Deagan Aurora (part 3) (Job No: 1256)

It can be seen that I tend to employ a systematic approach to overhauling percussion instruments, and vibraphones in particular typify my methods.  Sometimes I deviate from the logical order of doing things, so in 1256: Deagan Aurora (pt 1) I looked at the damper system and in 1256: Deagan Aurora (pt 2) I looked at the whole frame.  This was just because of the way my working week fell – it was Friday late morning when I started looking at this vibraphone, and I didn’t want to immerse myself into a new project only to have to break off immediately, so I removed what I thought would have been a small element.  Anyway in this post I hope to finish the instrument by looking at the final three elements: the resonators, motor and notes.

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In the photograph above, the resonators on the left have yet to be done, whereas the resonators on the right are complete.  What doesn’t come out so well in the photos is just how dirty these resonators were.  Thankfully it was a nice summer day, so I sat outside with a bucket of hot soapy water and literally scrubbed them until they were clean, whilst hosing off the filth periodically to prevent it from baking back on.  And that was just the tubes.

The important thing about vibraphone resonators are the butterfly valves that rotate, opening and closing the tube.  The tube, as the name implies, is simply an acoustic chamber that resonates in sympathy with the second harmonic of the note under which it is hung.  As the butterfly valve is rotated it opens and closes this acoustic chamber so it cycles through being activated and therefore heard, then not.  This is what give the vibraphone its sound and presumably its name; although the name is misleading because I have no idea what the “vibra” stands for, because it is not vibrato.  It should be called an Oscillating Amplitude (Second Harmonic) Metalaphone which would have been way more cool.  Of course I could be showing my ignorance and the “vibra” could be an aspect of the inventors name as in Adolf Sax.

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The butterflies are attached to a fan shaft which runs down the length of the resonator tubes, and this shaft is driven typically by a belt connected to a motor via pulley wheels. There are other designs, but they are just marketing gimmicks that add needless complication into a simple and efficient system and demonstrate (to me) complete ignorance of the principles of mechanical engineering, a misunderstanding of the acoustics, a lack of consideration for the gigging musician, or a combination of all three. This design works, it has always worked; it is simple, rarely goes wrong, and is quick and easy to set up when assembling the instrument. I never understand why manufacturers can be bothered to put effort into developing an alternative system that ultimately is worse than the starting point unless it is simply to give them something to talk about when they are trying to sell the instruments. My “USP” is that it sounds good, oh and it has a life time guarantee.

Because the fan shaft is so long, it needs to be supported, certainly at either end, but also in one or two other places. It is these supporting bushes that introduce noise into the system, and of course that noise is amplified through the resonator tubes. I often have to make up new bushes to replace parts that are damaged or simply missing as was the case on this Deagan vibraphone.

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All of this cleaning, making parts, repairing and polishing fan shafts, aligning, etc all takes time time, and unfortunately there really is no short cut; cutting corners results in a noisy system. So after all of this work, the next stage is the motor. This is where things went wrong for me. The problem is that I am damned if I do and damned if I don’t. Because the motors are generally very old, they are really dirty and essentially operating under a 15 tog duvet of dust which means that everything gets very hot – not good. However, because everything has been getting very hot for a very long time, all the wires are extremely brittle and on the very edge of breaking down – also not good. So if I leave things alone the motor will fail and if I try and clean and service it, the motor could fail. The final element is the wiring; because the motors are invariably very old, health and safety simply was not even taken into consideration. Today things are different, I simply cannot let an electric appliance leave my workshop if I know it to be unsafe – regardless of legislation on a personal level I will not let people expose themselves to life threatening dangers in ignorance. However there is legislation and appliances need to be inspected by a qualified person, and if the wiring is dangerous, then it fails the test and legally cannot be allowed to be used.

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So all I did was to put on a strain relief system. This meant desoldering wires, threading new cables through and reconnecting. After my intention was to blank off the exposed components. This minor bit of work introduced an inconsistent fault, which, whilst trying to identify gradually became less inconsistent until it achieved permanent. Ultimately, a decision has to be made – is it really worth spending time and effort trying to fix a motor that is forty years old? The answer is no.

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The final stage of the overhaul is to clean the notes. Finger grease, beer, sweat, spittle, smoke, etc multiplied by years equals a nasty film of crud that inhibits the notes from vibrating. Unless I have be asked to tune or refinish the notes, it just a case of cleaning it all off which requires more time and elbow grease. The results however are rewarding; not only do they look a lot better, they sound so much better and respond when played. When the whole instrument is assembled and clean notes go on it is like the icing on the cake, although it is the notes that are at the very heart of the instrument. But this is not unusual, it is the same with all instruments: for instance the strings on a violin, guitar or piano make the vibrations, but it is how the rest of the instrument utilises those vibrations that is important.


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3 comments on “Deagan Aurora (part 3) (Job No: 1256)

  1. Tiit Joamets

    Hello!

    Can you explain, what do you mean by: “The tube, as the name implies, is simply an acoustic chamber that resonates in sympathy with the second harmonic of the note under which it is hung?”
    Before reading this post I was sure that the resonator is in tune with the fundamental of the note above it. Now, being in my practice room, I checked again. Blowing air in a resonator produces the same note as the bar above it. And opening and closing the tube also seems to have effect only to the volume of the fundamental note while first and second harmonic of the bar seem to ring with the same volume and pitch with open and closed resonators. I admit that my measurements were made by ear since I don’t have a strobe tuner or anything like that.

    Thank you for attention,

    Tiit

    Reply
    • pauljefferies

      Hi Tiit
      You are probably right in that the resonator is tuned to the fundamental. A bit of confusion on my part; in fact the tuning of the resonator tubes vary from instrument to instrument and they are commonly tuned to the second harmonic because it reduces the length and volume of the tube. However modern vibes will indeed be probably tuned to the fundamental. You can hear the effect in the video. Thank you for picking me up on this!
      regards
      Paul

      Reply

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