Stereo splitter needed

[Muadzin]

I need a splitter to split the stereo signal coming from my PC. Can anyone recommend me a good circuit or can I use just two regular mono buffered splitters for guitar?

Thanks in advance!

[Ciaran Haslett]

It's the difference between line level amplitude vs instrument level that presents the problem.  

Best to either design 2 opamp buffers using a supply greater than 9V (be it single or bipolar) OR use a standard 9V opamp buffer and maybe use a dual pot to pad the input (but now the impedance becomes variable AND the tolerance of the pots can play havoc with balancing).

I have used both when I was splitting keyboards and the difference was minimal.  But if I was to do it again I'd stick with a charge pump/virtual supply

[Muadzin]

Lets see if I get it straight, two buffered opamp splitter circuits, run at 18v?

[Ciaran Haslett]

Yeah I should have explained that a bit better.  Try this...



Make a copy for the Right channel also.  You could use a TL074 instead of 2 072's.  For Vref you could either

A...supply with 18 volts and make a reference voltage with dividers
B...Use  charge pump to supply +/-9v where 0v (ground) becomes vref.

I'd go for option B as I'd rather have a bunch of 9V supplies kicking about than "that one supply that'll only work with that splitter thingy"

As with all things...I recommend breadboarding first.  The input cap could probably go as low as 10nF

Hope that helps

[Muadzin]

Thanks! Let's see if I again get this straight, if I use option B does that mean that ground to the splitter circuit gets replaced with -9v?

[Ciaran Haslett]

Thats right yeah.  the IC V+ pin to +9V, its "ground" pin to -9V and ref to ground (0V).

This arrangement will give a full 18V swing (well, almost) for line level signals before saturation.