When I overhaul a set of timps, there is a lot of work involved over a period of days or even weeks. My approach is to fix everything properly; I am after all a professional and that is what I am being paid to do. However not everyone is as conscientious, and in the end, you get what you pay for. So when I work on timpani, I am fixing problems associated with wear and tear, and the dogs dinner that the previous person made of the job. The posts on timpani pick out examples of problems I encounter, rather than me writing, and you reading the same thing every time I do a set of timpani (which is why I have coloured this bit blue).
When these Adams copper universal timpani were brought in to be overhauled, the customer was complaining, amongst other minor issues, about the drums buzzing. As soon as I heard the drums I knew what the problem was:
Adams universal timpani are built using the same method as Ludwig timps; the bearing edge is formed from a steel extrusion which is then fitted into the bowl. In this case the bowl is made of copper, but the same process is used with their fibreglass timpani. Fibreglass bowls are stuck to the metal ring with the same polyurethane resin (probably) used to make the bowl, however both Ludwig and consequently Adams have not used an adhesive but a mechanical fixing (pop rivets) to make the joint between a copper bowl and a steel hoop. The big problem is that copper bowls are spun into shape, and there is always a discrepancy between the size of the bowl and the steel bearing edge hoop. Spinning metal is a bit of a black art, so regardless of mechanical automation the size of the bowl will (and do) always vary. Rolling hoops is also one of those things that is difficult to do exactly. Therefore, this gap is almost bound to happen, so paper tape is used to fill the gap prior to riveting the bowl in position.
The principle of this method is a nice solution, but the application of the technique employed, by which I mean the use of packing tape, is not something that I would do. Being brutally honest, I cannot give conclusive, evidence based, acoustic arguments as to why is it a bad idea, but my gut feeling (and experience?) makes me think it is. There is a further problem of electrolytic corrosion – the copper of the bowl and the zinc plating on top of a steel hoop, are all joined with an aluminium rivet. Now this isn’t a major problem, but why would you even introduce it into the equation?
The really bad creak on the 26″ timpani turned out to be in one of the tuning nut boxes. This was difficult to find, and awkward to solve. It is one of those problems that I will have to look out for when I do this type of timp in the future.