CAPT X-Country Seminar 2 – 2022

From CAPT/ACAP Admin team: This X-Country presentation is being hosted on Zoom. CAPT/ACAP members will be emailed the connection details before the event. Follow the Members link to join our association.

Date: Saturday, Apr. 30, 11AM MDT (Alberta time zone)

Presenter for our second “X-Country” online workshop for 2022 is piano technician Ernest Unrau of Morden, Manitoba. Ernest will reveal “Insider Secrets of the C.Ha.S. Method of Equal Temperament”. C.Ha.S. (pronounced “CHAZ”, rhymes with “jazz”), is the acronym for the “Circular Harmonic System” concept of Equal Temperament developed by Alfredo Capurso, formerly of Messina, Italy and currently employed as a piano technician/tuner in London, England. Alfredo joined us at the 2017 CAPT convention in Toronto to share his aural implementation of the C.Ha.S. method firsthand, thanks to the introductions Ernest initiated while active as secretary for CAPT/ACAP.

Having collaborated extensively with Alfredo Capurso since 2010, Ernest’s contributions have included objectively demonstrating the principles of the C.Ha.S. method and implementing it on the Verituner ETD platform as the Zero-Balance C.Ha.S. method for Verituner. Perfecting this application involved challenges such as discovering and correcting a 12ths interval calculation “bug” in late 2017 which also led to him becoming a Verituner beta tester in early 2018 ultimately resulting in the Verituner update release in mid-2018. During this process some long-held myths of equal temperament tuning were quashed and tools were developed that offered the equivalent of an “MRI” for pianos. It became possible to not only evaluate the quality of a tuning, but also to improve the piano itself by analyzing and correcting soundboard impedance issues that caused tuning irregularities. Ernest also developed a refinement of Alfredo’s original equation, subsequently harmonizing the concept with the principle of Minimum Entropy proposed by Dr. Haye Hinrichsen** in addition to quantifying the double-octave principle proposed by Accu-Tuner developer and inventor, the late Dr. Albert Sanderson***.

In this workshop we will…
• demystify the mathematics of tuning calculations, including inharmonicity;
• pull back the curtain to reveal the key to the C.Ha.S. balance proportions
• show how C.Ha.S. is the principle that unifies the tuning concept;
• learn how C.Ha.S. through the zero-balance technique, quantifies and automates the double-octave principle proposed by Accu-Tuner developer and inventor, the late Dr. Albert Sanderson;
• shed light on and correct long-held tuning myths, such as the notion of only one equal temperament, exposing the shortcoming of the classic 12th-root-of-2 concept, the misstep of pure 12ths tuning, and thus revealing why C.Ha.S. is the truly “equal-tempered” approach;
• learn how to aurally define the optimal C.Ha.S. double-octave temperament stretch, adding further refinement to Rick Baldassin’s two-octave temperament CAPT masterclass (UBC Kelowna, 2014);
• Verituner style files will be made available for download or manual entry, enabling Verituner users to immediately begin using the method in their work;
• get an inside look at how to use the inharmonicity data to identify where/how to improve soundboard response;

Biography: Ernest Unrau was certified with the Piano Technicians Guild of Canada (PTGC) in 1984 in Regina following an apprenticeship with the late William (“Bill”) Weiss of Winnipeg, who was a founding member of PTGC (1979, “Piano Technicans Guild Canada”) and the newly formed CAPT/ACAP (1985). Ernest became a member of the CAPT/ACAP Administration Team in 2013. His varied eclectic employment and other pursuits have complemented his piano technology interests and innovations and include a dairy farming and beekeeping background with its accompanying mechanical maintenance experience; Advanced Radio Amateur certification (“Ham” radio) and accompanying electronic know-how including antenna construction and design; Grade 10 Royal Conservatory piano and Grade 9 Royal Conservatory voice examinations; Music Professor and Director, Nipawin Bible College, Nipawin, Sask.; MIDI sequencing experience; amateur computer programming with expertise in ARexx and several flavours of BASIC, “C” and AppleScript; community newspaper journalist, including newsroom darkroom technician and computer imaging expertise that spanned both the analogue and digital world of photography.


* C.Ha.S. …pronounced “CHaZ”, rhymes with “jazz”. C.Ha.S. = “Circular Harmonic System” of Equal Temperament method, concept developed by Alfredo Capurso.
** “Revising the Musical Equal Temperament”, by Dr. Haye Hinrichsen, Dept. of Theoretical Physics III, Faculty for Physics and Astronomy, Universität Würzburg, Fakultät für Physik und Astronomie Campus Süd, Am Hubland, 97074 Würzburg, Germany; Tel. +49- 931-31-84908. Download revision 3 at: <>
*** U.S. Patent # 5,285,711 assigned February 15, 1994; inventor Albert E. Sanderson, assignee Inventronics, Inc., Chelmsford, MA, USA.
“…Stated differently, the assumption that an inharmonicity exists with a constant slope is only valid over a range of notes, for example, only about the middle five octaves of a piano. Notes outside those tuned with direct reference to the narrow range may produce partials that do not coincide with partials produced by notes in the range. This becomes evident when a double octave is played. The double octave has become an important interval for determining tuning quality.
“…An analysis of different pianos also discloses that within a piano that the beat rates produced between a given order partial and a corresponding harmonic vary widely. …The smallest range, however, occurs with measurements between the first and fourth partials that produces a beat rate that varies from 0 to about 1.3 beats per second. Although this range based on fourth partials varies slightly from piano to piano, the range of beat frequencies consistently lies within limited narrow range. This constancy indicates that the best tuning would occur using double octave tuning.”
See U.S. patent document online <