Patent Application
20140174282
The present disclosure relates generally to electronic musical instruments, and particularly to pickups operative to transduce cymbal vibrations to electrical signals.
Cymbals have traditionally been an acoustic-only instrument. For live performance in large spaces or recording sessions, microphones are commonly used to pick up the cymbal sound for subsequent amplification and/or recording, but the desire is to remain faithful to the natural sound of the cymbals. Occasionally, a moderate post-processing effect such as reverb or equalization is applied to tailor the sound of the cymbal as required or desired.
The advent of electronic drum kits has naturally given rise to “electronic cymbals.” Like their drum counterparts, these devices are used as electronic “triggers,”—that is, the sound of the “cymbal” itself being struck is not amplified for listening or intended to be heard at all. The prior art “cymbal” (or more accurately, a plastic or plastic-covered replica of a cymbal) of this type is fabricated with an impact sensor, producing trigger signals that initiate playback of pre-recorded or canned “samples” of acoustic cymbal sounds when struck. The “sound” of the electronic cymbal is changed by changing the sample(s) that are triggered by the sensor being struck. While this approach offers advantages of virtually silent operation and “authentic” pre-recorded cymbal sounds, it suffers greatly in “feel” and “expression.” Drummers are accustomed to the feel of “stick-on-metal” that a traditional metal acoustic cymbal provides, and the very large range of sound variation achievable by striking an acoustic cymbal in different locations with varying types of strikes, strike force, and striking objects (sticks, mallets, brushes, etc.). Practical, cost-effective sample-triggering schemes are not available for providing the feel and range of expression that drummers are accustomed to with acoustic cymbals.
When, alternatively, a conventional microphone that responds to sound waves emanating from the vibrating acoustic cymbal is used, acoustic feedback and acoustic crosstalk from other instruments and ambient noise that is within range of the microphone become problematic, particularly for musical performances that are conducted at elevated sound volume levels.
A microphone is a specific example of a transducer, which in general is a device that is operative to convert an input signal or stimulus in one form into a corresponding output signal or response in another form. In the case of the microphone, the input signal is air pressure waves (sound), and the output signal is an electrical response signal.
An inexpensive and commonly-available microphone is the electret condenser microphone. Referring to prior art
Another type of transducer is an accelerometer. As the name indicates, an accelerometer measures acceleration, serving to convert accelerative forces to proportional electrical signals indicative of acceleration magnitude. Many types of accelerometers have been devised in the past. The majority of these contain a “seismic proof mass” whose tendency to resist changes in its spatial location (that is, its inertia) can be measured in some way. Capacitive accelerometers measure changes in the capacitance of a capacitor whose two plates are attached (directly or indirectly) to a compliantly-suspended proof mass and to a fixed accelerometer housing, respectively. When the accelerometer's housing is accelerated (moved) along the axis of interest, the proof mass tends to remain stationary due to its inertia, and due to its compliant suspension, the distance between the plates changes in proportion to the accelerative force being applied to the housing, thus changing the capacitance between them and providing an indication of the accelerative force.
The use of accelerometers as musical instrument transducers is known. However, those that are adequate for such applications are expensive and often require time-consuming and non-scalable customization, severely restricting their use. One problem with the use of existing accelerometers is that the proof mass in conventional accelerometers tends to dampen high frequency response, which contains much of the musical information of interest. The problems are compounded in the case of adding a proof mass to an existing electret microphone. The diaphragm of an electret microphone is absolutely diaphanous—thinner and more flexible than an insect wing. The amount of mass to be added would have to be extremely tiny (the diaphragm itself may only be 4 mm in diameter), and its smallness would make the dispensing and application of a consistent amount of adhesive difficult. This in turn would lead to inconsistency in the sound of the assembled transducer.
As described herein, a method for transducing cymbal vibrations includes mechanically coupling a hermetically-sealed microphone to the cymbal, and operating the hermetically-sealed microphone to provide an output electrical signal in proportion to the cymbal vibrations. The hermetically-sealed microphone is disposed in a casing defining an air gap between a wall of the casing and the microphone.
Also as described herein, a method for making a cymbal transducer includes sealing a sound pressure microphone in an airtight enclosure that includes an air gap between an enclosure wall and the microphone, and configuring the sealed sound pressure microphone for attachment to a cymbal.
Also as described herein, a cymbal transducer includes a sound pressure microphone, and a casing hermetically sealing the sound pressure microphone to prevent communication of air pressure differentials into the sound pressure microphone. The casing defines an air gap between a wall thereof and the sound pressure microphone.
Also as described herein, a cymbal system includes a cymbal, and a transducer couplable to the cymbal. The transducer has a sound pressure microphone and a casing hermetically sealing the sound pressure microphone to prevent communication of air pressure differentials into the sound pressure microphone. The casing defines an air gap between a wall thereof and the sound pressure microphone.
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more examples of embodiments and, together with the description of example embodiments, serve to explain the principles and implementations of the embodiments.
In the drawings:
Example embodiments are described herein in the context of a cymbal transducer using electret accelerometer. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Other embodiments will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the example embodiments as illustrated in the accompanying drawings. The same reference indicators will be used to the extent possible throughout the drawings and the following description to refer to the same or like items.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
The term “exemplary” when used herein denotes “serving as an example, instance or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.
In one embodiment, cymbal transducer 200 includes a housing 204 encapsulating a sound pressure microphone such as an electret microphone 206. Encapsulation in this sense should be taken to mean substantially or completely isolating the sound pressure microphone from external air pressure differentials. This is accomplished in one embodiment by hermetically sealing the microphone, such as electret microphone 206, within a casing 208 and housing 204. The casing 208 can be for example rubber or a suitable potting material or resin, or it can be a more rigid material, such as metal. Some considerations to take into account for the encapsulation are that air leakage will result in undesirable microphonic characteristics, while an excessively compliant (non-rigid) mounting will result in some attenuation of accelerative force, particularly at high frequencies. Furthermore, any looseness in the microphone mounting will result in audible and objectionable “buzzing” sounds when vibrated by a cymbal.
By thus encapsulating the electret microphone 206, its principal mode of operation becomes as an accelerometer. Vibrations along the axis of interest normal to the surface of the cymbal and designated A in
Electret microphone 206 may be an off-the-shelf component and need not include any additional mass coupled to the diaphragm 214, and little or no modification is necessary to deploy its transducer functionality in this configuration as an accelerometer for detecting the vibrations of cymbal 202. Moreover, because of the absence of such mass, high frequency response is not degraded. Further, configured as an accelerometer, it is insensitive to air pressure variations (sound), and does not suffer from some significant drawbacks of microphones, such as feedback and crosstalk. Thus, configured in this manner, encapsulated electret microphone 206 does not operate as a “microphone” per se, but rather as an accelerometer in which the housing 210 moves along its axis perpendicular to the plane of the diaphragm 216, while the diaphragm attempts to remain stationary and deflects due to its inertia. This inertia, which is small because of the small mass of the diaphragm 216, is nevertheless sufficient to induce the deflection, thanks to the extreme thinness and compliance of the diaphragm.
In one embodiment, cymbal transducer 200 is affixed to cymbal 202 using generally a fastener. In one embodiment, this fastener is of the form of a female configuration in which a threaded hole 218 is provided in housing 204 for threadingly engaging a screw 220 that passes through a hole 222 in cymbal 202. Screw 220 can be made captive to the cymbal to prevent its loss, by permanently affixing it in hole 222, through welding, adhesive, or other means. An alternative arrangement can use a male configuration, with a threaded member protruding from housing 204 for passage through hole 222 and threadingly mating with a nut (not shown), which can also be made captive to the cymbal by welding or the like. Hole 222 can be specially drilled in the cymbal, or, in the case of a conventional low volume perforated cymbal, can be one of the numerous existing perforations of the cymbal. These perforations occur in all the major zones of the cymbal, including the bell thereof, the preferred transducer location in one embodiment.
It may be desirable in some embodiments to minimize the contact of the cymbal transducer housing with the cymbal, in order to limit or control the nature of the forces that are transferred between the two components. This can be accomplished for example by tapering the housing of the transducer at the interface region of contact 224, as shown in
It may be desirable to provide a space between the electret microphone and the casing in certain embodiments. Referring to
While embodiments and applications have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts disclosed herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 13/595,863, filed Aug. 27, 2012, titled “CYMBAL TRANSDUCER USING ELECTRET ACCELEROMETER”, the entire disclosure of which is incorporated by reference herein.
