Bostjan Zupancic

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Bostjan Zupancic, also known as Russ Hayes, is a physicist and (primarily) 19-EDO guitarist/bassist. As of 2019, he has released 5 independent microtonal solo albums and participated in two microtonal bands.


Russ Hayes was born in 1980 in Detroit, Michigan, USA, and began playing music while attending primary school there. Because he feared he would be punished by the religious school he attended, he booked local shows under the pseudonym Bostjan Zupancic, starting around 1995.

He studied Physics, Mathematics, Chemistry, Music, and Theater at Oakland University in Rochester, Michigan, and continued studies in physics at Leningrad Electricotechnical University (LETI) in St. Petersburg.

Prior to playing microtonal music, Zupancic performed lead guitar in several (non xenharmonic) bands in the Detroit area, including the nümetal bands Unleashed (1995-1997) and Unhinged (2002-2004), and the alternative rock band Asshat (2002-2005). He performed guitar and lead vocals in the power metal band Khereb (2003-2006). Later, he performed bass in the Vermont band RaiZed on Radio, and performed lead guitar and vocals in the international band Hälberwolf (as Russ Hayes), and composed music for independent films, such as "13 Seconds," and independent video games, such as "Pete the Penguin."

Zupancic first publicly performed microtonal music in the funk/rock/electronic three-piece fusion band "Ox," based in the metropolitan Detroit area from 2003-2005.

In 2010, Zupancic published a comprehensive list of scales for 12-EDO and 19-EDO.

Approach to tuning

Zupancic has focused mostly on 19-EDO, but has also extensively studied just intonation 24-EDO, and the overtone series. He has also been known to discuss other systems, such as 22-EDO, 17-EDO, 31-EDO, 34-EDO, and Bohlen-Pierce tuning with limited depth.

Just Intonation

Zupancic has expressed support of the following 5-limit JI system for use with analysis of modern western musical idioms (so, this model excludes maqam, gamelan, and other non-western systems), using perfect (p), major (M), minor (m), augmented (A), and diminished (d) intervals. The system is limited to step sizes between adjacent intervals of 41.06, 111.73, 133.24, 182.40, 203.91, or 274.58 cents.

Table 1: 23 tone 5-limit JI system
Interval abbreviation Ratio cents
d2 128:125 41.06
m2 16:15 111.73
M2 9:8 203.91
d3 144:125 244.97
A2 75:64 274.58
m3 6:5 315.64
M3 5:4 386.31
d4 32:25 427.37
A3 675:512 478.49
p4 4:3 498.05
A4 45:32 590.22
d5 64:45 609.78
p5 3:2 701.96
d6 192:125 743.01
A5 25:16 772.63
m6 8:5 813.69
M6 5:3 884.36
d7 128:75 925.42
A6 225:128 976.54
m7 9:5 1017.60
M7 15:8 1088.27
A7 125:64 1158.94

Zupancic uses the intervals from Table 1 as a template to reference different intervals from other systems, but states that equal divisions are advantageous to JI in most instances where various instruments need to play together, due to technical limitations.


Zupancic believes that the 12-EDO is the most convenient system for representing western music ideas, because the number of notes is limited, but the notes available are all fair representations of something from Table 1.


Zupancic believes that 19-EDO is the most natural expansion of 12-EDO in the framework of western music theory. With fewer enharmonic equivalents, there are more tonalities that can be blended together in ways that were not possible with 12-EDO. And since major and minor tonalities are represented more closely to Table 1 than 12-EDO, it's not necessary to use exotic tonalities to justify the use of the system. This makes 19-EDO more of an expanded tuning system than a xenharmonic system, he argues.


Zupancic uses 24-EDO to represent Persian, Arabic, and Levant tonalities, as well as more dissonant xenharmonic tonalities.

Overtone Series

Zupancic uses the harmonic series to represent middle eastern tonalities as well, positing that establishing a drone as the root note of a movement of a piece, with lower-order harmonics to establish rhythmic chords and higher-order harmonics (with the major+h7 scale in the lower octave and the chromatic scale in the upper octave) to establish melody allows a rigid enough structure to meet a listener's natural expectations whilst allowing the performer enough freedom to compose expressive melodies.

Table 2: The 2-Octave Overtone scale
Interval abbreviation ratio cents
M2 9:8 203.91
M3 10:8 386.31
h4+ 11:8 551.32
p5 12:8 701.96
h6 13:8 840.53
h7 14:8 968.83
M7 15:8 1088.27
octave 16:8 1200
hm2 17:16 104.96
M2 18:16 203.91
hm3 19:16 297.51
M3 20:16 386.31
h4- 21:16 470.78
h4+ 22:16 551.32
hd5 23:16 628.27
p5 24:16 701.96
A5 25:16 772.63
h6 26:16 840.53
hd7 27:16 905.87
h7 28:16 968.83
hm7 29:16 1029.58
M7 30:16 1088.27
hA7 31:16 1145.04
octave 32:16 1200


As a session musician in Detroit in the late 1990's, Zupancic became interested in microtuning after working with country musicians, who would habitually temper the tuning of their instruments to best suit the key of the song being recorded. He then studied the sitar, and started working on developing a new tuning that could compromise between eastern and western tuning, with emphasis on sweetening the notes that country musicians tempered. At that point, he was oblivious to the vast microtonal knowledge that existed in academia. He identified the Ptolemeic intervals if 5-limit just intonation, and began focusing on two other tuning options: one that used the overtone series, with more notes available in higher octaves than lower octaves, and another tuning with 19 notes equally spaced between each octave. As a university student, Zupancic spoke with his professors about his "discovery" of these three "new" tuning systems, which were actually hundreds of years old and had been studied quite thoroughly well before Zupancic's birth.

Zupancic then turned his attention to gauging the reasons why these other tuning options had existed for so long without any mainstream exposure in western culture, and formed the thesis that 12-EDO took over merely out of convenience, and began to champion 19-EDO as a system that deserved to exist as an alternative tuning.

In 2003, Zupancic joined a then-unnamed band consisting of keyboards, drums, and guitar, which performed a mixture of rock, funk, and punk. All three musicians in the band made use of DIY instruments and unconventional objects. The band went on to record a demo, entitled "Detroit Justice" in 2005, which included two tracks in 19-EDO, as well as two medleys of cover songs in 12-EDO.

In 2006, Zupancic left the Detroit area and left the music scene, but in 2008, some demo recordings began circulating of Zupancic performing three songs in 19-EDO, and one song in 24-EDO, which went on to be included later in the album "Quiet Please" (2015), which featured both standard and microtonal songs heavily inspired by the Old Time Radio program "Quiet, Please" (written by Wyllis Cooper). The album was released only on home-made CD-R and received very little public attention, until it started to receive weekly airplay on college radio. The musical style of the release ranged from Funk-rock (Thirteen and Eight, 19-EDO) to Heavy Metal (Beezer's Cellar, 24-EDO) to Electronica (The Pathetic Fallacy, 12-EDO).

Vol I (2016) was performed entirely in 19-EDO tuning. The album, mostly modern metal in style, was independently released on CD and digital media to mixed reviews, but received limited syndicated airplay.

Happy Halloween (2016) was also performed entirely in 19-EDO. The release featured instrumental tracks with some sound effects and spoken word. It was released digitally, but promotional physical copies were also distributed at concerts between October and November of 2016. The track "Brain for Breakfast" was the first instance of 19-tone serialism used in a song.

Vol II (2017) was the direct follow-up to Vol I, and was met with mostly negative reviews, and received no airplay.

In September of 2017, Zupancic constructed an apparatus consisting of inductors and other electronic components to generate AC hum at several different frequencies, but only two "note" polyphony, with four total circuits. Zupancic then recorded an almost-12-minute long track with the instrument. Since the act of changing notes on the device was cumbersome, requiring components in one circuit to be modified by hand, while a sister circuit generated noise, the track was very slow-moving.

Nothing Special (2017) was released on CD to mixed reviews. The release featured one particular track that was ad libbed by Luna, a 4 year old Mealy Amazon parrot, on vocals. With positive reviews lauding the creativity of the music and the relatability of the lyrics, and negative reviews focusing on the long playtime of some of the tracks and lack of unified musical direction.

Life Cycle (2018) was released by Naegleria Fowleri, both digitally and on promotional CD, to very polarized reviews. Featuring an avante-garde death metal musical style, artificial intelligence drums, and a squawking parrot lead vocalist, the musical concept was coherent but also oddly specific. With Luna on lead vocals, and two other species of parrots (African Gray and Green Cheek Conure) featured as guest vocalists, the band has claimed to be the world's first multi-species microtonal band.

In February of 2019, Naegleria Fowleri was one of several microtonal artists featured on Microtonal Freedom (a Compilation Benefit Album For Lyn Ulbrecht).

Official Releases

Monsters (2001, non-micro)

Emotions (2002, mostly 12-EDO, some well-temperament)

Wyvern (with Khereb, 2005, non-micro)

Silent Harvest (with Khereb, 2006, non-micro)

Quiet Please (2015, mixture of 12-EDO, 19-EDO, and 24-EDO)

Hälberwolf (2015, non-micro)

Vol I (2016, 19-EDO)

Happy Halloween (2016, 19-EDO)

Vol II (2017, 19-EDO)

Literally Only Buzzing (2017, 19-EDO)

Nothing Special (2017, 19-EDO)

Life Cycle (with Naegleria Fowleri, 2018, 19-EDO)

Microtonal Freedom (a Compilation Benefit Album For Lyn Ulbricht) (track 13 "Messages" with Naegleria Fowleri, 2019, 19-EDO)


A Tribute to Kibbles and Bits (with Unleashed, 1996, non-micro)

Really Bad Recordings (as Russ Hayes, 1999, mostly 12-EDO, some well temperament)

Unhinged (with Unhinged, 2003, non-micro)

Demo (with Asshat, 2003, non-micro)

Detroit Justice (with Ox, 2005, 12-EDO and 19-EDO)

Micro Demo (as Bostjan Zupancic, 2008, 19-EDO) All songs were re-recorded for Quiet Please (2015)