Hi,

I have a mono source which I need to output to a mono line level output and also to stereo heaphones.

I have looked online for stereo headphone op-amp circuits and they all use 2 opamps (because normally the source would be stereo).

I only have 1 opamp left on my IC and am loathed to break into another, especially when my source is mono.

At the moment I am just splitting the output of the opamp and sending each branch through a 16 ohm resister and 220uF capacitor.

Is this OK? I'm guessing it may not be. I realise you can't just tie the left and right channel of the headphones together, as you would be essentially creating a much smaller load, as both headphones would be in parallel.

Should I adjust my output resister and capacitor values?

Here's the circuit, with the loads shown as resistors.

thanks
Paul

 

The plug for stereo headphones are wired with Left and Right channels plus Common.
For mono, use the L and R signals and ignore the common.
This will give you twice the impedance.

The head phones will be driven out of phase but your ears will not tell the difference.

 

Hmm, that's a cunning trick, but I think you would be able to hear that it's out of phase. When audio is 180° out of phase, it sounds as though its behind you, which would be a problem in my project.
Ideally I just need to split the signal to both headphones and keep the output impedance matched.

 

... but I think you would be able to hear that it's out of phase.

Not in headphones, I think. There's no issue of the out-of-phase waves hitting the same ear.

 

It works in headphones too, the out-of-phase sound is really uncomfortable.

 

I'm doing it right now with headphones for my crystal radio. I can't tell any difference.

 

It works in headphones too, the out-of-phase sound is really uncomfortable.

My hunch was wrong and kubeek's observation is shared by many others. Human hearing is pretty amazing.