## Headphone sensitivity and cross-talk. | |

Headphone sensitivity is specified as dBSPL @ 1 mW or as dBSPL @ 1 V.

Translating between the two:

dBSPL(V) = 10 * LOG * ( 1000 / R ) + dBSPL(mW) or

dBSPL(mW) = dBSPL(V) - 10 * LOG * ( 1000 / R ), where:

dBSPL(V) is the sensitivity in dBSPL @ 1 V

dBSPL(mW) is the sensitivity in dBSPL @ 1 mW

R is the nominal headphone impedance.

Example:

A 32 Ω headphone with a sensitivity of 100 dBSPL @ 1 mW has a sensitivity of:

10 * LOG ( 1000 / 32 ) + 100 = 115 dBSPL @ 1 V

This is a very simplified calculation for the cross-talk in 3-wire headphone connections.

Fig.1: Equivalent circuit for 3-wire headphone connection.

Ro: Amplifier output impedance. See amplifier data sheet.

Rg: Amplifier ground output impedance. This should be a very low value.

Rc: Connector resistance. This is normally only specified as a maximum value ( typically 50 mΩ ).

Rw1: Common cable resistance for the 2 channels.

Rw2: Cable resistance from output to each channel.

Rw3: Cable resistance from each transducer to common ground point A.

Rh: Nominal transducer impedance.

Assume one channel has signal and the other is muted and find the voltage in point A:

Rchannel = Ro + Rc + Rw2 + Rh + Rw3

Rground = 1 / ( 1 / ( Rg + Rc + Rw1 ) + 1 / Rchannel )

VA = Rground / ( Rground + Rchannel )

Find the voltage in the muted transducer:

V = VA * Rh / Rchannel

You can download a spread-sheet with the calculations here.

Ro | Rg | Rc | Rh | Rw1 | Rw2 | Rw3 | Cross-talk | Comment |

1 Ω | 10 mΩ | 50 mΩ | 32 Ω | 0.33 Ω (1) | 0.33 Ω (1) | 17 mΩ (2) | 40 dB | |

1 Ω | 10 mΩ | 50 mΩ | 32 Ω | 0 | 0.33 Ω (1) | 0.33 Ω (1) | 65 dB | A 4-wire connection with the 2 GND wires connected in the 3-way connector. |

1 Ω | 1 Ω | 50 mΩ | 32 Ω | 0.33 Ω (1) | 0.33 Ω (1) | 17 mΩ (2) | 25 dB | A "3-channel" amplifier. |

Note 1: 2 m 0.1 mm² wire.

Note 2: 10 cm 0.1 mm² wire.

Copyright Notice.

This web-page, including but not limited to all text, drawings and photos, is the intellectual property of Poul Petersen, and is Copyright ©.

Reproduction or re-publication by any means whatsoever is strictly prohibited under International Copyright laws.

The author grants the reader the right to use this information for personal use only.

Any commercial use is prohibited without express written authorization from Poul Petersen.

The information is provided on an "as-is" basis and is believed to be correct, however any use of the information is your own responsibility.

This web-site may contain links to web-sites outside Poul Petersen domain ( www.poulpetersen.dk ).

Poul Petersen has no control over and assumes no responsibility for the content of any web-site outside Poul Petersen own domain.

Poul Petersen does not use cookies to "enhance your experience" on this website.

Poul Petersen, C/Faya 14, 35120 Arguineguín, Las Palmas, Spain.

E-mail: pp@poulpetersen.dk

Copyright © Poul Petersen 2016..2019. Last update: 20191029. | Valid HTML! |