Equaliser Selection

Equaliser Selector

The Equaliser panel is used to select the type of equaliser whose responses REW is to model. Changing the equaliser type updates the filter panel, applying the settings appropriate to the selected equaliser. Filters already defined are retained where possible, but parameter values will be adjusted if necessary to comply with the ranges and resolutions of the chosen equaliser. The currently selected equaliser is shown in the panel title, with the sample rate at which it operates shown in brackets, and in the EQ Filters panel.

TMREQ
The TMREQ equaliser setting offers the full range of filters and filter settings supported by TMREQ (peaking = parametric, low pass, high pass, low shelf, high shelf and notch). Filters can be transferred over a serial connection to and from AV32R or AV192R using the Send filter settings to equaliser and Retrieve filter settings from equaliser actions. For the Peaking filters the bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The TMREQ setting allows 8 filters. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200001 Hz
Gain-15+60.1 dB
Q0.1500.1
BFD Pro DSP1124P/FBQ1000
The DSP1124P equaliser setting supports the DSP1124P's parametric filters, allowing 12 filters. Note that this equaliser is now sold under as the FBQ1000. Filters can be transferred over a Midi connection using the Send filter settings to equaliser action. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency2020000see below
Gain-48+161 dB
BW/6011201

The frequency control adjusts in the pseudo-1/60th octave steps DSP1124P supports (20 evenly spaced subdivisions of the ISO one-third octave intervals), with the one-third octave and fine adjustment values DSP1124P uses shown alongside the actual frequency in the EQ Filters Panel.

The "BW/60" control replicates the effect of the DSP1124P's bandwidth setting. This control sets the bandwidth of the filter between the half-gain points with:

Bandwidth (Hz) = centre frequency*(BW/60)*sqrt(2)

For example, at a bandwidth setting of 60/60 a filter centred on 1kHz with a gain of -6dB will have a bandwidth of 1,414Hz between the points where its response crosses -3dB. This bandwidth remains constant as the filter's gain is adjusted (Note that the Behringer DSP1100 software package does NOT correctly reproduce the way the bandwidth control actually operates, its bandwidths are too small by a factor of sqrt(2)).

Defining filter bandwidth in this way is not uncommon (the TMREQ filters use a similar definition). The relationship between Q and BW for the DSP1124P is

Q = 60/[(BW/60)*sqrt(2)]


so the bandwidth range of 1/60 to 120/60 gives a Q range from 42.4 to 0.35.
BFD Pro FBQ2496
The FBQ2496 equaliser setting supports the FBQ2496's parametric filters, allowing 20 filters. Filters can be transferred over a Midi connection using the Send filter settings to equaliser action but the transfer is not always reliable. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200001/60th octave
Gain-36+150.5 dB (1 dB below -15 dB)
Bandwidth1/6010octaves, see below

The frequency control adjusts in approximately 1/60th octave steps (more precisely, 1/200th of a decade).

The bandwidth control adjusts in 1/60 of an octave steps from 1/60 to 5/60 of an octave, then goes through 1/10, 1/9, 1/8, 1/7, 1/6, 1/5, 1/4, 1/3, 1/2, 3/4, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 10 octaves.

The relationship between Q and BW in octaves for the FBQ2496 is

Q = sqrt(2)/BW


so the bandwidth range of 1/60 to 10 octaves gives a Q range from 84.85 to 0.14.
DCX2496
The DCX2496 equaliser setting supports parametric filters (labelled "BP" for Band Pass) and low and high shelving filters (with 6 and 12 dB/octave slopes). It also allows two crossover filters to be defined, LP or HP (Butterworth 6, 12, 18, 24, 48 dB/oct, Bessel 12, 24 dB/oct, Linkwitz-Riley 12, 24, 48 dB/oct). It allows up to 9 EQ filters per channel, depending on the other processing the unit is doing. The parametric filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

where gain is from the absolute value of the dB figure so always >= 1. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency2020000106 steps per decade
Gain-15+150.1 dB
Q0.11020 steps per decade

The frequency control adjusts in steps of 1/106th of a decade. The Q control adjusts in steps of 1/20th of a decade, i.e. there are 20 Q values between 0.1 and 1 and another 20 between 1.0 and 10.
SMS-1
The SMS-1 equaliser setting supports parametric filters only, allowing 8 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

N.B. The SMS-1 filter shapes have not been verified against an actual unit.

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency151201 Hz
Gain-13+60.5 dB
Q0.320.00.1
QSC DSP-30
The DSP-30 equaliser setting supports parametric filters only, allowing 20 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

N.B. The DSP-30 filter shapes have not been verified against an actual unit.

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200000.1 Hz
Gain-120+120.1 dB
Q0.3500.01
Crown USM-810
The USM-810 equaliser setting supports parametric filters only, allowing 10 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

where gain is from the absolute value of the dB figure so always >= 1. N.B. The USM-810 filter shapes have not been verified against an actual unit.

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200001 Hz
Gain-24+240.1 dB
Q0.1350.01
miniDSP
The miniDSP equaliser setting supports the same filter types and resolutions as the Generic setting, but for 6 filters operating at 48 kHz. It is aimed at the miniDSP plug-in Advanced mode, which allows filters to be specified by their biquad coefficients. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the miniDSP software (note that the a1 and a2 coefficients are negated per the miniDSP format). An advantage of this is the very high filter frequency and Q resolution it allows, permitting exact targeting of modal resonances. The miniDSP plug-in has an Import REW File button on its Parametric EQ configuration screens to load the files.
miniDSP-96k
The miniDSP-96k equaliser setting supports the same filter types and resolutions as the Generic setting, but for 5 filters. It is aimed at miniDSP plug-ins that operate at 96 kHz. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the miniDSP software. The miniDSP plug-in has an Import REW File button on its Parametric EQ configuration screens to load the files.
miniDSP 2x4 HD
The miniDSP 2x4 HD equaliser setting supports the same filter types and resolutions as the Generic setting, but for 10 filters at 96 kHz. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the miniDSP software. The miniDSP plug-in has an Import REW File button on its Parametric EQ configuration screens to load the files.
nanoAVR
The miniDSP nanoAVR equaliser setting supports the same filter types and resolutions as the Generic setting, but for 10 filters at 96 kHz. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the miniDSP software. The miniDSP plug-in has an Import REW File button on its Parametric EQ configuration screens to load the files.
C-DSP 8x12
The miniDSP C-DSP 8x12 equaliser setting supports the same filter types and resolutions as the Generic setting, but for 10 filters at 192 kHz. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the miniDSP software. The miniDSP plug-in has an Import REW File button on its Parametric EQ configuration screens to load the files.
waveFLEX DSP A8
The DSP A8 equaliser supports the same filter types and resolutions as the Generic setting, but for 5 filters operating at 96 kHz. The Save Filter Coefficients to File action writes the filter coefficients to a file in a format suitable for use with the waveFLEX software.
ADA PEQ
The ADA equaliser setting supports parametric filters only, allowing 12 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

N.B. The ADA filter shapes have not been verified against an actual unit.

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200001 Hz
Gain-10+100.5 dB
Q0.1100.1
Xilica XP2040
The XP2040 equaliser setting supports parametric filters only, allowing 16 filters. The filter bandwidth is specified in octaves, but the corresponding bandwidth in Hz is shown in the filter controls panel. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20300001 Hz
Gain-30+150.25 dB
BW0.023.610.01 octaves
Emotiva UMC-200
The UMC-200 equaliser setting supports parametric filters only, allowing 11 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

where gain is from the absolute value of the dB figure so always >= 1. N.B. The UMC-200 filter shapes have not been verified against an actual unit.

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency2020000256 steps
Gain-15+30.25 dB
Q0.25240.125
Emotiva XMC-1
The XMC-1 equaliser setting supports parametric filters only, allowing 11 filters. The Save filter settings to file action writes the filter settings to a file in a format suitable for use with the Emotiva software. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200001 Hz
Gain-64+60.5 dB
Q0.6500.01
Dual Core
The Dual Core equaliser setting supports parametric filters only, allowing 16 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*(-3dB BW)

Q = centre frequency/(sqrt(gain)*(-3dB BW))

where gain is from the absolute value of the dB figure so always >= 1. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency5200001 Hz
Gain-36+120.1 dB
-3dB BW1100001
Rockford Fosgate 3Sixty.3
The 3Sixty.3 equaliser setting supports parametric filters only, allowing 20 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

where gain is from the absolute value of the dB figure so always >= 1. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200000.1 Hz
Gain-24+240.1 dB
Q0.160.01
rePhase
The rePhase equaliser setting supports parametric filters only. It allows up to 17 filters per channel. The Save filter settings to file action writes the filter settings to a file in a format suitable for use with the rePhase software. The parametric filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

where gain is from the absolute value of the dB figure so always >= 1. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency10240000.01 Hz
Gain-96+960.1 dB
Q0.1100.01
Outlaw Audio Model 976
The Model 976 equaliser setting supports 10 filters. The first filter is a low shelf, the last is a high shelf. The shelf filters have 12 dB/octave slope. The other 8 filters are peaking filters where the bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The filter adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency10200001 Hz up to 200Hz, then 10 Hz up to 2 kHz, then 100 Hz
Gain-20+30.5dB
Q0.514Values are 0.5, 1.0, 1.4, 2.0, 2.4, 2.9, 3.6, 4.8, 7.2 and 14
StormAudio
The StormAudio equaliser setting supports 12 parametric filters and 2 crossover filters. The crossover filter types supported are Butterworth and Linkwitz-Riley up to 8th order (48 dB/octave). The Save filter settings to file action writes the filter settings to a file in a format suitable for use with the StormAudio software. The parametric filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency16200001 Hz
Gain-96+480.25 dB
Q0.25320.25
Dutch & Dutch 8c
The Dutch & Dutch 8c Equaliser supports 24 filters, peaking and shelf which can be written to or read from the speakers over the local network. It also shows the speakers bass, treble and sub filter settings. On Windows a firewall prompt will appear to allow REW to access the network when the 8c equaliser is first selected. The peaking filter bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency15200000.01 Hz below 100 Hz, 0.1 Hz below 1 kHz, 1 Hz above 1 kHz
Gain-120+30.1 dB
Q0.1500.001


REW scans the local network for speakers when the 8c equaliser setting is selected and, if the 8c is the default equaliser in the Equaliser preferences, on startup. There is also a Scan network for speakers action in the filter tasks pane that will trigger a rescan and show the results in a dialog. The Send filter settings to speaker or group action writes the filter settings to the selected speaker or group of speakers. The Load filters from speaker or group action retrieves the selected speaker or group filter settings. When initially retrieved the filters will be set to Manual control, to allow REW to use a filter for automatic target matching set the control to Automatic. Filters that were set to automatic when they were sent to the speaker will be set to automatic when they are retrieved.

If the 8c is the default equaliser in the Equaliser preferences the measurement dialog will offer an option to measure with playback from the speakers, which uses measurement sweep files which the speakers contain. When measuring with playback from the speakers REW will capture the filter settings from the speaker when it is measured, they can be viewed in the Info dialog. Those settings are retained in the measurement file and allow iterative adjustment of filter settings, taking into account the filters that were active when the measurement was made. If the settings have been captured the Reset filters for current measurement action in the filter tasks pane will offer a choice of resetting the filters to the settings they had when the measurement was made or to None.

When the 8c is selected as the equaliser the target settings will be set to: and the target match range will be set to 20 .. 100 Hz, with a maximum match end frequency of 1000 Hz.
JL Audio TwK-88
The TwK-88 equaliser setting supports peaking filters only, allowing 10 filters. The filter bandwidth in Hz between the half gain points is given by:

Bandwidth = sqrt(gain)*centre frequency/Q

Where gain is less than one for cuts so cuts have narrower bandwidths for the same Q value as a boost. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200000.1 Hz
Gain-12+60.1 dB
Q0.25100.01
TimeZero2.6D/4.8D
The Elder Audio TimeZero2.6D/4.8D equaliser setting offers peaking, low shelf, high shelf, notch and all pass filters. For the Peaking filters the bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The TimeZero2.6D/4.8D setting allows 5 filters. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency20200000.1 Hz
Gain-16+120.5 dB
Q0.3119.40.01
Generic
The Generic Equaliser supports a full range of filters and filter settings (peaking = parametric, 1st and 2nd order low pass & high pass including adjustable Q 2nd order variants, low shelf and high shelf including adjustable Q variants, notch and all-pass) based on the Robert Bristow-Johnson 'Cookbook' equations. It also offers a pair of crossover filters with Bessel, Butterworth or Linkwitz-Riley characteristics up to 8th order.

The Save Filter Coefficients to File action writes the filter coefficients corresponding to the selected sample rate to a file in the selected format. Currently supported formats are miniDSP and SigmaStudio, note that the a1 and a2 coefficients are negated in the miniDSP format.

LPQ and HPQ filter types can be used to implement higher order filters as cascades of biquad filters. Here are the Q values for some common crossover types and orders, for odd orders the last section is LP1/HP1 (a first order section), those are highlighted in blue:

2Butterworth0.707
3Butterworth1.000LP1/HP1
4Butterworth1.3070.541
5Butterworth1.6180.618LP1/HP1
6Butterworth1.9320.7070.518
7Butterworth2.2470.8020.555LP1/HP1
8Butterworth2.5630.9000.6010.510
2Linkwitz-Riley0.500
4Linkwitz-Riley0.7070.707
8Linkwitz-Riley1.3070.5411.3070.541

For the Peaking filters the bandwidth in Hz between the half gain points is given by:

Bandwidth = centre frequency/Q

The Generic setting allows 20 filters. The adjustment ranges are:

ParameterMinimumMaximumResolution
Frequency10220000.01 Hz below 100 Hz, 0.1 Hz below 1 kHz, 1 Hz above 1 kHz
Gain-120+300.1 dB
Q0.1500.01
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