This document discusses the ribbon microphone. It describes the ribbon microphone's structure, which uses a lightweight aluminum ribbon placed in a magnetic field to function as both a conductor and a diaphragm. The ribbon microphone has a wide frequency response from 20-12,000 Hz due to its light ribbon. It has a figure-eight directivity pattern and is commonly used for drama recordings due to its ability to capture sound from both the front and back with dead sides.

1. Ribbon
Microphone
By Prof. Hitesh Dholakiya
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2. Outlines
❖ Basics of Ribbon Microphone
❖ Structure of Ribbon Microphone
❖ Elements of Ribbon Microphone
❖ Working of Ribbon Microphone
❖ Directivity of Ribbon Microphone
❖ Characteristics of Ribbon Microphone
❖ Features of Ribbon Microphone
❖ Applications of Ribbon Microphone
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3. Basics
❖ Moving coil Microphone – high frequency response is poor due to
mass of the diaphragm.
❖ Mechanical mass is equivalent to inductance – attenuates higher
frequency.
❖ To increase frequency response – light weight aluminum ribbon is
used in place of diaphragm and coil assembly.
❖ Ribbon acts as a conductor (placed in a magnetic field) as well as a
diaphragm.
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4. Structure of Ribbon Microphone
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5. Elements
❖ Magnet – horse shoe magnet with extended pole pieces –
provides strong magnetic field
❖ Ribbon – light aluminum foil – corrugated at right angles to its
length to provide greater surface area
❖ Main feature – lightness of ribbon – 0.2 mg – a few microns
thick and about 3 mm wide
❖ whole unit is enclosed in a circular or rectangular baffle
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6. Working
❖ Sound Pressure – Ribbon (an electric conductor) placed in magnetic
field – is made to move at right angles to magnetic field – change in
magnetic flux through ribbon – emf is induced across ribbon
❖ emf is proportional to the rate of change of flux – i.e. proportional
to sound waves striking the ribbon
❖ Driving mechanical force is proportional to the difference of the
pressures acting on two sides of ribbon – particle velocity of sound
waves – ‘Pressure Gradient’ or ‘ Velocity’ Microphone
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7. Directivity
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8. Characteristics
❖Frequency Response : mass is very small – low mechanical
inductance – results in good high frequency response up to 12000
Hz | stiffness of the suspension of ribbon is also small – results in
good low frequency response | overall frequency response is 20 to
12000 Hz
❖ Directivity : force of sound can be applied to the ribbon from the
front as well as from the rear side – bi-directional – Figure of Eight
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9. Features
❖ requires careful handling as ribbon is very light
❖ DC current through ribbon from a battery of meter can strain the ribbon –
resistance or continuity should not be measured with a meter
❖ should not be blown into – causes strain in ribbon – sensitive to breathing
too – kept at about 50 cm or more away from the source of sound
❖ slightest wind causes rumble noise in the output
❖ excellent transient response
❖ does not need external bias
❖ cost is high
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10. Applications
❑ Suitable for dramas – due to figure of eight pattern – side by side
❑ Two dead sides – dead area on stage
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