PLParEQ is a 10-band Phase-Linear Parametric Equalizer. Each filter may assume any of many different filter characteristics and operate in either traditional phase-warping mode or Refined Audiometrics' phase-linear mode. It uses the same internal DSP core as all of Refined Audiometrics other high-end products. Audio streams are treated in either stereo or mono. Individual filters can be applied to either or both stereo channels, middle only or side only.

Phase Linear Operation is achieved by processing your sound in both the forward-time and reverse-time directions through classic filters - all in realtime. This completely removes the phase warping caused by IIR filtering, and applies their roll-off twice. So each filter type becomes two: one for classic IIR filtering, and the other for Phase-Linear operation.

This plug-in can operate in traditional 32-bit mode (24-bit audio) or as a 64-bit plug-in. All internal processing is carried out in double-precision 64-bit floating point, regardless of external host mode.

For audio streams at sample rates below 80 kHz the DSP engine internally upsamples with high-quality Sinc interpolation, applies its filtering, and then downsamples back to your system sample rate.

You can run all of the filters at native sample rates higher than 80 kHz, and forego the internal upsampling conversions. Upper limits on the sample rate (> 96 kHz) are dictated primarily by your computer's capacity, and your need for high quality at the very lowest frequencies (below 100 Hz).

The blocks are reassembled using very high-quality windowing and 8-fold temporal overlap. IMD resulting from phase-linear operation has been measured at below -150 dB from peak signal levels. Corner frequencies for filters can be adjusted from 10 Hz to 30 kHz at all sample rates.

Computation proceeds in double-precision floating point throughout the entire DSP core. At the last stage of conversion back to 24-bit audio, Refined Audiometrics' dither with a carefully crafted TPDF dither from its internal 64-bit samples to the 24-bit mantissas utilized throughout by VST hosts. The noise floor is typically measured at around -180 dB/Root(Hz). TPDF dither is the best kind to use to avoid noise that correlates with the audio signal. The noise levels may become somewhat higher than produced by other forms of dither, but it remains white.

Features:

• High Quality Parametric Equalization.
• Selectable Phase-Linear or Traditional Filtering.
• 10 Bands + 22 Classic Filter Types.
• Selectable Stereo, Left, Right, Left+Right-, Middle, Side, or Middle+Side- Filtering.
• Output Stereo, Left, Right, Middle, or Side.
• Frequencies from 10 Hz to 30 kHz.
• Gain from -20 dB to +20 dB.
• Q from 0.20 to 20.
• Choice of K-20, K-18, K-17, K-14, or K-12 RMS-Wide Metering.
• 7 Different Quality Levels.
• Group Enable/Disable for Instant A/B.
• Filter Table displays settings in effect for all filters.
• Live Graph permits mouse dragging of Frequency, Gain, and Q.
• Global Attenuation/Gain control for -20 dB to +20 dB.
• Low Rate Audio is Upsampled by 2x, Filtered, and then Downsampled again.
• Uses High Quality Data Windowing.
• Sinc Interpolation on Upsampling.
• Performs 8-fold Temporal Overlap Processing.
• Sample Rates from 44.1 kHz to 192 kHz.
• Internal 64-bit Processing Throughout.
• Samples are Dithered back to 32-bits on Output.
• Uses 2-bit TPDF Dither.
• All Parameters are Fully Automatable.
• Measured IMD and Noise Floor Below -150 dBFS.

Available Filter Types:

• 2-Pole Resonant LowPass, HighPass, BandPass, Band Reject, and AllPass.
• 1-Pole LowPass and HighPass.
• 4-Pole Resonant LowPass and HighPass.
• Classic Low and High Shelving.
• Type 1, 2, and 3 Oxford-style Peaking Filters.
• 3 dB/octave LowPass and HighPass.
• 1/F, A-Weighted, B-Weighted, and C-Weighted Filters.
• 6-Pole Notch Filter.