Field of the Invention

[2] The present invention relates to a phantom powered circuit for selectively boosting an analogue audio signal.

Summary of the Disclosure

[3] In accordance with certain embodiments provided herein, there is provided a circuit for selectively boosting an analogue audio signal. Specifically, as will be described in further detail below, the circuit may be utilised during onstage performances and the like wherein, when required, such as during a solo or the like, the circuit may be user activated to boost an audio signal.

[4] For example, an audio signal received from a microphone may be selectively boosted during a vocal solo or the like.

[5] Further specifically, in embodiments, the circuit provided herein may be utilised for active microphones such as those comprising condenser microphones requiring a power source. As will become apparent from the ensuing description, the circuit allows for the boosting of the audio signal while providing phantom power (such as at 48 V) to the active microphone or other input electrical componentry requiring power.

[6] As such, according to one aspect, there is provided a phantom powered circuit for selectively boosting an analogue audio signal, the circuit comprising: an input for receiving an input audio signal from active input requiring power (such as an active microphone, pickup or like requiring power); an output for outputting an output audio signal; a DC block between the input and the output, the DC block in a further preferred embodiment, and comprising an input transformer connected to the input and an output transformer connected to the output; and a boosting circuit between the input transformer and the output transformer, the boosting circuit selectively user operable in use to selectively boost the audio signal; and a phantom power line connected between the output and input transformers, the phantom power line configured for bypassing the DC block by supplying DC power from the output to the input.

[7] The phantom power line may be connected to respective centre taps of the output and input transformers.

[8] The boosting circuit may be configured to attenuate the audio signal in a default configuration and wherein, when selectively user operated, to not attenuate the audio signal.

[9] The boosting circuit may comprise a resistive network connected between the input and the output, the resistive network configured to attenuate the audio input signal such that the output audio signal may be attenuated; and a switch network connected to the resistive network, the switch network user selectively operable to configure the resistive network such that the output audio signal may be not attenuated.

[10] The switch network may be configured to bypass the resistive network

[11] The resistive network may comprise a resistor divider network.

[12] The resistor divider network may be a fixed resistor divider network.

[13] The resistor divider network may be a user configurable variable resistor divider network.

[14] The resistor divider network may comprise a set of resistor divider networks each configured to produce a predetermined volume drop and wherein each of the set of resistor divider networks may be user selectively connectable.

[15] The resistor divider network may be configured to attenuate the output audio signals so as to produce an approximate 3 dB volume drop.

[16] The resistor network may comprise a first resistor and a second resistor in series, the output being connected between the first resistor and the second resistor; and the switch network may comprise a first switch in parallel with the first resistor and a second switch in series with the second resistor.

[17] The switches are configured to default to a configuration wherein the audio signal flows through the resistive network.

[18] The switch network may be user selectively operable to reverse the switch positions of the switches.

[19] The switches are configured to change state substantially simultaneously.

[20] The circuit may comprise a double pole double throw switch comprising the first switch and the second switch.

[21] The boosting circuit may comprise an active amplifier.

[22] The resistive network may be directly connected to the input.

[23] The resistive network may be directly connected to the output.

[24] The resistive network may be directly connected to the input transformer.

[25] The resistive network may be directly connected to the output transformer.

[26] The active amplifier may be powered from power supplied by the phantom power line.

[27] The circuit may further comprise an effects loop output and an effects loop input for signal conditioning/processing of the audio signal using a signal conditioning/processing circuit.

[28] The circuit may further comprise an output signal level adjustment means configured for controlling the level of audio signal output to the effects loop input.

[29] The circuit may further comprise a further input signal level adjustment means configured for controlling the level of audio signal input from the effects loop output. [30] The circuit may further comprise a plurality of effects loop outputs and a plurality of associate effects loops inputs for signal conditioning/processing of the audio signal using a plurality of signal conditioning/processing circuit.

[31] Other aspects of the invention are also disclosed. Brief Description of the Drawings

[32] Notwithstanding any other forms which may fall within the scope of the present invention, a preferred embodiment of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[33] Figure 1 shows a circuit for selectively boosting an analogue audio signal in accordance with a first embodiment of the present disclosure;

[34] Figure 2 shows circuit for selectively boosting an analogue audio signal comprising an active circuit in accordance with a second embodiment of the present disclosure;

[35] Figure 3 shows circuit for selectively boosting an analogue audio signal wherein the audio signal may be fed through an effects loop in accordance with a third embodiment of the present disclosure.

Description of Embodiments

[36] For the purposes of promoting an understanding of the principles in accordance with the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the disclosure as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the disclosure.

[37] Before the structures, systems and associated methods relating to the circuit for selectively boosting an audio signal are disclosed and described, it is to be understood that this disclosure is not limited to the particular configurations, process steps, and materials disclosed herein as such may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the disclosure will be limited only by the claims and equivalents thereof.

[38] In describing and claiming the subject matter of the disclosure, the following terminology will be used in accordance with the definitions set out below.

[39] It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. [40] As used herein, the terms "comprising," "including," "containing," "characterised by," and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps.

[41] It should be noted in the following description that like or the same reference numerals in different embodiments denote the same or similar features.

[42] In the accompanying illustrations, there is shown a circuit for selectively boosting an analogue audio signal. As will be described in further detail below, the circuit may be utilised by musicians and the like for selectively increasing the relative volume of an audio signal, such as when performing solos and the like.

[43] Specifically, the circuit may lower the voltage of an audio signal path in a default state such that, during normal playing, the circuit lowers the voltage by approximately 3 dB. However, it should be appreciated that in other embodiments, the circuit may be configured to lower the voltage by other ratios.

[44] Now, when the musician wishes to perform a solo for example, or otherwise requires an increase in the volume, the musician may control the circuit to boost the audio signal such that the circuit returns a voltage to the normal voltage level (or boosts the voltage level even further) to increase the volume of the audio signal.

[45] Specifically, in the embodiments that follow, the circuit may comprise a passive circuit as is described below with reference to the first embodiment and an active circuit described below with reference to the second and third embodiments.

[46] In embodiments, the circuit may be foot activatable or controlled remotely, such as by wired or wireless interface.

[47] In embodiments, the circuit may be packaged in portable small form factor electronics componentry housing so as to be readily portable for deployment on stage, music sets and the like. Additionally, the circuit may form part of a mixer, wireless system, other audio processing unit or the like.

[48] Furthermore, the circuit may provide phantom power for those inputs requiring power, such as active microphone such as condenser microphones.

[49] As such, the circuit is configured for selectively boosting an analogue audio signal in comprising an input for receiving an input audio signal from an active microphone and an output for outputting an output audio signal. The circuit further comprises a DC block between the input and the output, the DC block allowing the audio signal to pass between the input and the output and comprising an input transformer connected to the input and an output transformer connected to the output. The circuit further comprises a boosting circuit between the input transformer and the output transformer, the boosting circuit selectively user operable in use to selectively boost the audio signal. As alluded to above, the boosting circuit may be a passive circuit is a substantially shown in figure 1 wherein, in a default configuration, the boosting circuit is configured to attenuate the audio signal wherein, when user activated, the boosting circuit is configured to not attenuate the audio signal or at least attenuate the audio signal by a lesser amount. In other embodiments such as that which is described with reference the second and third embodiments below, the booster circuit may comprise an active amplifier and therefore may control the gain of the audio signal so as to actively boost the audio signal when required.

[50] The circuit preferably further comprises a phantom power line connected between the output and input transformers, the phantom power line configured for bypassing the DC block by supplying DC power from the output to the active microphone.

Passive circuit in accordance with a first embodiment

[51] Referring to figure 1, there will now be described a passive circuit in further detail for selectively boosting an audio signal from a musical instrument, microphone or the like in accordance with a first embodiment. As will also become apparent, in a preferred embodiment, the passive circuit 1 is further configured for supplying phantom power to the input, so as to be utilised for an active microphone such as a condenser microphone.

[52] The passive circuit 1 comprises an input 2 for receiving an input audio signal from the musical instrument, microphone or other input. For example, input audio signal may be received from a microphone especially, in a preferred environment, and active microphone requiring DC powering, but, in other embodiments, may be received from any other source, such as an electrical guitar pickup, a line level signal or the like. Furthermore, the circuit comprises an output 3 to output an audio signal such as to a mixer, amplifier or the like.

[53] Furthermore, the circuit comprises a resistive network connected between the input 2 and the output 3.

[54] The resistive network is configured to attenuate the audio input signal in a default configuration such that the output audio signal is attenuated.

[55] As alluded to above, in one embodiment, the resistive network (comprising resistors Rl 6 and R2 7 in the embodiments shown) is configured such that the voltage of the output audio signal is attenuated so as to produce substantially 3 dB drop in volume.

[56] Whereas in figure 1, the resistive network is shown as fixed, in embodiments, the resistive network may be a variable resistive network, so as to allow the user selection of an appropriate volume drop. For example, in embodiments, the variable resistive network may comprise a variable resistor/potentiometer or the like so as to allow for the scaling of the volume drop. In other embodiments, the resistive network may comprise a set of resistive networks and associated user operable selection switches so as to allow for a user selection of discrete preconfigured volume drop amounts.

[57] In embodiments, the resistive divider connected between an input transformer Tl 4 and an output transformer T2 5 wherein, in embodiments, the resistive divider may be connected across only some of the windings of the transformers.

[58] The circuit 1 may further comprise a switch network (comprising switches SI 9 and S2 8) connected to the resistive network. The switch network is user selectively operable to configure the resistive network such that the audio signal can be non-attenuated or attenuated.

[59] As such, in use, the circuit 1 is configured such that the output audio signal at the output is attenuated so as to provide the appropriate volume drop. However, when required, such as when the musician performs a solo as alluded to above, the switch network is configured by the user so as to configure the resistive network such that the output audio signal at the output is non-attenuated.

[60] In the embodiment shown in Figure 1, the switch network is configured to allow the audio signal to bypass the resistive network. Specifically, in the embodiment shown, the resistive network comprises a divider network as is shown in figure 1 comprising resistor Rl 6 and resistor R2 7.

[61] Furthermore, the switch network may comprise a pair of switches comprising switch SI 9 in parallel with the resistor Rl 9 and switch S2 8 in series with resistor R2 7.

[62] As can be seen, SI 9 may be open by default and S2 8 closed by default.

[63] In the default configuration, switches SI 9 and S2 8 may be configured such that the resistor divider provided by Rl 9 and R2 7 is operably connected. However, when actuated by the user, switches SI 9 and S2 8 may open/close simultaneously such that resistor Rl 6 is bypassed and resistor

R2 7 disconnected from the network such that the input is directly electrically connected to the output.

[64] In embodiments, so as to allow for the simultaneous throwing of switches SI 9 and S2 8, the circuit may comprise a double pole double throw switch.

[65] The switch or switches may be mechanical or be of a purely electronic variety i.e. I.C. or FET switch(es).

[66] In embodiments, the resistive network may be utilised in conjunction with an active circuit, such as that which may comprises active opamps, including in the second embodiment described in further detail below with reference to figure 2.

[67] In a preferred embodiment, the circuit 1 may comprise a DC block allowing the audio signal to pass between the input and the output. In the embodiment shown in figure 1, the DC block may comprise at least one transformer. In the preferred embodiment shown, the circuit 1 comprises an input transformer Tl 4 and an output transformer T2 5.

[68] In a further preferred embodiment, the circuit comprises 1 a phantom power line 10 connected between the output and input transformers, the phantom power line configured for bypassing the DC block by supplying DC power from the output to the active microphone.

[69] As alluded to above, the phantom power line 10 may be utilised for applications where the input requires power, such as when utilising an active microphone such as a condenser microphone.

[70] As such, as can be seen, the circuit 1 may comprise the phantom power line 10 operably coupling the input and the output.

[71] In one embodiment, the phantom power line 10 is electrically connected to the centre taps of the respective transformers. In this manner, the circuit 1 is configured to pass the AC audio signal and allow for the DC voltage supplied from the mixer to power the microphone or other electronic circuitry input.

Circuit in accordance with a second embodiment

[72] Turning now to figure 2, there is shown the circuit 1 in accordance with a second embodiment. As can be seen, the circuit 1 is characterised in that the circuit 1 comprises an active circuit 11 in lieu of the passive resistive and switch network provided above. The active circuit 1 may be utilised for superior frequency response as opposed to that of the passive network of the first embodiment.

[73] As alluded to above, in these embodiments comprising an active circuit 1, the active circuit 1 may actively control the gain of the audio signal in actively boosting the audio signal. In other words, the active circuit 1 is able to actively boost the audio signal as opposed to merely attenuate or not attenuate the audio signal as was described above for the passive circuit.

[74] Specifically, in this embodiment, the functionality of the dividing resistive network provided above is substituted with an active circuit, such as an opamp having an associated dividing resistive network configured for providing the voltage level attenuation described above. Specifically, the resistive divider may be part of the active circuit or the resistive divider may be part of a feedback circuit within the active circuit.

[75] Furthermore, the dividing resistive network associated with the active circuit may be switched utilising electronic switching as opposed to the mechanical switching described above, such as by comprising FET switching which, when switched, configures the opamp (or the like) such that the output voltage is substantially non-attenuated.

[76] In embodiments, the active circuit may comprise different types of amplifiers including discreet, valve, opamps, FET, hybrid amplifiers and the like. As such, the gain may be selectively cut or boosted in the same manner as is the case for in the resistive divider circuit of the first embodiment shown in figure 1 and by using the same or similar means of control, either directly connected or remotely.

[77] Furthermore, the resistive network associated with the active amplifier may differ to that which is described above with reference to the passive circuit of the first embodiment. Specifically, the resistive network may be used between the input transformer Tl 4 and the active circuit 11 or vice versa. Furthermore, the resistive network may be used in the feedback loop of an amplifier of the active circuit 11, such as an op amp.

[78] In one embodiment, such feedback may be increased using a FET switch that shorts the feedback loop of an opamp, thus reducing the gain from 1.6 to 1. Furthermore, the other half of the opamp can be used to boost the signal from mic level to guitar pedal level (for feeding to the signal conditioning/processing circuit 12 described in further detail below) or line level. The return from the signal conditioning/processing circuit 12 (such as one comprising guitar pedals) is then reduced back to microphone level.

[79] The overall gain of the circuit 1 can also be adjusted by any means to increase or decrease the output signal relative to the input signal.

[80] In embodiments, power for the active circuit 11 may also be drawn from the phantom power supply 10. However, in other embodiments, the active circuit 11 may be powered independently.

Circuit in accordance with a third embodiment

[81] Turning now to figure 3, there is shown the circuit 1 in accordance with a third embodiment.

[82] As can be seen from figure 3, the circuit 1 yet comprises the active circuit 11 of the second embodiment of figure 2 however, the circuit 1 feeds the audio signal out to a signal conditioning/processing circuit 12 as an "effects loop".

[83] For example, in embodiments, the audio signal may be fed to various guitar effects pedals, such as those adding reverb and the like.

[84] As can be seen, the active circuit 11 has an effects loop output feeding into an effects loop input 14 of the signal conditioning processing circuit 12 and an associated input for receiving the condition/processed signal from an associated output 13 of the signal conditioning/processing circuit 12.

[85] In embodiments, the active circuit 11 may be configured to control the signal level fed to the processing circuit 12. In this embodiment, the circuit 1 may comprise an output signal level adjustment means configured for controlling the level of the audio signal output to the effects loop output. Furthermore, in embodiments, the circuit 1 may further comprise an input signal level adjustment means configured for controlling the level of audio signal input from the effects loop output. [86] In further embodiments, the active circuit 11 may feed the audio signal to a plurality of signal conditioning/processing circuits 12 substantially simultaneously wherein, in yet further embodiments, the active circuit 11 may control the levels fed to each of the plurality of the signal conditioning/processing circuits 12. Such control may be achieved by a signal level adjustment means, such as that which comprises a passive or active divider resistive network which may be set or continuously variable. The active circuit 11 may control the levels fed from each of the plurality of the signal conditioning/processing circuits 12. Such control may be achieved by a signal level adjustment means, such as that which comprises a passive or active divider resistive network which may be set or continuously variable.

[87] Furthermore, an interface such as that which utilises transformers in a similar or more conventional manner to those described above may be interposed between the active circuit 11 and the at least one signal conditioning/processing circuit 12 on any input or output.

Application

[88] As can be appreciated, the circuit 1 described above may be configured for the following applications:

a. Acoustic guitars with built-in microphones and/or transducers and/or preamp outputs b. Electric guitars with built-in microphone, transducer, pickups and/or preamp outputs c. Electronic instruments such as keyboards and drum machines

d. Wireless microphone systems incorporated into the wireless system with or without a remote control

e. For insertion into the sound reproduction signal path (usually through a mixer) with or without a remote control

f. For insertion over a subgroup of instruments such as a multi-microphone percussion set up

g. Insertion over a subgroup of instruments such as a horn section or backup singers h. For use with contact microphones used in musical instruments or other applications i. For insertion into the microphone signal path of a vocalist or instrumentalist such as a brass or woodwind player in a live or recording situation, such that the musician can operate the switching circuit at any time. Interpretation

Embodiments:

[89] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[90] Similarly it should be appreciated that in the above description of example embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description of Specific Embodiments are hereby expressly incorporated into this Detailed Description of Specific Embodiments, with each claim standing on its own as a separate embodiment of this invention.

[91] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Different Instances of Objects

[92] As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

Specific Details

[93] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Terminology

[94] In describing the preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "forward", "rearward", "radially", "peripherally", "upwardly", "downwardly", and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

Comprising and Including

[95] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

[96] Any one of the terms: including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

Scope of Invention

[97] Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

[98] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.