iv got two turntables and a mixer rigged to a technics amp and there is a buzzing sound coming form both turntables through both speakers, is this because they are not earthed?

Sounds very much like the case. If you open the plug you'll probably find that it's just twin power cable with no earth. If your turntable has a separate earth lead and you have the same problem when you connect it to your mixing desk then the likelihood is that the mixing desk is also twin power cable with no earth. Most, if not all Hi-Fi amplifiers are earthed via the power socket so you shouldn't have this problem.

You need to try and connect the turntable chassis to a good earth source.

Sorry to get complicated on you here m8 but you could also have an "earth loop" ie too many earths.