.4 only LEO display output level: 10,0, +10 and +18 dBu. Electronic balanced / unbalanced input. Output Bitmap for the servo balanced / unbalanced. Generality speaking. the signal flow equalizer is the weakest link.”
    • 100% 5-star reviews out of 6 reviews
  • dbx 215s Dual Channel 15-Band Graphic Equalizer ($160) “When the pros need an EQ, they turn to dbx. The dbx 215s includes two 15-band channels of 2/3-octave equalization, ±12 dB input gain, switchable ±6 dB or ±12 dB boost/cut range, 20mm nonconductive sliders, an intuitive user interface, and output level metering. From its extended 10Hz to 50kHz frequency response and 112 dB dynamic range to the quality componentry and meticulous attention to detail, the 215s offers exceptional sound and rugged reliability that guarantees you will always sound your best.”
    • 90% 4-5 star reviews and 3% 1-star reviews.
  • dbx 231s Dual Channel 31-Band Graphic Equalizer ($200) “When the pros need an EQ, they turn to dbx. The dbx 231s includes two 31-band channels of 1/3-octave equalization, ±12 dB input gain, switchable ±6 dB or ±12 dB boost/cut range, 20mm nonconductive sliders, an intuitive user interface, and output level metering. From its extended 10Hz to 50kHz frequency response and 112 dB dynamic range to the quality componentry and meticulous attention to detail, the 231s offers exceptional sound and rugged reliability that guarantees you will always sound your best.”
    • 90% 4-5 star reviews and 3% 1-star reviews.
  • Peavey PV231EQ Dual Channel 31-band Equalizer ($180)
    • 80% 4-5 star reviews, 20% 1-star reviews.
  • Rockville REQ231 Dual 31 Band 1/3 Octave Graphic Equalizer With Sub-Output ($100) “The Rockville REQ231 is an extremely high quality professional rack mountable equalizer. This is a 2 channel equalizer with 31 bands per channel. The main focus on this was sound quality and making it rugged and tough. We wanted to build a professional product that will instantly make a good speaker sound better, and after months of testing we know we did it! This graphic EQ also has a low cut crossover filter switch, with status LED, that helps remove rumble from mics. Another great feature is the bypass switch, with LED indicator, which is very convenient when doing sound checks. We added a sub output with frequency controls which is something that we see a need for. Many brands for some odd reason do not give you a sub output and sub controls. We made sure to include this important function. If you want the best sounding EQ on the market at a great price, then we highly recommend you try out our REQ231. If you are unsatisfied with the quality we will give you a 90 day money back guarantee including return shipping!”
    • 96% 5-star reviews and 4% 4-star reviews with 25 total reviews.

 

Learn More

The description below is from the Behringer FBQ800 product description but mostly applies to all equalizers.

Why do I need an equalizer?

If we all lived in a perfect world, there would be no need for audio equalization. Sound systems would be perfect and would reproduce perfect signals in all their glorious perfection. Also, everyone in that perfect world would like the same amount of bass, midrange and high frequency, and there would be no such thing as feedback. But the world isn’t perfect, is it? Even the best sound system can benefit from the use of a good EQ – like the FBQ800.

How Does it Work?

Imagine the frequency range of the sound you hear as a highway, a very wide one with nine lanes. Each of these “lanes” represents a single octave of the sonic spectrum. The first four lanes, labeled 63 – 500 (Hz) contain the really low frequency sound content, mainly bass, bass vocals, and the kick and tom drums. The three lanes labeled 1 k, 2 k and 4 k (Hz), make up the fundamental zone of most musical instruments and the male and female vocals. 8 k and 16 k cover the frequency range of cymbals, snare drums and higher pitched percussion instruments. The FBQ800 allows you to control the flow of audio traffic in each of these nine lanes. When properly applied, EQ makes it possible to hear all of these frequency ranges equally, thus the term equalization.

Feedback Elimination

When a specific frequency, or range of frequencies, reaches too high a level, feedback occurs – that all-too-familiar squeal or howl you get when the mic is too close to the speaker. Basically, feedback happens when there is so much of a particular frequency that it is picked up by the mic and run through the system again. That’s why feedback typically gets louder and louder the longer it’s allowed to occur. Needless to say, this kind of feedback is very undesirable.

This is where the FBQ800’s Feedback Detection System really works its magic. In this ingenious circuitry, LEDs on the individual faders light up when that frequency band is approaching the danger zone. All you need do is lower the illuminated slider until the LED blinks out – voilà, feedback problem solved! What once required a highly trained ear is now an activity that even a child can master.

Sonic Toolkit…

That really is the best way to describe the FBQ800. With its nine frequency bands, you easily fine-tune your sound and instantly eliminate feedback. And each fader can be used to boost or cut the frequency range it controls by as much as 12 dB (and that’s a lot!).

Special attention is paid to the low frequency zone. In addition to low frequency faders, the FBQ800 features a Low Cut fi lter for removing unwanted low frequencies such as fl oor rumble, room resonance, electrical hum, etc. This is especially handy if your system is being used for speech rather than music.

To Boost or to Cut, That is the Question

Raising and lowering specific frequency bands can improve the frequency response of any room’s acoustics. For instance, if the room you’re in is “bass-heavy,” lowering the 63 and 125 Hz faders can help eliminate an overall “boomy” or “muddy” sound. Likewise, gently boosting the 8 and 16 k sliders can add sparkle to a somewhat “dark” mix. Are the vocals getting lost in the mix? Raising the level of the 1 k slider can help bring them out.

It’s important to note that raising a single fader level is not always the best solution; it’s often better to lower the bands surrounding the frequency you want to bring out, and then boost the overall volume level to achieve better headroom.

Built for Accuracy and Reliability

Speaking of headroom, FBQ800’s 6-digit LED Input/Output meters and level control are provided for precise level maintenance. Longterm reliability is ensured, thanks to high-quality illuminated faders and switches, and our ultra low-noise audio operational amplifi ers provide outstanding sonic performance. In addition, all Mini Series components may be stacked to create an ultracompact signal processing solution.