Phantom powered preamp converter

A phantom powered preamp for use with a microphone cartridge having a unique mechanical interface. The unique mechanical interface allows the phantom powered preamp to function with both ¼ and ½ inch microphone cartridges. The phantom powered preamp including a housing base having a PC board assembly and a connector, the PC board assembly being electrically coupled to the connector; a preamp tip having an adapter and a guard tube, the PC board assembly extending from the housing base to the preamp tip and being electrically coupled to the adapter and the guard tube, the adapter being configured to be electrically coupled to the microphone cartridge, the guard tube being configured to surround a portion of the PC board assembly within the preamp tip; and a first converter being configured to releasably engage the preamp tip or the housing base to reduce edge diffraction.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to preamplifiers for microphone testing and measurement, and more specifically to an improved phantom powered preamp for microphone test and measurement.

Description of Related Art

Phantom power may be sourced from a special power supply or any other equipment with phantom powering circuitry such as mixers and amplifiers commonly used in the audio recording industry. Phantom power provides DC electric power to the electronics of the microphone system. IEC 61938, incorporated herein by reference, provides internationally recognized standards for phantom power systems.

Phantom powering consists of a phantom circuit where direct current is applied equally through the two signal lines of a balanced audio connector (e.g., both pins 2 and 3 of an XLR connector). The supply voltage is referenced to the ground pin of the connector (e.g., pin 1 of an XLR), which may be connected to the cable shield or a ground wire in the cable or both. When phantom powering was introduced, one of its advantages was that the same type of balanced, shielded microphone cable that studios were already using for dynamic microphones could be used for condenser microphones. Other microphones require special, multi-conductor cables.

Traditional preamp/adapter combinations require a guard to be extended through the adapter to effectively reduce parasitic capacitance. Moreover, reduced acoustic diffraction effects are due to the simplified geometry of a complete system. Designs that use standard adapters to interface the microphone to the preamp introduce diameter changes (e.g., edges or slopes) that degrade acoustic performance.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present disclosure provides for a phantom powered preamp for use with a microphone cartridge having a unique mechanical interface. The novel phantom powered preamp includes in certain aspects a housing base having a PC board assembly and a connector, the PC board assembly being electrically coupled to the connector; a preamp tip having an adapter and a guard tube, the PC board assembly extending from the housing base to the preamp tip and being electrically coupled to the adapter and the guard tube, the adapter being configured to be electrically coupled to the microphone cartridge, the guard tube being configured to surround a portion of the PC board assembly within the preamp tip; and a first converter being configured to releasably engage the preamp tip or the housing base to reduce edge diffraction.

Another embodiment of the present disclosure provides for a phantom powered preamp for use with a microphone cartridge having a unique mechanical interface. The novel phantom powered preamp includes in certain aspects a housing base having a PC board assembly and a connector, the PC board assembly being electrically coupled to the connector; a preamp tip having an adapter and a guard tube, the PC board assembly extending from the housing base to the preamp tip and being electrically coupled to the adapter and the guard tube, the adapter being configured to be electrically coupled to the microphone cartridge, the guard tube being configured to surround a portion of the PC board assembly within the preamp tip, wherein the housing base and the preamp tip are a unitary structure; and a converter being configured to releasably engage the preamp tip or the housing base to reduce edge diffraction.

Yet another embodiment of the present disclosure provides for a phantom powered preamp for use with a microphone cartridge having a unique mechanical interface. The novel phantom powered preamp includes in certain aspects a housing base having a PC board assembly and a connector, the PC board assembly being electrically coupled to the connector; a preamp tip having an adapter and a guard tube, the PC board assembly extending from the housing base to the preamp tip and being electrically coupled to the adapter and the guard tube, the adapter being configured to be electrically coupled to the microphone cartridge, the guard tube being configured to surround a portion of the PC board assembly within the preamp tip; a first converter having a distal end having a first diameter; and a second converter having a distal end having a second diameter greater than the first diameter of the first converter, the first converter and the second converter being configured to interchangeably engage the preamp tip or the housing base.

A further embodiment is disclosed wherein the phantom powered preamp includes some or all of the following: the adapter being a pogo adapter; further comprising at least one support bracket connected to the PC board assembly; the at least one support bracket being connected to the PC board assembly by at least one screw; the guard tube being made of metal or an electrically conductive material; the guard tube being further configured to surround the adapter of the preamp tip; the preamp tip further including a microphone interface; the preamp tip further including an inner insulator and an outer insulator, the inner insulator electrically insulating the adapter from the guard tube, the outer insulator electrically insulating the guard tube from the preamp tip; the housing base further including a spring, the spring being positioned at an opposite end of the connector of the housing base; the spring is configured to carry a ground connection to the housing base; the first converter being one of a ¼ inch converter and a ½ inch converter; the ¼ inch converter tapering at an angle; the housing base including a distal end and a proximal end, the distal end of the housing base sloping at an angle forming a tapered distal end; the angle of the ¼ inch converter and the angle of the distal end of the housing base being approximately the same angle; a distal end of the first converter is configured to be releasably engaged to the microphone cartridge; the ½ inch converter being cylindrical in shape; the preamp tip including a distal end and a proximal end, the proximal end of the preamp tip being proximate to the housing base, the proximal end of the preamp tip including threads for receiving the first converter; the first converter having a distal end having a first diameter, further comprising a second converter having a distal end having a second diameter greater than the first diameter, wherein the first converter and the second converter are configured to interchangeably engage the preamp tip; and the housing base and the preamp tip being a unitary structure.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description set forth below is intended as a description of various configurations of the present invention and is not intended to represent the only configurations in which the present invention may be practiced. It will be apparent, however, to those of ordinary skill in the art that the present invention is not limited to the specific details set forth herein and may be practiced without these specific details.

It is to be appreciated that the present teaching is by way of example only, not by limitation. The concepts herein are not limited to use or application with a specific system or method. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, it will be appreciated that the principles herein may be applied equally in other types of systems and methods.

Referring toFIGS. 1-6, the present invention is described as a phantom powered preamp100that may use phantom power from a power source. In certain embodiments, the present invention may allow the phantom powered preamp100to connect to different sizes of precision condenser microphones (e.g., ½ inch microphone56and ¼ inch microphone54). This allows the phantom powered preamp100to provide a wide frequency range, a wide range of inherent noise, maximum sound pressure level, sensitivity, and microphone sound field response types (e.g., free-field, random incidence, and pressure) for microphone systems using the phantom powered preamp100. Table 1 provides example configurations/specifications that may be achieved with selected microphone cartridges54,56along with the phantom powered preamp100.

The phantom powered preamp100may provide durability and flexibility by being configured to be operable with the precision condenser microphones manufactured by PCB Piezotronics (e.g., Model Nos. 377B02, 377A06, and 377C01) and prepolarized condenser microphones manufactured by others with the same or similar mating/mounting geometry. This may allow the phantom powered preamp100to be operated with equipment commonly used in the audio industry, such as mixing boards or studio microphone preamplifiers, e.g., the Millennia Media HV-3C.

In one embodiment, the phantom powered preamp100may include a housing base30that may house electrical components of the phantom powered preamp100and a preamp tip32that may further house the electrical components of the phantom powered preamp100and a mechanical microphone interface (e.g., ¼ inch microphone interface58and ½ inch microphone interface60). The preamp tip32may be an extension of or connected to the housing base30of the phantom powered preamp100.

As illustrated inFIG. 4, the housing base30of the phantom powered preamp100may include PC board assembly10(which may extend into the preamp tip32), an XLR connector24, a spring26, an internal retaining ring28, a support bracket34, a screw36, an XLR ground lug epoxy42, and a wire44.

The PC board assembly10of the phantom powered preamp100may include discrete transistors, resistors, capacitors, and/or diodes. The PC board assembly10may also include integrated circuits (e.g., op amps). A function of the integrated circuits may be to condition a high impedance output signal of the microphone54,56to a low impedance. The PC board assembly10may also include additional amplification and/or conditioning circuitry suitable for the intended purpose and understood by one of ordinary skill in the art. As shown inFIG. 4, the PC board assembly10may extend from the housing base30to the preamp tip32of the phantom powered preamp100.

The XLR connector24of the phantom powered preamp100may be a 3 pin male XLR connector. The XLR connector24may provide an interface to cabling, e.g., cabling to the power source. The XLR connector24may be an electrical connector found on professional audio, video, and stage lighting equipment. The XLR connector24may be circular in design and have between 3 and 7 connector pins. The XLR connector24may be associated with balanced audio interconnection, including AES3 digital audio, but may also be used for lighting control, low-voltage power supplies, and other applications. The XLR connector24may be available from a number of manufacturers and are covered by an international standard for dimensions, IEC 61076-2-103, incorporated herein by reference. The XLR connector may be any connector suitable for the intended purpose and understood by one of ordinary skill in the art.

The spring26of the phantom powered preamp100may carry a ground connection to the housing base30of the phantom powered preamp100. The spring26may also be positioned in an interior region of the housing base30and proximate to an end closest to the preamp tip32. The spring26may be made of metal or any other conductive material suitable for the intended purpose and understood by one of ordinary skill in the art.

The internal retaining ring28of the phantom powered preamp100may hold the PC board assembly10, and all components attached thereto, in the housing base30and the preamp tip32of the phantom powered preamp100. The internal retaining ring28may be made of plastic, rubber, a polymer, polyurethane, or any other material suitable for the intended purpose and understood by one of ordinary skill in the art.

The support bracket34of the phantom powered preamp100may support a narrow section of the PC board assembly10of the phantom powered preamp100. The support bracket34may include at least two support brackets and be positioned within the housing base30and the preamp tip32of the phantom powered preamp100. The at least two support brackets34may be positioned on a top and bottom surface of the PC board assembly10of the phantom powered preamp100to provide additional support to the PC board assembly10.

The screw36of the phantom powered preamp100may be at least one screw that may affix the at least two support brackets of the support bracket34to the top and/or bottom surface of the PC board assembly10of the phantom powered preamp100.

The XLR ground lug epoxy42of the phantom powered preamp100may securely hold a ground lug of the XLR connector24in place. The XLR ground lug epoxy42may be epoxy, glue, resin, or any other adhesive suitable for the intended purpose and understood by one of ordinary skill in the art.

The wire44of the phantom powered preamp100may electrically couple the XLR connector24to the PC board assembly10of the phantom powered preamp100. The wire44may also be any type of connector suitable for the intended purpose and understood by one of ordinary skill in the art.

As illustrated inFIG. 5, the preamp tip32of the phantom powered preamp100may include a pogo contact12, an inner insulator14, a pogo adapter16, a guard tube18, an O-ring20, an outer insulator22, a guard tube polyamide tape38, a preamp tip epoxy40, a screw epoxy46, and a screw polyamide tape48.

The pogo contact12and the pogo adapter16of the phantom powered preamp100may provide a signal connection between the microphone54,56and the phantom powered preamp100. For example, the pogo contact12may be a pogo pin that may be used in electronics to establish a connection (e.g., usually temporary) between the PC board assembly10and the microphone54,56. The pogo pin may be in the shape of a slender cylinder containing a spring-loaded pin. The pogo adapter16may be securely fastened to the PC board assembly10, and the pogo contact12may be securely fastened to the pogo adapter16, thereby electrically coupling the PC board assembly10to the microphone45,56.

The inner insulator14of the phantom powered preamp100may electrically insulate the pogo contact12from the guard tube18and may center the pogo contact12. The outer insulator22of the phantom powered preamp100may electrically insulate the guard tube18from the preamp tip32and may center the guard tube18. The inner insulator14and the outer insulator22may be made of any insulative material suitable for the intended purpose and understood by one of ordinary skill in the art.

The O-ring20of the phantom powered preamp100may decrease compliance and may be made of rubber, latex, polymer, or any other material suitable for the intended purpose and understood by one of ordinary skill in the art.

The guard tube polyamide tape38of the phantom powered preamp100may electrically insulate the guard tube18from the preamp tip32of the phantom powered preamp100. The screw polyamide tape48of the phantom powered preamp100may secure the at least one screw36in place while the screw epoxy46is curing.

The preamp tip epoxy40of the phantom powered preamp100may permanently affix the housing base30to the preamp tip32of the phantom powered preamp100. The screw epoxy46of the phantom powered preamp100may lock the at least one screw36into the support brackets34of the phantom powered preamp100. The preamp tip epoxy40and the screw epoxy46may be epoxy, glue, resin, or any other adhesive suitable for the intended purpose and understood by one of ordinary skill in the art.

The phantom powered preamp100may be configured to be connectable to a ¼ inch converter50and a ½ inch converter52. The ½ inch converter52may be generally cylindrical in shape. The ¼ inch converter50of the phantom powered preamp100may provide a smooth transition from the preamp tip32to the housing base30to reduce edge diffraction. The ½ inch converter52of the phantom powered preamp100may provide a smooth transition from the ½ inch microphone56to the housing base30to reduce edge diffraction. Users of the phantom powered preamp100may also leave the microphone56connected to the converter52to reduce wear on the microphone52thread.

The unique mechanical interface between the microphones54,56(e.g., microphone cartridges) and the phantom powered preamp100may provide a method for mechanically adapting to different size microphones54,56(e.g., ¼ inch and ½ inch) without using an adapter to connect to small, fine microphone threads. Connecting the microphones54,56directly to the phantom powered preamp100may provide a stronger, more rugged connection and a more compact design because this does not change the overall length of the phantom powered preamp100.

The guard tube18housed in the preamp tip32may reduce parasitic capacitance of the phantom powered preamp100. The phantom powered preamp100may not need another guard to maintain low parasitic capacitance. The guard tube18of the phantom powered preamp100may be a metal tube surrounding an output node of the microphone54,56driven by a low impedance source with a voltage signal equal in magnitude and phase to the output from the microphone54,56. This, in turn, eliminates the voltage across the stray capacitance at the input to the preamp tip32, thereby negating its effect on the microphone54,56. The phantom powered preamp100may maintain the position of the microphone54,46output node for different microphone cartridge54,56sizes so that the guard tube18in the preamp tip32may be effective for all compatible microphones54,56. An illustration of the guard tube18is shown inFIG. 6.

As further illustrated inFIG. 6, the guard tube18of the phantom powered preamp100may be inside an elongated, generally cylindrical section of the phantom powered preamp100. The guard tube18may be a conductive tube that encapsulates front end electronics. The guard tube18may be soldered to the PC board assembly10and may be the same electrical potential as the input voltage from the microphone54,56. This may reduce or eliminate parasitic capacitance in a preamplifier circuit path to optimize performance of the phantom powered preamp100.

The phantom powered preamp100may further include threads62between the housing base30and the preamp tip32. The threads62may also be on an exterior surface of the preamp tip32and approximate to a side of the preamp tip32that may be the closest to the housing base30. The threads62of the phantom powered preamp100may not wear appreciably with repeated use.

FIG. 3is a side elevational view of the phantom powered preamp100including the housing base30. The housing base30of the phantom powered preamp100may be an elongated, generally cylindrical section. The preamp tip32of the phantom powered preamp100may receive the converter sections50,52. The distal end of the preamp tip32(e.g., leftmost portion ofFIG. 3) may be a connector for an electrical connection to the microphone cartridge54,56. The distal end of the converter sections50,52may provide a mechanical connection and be releasably engaged to the microphone cartridge54,56. For example, the microphone cartridge54,56may be electrically coupled to the preamp tip32and mechanically coupled to the ½ inch converter52.

Therefore, while the presently-preferred forms of the phantom powered preamp100have been shown and described, and several modifications discussed, persons skilled in this art will readily appreciate that various additional changes may be made without departing from the scope of the invention disclosed herein. For example, adaptation to other microphone sizes (e.g., 1 inch diameter microphones) and non-phantom powered preamp topologies, and mechanical adaptation to other preamp topologies (e.g., ICP®, multi-wire). Other mechanical interfaces to connect the converters to the housing (such as bayonet style, ball detents, double start threads, magnets).