An excerpt from my Improve Your Bowing Technique online course is featured in the January 2012 edition of Strings magazine. If your bow strokes sound better on some strings than others, it could be that you need to adjust your bow’s contact point. Where the bow literally contacts the string along it’s length is pivotal to creating a pure tone. These contact points, or “sounding points” vary depending on which string you are playing on, what left hand position you are playing in, how fast you are bowing, and how much pressure you are using. Whew, and you thought just keeping the bow in the same spot right down the middle would be enough to sound like Joshua Bell or HIlary Hahn!
http://stringsmagazine.com/bowing-tips-3-easy-ways-to-improve-your-string-crossings/