WO2007132235A2

WO2007132235A2 - Musical instrument comprising a stringed body in a closed cavity

Info

Publication number: WO2007132235A2
Application number: PCT/GB2007/001792
Authority: WO
Inventors: Andrew Michael Mcevoy
Original assignee: Zarre Limited
Priority date: 2006-05-16
Filing date: 2007-05-16
Publication date: 2007-11-22
Also published as: GB0820499D0; WO2007132235A3; GB2450671A; GB0609628D0; GB2450671B

Abstract

A musical instrument is described. The instrument is a stringed, bass instrument including a substantially closed cavity therein. A transducer within the cavity arranged to convert sound within the cavity into an electrical signal for amplification.

Description

Musical Instrument

Field of the Invention

The present invention relates to musical instruments, in particular to stringed musical instruments .

Background to the Invention

An electrical signal representing the sound' of a stringed musical instrument can be obtained by using a microphone to convert the sound output from the instrument . ,

However, use of a microphone to convert the sound output from an instrument into an electrical signal has a number of disadvantages. The positioning of the microphone

-relative to the instrument and ■ .the .. acoustic characteristics of the room in which the .instrument is being played have a significant effect on the microphone output. Furthermore, if the electrical signal from the microphone is used to produce amplified sound then unwanted resonance known as feedback can occur.

Feedback is a particular problem for acoustic instruments because the sound box and other resonant structures of such instruments are designed to resonate at the instrument's output frequency to make the instrument more audible than vibrating strings alone. This gives rise to the risk of feedback, because the resonant structures respond to both the vibration of the strings and to the amplified sound. .Electric instruments rely on amplification to produce a significant sound output, and comprise an electromechanical transducer, e.g. a piezoelectric transducer mounted at the bridge of the instrument, to provide an electrical signal representing the movement of the strings. The electrical signal from the transducer can be amplified and supplied to a loudspeaker to provide . the instrument's sound output. . .

Electric instruments typically do not suffer as much with the feedback problems outlined above. By using . electrical amplification no sound box or other highly resonant structures are required. However, the absence of sound box or other highly resonant structures means that, the t-imbre of sound output from an electric . ^'instrument is' typically, quite different to that of .^• an . equivalent acoustic instrument, and may lack tonal depth^1".

- Instruments incorporating resonant structures along with electromechanical transducers have been developed, but may still suffer from feedback problems. In addition such instruments may not include means for a musician to control the electrical output signal from the ^• instrument to take advantage of any additional tonal depth provided by the resonant structure.

It is an aim of preferred embodiments of the present invention to address at least one problem associated with the prior art, whether identified herein or otherwise. Summary of the Invention

In a first aspect, the present invention provides a musical instrument comprising: a stringed body including a 5 substantially closed cavity therein; and a first transducer within the cavity arranged to convert sound within the cavity into an electrical signal .

Suitably, the dimensions of the cavity are adjustable. 10 Suitably, the dimensions of the cavity can . be predetermined to give a desired sound resonance within the cavity when the instrument is played. Suitably, the dimensions- of the cavity can be adjusted to produce sound resonance at approximately 41Hz.

■15

Suitably,^•• the cavity comprises one closed end and^' a. piston movably installed at a second end. Suitably, the : piston is arranged with a free end extending from the body of. the instrument. The piston may comprise a closed ended tube.

20 Suitably the free end of the piston comprises a support structure for the instrument. Suitably, the free end of the piston comprises a ground engaging stand for the instrument. Suitably the free end of the piston comprises a spike .

25

Suitably, the cavity is axially long in comparison to its other dimensions. Suitably, the length of the cavity is adjustable by movement of the piston. Suitably, the cavity and piston are substantially cylindrical. 0

Suitably, the first transducer is arranged at an end of the cavity. Suitably, the first transducer is arranged at the closed end of the cavity. Suitably, the transducer is a microphone, preferably a condenser microphone. Suitably, the instrument comprises a bass instrument. Suitably, the instrument comprises four, five or six strings arranged to vibrate between a bridge and a nut . ^■Suitably the strings can be tuned using machine heads mounted at a headstock. Suitably, the instrument comprises a neck. Suitably, the cavity extends within the neck.

Suitably, the instrument comprises a second transducer to convert vibration of the strings into an electrical output signal . Suitably, the second transducer comprises one or both of a magnetic pickup and a piezoelectric pickup. ^■

The electrical ■ output of the instrument may be made up of a combination- Of- the' electrical outputs of the first and second transducers', ^:or of the output of only one of the first or second transducers.

Suitably, the instrument comprises on-board circuitry to allow a musician to adjust the electrical output of the instrument. Suitably the instrument comprises a mixer to adjust the mix of the outputs from the first and second transducers in the electrical output of the instrument. Suitably, the mixer can be controlled by a musician to adjust the mix of the outputs from the first and second transducers in the electrical output of the instrument .

Suitably, the cavity and/or the piston comprise sensors to detect the position of the piston within the cavity and

• pass the detected position information to the on-board circuitry to adjust the electrical output of the instrument. Suitably the detected position information can be passed to the mixer to adjust the mix of the outputs from the first and second transducers in the electrical output of the instrument .

Suitably, the on board circuitry comprises a visual indicator operable in use to display information relating to the electrical output of the instrument. Suitably, the visual indicator comprises a multi-coloured light emitting diode package. Suitably, the on board circuitry comprises a first visual indicator arranged at the headstock, and a second visual indicator arranged at the bridge.

Suitably, the instrument comprises a tilt switch. Suitably, when the instrument is positioned in a substantially upright orientation the tilt switch causes the mixer to include the ^■electrical ^■ signal . from the first transducer in the electrical output of the instrument. Suitably, when the instrument is in a substantially horizontal orientation the tilt switch causes the mixer to reduce the electrical signal from the first transducer in the electrical output of the instrument . Suitably, when the instrument is in a substantially horizontal orientation the tilt switch causes the mixer to eliminate the electrical signal from the first transducer from the electrical output of the instrument .

Brief Introduction to the Drawings

For a better understanding of the invention, and to show how .embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 ^■ shows a front perspective view of a musical instrument according to a first preferred embodiment of the present invention; 5

Figure 2 shows a side sectional view of the spike, cavity and associated electrical components of the instrument of Figure 1 ;

10 Figure 3 shows a side view of the spike- and ' cavity of the ^{■ ■} instrument of sectional Figure 1, and the associated quick release mechanism.

Figures 4a and 4b show a side perspective view of a bung is for 'use with the instrument of Figure 1. and- a side view of the bung in use ; and

Figure 5 shows a schematic overview of the .spike, cavity and on-board electronics of the instrument of Figure 1. ' 20

Description of Preferred Embodiments

Referring now to Figure 1 there is shown a musical 25 instrument 1. The musical instrument 1 is a stringed, bass instrument comprising a body 3. The body includes a neck 5. The instrument 1 comprises four strings 2 of scale length approximately 87.63cm (34.5 inches) between bridge 4 and nut 6. The exact scale length is adjustable 30 by movable bridge-saddles. The strings 2 may typically be tuned using machine heads 8 so that when played the open strings produce the same notes as a standard double bass/ bass guitar. The instrument 1 comprises piezoelectric pickups 7 mounted at the bridge, and a magnetic pickup 9 beneath the strings 2. On-board electronics allow a musician to control the output volume and tone via controls 13.

The instrument 1 can be played in an upright position like a double bass. A spike 11 extends from a cavity 20 in the body 3 and neck 5 and provides the support needed to allow the instrument to be played in an upright position. The spike 11 may be substantially tubular and closed at the free end away from the body 3.

Figure 2 shows the cavity 20 and the spike 11. The cavity 20 has a closed end in the neck 5 at which a microphone 22 is positioned. The microphone 22 can be located in a shock resistant mounting, preferably a neoprene washer 23. The arrow in Figure 2 indicates the push-fit of the microphone 22 in the washer 23. When the instrument is being played, air in the cavity 20 and optionally the air in the spike 11 vibrates, generating an electrical signal from the microphone 22. The signal from the microphone 22 can be used as part of the output from the instrument 1 together with the outputs from the pickups 7,9. By varying the position of the spike 11 within the cavity 20 the length of the cavity 20 varies, which has an effect on the sound within the cavity 20 and therefore on the output of the microphone 22. In this way the instrument 1 can provide an acoustic timbre when played in the upright position. Preferably, when the spike 11 is fully extended the cavity has a resonant frequency of approximately 41Hz. The spike 11 acts as a piston and can be secured substantially within the cavity 20 with a quick-release mechanism such as a quick release clamp 25. With the spike 11 in this configuration the instrument 1 can be played in a substantially horizontal position like a bass guitar. Strap buckles (not shown) can be provided on the body 3 to allow a musician to play the instrument 1 like a bass guitar while standing.

With the spike 11 filling the cavity 20 with a quick-release mechanism such as a quick-release clamp 25. no significant sound is generated within the cavity for the microphone 22 to detect . The output from the instrument 1 is provided by the pickups 7,9. In this way the instrument 1 can provide an output • similar- _.to an electric bass guitar when played in the substantially horizontal position. , ,

A mercury tilt switch or the like can be provided in the instrument 1 to completely disconnect the microphone 22 when the instrument is being played substantially horizontally.

■Figure 3 further shows a cross sectional view of the spike 11 and the cavity 20 within the body 3 and neck 5.

The spike 11 comprises a tubular portion of approximately 16.1mm diameter by 800mm length by 2mm wall thickness, and is preferably made from aluminium. Preferably the tube can contain a layer of epoxy resin material or other filler to reduce mechanical vibration of components within the spike. A point 12 is provided, comprising a tapering section of approximately 50mm length which extends from the tubular portion and which finishes at a flat tip of approximately 3mm diameter. The point 12 is preferably releasable from the tubular portion for replacement, or to allow a differently shaped end piece to be fitted if desired.

The cavity 20 is approximately 700mm in length and is lined by a substantially tubular sleeve 21 of inner diameter 18mm by 2mm wall thickness. The sleeve 21 is preferably made from aluminium.

The spike 11 can slide in and out of the sleeve 21, and can be held in a desired position relative to the sleeve 21 by a quick release mechanism 25 mounted to the body 3. The quick release mechanism 25 comprises a lever actuated cam, which Is mounted proximate to the end of the sleeve 21. Alternatively, other fixings such as a vice-like mechanism or a barrel clutch can be used to hold the spike 11 in position^' relative to the sleeve 21.

In addition to the variation in sound that is produced by the differing length column of vibrating air within the cavity 20, sensors may be used to detect the position of the spike 11 in the cavity 20 and to apply signal processing to the signals from the microphone 22 and the pickups 7,9.

For example, permanent magnets 27 held in the spike 11 by a plastic former 26 can be detected by reed switches 28, Hall effect sensors etc. mounted around the sleeve 21. A range of magnets can be used, with neodyminium-iron-boron preferred due to the sharp polar pattern that can be produced with this material. The number, size and positioning of magnets and sensors can be selected to achieve a desired accuracy for spike position sensing.

A wide range of effects can be used to vary the output of the instrument 1 dependent on the sensed position of the spike 11. For example, the balance between each of the pickups 7,9 and the microphone 22 in the output can be changed; the tone of the output of one or more of the outputs from the pickups 7,9 and the microphone 22 can be changed; the output from one or more of the . pickups 7,9 and the microphone 22 can be compressed, etc. Also, the instrument may be configured to provide a stereo output, with the left and right channels derived from different combination of pickup and microphone outputs, and/or by using signal processing such as phasing or flanging to generate a stereo .output .

The instrument 1 comprises visible indicators .15 which .are. arranged to give a display indicative of the configuration that has been selected by the position of the spike 11. The visual indicators preferably comprise light emitting diodes (LEDs) which can display in one or more colours to indicate the selected configuration. The LEDs are preferably positioned in the headstock and adjacent to the bridge so that at least one LED is easily visible to a musician when the instrument is being played in either the upright or horizontal position.

When the instrument 1 is played in an upright position the point 12 may engage the floor. Alternatively a suitably shaped ferrule (not shown) can cap the point 12 to reduce slippage and protect the floor surface. A particularly preferred arrangement to reduce slippage and protect floor surfaces is provided by the bung of Figures 4a and 4b. As also shown in Figure 2 the bung 30 comprises a foot plate 31 coupled to a receptacle 32. In use a musician places a foot on the foot plate 31 to hold the bung 30 in place on the floor. The receptacle 32 can then receive the point 12, thereby maintaining the instrument 1 in a desired position relative to the musician.

By using a ferrule or a bung 30 of a rubber-like material with suitable damping properties the coupling of mechanical vibrators into the instrument from a floor or stage surface can be reduced.

To facilitate the playing of the instrument 1, particularly when the instrument is played in- a substantially horizontal position the neck 5 may comprise a groove in its non-stringed surface .to receive a musician's thumb. The neck .5 tapers- toward the nut end and the groove may be of decreased depth and/or thickness at the nut end where the depth and width of the neck is smaller and playing is therefore easier. Also, the body 3 may comprise a curved concave recess to engage a musician's body/thigh when played in the horizontal position. Engagement of the recess with the musician's body/thigh helps maintain the instrument in the correct position, is particularly important if the instrument is played with the musician seated.

To further locate the instrument 1 in position when being played a ferromagnetic, e.g. stainless steel back plate can be positioned on the instrument 1. A musician can place a suitably shaped magnet in a pocket of his/her clothing which will attract the back plate and hold the instrument 1 in place. Clearly, the back plate could also be made as a magnet, with the musician then able to carry- suitably shaped piece of ferromagnetic material or another correctly orientated magnet in his/her pocket .

Figure 5 shows a schematic overview of the spike 11, cavity 20 and the on-board electronics of the instrument 1.

The instrument 1 preferably comprises 'a circuit board 33 comprising active on-board electronics. Power, can be supplied to the instrument by the 48 volt phantom power supply available on many modern amplifiers and mixing, desks. Preferably the instrument 1 comprises a balanced, ■ preferably XLR type connector 34 to receive the .phantom supply and to provide a balanced output . A rechargeable internal battery 35 is provided within the instrument 1 to power the on-board electronics, and can be . charged using the phantom power connection.

Charging contacts for the internal battery are provided in the form of metal spikes 39 extending from the body 3. The charging contacts 39 are designed to engage a suitable charger. Ideally, a suitable charger can be incorporated into a support stand for the instrument 1, allowing the internal battery 35 to be recharged when the instrument 1 is not being played. A suitable charger can be incorporated into a protective case for the instrument 1, allowing the internal battery 35 to be charged while the instrument 1 is stored. Most conveniently the case/charger can be formed to include a stand and therefore one accessory can provide the charging, storing and supporting functionality. The embodiments of the instrument described herein offer a range of playing configurations and a high degree of flexibility in the sound output of the instrument. ^• The instrument can be used to provide a natural acoustic sound without encountering significant feedback^' problems, and can be conveniently re-configured to produce an electric sound if required.

Although the preferred embodiment described herein comprises a bass instrument, other sizes of instrument could be produced, e.g. cello sized, or guitar sized.

Although a few preferred embodiments have been shown and described, it will be appreciated by those -_.skilled^'- in* the art that various changes and modifications might be made without departing from the scope of the^';., invention, as defined in the appended claims. ^•.. -

. r

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this •specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims-, abstract and drawings) , or to any. novel one, or any novel combination, of the steps of- any method or process so disclosed. . ^■ ..

Claims

CLAIMS :

1. A musical instrument comprising: a stringed body- including a substantially closed cavity therein; and a first transducer within the cavity arranged to convert sound within the cavity into an electrical signal.

2. The musical instrument of claim 1, wherein the cavity is axially long in comparison to its other dimensions.

3. The musical instrument of claim 1 or 2 wherein the dimensions of the cavity are adjustable.

4. The musical instrument of claim 3, wherein the cavity comprises one closed end, and a piston movably installed^' at a second end.

5. The musical instrument of claim 4, wherein the length of the cavity is adjustable by movement of the piston.

6. The musical instrument of claim 4 or of claim 5, wherein the cavity and piston are substantially cylindrical.

7. The musical instrument of any one of claims 4, 5 or 6, wherein the piston comprises a closed ended tube.

8. The musical instrument of any one of claims 4-7, wherein the piston is arranged with a free end extending from the body of the instrument.

9. The musical instrument of claim 8, wherein the free end of the piston comprises a support structure for the instrument .

10. The musical instrument of claim 9, wherein the free end of the piston comprises a ground engaging stand for the instrument .

11. The musical instrument of claim 10, wherein the free end of the piston comprises a spike.

12. The musical instrument of any preceding claim, wherein the first transducer is arranged at an end of the cavity.

13. The musical instrument of any preceding claim, wherein the first transducer is a microphone.

14. The musical instrument of any preceding claim comprising a bass instrument, with the dimensions of the cavity adjustable to produce sound resonance at approximately 41Hz.

15. The musical instrument of any preceding claim, comprising a stringed instrument including a neck.

16. The musical instrument of claim 15, wherein the cavity extends, at least partially, within the neck.

17. The musical instrument of claim 15 or 16, comprising a second transducer to convert vibration of the strings into an electrical output signal.

18. The musical instrument of claim 17, wherein the second transducer comprises one or both of a magnetic pickup and a piezoelectric pickup.

19. The musical instrument of claim 17 or 18, wherein the electrical output of the instrument is made up of a combination of the electrical outputs of the first and second transducers, or of the output of only one of the first or second transducers .

20.. The musical instrument of claim 19, wherein the ^•instrument comprises on-board circuitry to. allow a musician to adjust the electrical output of the instrument, including a mixer to adjust the mix of the outputs from the first and second transducers in the electrical output of the instrument .

21. The musical instrument of claim 20, wherein the cavity and/or the piston comprise sensors to detect the position of the piston within the cavity and pass the detected position information to the on-board circuitry to adjust the electrical output of the instrument according to the detected position.

22. The musical instrument of claim 21, wherein the detected position information is passed to the mixer to adjust the mix of the outputs from the first and second transducers in the electrical output of the instrument .

23. The musical instrument of claim 21 or 22, comprising a tilt switch, and wherein when the instrument is positioned in a substantially upright orientation the tilt switch causes the mixer to include the electrical signal from the first transducer in the electrical output of the instrument .

24. The musical instrument of claim 23, wherein when the instrument is in a substantially horizontal orientation the tilt switch causes the mixer to reduce the electrical signal from the first transducer in the electrical output of the instrument .

25. The musical instrument of claim 23 or 24, wherein when the instrument is in a substantially. horizontal orientation the tilt switch causes the mixer .to- eliminate the^' electrical signal from the first transducer from . the electrical output of the instrument . .:. . ^■ • ^■

26 . A musical instrument substantially , .as .. herein described, with particular reference to the - accompanying drawings . ^{■ •} . . ^{■ '}