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In my circuit, wt-32 gives 4 analog outputs(l+,l-,r+,r-). I want to connect them to a headphone jack. I thought of using 2 lm386 audio amplifiers as shown below:Schematic

Will this connection work? or Am I making some mistakes.

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The LM386 isn't quite suitable for what you need. Firstly it has a minimum gain of 20 so it's going to be pounding out loud and distorting badly. The second thing is that this type of amplifier benefits from a bypass capacitor from pin 7 to ground - it greatly enhances rejection of power supply noise - take a look at the top middle graph on page 4 to see the effects.

Thirdly, and quite importantly you need an output capacitor to stop dc voltages being shorted by the low impedance of your speaker - take a look at the application diagrams on page 5 onwards to see what I mean - it's mostly shown as a 250uF capacitor for your reference.

Fourthly, in most applications where the device is being used as a normal amplifier, it is operated with a single ended input - I'm not sure the data sheet adequately informs anyone that operating differentially (as you have it) is ideal.

You can get this device to work as a headphone amp but you'll probably need to reduce the signals going into it.

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  • \$\begingroup\$ Thank You for the suggestion. What should be done to replace this? \$\endgroup\$
    – Sanjay
    Jan 6 '14 at 13:57
  • \$\begingroup\$ You can get this device to work - you'll probably need to attenuate the input to stop it clipping and destroying your eardrums but there's a fair chance it'll work. A lot of people use slightly specialist op-amps as headphone amps but you haven't specified what supply voltages you are running at or what impedance the headphones are so it's difficult to advise anything else. \$\endgroup\$
    – Andy aka
    Jan 6 '14 at 14:12
  • \$\begingroup\$ Supply voltage is 5V and I want it to work for most of the headphones available. I came across tpa6112 but it is not available in nearby shops. So I needed some replacement. \$\endgroup\$
    – Sanjay
    Jan 6 '14 at 14:25
  • \$\begingroup\$ Reading this article convinces me the input can work differentially as expected: electrosmash.com/lm386-analysis - they link another article that shows a it similarly to how you have it drawn - but you'll still need to reduce the signal input. The extra article is whites.sdsmt.edu/classes/ee322/class_notes/322Lecture30.pdf - look at page 9 and note that you'll probably need to add something like 100R across the lines feeding C20 and C21. \$\endgroup\$
    – Andy aka
    Jan 6 '14 at 14:34

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