A Premier 751 vibraphone in to have a service. Particular issues are inconsistent damping and note sustain.
The Premier 751 Vibe is no longer made, so all spare parts are now obsolete. When Premier stopped making this vibraphone, I was invited over to buy all the remaining spares. Therefore if I don’t have it, then its unlikely that anyone else will – unless of course that they don’t do many of these very common vibes!
One of the problems with the fan shafts being noisy is the central bearing (pictured above). In order to get this on the fan shaft (because it can’t go past the butterflies), the top of the bearing is sliced through, therefore it loses structural rigidity. This becomes a real problem when it is forced into the resonators; forced because they were made a little bit too long, so they have to be bent to get them in. The same thing happens at the low end, but there the bearing doesn’t have to be cut. This bend creates a pinch point on the rotating shaft, and an ambiguity in positioning, this is where the noise comes from. Thankfully because these spare have run out, I now have no option but to make a replacement, which means that I may as well solve the problem permanently.
First on the list of improvements is better material, I use a low friction nylon. I would have used PTFE, but in
this instance it needs to hold a thread. The originals are moulded plastic, so they start with a structure and add bits to the design for strength, because mine are cut from a sheet of material, I start with a block and remove bits where needed, but there is still a big increase in mass. Therefore mine are way stronger than they need to be (which means that they should never need changing).
There is of course another benefit. These bearings are now made when needed, and modified so that the holes are all aligned correctly so that the fan shaft runs true. They are essentially matched sets.
The central bearing is made in two halves and held together with machine screws, but all of the bearings have a little hole for oiling. This is the complete opposite to progress – I have copied a concept used on vibes made in the 1930’s in the UK (where we invented engineering and are still unsurpassed), all I have done is used modern materials.
The only problem is that they don’t fit! I went through several designs a few years ago, trying to make them so that would go in the space available, but they all failed. Since then, I decided simply to increase the available space. This means cutting the resonator tubes, and unlike every other time I have seen a tube modified, I remove the tubes from the set to work on them and not damage all the others. It’s a no brainer!
As can be seen above, I have increased the chord length of the cut out, and its depth.