Hello there in iphone world.
Well there a few things. First off, I don’t think 14x is a supported writing speed, sometimes when you pick an odd speed the software will revert to another speed. But usually its multiples of 4x, like 16x, 24x, 32x, that type of thing. Secondly, make sure your software is ‘finalizing’ the disc, if its not finalized then it won’t play in most standalone players. Another possiblity is the quality of the blank discs, but since your pc can play it then thats probably not the problem.
To see what speeds your burner supports for those particular CD’s, download the free program cdspeed2000, put in a blank disc and look under the ‘info’ tab, it should give a list of what speeds are supported by your burner.