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More About The Acoustics of Resonators

Learning - Enlightenment

 

 

More about the acoustics of Resonators (Part 3)

Why Malletech "SST" (Super Smooth Technology) is such an important advancement in sound

 

Back in the early days when marimba and xylophone were used mostly in "novelty music," there was a vaudeville act in which the marimba player stops in the middle of his performance, feigning a problem with the instrument.  He taps several times on a particular bar on the sharp keyboard and looks at the audience with a face that says "what's wrong with this note?"  He then moves the bar aside, and with astonishment, pulls a banana out of the resonator!  As the band starts back up, he eats the banana, puts the bar back in place and starts playing again, happy, finally, with sound of that note.

Today it would be unusual for a musician to find a banana in a resonator, but it would not be unusual to find, screws, nuts, bolts, rivets, felt pads, tubes within tubes, and numerous structural braces crisscrossing and obstructing the sound field.

What does that do to the resonance?

Malletech has discovered that every single internal encumbrance within the tube creates airflow eddies that disturb and resist smooth airflow.  Disturbance and resistance of airflow lowers volume and produces additional, unwanted non-harmonic overtones.

Most marimba manufacturers seem to be proud of the "rich mix of harmonics" that their bottom resonators produce, and some actually use wording similar to that in their advertising. However, bottom-flared, rectangle, teardrop and oval shapes are less sensitive to the fundamental and have hundreds of non-harmonic overtones that distract from a clear sense of pitch.  Manufacturers have all known for decades that any shape other than a round resonator tube produces non-harmonic overtones, but all the "school instrument" companies continue to use those shapes because they are far less expensive to manufacture.

Why do those flared and oval resonator shapes (and the internal braces, flap "tuners," and tubes-within-tubes that those types of designs must have) create "out of focus," "muddy" bass sounds and uneven volume, bar to bar, note to note?  Even with modern "perfect" triple harmonic tuning, marimba bars still contain several disturbing, out of tune overtones and uncontrollable modes of vibration.  These out of tune harmonics (frequently "in the cracks" between notes, or at undesirable tri-tones and sevenths) are picked up and amplified by those types of resonators.  Why?  That’s because flared bottom, oval and rectangular tubes do not contain the natural harmonic series (octaves, fifths, thirds, etc.) that we are used to hearing from strings, woodwind and brass instruments, as well as the best bass organ pipes.  They contain literally hundreds of out-of-tune resonances.  Blow into a rectangular or oval resonator and you will hear that it is very difficult to hear a fundamental pitch.  Blow into a round resonators and it "sings" a clear pitch.

An example of hundreds of overtones is found on a cymbal.  When you strike a cymbal, you can't indentify an exact pitch.  There are exact pitches in there, but there are so many of them, so close and randomly structured, that the ear can not pick out an organized pitch structure as it can when the fundamental, octaves, thirds and fifths are predominant -- as they are on a bass viol, organ, trombone or piano.

If you don't know what is meant by "out of focus" and "muddy" tone, listen to a bass bar on an Orff instrument – a rosewood or synthetic bass bar over a rectangular resonator box.  While these pre-school and grade-school learning instruments can be "charming," if you heard the same bar over a round tubular resonator, your mouth would drop open with disbelief that it could be the same bar. Needless to say, over the round tubular resonator, the Orff bar has far more volume and clarity of pitch – it "improves."  This is not an "opinion" or "a matter of personal taste."  This is an acoustic reality that can be heard by any trained musician or music lover once you know the difference.  "In tune" is better than "out of tune." Clear pitch and perfect natural overtones are superior to the alternative.

The same Orff experiment has been done hundreds of times with 5-octave marimbas.  Take off the "worst bar" from an instrument that has flared or oval resonators and put it over a Malletech Imperial or Roadster resonator.  Mouths drop open and groups of percussionists laugh out loud the first time they hear the difference.  Almost every time, the "bad bar" sounds great on the round resonator.

The reason?  Round resonators, plugged on one end, don’t even contain out of tune harmonic pitches.  Round tubes only resonate the fundamental and desirable natural overtones. The result is that the "bad" sounds of the bar are not amplified and therefore the tone in the low range is cleaner, more "in focus" and therefore, much more powerful.

That is the theory behind our development of SST.  While it is a very expensive process to manufacturer, we have eliminated the last bits of internal resistance to natural harmonic resonance.  While our silver-soldered (brass) and "tig-welded" (aluminum) resonators are the current world standard for power and in-tune harmonic content, smoothly bent tubes, without the little bumps and corners are a little bit better.  How much better?  Enough that the musicians who have participated in our "backs-turned blindfold tests" can clearly hear the improvement.  Tested with the same bar, the SST resonators are a bit louder, a bit longer ringing and "cleaner" in pitch – especially when combined with higher notes.

 

Patented.  Available since late 2011.