An electronic musical instrument for reproducing chords or pure tones in a fixed interval scale, called Modified Eastern Music Tru-Scale Octave Transformation by the inventors, without overtone collision. The instrument includes a memory for storing and reproducing the 24 octave frequency interval system. The inventive instrument reproduces single or multiple notes with an interval system which eliminates dissonance, and allows complete modulation in all key signatures and pure tone relationships without altering the keyboard. The invention also contemplates the use of the Modified Eastern Music Tru-Scale frequencies with all MIDI interface compatible instruments or devices, in conjunction with a suitable frequency generator, or through internal or external memory sources. The invention also can be applied to a fretted stringed musical instrument which provides a novel fretboard for generating overtone collision-free tones with complete modulation of the Modified Eastern Music Tru-Scale Octave Transformation. Generation of these frequencies might be acoustical or "direct" (to an amplifier) electronic production. The string length, determined by a ratio, is calculated to produce a closed number relationships for independent time-space frequencies.