# Equalizer 12 Band

## Functionality

Equalizers are possibly the most used signal processors in a studio environment. With an equalizer you can alter the frequency spectrum of an instrument with different types of filters. Equalizers are used to increase or decrease the volume of different frequency ranges. You may add some presence to your track, cut unneccessary sub frequencies, make "room" for mixing a signal with others without producing indifferent mud, brighten dull recordings or "fix" an unsatisfying but not reproducable recording - Equalizers are the swiss army knife in audio production.
The 12 band equalizer is typically used for mastering purposes and to process the most outstanding signals with the need of a lot of corrections in a mix. Eight peak filters and fullsize bass/treble sections provide a lot of ways of manipulation.

## Filters

The Calf Equalizer 12 Band consists of three different types of filters:

- Hipass/Lowpass: These filters cut the signal above or below the center frequency. Highpass filters will cut all lower frequencies away while Lowpass filters do the opposite.
- Shelving filters: This type of filter got it's name from it's characteristics - it looks like the shelv of a cow. A highshelf filter increases or decreases all frequencies above the center frequency equally, the lowpass does vice versa.
- Peak filters: Peak or bell filters increase or decrease the frequencies around the center frequency. A high quality setting of this filter results in a needle while lower quality settings produce a wider bell.

Calf Equalizers are designed to give you the most control over your frequency response. The peak filters can add or subtract up to 36dB at a really high Q to your signal. This can result in a self resonating tone in comparison to a nearly complete removal of a single narrow band.

Please be aware that very high Q settings (above ~20) may create zipper noise when used in the bass band. Higher frequencies shouldn't be affected this way by high Q settings which is the reason why the settings aren't narrowed down to a range which works in every band without additional noise.

## Tips

Please note:
All values stated here are not the wisdom of mankind. They should only act as an indicator to have a look at or to give you some inspiration for your own experiments.
Only trust your ears!

A typical vocal recording is normally EQ'ed with a highpass to filter out sub frequencies or reduce a possible {nahbesprechungseffekt}. It is typically set between 70 and 100Hz. Some studio microphones need some more brilliance which is achieved through a highshelf between 4 and 8kHz. If you have to add more than 10 or 12dB something went wrong with your recording. If your artist sounds a bit dull or can't stand with some screaming metal guitars you may want to add a wider bell around 3-4kHz. To remove a muddy sound lower everything below 250-500Hz with a lowshelf a bit. Some "woody" frequencies which are adding up with acoustic guitars or pianos can be found around 500-1000Hz and can be decreased with a default peak up to -6 or -8 dB. But the hardest part is to remove unneccessary formants from your signal.

The needles produced by Calf Equalizers are the perfect solution to remove so called formants or resonances from your signal. Formants are essential for the "timbre" or the sound of an acoustic source and are oscillating at fixed frequencies. They give colour to an instrument or a voice but can easily screw the listener's ears especially in highly compressed and limited masters. They come from fixed sizes, lengths or volumes of a natural sound source. Resonances appear if oscillating air or material brings other material into resonance so both oscillations will add up to a noticeable sound.
Typical annoying formants in vocals can be found around 2500-3500Hz and between 400-800Hz. To find them it's neccessary to hear them, removing some needles only "to do something" isn't a good idea at all. You can search for formants or resonants with a narrow peak (above 50) and a high gain (18-24dB) walking through the frequency range. If you hit one of them your signal will answer with a loud whistling tone at the frequency. If you don't remove the exact frequency you may make your problem worse.
Normally formants and resonances will appear even on higher loudness levels when adding some mastering to your mix.
If you notice some annoying frequencies in your final mix they may appear due to interfering signals sharing the same frequency spectrum. Removing those noises with the mastering EQ could affect too many different signals so it could be better to clearly identify the interfering channels to decrease the level of the frequency in all or better only one of them.

To create some oldscool sounds like radio, telephone, grammophone or megaphone first of all cut away lower frequencies and the heights with the high/lowpasses. Narrower settings will resuld in "older" or thinner sounds. High- and lowpass should be around 800-2000Hz. Old telephones transmitted at about 1000Hz, grammophones are slightly "sharper" (higher) - test around a bit. To add the final character of your sound source add a peak filter at 6-12dB to accentuate the desired frequencies. Old radios or grammophones may need some additional sharpness at 2-3kHz while megaphones would stay below 1kHz.
A second peak filter may refine your sound, a megaphone for example could benefit from another peak above 2kHz. The higher the rolloff and peak the more oldscool your signal will sound. For more realistic sounddesign you should add a saturator right before the equalizer to slighly (or heavily) distort your signal.

If you add some brilliance to your signal for example but the attack of the sound (or the consonants from a vocal track) are rising to annoying levels you may want to add a deesser or a sidechain compressor in split mode afterwards to reduce the peaks in this frequency range.
With this trick it's possible to fix some problems with "untight" recordings. Imagine you have recorded a heavy-metal drummer who doesn't hit the bassdrum with a steady pressure so a lot of the kicks doesn't stick out the rest of the mix. Add such a lot of kick (somewhere between 5-9kHz) to the bassdrum until the softer beats are present. Then add a split-deesser after the equalizer to massively limit the high frequency range again. And have a beer and some small-talk with the guy..

## Controls

- Input L/R: The level after the input knob. The LED's flash on levels above 0dB
- Bypass: Don't process anything, just bypass the signal
- Input knob: Control the input level before the signal is processed
- Output L/R: The level after processing and after the output knob. The LED's flash on levels above 0dB
- Output knob: Control the output of the plugin - clipping could destroy your signal
- Individual Graphs: Show an individual graph for each active band
- Analyzer: Activate a subtle Analyzer in the background. The mode switch selects the source for the Analyzer view. "Difference" shows input and output in the same view, green marks addition and red subtraction.
- Low/Highpass Active: Power on this filter and select an operating mode. Inactive Filters don't use any CPU
- Low/Highpass Frequency: The center frequency of the filter
- Low/Highpass Rolloff: The level of reduction below or above the center frequency. The value determines how many dB's per ocatve the signal rolls off
- Low/Highshelf Frequency: The center frequency of the filter
- Low/Highshelf Level: The amount in dB's the center frequency is increased or decreased
- Low/Highshelf Active: Power on this filter and select an operating mode. Inactive Filters don't use any CPU
- Peak Frequency: The center frequency of the filter
- Peak Level: The amount in dB's the center frequency is increased or decreased
- Peak Q: The quality of the filter. Higher values create needles, lower ones bell filters
- Peak Active: Power on this filter and select an operating mode. Inactive Filters don't use any CPU
- Line Graph: The line graph shows a frequency response curve with some handles to interactively change the settings of active filters. Please refer to the corresponding section in the Controls manual.