how to mix sound from notebook and external sound card and get headphones output

[burence73]

Hi all,

I want to mix sounds from notebook and external sound card (guitar is connect to it) and get mixed sound on my headphones.
I want to hear mixed sound from youtube and my guitar while playing.

I am beginner in electronics and after reading a lot of threads and I'm a little bit confused what is best solution.

I need advice what device to build:
Active or passive mixer or headphone amplifier with crossfeed?

Thank you in advance.

[sofaspud]

At some point, the kind of headphones you're using is a factor. That said, I think you could use an active solution of an op amp mixer with volume control on each input. A common IC like a NE5532 may provide enough output for your 'phones.

[burence73]

Thanx sofaspud!

Could you please recommend some schematic of op amp mixer with NE5532?

[sofaspud]

This schematic is from the Learn about Electronics website. I took the liberty of changing their 3-input mixer into the 2-input circuit you need.
The purpose of the second op amp is to maintain the same phase as the input signal. If you use it, put a resistor of 50-100 ohms between its output and the headphone jack. If you don't use it, make R6 that 50-100 ohm resistor.
The above description is for a mono output. If you want stereo, you'll need to make 2 of these circuits, one each for left and right channels.
You'll need a small power supply also. ±12VDC would work fine and be easy to build.

[sofaspud]

I neglected to say there's a few ways to combine these signals to the headphones.
*Left, right, and guitar on both sides of headphones.
*Left side, right side, and guitar on one side.
*Left side, right side, and guitar on both sides.
Not sure which you want, but each require a slightly different circuit based on the schematic above.

[burence73]

Thank you for quick reply.

These two options are OK:

*Left, right, and guitar on both sides of headphones.
*Left side, right side, and guitar on both sides.

[wwenze]

What external sound card are you using that can't do this already?

[burence73]

I'm using Lexicon Alpha


but with "Monitor Mix" pot on middle postion I don't get clear sound from both channels (guitar is line in 1, headphones output from notebook is line in 2).

If I turn "Monitor Mix" pot completly to the right I only can hear well a guitar (with effect) and vice versa. If I turn pot to the left I can only hear a clear and nice sound from notebook.

In the middle position I can hear:

- guitar (clean sound of guitar)
- guitar sound with distorion or some other effect from guitar rig
- sound from notebook

and all these sounds are not clear

[sofaspud]

That's a good question; maybe there is a hardware or software solution. I don't think any card I've owned could do it, but then again I've never tried. Anyhow, here's the new schemo. Mono so nothing needs duplicated for another channel.

[burence73]

Originally Posted by sofaspud

At some point, the kind of headphones you're using is a factor.

I'm using entry-level headphones Sennheiser HD 415 (nominal impedance 32 Ohm). I hope that will not be a problem