I have a violin student who recently purchased a violin from a music shop. It's not a professional grade violin, but it is still a nice student model. My student's intonation seemed to get worse after he got it, and I finally noticed something I've never seen before...
Although each string is in perfect tune with each other, he has to place his fingers higher on the fingerboard for every higher string. For example, the G string finger placement is normal. The D finger placement is a little more spread out (i.e. the third finger on the D string isn't in tune unless it's higher than the third finger on the G string). And then the A and E string finger placements have to be even more spread out to be in tune. I hope that makes sense.
Anyway, I use tape to let him know where to place his fingers, and after going through each string, the tape isn't straight across the fingerboard as it usually is, but is tilted at quite a noticeable angle.
Can anyone tell me what the problem is? It must be a problem with the violin, but I'm not sure what it is. And it sounds like such a strange problem. I've been teaching for years, and have never seen this problem before. Obviously, he needs to get it fixed because it is affecting his playing and intonation.