The first part of this blog is 1205: Premier 751 (part 1)
Looking at the pedal bar, shows one reason for the wobbly frame:
This bar joins the bottom of the vibe together, and is the fulcrum around which the damper pedal rotates. The two plastic ends have a locating peg inside a profiled end to suit the leg frames, the hole (pictured) at either end accepts a “J” bolt which is tightened to secure the whole frame. As can be seen, the holes in the very thin walled tube get badly worn (on the left it is broken out, relying on only the plastic insert). If the legs aren’t held in place securely at the bottom, there is obviously no chance that vibraphone will be stable.
The good news is this has inspired me to write a blog about my top ten bad designs. In which the Premier 751 vibraphone appear twice, because the second bad design concept is using the resonator tubes as a structural element.
The front row of tubes form a diagonal line from the low notes to the upper notes, this diagonal can be utilised to make a triangle which are very strong. Triangles are very strong, which is why they are seen on all of my frames, and why I give a lifetime guarantee (my lifetime). The problem with the Premier 751 vibraphone is that the resonators are fixed at the high end (if you disregard the rubber band!), in other words the peak of the triangle is open, so its not really a triangle at all, and therefore not strong at all.
So, the non triangle combined with a badly attached bottom bar results in a frame that wants to wobble, and succeeds really well. It’s a good job they came to me with it then, isn’t it? What I have done is make a bar to fix the legs, thus creating a parallelogram – the notes rails, and the pedal bar being the two parallel sides. A second bar hinged at the top of the leg frame, and fixed on the first bar creates my (integral) triangle for strength, and prevents the legs from going rhomboid. Simple (but its how you apply it that makes the difference!)
What I find annoying, is having to re-do other peoples repairs. This vibe had loads of issues, lots of little things that someone had made a dogs dinner of. For instance:
Welding and soldering the butterflies on. Between the butterflies is where the fan shaft runs through the central bearing. Now it has welding marks, and filing marks, and guess what, now it has an annoying “tick, tick, tick, tick” sound as it rotates. I have spent the time to clean it all up, and it is nearly gone, but essentially the fan shaft is ruined.
Anyway, rant over. After repositioning the damper springs, that were put in wrong (in fairness, these were not of consistent quality as a spare part when they were available), and re felting the bar, and the notes cleaned, the vibes are done.
For the remaining time the vibes are sitting in my workshop, I bed the notes into the new felt. I leave the connecting rods off the pedal, set the damper bar high, and pull the notes down with a clamped beam.