There is often a lot of confusion between gongs and tam tams, but it’s very simple. In short, a tam tam is in fact a flat faced gong that doesn’t have a defined pitch. Allow me to elaborate.
If you take a circular piece of metal, besides cymbals, then you have a gong. These can be made of numerous metals - usually brass, bronze, copper, and other alloys – and can come in all shapes and sizes. The Gong can be completely flat, it can be hammered around the edges to create a curved lip, it can have hammering in the centre of the gong to create a nipple, and it can be tuned to a particular note or no note at all.
As explained up above, a tam tam is a gong, but a gong without any specific note. Tam tam’s have no nipple in the middle and may be flat the whole way across or may have a slight lip at the edge. Paiste Symphonic Gongs are the most common tam tams and they range from between 20” and 80”. Wind Gongs are also very popular and are often used in orchestras as well as being used for healing.