FIELD OF THE INVENTION The invention is directed to improved circuitry for audio signal amplification and, more specifically, to an amplifier design that incorporates a unique biasing subcircuit for preloading the amplifier with a known error value thereby reducing movement of a bias point of the amplifier along its hysteresis curve.

BACKGROUND OF THE INVENTION While it is easy to understand that lowering distortion in an amplifier is beneficial, it has been well documented in the high-end audio industry that merely having low distortion figures does not guarantee high performance audio. Particularly, the argument of"analog vs. digital" or"tubes vs. transistors"has gone on for decades with no clear resolution as to the better technology. It seems to defy logic that a higher distortion (0.5%) tube amp would sound better than a considerably lower distortion (0.005%) transistor amp. Transistor amps are superior in dominating the bass region because of their direct (transformer-less) output, low impedance drive to loudspeakers. In addition, because the Total Harmonic Distortion (THD) of a transistor amp is low, the amp also exhibits better linearity (for bass frequencies). However, a transistor amp does not seem to be able to compete with the"transparent"nature of tube amps when processing more complex and dynamic waveforms such as speech or music especially at higher frequencies.

Consider a signal as it is inputted to an amplifier: as the number of obstacles (circuit elements) in the path (amplifier circuitry) increases, so does the amount of damage to the original, pure input signal. Tube amplifiers have a relatively low parts count (one or two triodes and a pair of output tubes). As such, the input signal integrity remains mostly intact and the output waveform or"sound"of the tube amplifier is an easy and enjoyable listening experience. However, for the same reason of the low parts count and low feedback, a tube amplifier's finite linearity degrades causing a small displacement of phase angles in the output waveform that generates harmonics. This displacement or error is detected by a THD analyzer using a sine wave reference signal. While the THD analyzer detects this type of distortion, a listener does not sense a greatly decreased quality output signal. As such, the tube amplifier can adequately perform with minor"phase"error to the output signal.

Transistor amplifiers (e. g., operational amplifiers or op amps) use a fair number of circuit elements in order to create sufficient open loop gain so that a negative feed back (NFB) loop can be used to lower any distortion. The NFB loop is a phase locked loop or servo system designed to force the output signal to closely match the input signal.

Classically, the greater the amount of NFB applied to the input signal, the lower the distortion level at output. As such, a THD analyzer indicates that the input signal was processed through the amplifier apparently unharmed. That is, there are little or no detectable harmonics in the output signal because the high level of NFB does not allow phase shift to occur. However, the integrity and believability of the complex (musical) signal is badly damaged by a series of obstacles and events which are imposed on the signal as it makes its way to the output. As such, what the listener hears is not a true representation of the original input signal. The advantage of using NFB to maintain or improve the integrity of the input signal as it processed by a transistor amplifier is reduced because

phase-shifting is not the only type of signal distortion.

Moreover, to be effective, the NFB (including the non-phase- shift-damaged signal) has to be combined with the input signal in real time to be effective.

A closer examination of the NFB loop reveals its inadequacy as a non-phase-shift-error reducing mechanism.

Upon an original signal first entering an op amp (at the differential or input stage), the inverting input senses no feedback signal because this original signal (i. e., the first sound fragment) is still traveling down the signal path (numerous circuit elements). Since at this time there is no feedback signal, the instantaneous"solution" developed by the input stage is to turn up the drive to the output stage until a feedback signal is received. Hence, the input stage is trying to establish a"link"to the output stage to properly process the input signal. Until the op amp has established this"link" (e. g., via feedback) there is a fatal error in that the op amp has apparently lost contact with the traveling signal. When the output finally does appear, it is not a good representation of what was applied to the input because no correction (via feedback) has been imposed on the signal as it entered the stage. To further compound this condition, the time-delayed feedback signal is combined with another signal (i. e., the second sound fragment) currently entering the op amp. This new signal has no relation to the feedback signal. In other words, what is being fed back to the input is old information. For this reason, the use of more NFB only causes more damage to the signal. This condition not only occurs for a brief moment at the startup of a signal entering the op amp, but also whenever the signal potential and polarity crosses over from positive to negative and vice versa as explained in greater detail below.

This type of signal damage occurs because the op amp output terminal is held at ground potential (zero volts) because of the attached load resistance. Since an initial feedback signal is generated only after the combined delay times of all the devices in the circuit have been overcome,

a hysteresis curve effect occurs in the amplifier. For example, an amplifier in a steady state condition may be positively biased at bias point"P". During a voltage swing, if the output terminal detects an impedance (combination of resistive and capacitive loading), the feedback solution calls for additional source mode current to compensate for the load resistor and charge the capacitor in parallel. As a positive going signal reaches the peak of its potential and turns in the negative direction, the load resistor voltage and current drops and capacitor starts discharging. If the signal is a high frequency signal with a rapid turn in the downward direction, it is possible that the charge still remaining on the capacitor will cause the input stage to"think"that the output terminal has fallen behind or is not responding. The new solution then calls for sink mode current to force the output terminal voltage downward to quickly discharge the capacitor. When the circuit responds in this manner, it moves from bias point "P"along the hysteresis curve from positive"source mode" to negative"sink mode"ultimately coming to rest a bias point"N". As such, the initial"link"is broken for a short period and is then re-established at the negative region of the hysteresis curve. Since the amplifier has no reference during this transition, it"blacks out"and any data entering the stage (e. g., a third sound fragment) for the duration of the blackout is essentially lost.

The random nature of musical information increases the likelihood that these rapid signal turns occur very often.

Every time such a turn occurs, there is a shifting of bias point along the hysteresis curve and resultant op amp "blackout". Additionally, the random switching from source mode to sink mode at places other than the zero crossover point causes a"backlash"within the NFB loop. An analogy can be drawn between the op amp and a gearbox for amplifying mechanical motion. Once an initial force is applied to an input shaft attached to a first gear, the small space between the teeth of first gear and the teeth of a second gear must be overcome before the second gear turns.

Likewise, the spaces between all remaining gears must be overcome until an output shaft begins to turn. If a clockwise force on the input shaft is reversed (made counter-clockwise) the gears will momentarily lose contact with each other because of the spaces between the teeth or "play". During this time, the output shaft is not responding accordingly and"black outs", until all the "play"is taken up, then the output shaft moves proportionally (in the new direction). The loss of contact not only occurs at the general reversal of direction but also when the mechanical model includes the effect of mass or inertia on the output shaft. Any drag experienced by the output shaft may call for the reversal of previous gears just to stop the forward motion of the output shaft. The play in the gear teeth is analogous to the bias point movement along the hysteresis curve and blacking out phenomenon of the op amp.

The exact velocity and duration of the random input signal turns and resultant blackouts have a specific size and represent the smallest useable signal level that can be processed by the op amp. Unfortunately, this useable signal level is often greater than small signals that represent the quieter background objects of a sound image. As such these small signals are lost whenever the circuit moves along the hysteresis curve from the positive region to the negative region and vice versa. The overall effect is a"digitizing" of the input signal with some bits missing from the output signal. This distortion affects the continuity of the signal, limits the depth of an audio image and removes the lifelike believability of the audio image (e. g., when projected by a loudspeaker).

To summarize, a tube amplifier delivers a slightly phase damaged signal but retains signal continuity. As such, tube amps sound more lifelike due to the analog nature of human auditory sensing abilities. Transistor amplifiers sound better because they have a higher degree of linearity through the use of NFB. However, the characteristics of transistor circuitry cause critical signal blackouts that

are detected by humans which decreases signal quality and listening experience. Therefore, there is a need in the art for an amplifier that retains the continuity of an input signal yet performs in a low or non-distorting, highly linear manner without relying on NFB to provide correction signals.

SUMMARY OF THE INVENTION The disadvantages heretofore associated with the prior art are overcome by an inventive signal amplifying device which includes a main amplifier engine having an input stage and an output stage connected thereto and a current generator connected to said main amplifier engine.

Specifically, the current generator is connected to the output stage of the main amplifier engine and provides a current to the input stage via the output stage. This backtracking current pre-biases the amplifying device so that is does not rely on negative feedback for signal correction purposes. The apparatus further has a buffer connected to the main amplifier engine which serves as a high output impedance device. The apparatus further has a filter disposed between the main amplifier engine and the current generator which prevents AC signals processed by the amplifying device from entering or otherwise corrupting the current generator.

The amplifying device serves as a building block by which a variety of higher order circuits can be configured.

In one embodiment, a clone generating circuit is configured from three amplifying devices. A first amplifier device acts as a transmitter, a second amplifier device acts as a stable current source for the transmitter and a third acts as a receiver of signals generated by the transmitter. In a second embodiment, several receivers of the first embodiment are linked together to create a high gain output signal that is a enlarged scale clone of the input signal. In a third embodiment, a power amplifier is configured for driving high end audio speakers. The power amplifier has an transmitter section, a receiver section and an output section. The

output section is a slightly modified version of the amplifier device that contains a more robust output buffer and separate biasing network. In a final embodiment, elements from all of the above circuits are configured to form a holographic cloning amplifier. As such, an input signal is not only duplicated without distortion, but also amplified so that it can be projected by conventional audio transducers to produce a holographic wavefront.

The embodiments discussed use only two speakers and only two electrical channels (left and right). The circuits do not manipulate the original signal by phase or frequency or by adding, subtracting or otherwise combining the two original channels to create a third (or more) signal (s).

Instead, original signals are processed in an improved linear and continuous manner so that the embedded spatial coding of any object in the original recording can be restored to it's original location in the projected soundfield during playback.

Brief Description of the Figures The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: FIG. 1 depicts a schematic block diagram of a basic amplifier circuit in accordance with the subject invention; FIG. 2a depicts a graph of voltage vs. time of an output waveform created by the circuit of the subject invention; FIG. 2b depicts a graph of voltage vs. time of an output waveform created by a prior art amplifier circuit; FIG. 3 depicts a schematic block diagram of a clone signal generating circuit in accordance with the subject invention; FIG. 4 depicts an alternate arrangement of the clone generating circuit configured to output a high gain signal; FIG. 5 depicts a schematic block diagram of a power amplifier circuit in accordance with subject invention;

FIG. 6 depicts a detailed circuit diagram of a preferred embodiment of the power amplifier of FIG. 5 for creating a high gain, holographic output signal suitable for driving audio transducers (speakers); FIG. 7a depicts a model representation of a recording studio containing three spatially arranged instruments each providing two distinct magnitude and phase vectors to recording devices; and FIG. 7b depicts a model representation of a playback room containing audio transducers that project the above mentioned instrument vectors as a holographic wavefront created by the circuits of the subject invention.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

DETAILED DESCRIPTION The subject invention provides for the reconfiguring of a conventional op amp circuit to operate in an"errorless" mode. That is, the circuit no longer waits for and then reacts to an initial error signal from the input. Instead, the circuit is"booted up"with a set of permanent and pre- programmed instructions. An exact, known error is injecte into the output of the amplifier, so that the differential front end (input) provides an immediate solution. The solution is passed through the circuit elements comprising the op amp to the output stage to fix the known error. As such, a link is immediately established between the input and output. The known error is created by injecting pure DC into the output of the op amp. The input detects this condition as a serious error at the output stage since the output level should be"zeroed out."The solution for the known error corrects the circuit (i. e., the offset potential is returned to normal) and biases the differential front end to a particular point of the hysteresis curve. As long as the known error does not change and there is no other activity, then the solution and instructions (through the

link) never change and the circuit remains"locked"at a set condition.

Specifically and in greater detail, FIG. 1 depicts a block diagram representation of basic amplifier circuit 100 in accordance with the present invention. The basic amplifier circuit 100 comprises a main amplifier engine 102, a buffer 104, a current generator 106 and a filter 108. An input signal 116 enters the circuit 100 via an input channel 112 connected to the main amplifier engine 102. Conversely, an (amplified) output signal 118 exits the circuit 100 via an output channel 114 also connected to the main amplifier engine 102 via the buffer 104. The main amplifier engine 102 further comprises an input stage 122 and an output stage 120 that perform the necessary operations on the input signal 116 (and other signals described below) to provide the amplified (i. e., increased magnitude) signal 118. The current generator 106 is connected to the output stage 120 of the main amplifier engine 102. The filter 108 is interposed between the current generator 106 and the output stage 120. The main amplifier engine 102 is any circuit component known to those skilled in the art that is capable of amplifying signals such as an UA 741 op amp. Likewise the input channel 112 and output channel 114 are fabricated from known circuit components and connectors. However, it will be clear to the reader that many other types of amplifiers, circuit components and connectors may be substituted for the above mentioned devices and this invention should not be limited solely to the devices listed.

In operation and as discussed earlier above, a predetermined"error"signal is provided to the main amplifier engine 102 to initially bias it in a predetermined direction. The error signal is provided by the current generator 106 in the form of a very low magnitude DC current flow referred to as a thread current (depicted by arrows 124). The thread current 124 follows a path 126 from the current generator 106, through the filter 108 and output stage 120 into the input stage 122. Effectively, the thread

current is executing a one-time unidirectional charging of the N junctions of semiconductor devices within the main amplifier engine 102 before any NFB is applied to the devices. As such, the gain of the main amplifier engine 102 is set to a single value in"open loop mode"and not limited by or derived from NFB. This predetermined error input has a known effect on the basic amplifier circuit 100 in that a) the circuit 100 recognizes the predetermined error as a near fatal offset error in the output stage; b) the circuit 100 derives the same known solution and set of instructions for removing the error every time the circuit is initially biased; c) the known solution causes the input stage 122 of the main amplifier engine 102 to experience a permanent biasing point; and d) the known error is constantly provided to the circuit 100 so that the known solution maintains a continuous link or"wet"connection between the input stage 122 and the output stage 120. The term"wet connection"is known to those in the field of the invention and is understood to be a link between two points that although is barely existing or perceptible, is functional in establishing communication between said points.

Since the circuit is forced to maintain a continuous link between the input and output stages, any input signal 116 triggers an immediate output signal 118. For the circuits depicted and discussed in this disclosure, the initial biasing shifts the circuit into a positively biased region. However, this does not preclude other biasing schemes (i. e., into a negatively biased region) which would be apparent to those skilled in the art. In other words, as an input signal rises and falls, the circuit remains slightly more or slightly less positively biased. As such, the input stage never moves through the negative portion of the hysteresis curve. Hence, the amplifier suffers no "blackout"period and does not alter its single bias point.

The current generator 106 is an extremely pure element or elements (reference source) capable of delivering an

extremely stable current (on the order of 15 parts per billion) and having an impedance of approximately several Gohms. Various devices and configurations of circuit elements can achieve these desired characteristics and are explained in greater detail below.

The effects of the aforementioned known error upon the circuit 100 are more readily seen by comparing FIGS. 2a and 2b. FIG. 2a depicts a graph of signal voltage vs. time in the subject invention and FIG. 2b depicts a graph of the same parameters in prior art amplifiers. In FIG. 2a, an entire input signal is treated as positive wavefront, 10V Peak-to-Peak (ac). Since the circuit has been previously positively biased and locked via the DC thread current, the gain is constant throughout the 360 degrees of the input signal and no hysteresis or harmonics is realized. In FIG.

2b, an input signal 204 is treated as a typical 10v Peak-to- Peak (ac) signal with actual positive 206 and negative 208 wavefronts respectively. This results in various inaccuracies during signal processing. For example, small differences in the gain values of positive and negative portions of a typical differential op amp result in the actual positive wavefront 206 having a magnitude (+4.9V Peak) which is slightly different from an ideal positive wavefront 210 magnitude (+5.0V Peak) and the actual negative wavefront 208 magnitude (-5.0V Peak). Such a condition causes harmonic distortion. Additionally, as the actual positive wavefront 206 transitions to the actual negative wavefront 208 at the various crossover points 212 in the signal, the circuit travels into the negative region of the hysteresis curve and attempts to rebias the circuit to perform accordingly. The time taken by the circuit to rebias is the referred to"blackout period". During this period, the circuit cannot process the very small portions of the input signal that represent background sounds.

Hence, these very small portions are lost and the amplified output signal is incomplete and distorted.

Additional circuit elements (i. e., load and feedback resistors) connected to the output channel of an amplifier

cause variations in the corrective instructions of a typical closed loop gain feedback signal. The subject invention provides a means for isolating the main amplifier engine 102 from the rest of the circuit 100. Specifically, the buffer 104 is an ultra high impedance (approximately 20Gohms), unity gain element that replaces load and feedback resistors and maintains the output channel in a nearly unloaded condition. As such, the buffer 104 prevents the output channel from having to source or sink additional current into a load resistor as voltage swings occur. Additionally, the buffer nearly matches the ultra high impedance of the current generator. Therefore, only the predetermined error is transmitted back to the input stage 122 via path 126 under dynamic conditions (the rise and fall of the input signal).

As mentioned above, the purity of the thread current 124 hence the current generator 106 are of great importance to the proper operation of the basic amplifier circuit 100.

Stability of the thread current 124 is additionally maintained via the filter 108. The filter 108 prevents any AC signal components from entering the current generator 106 while allowing the small (on the order of picoamperes) thread current to flow along path 126.

Additionally, the basic amplifier circuit 100 further comprises a feedback loop 110. Similar to typical amplifier circuits, the feedback loop 110 is connected between the output and input channels 114 and 112 to reduce the level of harmonic distortion in the output signal 118. In traditional amplifiers however, load and feedback resistors in the feedback loop limit the gain of the circuit. Since the thread current 124 is applied directly to the output stage 120, a continuous and constant gain is realized in the circuit 100 regardless of load and feedback resistor values.

That is, the circuit operates with a linear current transfer function whereby virtually all of the open loop voltage gain of the circuit is used to drive the feedback resistor solely for setting gain. Since the circuit has been previously biased by the thread current to maintain zero offset at the

output, a true phase lock loop is established and any attempts to add new current at the input results in an instantaneous (voltage) movement at the output.

Negative feedback (denoted by arrow 128) applied to the input stage 122 comprises a trickle current from the buffer and a feedback signal. Since the circuit 100 is stabilized, the output signal 118 (hence the negative feedback) is in sync with the input signal 116. With constant and continuous gain, small (background) signals are maintained throughout and processed by the circuit. The resultant output signal is totally stabilized"sound image"that contains foreground and background signals duplicated with the exact distance and phase angle of the original sound in relationship to recording devices (i. e., microphones in a recording studio). It should be noted that the high level of resolution afforded by the subject circuit is proportional to the purity of the thread current.

The above discussed basic amplifier circuit can be used in a variety of configurations to create extremely pure, nearly undistorted (either harmonic or small-signal-blacked- out) output waveforms. To facilitate further review of the disclosure, such output waveforms are referred to as clones.

One specific application for the basic amplifier circuit (BAC) 100 is for generating a clone signal is depicted in FIG. 3. FIG. 3 depicts a modified block diagram of a preferred clone generating circuit 300 comprising a transmitter portion 320 and a receiver portion 330. The circuit 300 is contained in an electromagnetic cage 332.

The cage can be fabricated from any type of material that prevents undesirable electromagnetic radiation or interference from entering and includes p METAL (MU) or similar steel alloys that are electromagnetically impermeable. A plurality of BAC's 100 are arranged within the circuit to provide an output clone of an input signal.

Specifically, an input signal 302 is applied to a first BAC 1001 (at an inverting input 303) through an input impedance (resistor) Ri 304. An inverted output signal 310 appears at node 312 and is reapplied to the BAC 1001 via an appropriate

feedback resistor Rf 306. For clarity it should be noted that the feedback loop 110 of the BAC 100, is shown although it is part of the BAC block. An LED 308 is connected to the BAC 100. (specifically the current leg of buffer 104). Pure DC current is applied to the clone generating circuit 300 via a second BAC 1002. The second BAC 100-hais no feedback resistor and is driven with a reference voltage 316 to ensure no output voltage fluctuations across load resistor 318. As such, it is seen that current modulation occurs in the LED 308 primarily by the current fluctuations of the output signal 310 across a dummy load resistor 314.

An IR transmission 319 caused by these fluctuations are received by the receiver portion 330 of the circuit 300.

The receiver portion 330 further comprises a third BAC 100, having a feedback resistor Rf 322. The receiver portion has a means 324 for receiving the IR transmission 319 connected to the BAC 1003. In a preferred embodiment of the invention, the receiving means is a PIN diode connected to an inverting input 326 of the BAC 1003. The resulting output signal 328 seen at node 336 is a clone of the input signal 302.

From the above clone generating circuit 300, one can derive any number of summing circuits from which to produce gain from a plurality of clone generating circuits. One such embodiment is depicted in FIG. 4. Specifically, FIG.

4 depicts a high level block diagram of a gain circuit 400 created by"stacking"a plurality of receiver circuit portions 330 in the basic clone generating circuit 300. In a preferred embodiment of the invention, a single transmitter 320 provides a signal to four receivers 330.

The receivers 330 are easily stacked because each receiver 330 is phase locked to the transmitter 320. If each receiver produces 10 volts RMS, a series combination of these devices yields a total of 40 RMS. Thus, a voltage gain of 12db in realized with no decrease in performance or increase in distortion. Many other combinations of the clone circuit are possible for creating a desired gain; such combinations are considered within the spirit and scope of the subject invention.

A highly useful amplifier configuration employing the subject invention is shown in FIG. 5. Specifically, a block diagram of a power amplifier circuit 500 is depicted. The power amplifier 500 consists of a transmitter section 502, a receiver section 504 and an output section 506. The transmitter section 502 is preferably the transmitter portion 320 and the receiver section 504 is preferably the receiver section 330 of the clone generating circuit 300 respectively. An input signal 510 enters the transmitter section 502 and is transmitted to the receiver section via an IR transmission 512. A clone output signal 514 is thus generated at node 508. In that way, the power amplifier circuit 500 enjoys the benefit of a floating output signal at the node 508 protected by an electromagnetic shield 332.

As such, the output signal is far less susceptible to the degrading effects of interference and there is no grounding problem between the transmitter section 502 and the remaining portions of the circuit 500.

The output section 506 is a BAC 100 that has been slightly modified. That is, the buffer 104 is further broken down into a biasing network 516 and an output buffer section 518. The biasing network 516 provides the required thread current back through the output section 506 and the output buffer section 518 is a high impedance device (or devices) capable of delivering high output voltage values without the need for sourcing or sinking additional current from the output section 506. In a preferred embodiment of the invention, the output buffer section 518 is a pair of FET transistors having their gates connected to the biasing network 516 and the drain of a first FET connected to the source of a second FET to form a power amp output node 530.

The output section 506 is connected to the receiver section 504 via a connecting resistor Rc 520. Specifically, Rc 520 is connected between output node 508 and a non- inverting terminal 524 of the output section 506. The power amp output node 530 is connected to an inverting terminal 526 of the output section and also forms a common ground connection between the receiver section 504 and the output

section 506. A power ground node 532 is connected to the non-inverting terminal 524 via feedback resistor Rp to form a feedback loop. Although it may not be apparent at first, the output section 506 acts like an inverting stage even though a signal is not inverted at power amp output node 530. This is because the junction of Rc and Rp form a current node and to the floating clone output signal 514 it appears as if the load is a resistor (e. g., Rc=10kohm) to ground (virtual ground). The cancellation of current at this point is supplied by Rp (e. g., 40kohm) acting as negative feedback coming from the power (speaker) ground.

This is because the relative movement of the output section 506 circuitry is away from ground causing the 40k resistor to develop a 40v drop compared to the 10k resistor with it's 10v drop. The entire circuitry (except for the transmitter) is"riding"on the speaker output signal. Therefore it acts like an"inverted"inverting stage or non-inverting stage with a gain of 4 (12db). The result is a phase driven output stage that is truly phase locked to a"motionless" current node. The current node will always stay within microvolts of the speaker output even when fully driven.

Using the basic amplifier circuit 100 as a building block, it is possible to create a specific and preferred embodiment of the power amplifier discussed above. This device, called a holographic cloning amplifier or HCAT, contains the necessary components and configuration to create a holographic"sound image". That is, an input signal is amplified and projected (i. e., through a standard audio speaker) to create an output signal that contains not only all of the input signal (no blacked out or missing parts of the signal due to the above discussed distortion) but also the precise spatial arrangement of all sources used to create the original input signal. For example and as seen in FIG 7a., three instruments: a guitar 702; a triangle 704 and a drum set 706 are used to create an input signal 708 (song) detected by recording devices 710 in a recording studio 700. The instruments, are spatially arranged about the recording studio 700. As such, the signal strength of

each instrument varies in relation to the others relative to its position in the studio as well as the volume at which it is played. Therefore, a sound field having"depth"exists in the input signal 708. Prior art amplifiers destroy this depth via distortion. The HCAT, described in greater detail below, preserves the"depth"quality of the input signal so that the output signal appears as a hologram or 3- dimensional sound image thus preserving the original spatial arrangement of the instruments.

An HCAT 600 is depicted in the circuit diagram of FIG.

6. The HCAT comprises an input stage 602, a gain stage 604 and an output stage 606. The input stage 602 is preferably the transmitter section 320 discussed above. As such, the input stage 602 is capable of creating an IR (or similar radiation) transmission 608 for receiving at the gain stage 604. The gain stage 604 is preferably a slightly modified version of receiver section 330 connected to a slightly modified version of output stage 506 of the power amplifier 500. Specifically, these two components are cascaded together to create a clone output signal at intermediate gain stage output node 610 and an amplified output signal at final gain stage output node 612. The final gain stage output node 612 is connected to the output stage 606 at a non-inverting input 614 of an output stage op amp 616.

Upon reviewing FIG. 6, the reader can see that the HCAT 600 is fabricated using standard, off-the-shelf circuit components that are readily available from manufactures in the semiconductor and electronic component industry. The BAC 100 and its distinct components are readily seen. For example when comparing FIGS 1 and 6, at the input stage 602, op amp 620i is equivalent to main amplifier engine 102, npn transistor 6301 is equivalent to buffer 104, capacitor 640, is equivalent to filter 108 and subcircuit 650, is equivalent to current generator 106. Similarly, in the gain stage 604, op amps 6202 and 6203 are equivalent to main amplifier engine 102, npn transistors 630 and 630, are equivalent to buffer 104, capacitors 640 and 6403 are equivalent to filter 108 and subcircuit 650, is equivalent to current generator 106.

Similar to power amplifier 500, HCAT 600 is electrically floating and electromagnetically protected to preserve signal integrity throughout the circuit. Optionally, a heating means 618 is disposed proximate one or more of the op amps 620X. Specifically, an FET transistor is placed on top of the op amp chip (not shown). The heating means is sometimes required when the op amp is not drawing sufficient current on its own to develop the proper switching speeds for normal circuit operation and to raise the open loop gain. The heat provided by the transistor 618 provides the required heat not only to the op amp, but also to other circuit devices such as transistors 630X. This occurs because all of the devices are disposed within the same medium and environmental conditions. Therefore, the generated heat radiates to other circuit components.

Unlike most audio circuits used to create the illusion of three-dimensional sound, the embodiments discussed use only 2 loudspeakers and only two electrical channels (left and right). The embodiments do not manipulate the original signal by phase or frequency or by adding, subtracting or otherwise combining the two original channels to create a third (or more) signal (s). Instead the present invention processes an audio signal so that the embedded spatial coding of any object in the original recording can be restored to it's original location in the projected soundfield during playback. This is graphically represented in FIG. 7b whereby audio transducers 712 in a playback room 7001, project the appropriate magnitude and phase of each instrument of the song 708. The guitar hologram 7021, triangle hologram 7041, and drum set hologram 7061, appear in the same spatial locations that their"real"counterparts occupied during recording. Thus, the HCAT 600 produces an amplified signal of such purity that it naturally displays a holographic wavefront.