how to mix stereo into center channel

[bob_v5]

How can i mix my left and right channel to get a center channel? On the link ive included it show how to do it with opamps, but i want to do it with as few parts as possible. I want to use M6 mixing as explained below.From what ive read mixing the signals with a pair of 12k resistors would work. Is it really that simple?


"The summing amp has a gain of -12dB for two reasons: both the stereo-to-mono conversion and the unbalanced-to-balanced conversion require a gain loss of 6dB. To explain further, the stereo-to-mono conversion uses a convention where the output is (L+R)-6dB. Thus, a sound in the centre of the stereo image is added together and appears at the same level as each of the original channels. As that sound moves to one speaker only, the output of the converter is 6dB less, representing the reduced output heard from a stereo setup. This convention is widespread in broadcasting and is known as M6 - it produces a good compromise on mono equipment while still maintaining the headroom available in the audio path."
http://www.mhennessy.f9.co.uk/preamp/analogue.htm