Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Trifield alternatives

Trifield is not just a simple channel upmixer, it’s a very specific way of doing it which has certain unique features and benefits. To quote from an article around the time of the 565, when these things were discussed a fair bit-

“the signals for the left, right and centre speakers are calculated in an MST matrix, which is a phase-
amplitude shuffler that redistributes the sounds on a constant energy-with-frequency basis. Meridian claims that the process offers significant improvements over the Blumlein stereo system, which converts phase differences between the microphone signals into amplitude differences in the speaker signals. Trifield's major advantages are that "the frontal signals are redistributed to have different stereo widths at low and high frequencies, ‘correcting' for the fact that we perceive two-channel stereo width differently according to frequency; the frontal image is constant energy in terms of the input left-right original; the frontal width of the stereo image can be adjusted."

There is a fuller article here going into some detail in the history and differences, which is more about the original Gerzon approach - Meridian goes beyond this using DSP to achieve some aspects not possible in the analogue domain.