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  • Registered: ‎09-10-2014
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Maximum Output Voltage for Thinkpad x220 combo mic/audio jack

2014-09-10, 21:25 PM

Hello I was wondering about the maximum output voltage of the thinkpad x220 that can come from the combo mic/audio jack used to put headphones in. I have looked at the lenovo x220 thinkpad detailed specifications and searched around the forums. I then looked at the lenovo thinkpad pdf manuals and found this:


Using headphones or earphones
If your computer has both a headphone connector and an audio-out connector, always use the headphone
connector for headphones (also called a headset) or earphones.
Excessive sound pressure from earphones and headphones can cause hearing loss. Adjustment of
xiv User Guide
the equalizer to maximum increases the earphones and headphones output voltage and therefore the
sound pressure level.
Excessive use of headphones or earphones for a long period of time at high volume can be dangerous if the
output of the headphone or earphone connectors do not comply with specifications of EN 50332-2. The
headphone output connector of your computer complies with EN 50332-2 Sub clause 7. This specification
limits the computer’s maximum wide band true RMS output voltage to 150 mV. To help protect against
hearing loss, ensure that the headphones or earphones you use also comply with EN 50332-2 (Clause 7
limits) for a wide band characteristic voltage of 75 mV. Using headphones that do not comply with EN
50332-2 can be dangerous due to excessive sound pressure levels.
If your Lenovo computer came with headphones or earphones in the package, as a set, the combination of
the headphones or earphones and the computer already complies with the specifications of EN 50332-1.
If different headphones or earphones are used, ensure that they comply with EN 50332-1 (Clause 6.5
Limitation Values). Using headphones that do not comply with EN 50332-1 can be dangerous due to
excessive sound pressure levels.


So I am guessing the maximum output voltage is 150mv?



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Re: Maximum Output Voltage for Thinkpad x220 combo mic/audio jack

2014-09-10, 22:08 PM

x220 uses Conexant CX20672 HD-Audio codec. Its headphone port delivers 31 mW per channel into 32 Ohms loads.

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