Tag: hoop

Adams Universal Timpani (Job No: 1263)

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.

Slingerland timp (part 2) (Job No: 1247)

The first part of this post can be read in 1247: Slingerland timp (part 1), in which the base casting was overhauled.

Now the casting is back from being welded and has been painted and re-assembled.  The leg wobble has been corrected with larger bolts and spacers to ensure a tight fit.  I replaced the link bar between the two legs with a solid strip of steel so they cannot become untied whilst the drum is being moved.


With everything reassembled it is just a matter of putting on a new drum head…

However, the drum head didn’t fit the counter hoop!  The cause of the problem (and two and half hours of my life being wasted) is because Slingerland made the hoop on the small side, and Ludwig mad the head on the big side.

I learnt at school that if you multiply the diametre of a circle by pi you get the circumference.  Now I work with circles all the time, and I know that pi equals 3.14159 off the top of my head (it is actually a lot, lot longer, but to 5 decimal places is good enough for me!), but many calculators have a button marked π.  So why is it seemingly impossible for major manufacturers to make a circle of the correct diametre?

So first I have to make as much room inside the counter hoop as possible by planishing the rivets that hold the lugs on as flat as I can.


Then I have to squeeze the head in mechanically, and use a hammer and block to seat it against the surface of the hoop so it sits flat on the drum.  Just look how tight it is:


For me this is just another example of how so many instruments are made by people who don’t understand how important these supossedly minor details are to the overall quality of the sound.  If a drum head is too tight in the counterhoop it chokes the sound.  As it happens I got the drum to sound great, which took a few tricks, but was an unexpected surprise (and a releif!)