The stereo correction techniques collectively known as FRANCINSTIEN have been continuously developed since the 1990s when the first, passive matrix was produced and sold by Perfect Pitch Music.
Go to this link for history and background on what FRANCINSTIEN does.
Alternatively, if you're short of time, here is the one minute guide to FRANCINSTIEN.
Gradual improvements to the FRANCINSTIEN have included: better matrix components (in the PLUS); the addition of buffer amplifiers (Acif); the recalculation of the crosstalk components (Bride of FRANCINSTIEN).
However, the most radical improvement came with FRANCINSTIEN T-Sym which was launched in 2016 as part of Pspatial Audio's Stereo Sauce software.
FRANCINSTIEN T-Sym is radical because it incorporates findings derived from a theoretical analysis of a stereophonic sound reproduction system as a sub-optimal wavefront reconstruction system which post-dates the original research which informed the original Stereo Shuffling techniques by thirty years1.
Bennett, Barker and Edeko's theoretical analysis of a two-loudspeaker stereo system as a flawed "audio hologram" permits us to build a complete theoretical model for the derivation of two-channel stereo correction signals so that we can correct for shortcomings in stereo with unparalleled accuracy.
But T-Sym was developed for Pspatial Audio's Stereo Sauce software as a purely digital, file-based process and was implemented with non-causal digital filters. No direct real-time implementation of FRANCINSTIEN T-Sym is therefore possible. (At least in a universe where time only runs in one direction!)
FRANCINSTIEN WARP (for WAvefront Recontruction Processor) is an innovative, real-time implementation of the original, non-causal FRANCINSTIEN T-Sym algorithm.
The FRANCINSTIEN WARP is a line-level device, designed to be used between a source and a preamplifier (or integrated amplifier). The analogue circuitry is of the highest possible quality - with cutting-edge op-amps and audiophile passive components used in unique analogue signal-processing circuitry. The WARP processor itself is partnered by an external, universal power-supply.
Size: WARP: 112 × 50 × 225 mm (W-H-L) : RESOLVE PSU: 112 × 50 × 225 mm (W-H-L)
WARP Supply: 12V DC input on screw locking connector
Consumption: Less than 4 Watts in all configurations and active.
Sensitivity: Nominal 250mV RMS (2V RMS for 0dBFS)
Input load: 50kohms
Frequency response: Programme dependent
Crosstalk: Programme dependent
Total output noise: 10μV RMS, A-weighted
Maximum input signal (prior to clipping): 3.9V RMS
Headroom (wrt nominal sensitivity): 24dB
1 Bennett, J.C. et al. A New Approach to the Assessment of Stereophonic Sound System Performance. J.Audio Eng. Soc., Vol.33, No.5, 1985 (May)
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