READ THIS FIRST — MY CALIBRATION INFORMATION The Importance of Calibration in CTXMatrix Crosstalk cancellation is one of the most precise forms of audio processing. Unlike conventional stereo, where the brain compensates for many imperfections, CTXMatrix depends directly on your hearing, your speaker geometry, and your calibration accuracy. This is why calibration is not optional — it is the foundation of the entire experience. ​ Your Hearing Determines the Accuracy CTXMatrix relies on the same cues your brain uses to localise sound: ITD (Interaural Time Difference) ILD (Interaural Level Difference) These cues are: frequency‑dependent inconsistent across individuals influenced by head shape, ear shape, and room reflections sensitive to very small changes in attenuation and delay Because of this, your calibration values will never be identical to someone else’s. They must be tuned by ear, using careful listening and repeatable test material. ​ How I Tune CTXMatrix I use a combination of: test tones speech mono vocal recordings stereo Speech is especially useful because both ITD and ILD cues are active in the most sensitive range (roughly 500–5000 Hz). This makes it easier to detect: tonal coloration phase pressure on one ear incorrect localisation blurred transients When the calibration is correct: the centre is sharp the attack is clean no phase “pulling” is felt in either ear the sound is tonally neutral the cancellation is stable When calibration is wrong: the attack becomes blurred the centre becomes slightly defocused the tonal balance shifts the sound loses incisiveness These are reliable indicators. ​ ​ Example Calibration Sets (Attenuation / Delay) Below are some of the calibration sets I have used over the past year. All attenuation values are negative, and all delays are in samples (smp) — not to be confused with the recording’s sample rate. ​ Set A 1.9 / 8 1.6 / 12 2.0 / 10 2.0 / 8 Set B 4.9 / 8 4.2 / 9 2.5 / 11 4.9 / 8 ​ Set C 8.2 / 13 4.9 / 11 5.3 / 12 7.3 / 12 ​ Set D (current, tuned with vocals — cleanest so far) 7.6 / 13 1.9 / 11 1.7 / 12 8.3 / 11 ​ These sets all “sound good” at first listen, but when compared directly to stereo, the wrong values reveal themselves through: coloration blurred attack slight phase pressure loss of sharpness This is why calibration must be done carefully and patiently. ​ A Track That Reveals Calibration Accuracy If you want to hear the beauty of correct cancellation, play: Patricia Barber – Black Magic Woman (drum section) With correct calibration: the drums become extremely clean the transients are razor‑sharp the spatial cues are stable the centre is perfectly locked If calibration is wrong, the same passage will sound: softer less defined slightly phasey tonally uneven This track is an excellent diagnostic tool. ​ Why Level Matching Matters — And Why Underpowered Amplifiers Can Mislead Listeners When CTXMatrix is inserted into the signal chain, the output level drops immediately. This is intentional: the attenuation prevents internal clipping during the cancellation process and ensures clean headroom inside the plugin. However, this creates a practical challenge during listening tests: To compare CTXMatrix with normal stereo, both must be played back at the same perceived loudness. If the amplifier does not have enough clean power to restore the lost level, turning up the volume to match stereo loudness can cause: compression harmonic distortion loss of transient clarity reduced centre focus a softer or less incisive sound These effects are not caused by CTXMatrix. They are caused by the amplifier being pushed beyond its clean operating range during level matching. In other words: If the sound is not incisive, the cancellation is wrong — or the amplifier is distorting. CTXMatrix is designed for systems capable of delivering clean power. As long as your amplifier can regain the attenuation without strain, the results should be sharp, stable, and tonally neutral. ​ Final Thoughts Calibration is a skill, and like any skill, it improves with practice. If you are new to CTXMatrix or want to refine your technique, I strongly recommend reading my page on Mastering the Occlusion Test, where I explain how to use speech, phase pressure, and ear‑based cues to achieve the most accurate results. If you are unsure about your settings or want to verify your calibration, feel free to reach out — I’m always happy to help users achieve the most accurate performance from CTXMatrix.