Musicians often talk about their “instruments getting better with time and playing.” Clearly, the more we gently flex the soundboard and backboard, the more supple the wood becomes – and the better the instrument responds to the string’s energy transmitted to it via the bridge.
The process of breaking in an instrument mechanically, and flexing its structure, is not new and many interesting studies exist on early methods of “vibration treatment” and”dedamping.” (See Selected Reading, below.)
Taking an idea from my friend Ron Saul, I built a break-in fixture which is basically a support frame mounted to a platform. Mounted on the frame is a 25-rpm motor with a an eccentric arm mounted to it’s shaft. The eccentric arm connects to a pendulum suspended in the middle of the support frame. Clamped to the bottom of the pendulum is a hotel key card cut in half (basically, a long wedge shape). [The plastic from the key card works better than a flatpick because the 4″ long plastic piece of key card is more flexible.] The height of the keycard is adjusted so that the card will strike all eight strings as the pendulum swings back and forth.
The mandolin is secured to the baseboard with four rubber-padded clamps and snugged in place.
All parts and clamps are also secured with duct tape to ensure nothing comes loose or will fall on the mandolin. (Tape not shown here so you can see all the parts.)
Every revolution of the motor provides two strums; one to the left, the other to the right. So, the instrument is strummed 50 times per minute.
After 16 hours (two 8-hour days) of strumming, the instruments are VERY noticeably broken in, and it does make a BIG difference.
Break-in Service: If this looks like either too much work or too much noise, offer a break-in (“de-damping”) service. For more information, click here De-Damping Service.
Note: The fixture stands 30″ tall so that the arc of the pendulum’s swing would cause the “pick” to strike all strings with almost-equal depth and force.
• Artificial aging by vibratory means, Gottfried Lehmann, Experiences and Observations on the Effectiveness of a Procedure for Vibration Treatment of String Instruments. http://www.henrystrobel.com/lehmannweb.pdf
• A means for inhibiting the damping qualities of an instrument, von Reumont, De-damping Process. http://www.henrystrobel.com/vibrate.htm
• A mechanical device to accelerate de-damping for violin family instruments, http://www.violin-reverb.de/violin/dedamping.htm
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