Owner manual

Instruction sheet

3B SCIENTIFIC® PHYSICS

U15100 Monochord

4/03 ALF

The Monochord demonstrates how the pitch of the

sound produced by vibrating strings is dependent on

their tension, length and thickness.

1. Description, technical data

The monochord consists of a wooden sound box over

which two steel strings and a nylon string are stretched.

The tension of two of the strings can be adjusted by

means of tuning pegs at one end while the third is

adjusted by running it over a pulley and attaching weights

or a dynamometer. The effective length of the strings

can be adjusted using two moveable bridges. The lengths

can be read from a scale on the side of the box.

Dimensions of sound box: 700 mm x 90 mm x 70 mm

Scale length: 600 mm

Scale divisions: cm and dm

2. Instructions for use

• Excite the strings by plucking them or bowing them.

• The desired length of the strings can be set by mov-

ing the bridges and can be read from the scale.

Name of Frequency Interval Ratio of string

note ratioroot : overtone lengthsroot : overtone

c : c 1:1 root 1:1

c : d 8:9 second 9:8

c : e 4:5 major third 5:4

c : f 3:4 fourth 4:3

c : g 2:3 fifth 3:2

c : a 3:5 major sixth 5:3

c : h 8:15 major seventh 15:8

c : c` 1:2 octave 2:1

c : g` 1:3 3:1

c : c`` 1:4 4:1

c : e`` 1:5 5:1

c : g`` 1:6 6:1

A major scale can be generated by adjusted the length of the strings to the following ratios:

1 Tuning peg

2 Pulley

3 Adjustable bridge

4 Sound box

5 Scale

PAGE 1
® 3B SCIENTIFIC® PHYSICS U15100 Monochord Instruction sheet 4/03 ALF 1 Tuning peg 2 Pulley 3 Adjustable bridge 4 Sound box 5 Scale 3 3 2 1 4 5 can be adjusted using two moveable bridges. The lengths can be read from a scale on the side of the box. The Monochord demonstrates how the pitch of the sound produced by vibrating strings is dependent on their tension, length and thickness. Dimensions of sound box: 700 mm x 90 mm x 70 mm Scale length: 600 mm Scale divisions: cm and dm 1.
PAGE 2
To determine the frequency ratios: • Tune two strings to the same note. • Move the bridge under one of the two strings to a position given by the ratios for the major scale. • Determine the frequency ratio from the ratio of string lengths. All the notes of the major scale are consonant apart from the second and the seventh. With the third string, chords such as the major triad can be played. The procedure for that is as follows: • Tune a second string in the ratio 4:5 (major third) to the first.