Measurement Rig

The Impact Hammer Rig is a tool for measuring the sound output of violins and violas. Based on an approach devised by Martin Schleske, Joseph Curtin developed the rig through several generations of prototypes and then worked with furniture-designer Garry Venable to produce a tool that is ruggedly built, portable, and capable of calibrated, laboratory-grade acoustical measurements.

measurerig4

Features

  • Accommodates violins and violas of any size
  • Instruments can be mounted and measured in minutes
  • 3-axis positioning stage allows quick, precise alignment of hammer with corner of bridge
Impact Hammer Rig: 3-axis positioning stage.

Impact Hammer Rig: 3-axis positioning stage.

  • Custom-made hammer tip yields meaningful data up to about 8,000 Hertz
  • Cable release allows hammer to be triggered while operating a computer
  • Hammer assembly can be detached and used as a free-standing unit for other measurement purposes
Impact Hammer Rig: Hammer assembly.

Impact Hammer Rig: Hammer assembly.

  • Instruments can be rotated 360 degrees with respect to microphone
  • Microphone can be rotated 360 degrees with respect to room
  • Microphone can be quickly positioned anywhere between 5 and 50 centimeters from center of instrument
  • Built with anodized aluminum and oil-finished cherry and paduk wood
  • Entire rig can be quickly disassembled and packed into a standard carry-on suitcase
  • Mounts on a pro-audio speaker stand with a 1-½” shaft, or camera tripod legs with a 3/8th or ¼ inch stud (see below).
Impact Hammer Rig: measure

Impact Hammer Rig: measure

Price

$2,800 plus shipping & applicable taxes. This does not include the associated equipment and software listed below. If you are interested in purchasing a rig, please contact Joseph Curtin.

Impact Hammer Rig: ICP Sensor Signal Conditioner.

Impact Hammer Rig: ICP Sensor Signal Conditioner.

Associated Equipment

The Rig is built around but does not include the equipment and software listed below. These are best purchased directly from the manufactures or a licensed retailer in order to take advantage of warranties and after-sales service.

  • PCB Force Hammer (model 086C80) & power supply (e.g., model 480E09). Total cost around $1,200.
  • Cardioid condenser measurement microphone, such as Earthworks SR20 (about $620). Good measurements are possible with less expensive mics. Calibrated mics are more costly, but allow measurements to be made in absolute rather than relative terms.
  • USB or FireWire based stereo soundcard with phantom power for microphone, such as Edirol UA25 (about $240).
  • Custom-made software is available from George Stoppani(www.stoppani.co.uk) who has developed a suite of applications suited to both modal analysis and sound radiation measurements.
  • SpectraPlus acoustical analysis software(www.SpectraPlus.com) is a general purpose commercial application. Version 5.0 with three-option package ($595) is the least expensive that will do the job. The 6-option package is recommended ($795) or the full 10 options ($995).
  • Pro-audio speaker stand with 1-1/2″ shaft: Ultimate Support, model TS 80B, available from companies such as Musician’s Friend(www.musiciansfriend.com), (1-800-391-8762) for about $80. For added portability, use lightweight camera tripod legs in place of speaker stand. Velbon 540A graphite tripod legs (available online from B&H Photo and other suppliers for about $275) is ideal for travel, as it is very light (2.7lb) and folds down to 16.5″. It is not as sturdy as a speaker stand, but does just fine in a hotel room or concert hall. This tripod has a ¼” stud, but the rig comes with an adaptor.
Impact Hammer Rig: Disassembled.

Impact Hammer Rig: Disassembled.

For more info: link** – An introduction to measuring violin radiation

Disclaimer

Making meaningful, repeatable acoustical measurements requires an understanding of the basics of violin acoustics and signal analysis along with a working familiarity with the relevant hardware and software. While the Rig comes with a basic instruction manual and some suggested background reading, Joseph Curtin can otherwise provide only very limited after-sales consulting. Prospective users should consider getting hands-on experience at the VSA Oberlin Acoustics Workshop. For information about the Workshop, contact Fan Tao at Fan.Tao@daddario.com.

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