Hi all,

I've attached the output of an audio op amp to a pair of headphones (the input to it is an mp3 player) and I'm hearing a clicking noise in addition to the song. Does anyone know what would cause that?

Thanks,
DRN

 

Reduce the volume of the mp3 player and check

 

Thanks, but no luck

 

Headphones are a heavy load for an op amp. The clicks may be the waveform clipping. Op amps are happier with at least several hundred ohms load (the OPA134 will drive 600 ohms), and headphones are more like 32 ohms.

 

next is that are you sure your MP3 songs are clean with clipping signals.
Try hearing them from speaker and make sure it is clean, if they are then OPAMP supply may be too low or faulty

 

Headphones are a heavy load for an op amp. The clicks may be the waveform clipping. Op amps are happier with at least several hundred ohms load (the OPA134 will drive 600 ohms), and headphones are more like 32 ohms.

That doesn't make sense.

This:

Headphones are a heavy load for an op amp.

- Indicates high impedance.

Contradicts with this:

and headphones are more like 32 ohms.

- Indicates low impedance.

Headphones for MP3 players are generally high impedance.

Austin

 

The convention is that the heavier the load is, the more power it requires. 32 ohms is a heavier load than 600 ohms.

I could be mistaken, but headphone and ear bud impedances seem all over the map:

http://www.apple.com/ipod/in-ear-headphones/

http://www.zagg.com/audio/zbuds-iphone-earbuds.php

http://www.yuin.eu/yuin/

http://www.mobiletechreview.com/iPod/XtremeMac_FS1_earbuds.htm

 

You're right, Beenthere - they are all over the map. Seems like 32 Ohms is popular nowadays. Back in the 70's all headphones were 8 Ohms, except for the piezo ear plugs.

You really need to use an audio amplifier like a 386.

 

The convention is that the heavier the load is, the more power it requires. 32 ohms is a heavier load than 600 ohms.

I could be mistaken, but headphone and ear bud impedances seem all over the map:

http://www.apple.com/ipod/in-ear-headphones/

http://www.zagg.com/audio/zbuds-iphone-earbuds.php

http://www.yuin.eu/yuin/

http://www.mobiletechreview.com/iPod/XtremeMac_FS1_earbuds.htm

Ok, thanks for elucidating.

Austin