BTE Audio has extended its line of Equalization Algorithms with the PEQ4, a high performance digital equalization algorithm that simulates the sound and feel of the world-renowned parallel parametric equalizers. With its proprietary topology, the PEQ4 algorithm simultaneously achieves both absolute sonic accuracy and extremely high processing efficiency. Targeted at desktop and embedded professional audio applications, the PEQ4 algorithm will enable "quality-conscious third-parties to incorporate the highly revered High-End Outboard EQ sound into their products".

PEQ4 - Parallel Parametric Equalizer Algorithm
In earliest parametric equalizer units, all filter bands are connected in parallel rather than in series-cascade as in conventional parametric equalizers. The parallel architecture has a distinctive musicality due to different phase behavior and smoother interaction between adjacent bands. In order to achieve symmetrical curves for boost and attenuation, filter bands are placed in feedback paths during attenuation. While trivial to implement in the analog domain, implementation of these feedback paths in the digital domain is rather involved due to the resulting delay-free feedback loops which are considered as uncomputable in classical digital signal processing theory. The PEQ4 Algorithm accurately and efficiently simulates the latest version of "first generation" units in the digital domain with its meticulously designed topology which inherently has the ability to authentically emulate delay-free feedback loops.

Key Features:

• Extremely High Processing Efficiency.
• Supports sampling frequencies up to 384 kHz.
• Clickless parameter update.
• Proprietary topology which is optimized for low latency, low noise and high dynamic range.
• Supports both 32 bit (single precision) and 64 bit (double precision) floating-point processing.
• Built-in reference-quality upsampling algorithm which is automatically enabled at sampling frequencies below 88.2 kHz.
• Clearly and concisely implemented in pure C++: portable to any platform that is supported by a C++ compiler.

Specifications
The PEQ4 Parallel Parametric Equalizer Algorithm features five overlapping bands which have the following specifications:

• Low Frequency Shelving/Peaking: Selectable filter type: Shelving or Peaking. Center Frequency is continuously variable from 8Hz to 800Hz. Quality Factor(Q) is continuously variable from 0.38 to 4.72 in Peaking mode. The amount of boost or attenuation is continuously variable from -12 dB to 12 dB.
• Low Mid Frequency Peaking: Center Frequency is continuously variable from 8Hz to 800Hz. Quality Factor(Q) is continuously variable from 0.38 to 4.72. The amount of boost or attenuation is continuously variable from -12 dB to 12 dB.
• Mid Frequency Peaking: Center Frequency is continuously variable from 80Hz to 8kHz. Quality Factor(Q) is continuously variable from 0.38 to 4.72. The amount of boost or attenuation is continuously variable from -12 dB to 12 dB.
• High Mid Frequency Peaking: Center Frequency is continuously variable from 120Hz to 25.6kHz. Quality Factor(Q) is continuously variable from 0.38 to 4.72. The amount of boost or attenuation is continuously variable from -12 dB to 12 dB.
• High Frequency Shelving/Peaking: Selectable filter type: Shelving or Peaking. Center Frequency is continuously variable from 120Hz to 25.6kHz. Quality Factor(Q) is continuously variable from 0.38 to 4.72 in Peaking mode. The amount of boost or attenuation is continuously variable from -12 dB to 12 dB.

Applications:

• Software Plug-ins
• Digital Audio Workstations
• Digital Mixing Consoles
• Hardware Effect Processors

PEQ4 Demo
In order to demonstrate the sound and performance of the PEQ4 Algorithm, BTE Audio has integrated it into a VST Plug-in. Please note that PEQ4 Demo requires a WIBU Systems CodeMeter Stick and it is only available to well-established audio hardware and software manufacturers.