Optimization Tools
"ALPEQO" Parametric EQ Optimizer

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Download ALPEQO Lite
Additional Information



Alango’s Parametric EQ Optimizer “ALPEQO” technology enables identification of parameters for a set of 2nd order, equalizing Infinite Impulse Response (IIR) filters that will provide a combined frequency response as close as possible to the targeted response. The following filters can be included into the set:

  • Master gain
  • Low shelf (Gain, Cutoff frequency, Q)
  • High shelf (Gain, Cutoff frequency, Q)
  • Bell (Gain, Cutoff frequency, Q)

The input data for the algorithm consist of the number and definition of the filters, the target frequency response and two frequency response curves specifying maximum deviation from the target.

The maximal number of filters in the set is, theoretically, not limited, but can affect the time and stability of the optimization process.

The number of filters of each type in the set is arbitrary. For example, it is possible to set all filters as Bell shaped filters.

ALPEQO returns optimal parameters for each filter and the success indicator.

The optimization time depends on the number of filters in the set and the complexity of the target response, but, in general, takes a few seconds on a modern Windows computer.


In mass production of audio products (e.g., headphones and speakers), excessive frequency magnitude variation can result from transducer/speaker tolerance or batch deviation. This can degrade outgoing production yield and reduce profitability of the manufacturer.

An OEM may procure tighter tolerance speaker and electronic components, but this practice adds cost even though outgoing yield might be improved.

Alango ALPEQO filter optimization tool enables individual parametric equalization of devices during the manufacturing using simple, second order digital filters to correct frequency response variations.

ALPEQO takes a measured magnitude response curve of a device under test, and within seconds, derives filter parameters for optimal correction based on the target magnitude response limits.

ALPEQO is a standalone tool, easily embedded into any MS Windows PC-based test and measurement system.


ALPEQO Lite allows you to test ALPEQO for yourself.

(Microsoft Windows is required to install and run ALPEQO Lite.)

User Guide (PDF):

Download ALPEQO Lite User Guide

Download ALPEQO Lite (for Microsoft Windows)

The following graphs depict a real-life example of a speaker characterized by a deviant magnitude response, which is then fitted into the target limits using filters calculated with ALPEQO. The target magnitude response is graphically depicted in dB between 20Hz and 15kHz.

Before frequency magnitude response adjustment:
After frequency magnitude response adjustment:
Additional Information

ALPEQO presentation (PowerPoint .PPSX)

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