How to add headphones in stereo BTL amps

Discussion in 'The Projects Forum' started by superduper, Jun 25, 2011.

  1. superduper

    Thread Starter Active Member

    Dec 5, 2010
    I have a couple questions which I hope someone can answer. I've attached an image for reference.

    (1) In the example, the headphone jack has 6-pins. How do you read the schematic for that jack? I find it confusing. I presume there is a switch in there someplace. I also presume that the contacts as shown is in the default relaxed position but it's not entirely clear to me what happens when a plug is inserted.

    (2) In BTL amps, the speaker legs are driven directly by the two outputs of the amp, correct? (the example shows the 2 amps of an AN7145 module bridged and the outputs are pins 2 and 17). So in a stereo application using BTL amps, each of the 2 speakers are connected directly to their own respective amp with no common connections. Headphones however seem to always share a common ground. So my question is how are headphones normally integrated into applications when BTL amps are used. As you can probably tell, I'm just trying to understand using the attached as a sample how to add headphones into BTL type amp setups.

    Thanks in advance for any assistance to help me understand this.