This doesn't work, I just get a headache. The base tones in the 150-165 range are disturbing. Alpha is not the brain wave of concentration, it's the brain wave of relaxation and wandering thoughts. I'm going to do some other experiments.
I link to a number of studies in the description that discuss the common "focused attention" range. Also, keep the volume low and be sure to DISABLE any filters on your device (DTS, surround enhancers, bass boost, etc) as they will interfere with proper audio playback.
Rursus