Ribbon Microphone

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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