Note: ‘Equivalent scale’ is essentially a measure which can tell you how far up within its working pitch range a particular string is. Simplifying somewhat, the upper limit of the working range is when the string would break; the lower limit is when it will not produce a clear note of defined pitch. Within these limits, a string will produce a note, but the quality of the sound will be noticeably different if the ‘equivalent scales’ of two adjacent strings are too far apart.