Patent Description:
The present invention relates to an article of manufacture for modifying electrical and/or audio signals. In particular, signals are mixed and modified by a fade device to provide a resulting signal.

Some fade devices used to process musical signals are known. For example, these include fade-in, fade-out devices used to introduce a signal or to decay a signal. Fade devices may also process two signals simultaneously. For example, they may decay a first signal while introducing a second signal. These devices are typically known as "cross-faders. " For example <CIT> discloses a crossfader with associated fading response curves which is adjustable through manipulation of a rotary knob. The rotary knob allows modifying the steepness of the response curve to adjust how fast or slow the crossfade gains of each input channels are modified when the fader is moved this enables setting the amount of overlap (merge time) of the two channels.

In the present invention, a fade device comprises a crossfader and a mixer interconnected via microprocessor. A crossfader slider control generates slider signals indicative of slider positions and a rotary control is connected to the processor such that a first direction of rotary control movement for creating a delayed slider position signal and a second direction of rotary control movement for creating a predicted future slider position signal. The mixer is configured to receive a first audio input, a second audio input, and one of a) the delayed slider position signal or b) the predicted future slider position signal, and combine an audio signal derived from the first audio input and an audio signal derived from the second audio input to provide a mixer output. The gain of at least one of the derived signals is controlled by the delayed slider position signal or the predicted future slider position signal. A processor main motion buffer indicates a sequence of actual slider positions and the times therebetween; and the processor is configured to create a delayed recording of the actual slider position versus time in a delayed slider position buffer to provide the delayed slider position signal; and create a prediction of slider position based on third derivatives of actual slider position versus time to provide the predicted future slider position signal.

The present invention is described with reference to the accompanying figures. These figures, incorporated herein and forming part of the specification, illustrate the invention and, together with the description, further serve to explain its principles enabling a person skilled in the relevant art to make and use the invention.

The disclosure provided in the following pages describes examples of some embodiments of the invention. The designs, figures, and description are nonlimiting examples of embodiments they disclose. For example, other embodiments of the disclosed device and/or method may or may not include the features described herein. Moreover, disclosed advantages and benefits may apply to only certain embodiments of the invention and should not be used to limit the disclosed invention.

To the extent parts, components and functions of the described invention exchange electric power or signals, the associated interconnections and couplings may be direct or indirect unless explicitly described as being limited to one or the other. Notably, parts that are connected or coupled may be indirectly connected and may have interposed devices including devices known to persons of ordinary skill in the art.

In this application, signal levels may be varied, for example varied by a potentiometer, optical device, encoder, or touch device for example a touch sensitive device using capacitance or inductance. These devices where suitable may be operated via rotary, linear, or curvilinear motion or touch. Where a signal level is varied, any of these devices may be used where appropriate. For example, when this specification mentions a particular device for varying signal level or indicating position, such as a potentiometer, other embodiments include any of those mentioned above (e.g., encoder).

<FIG> shows an embodiment of the invention 100A. Here, input signals such a first input <NUM> and a second input <NUM> pass through a mixer <NUM> and produce an output <NUM>, <NUM>. In various embodiments, a selector <NUM> provides a signal derived from the mixer to an effects processor <NUM> with output <NUM> or provides a signal <NUM> as an output. Here, the mixer is a voltage controlled mixer. In other embodiments, where suitable, a voltage controlled, frequency controlled, level controlled, phase controlled, or another similar mixer may be used.

<FIG> shows an embodiment of the invention 100B. Here, a crossfader device
<NUM>
x0 in crossfader block C provides an output to a mixer <NUM> such as a voltage controlled mixer in an audio signal processing block A. The audio signal processing block includes input signals such a first input <NUM> and a second input <NUM> that pass through a mixer <NUM> and produce an output <NUM>, <NUM>. In various embodiments, a selector <NUM> provides a signal derived from the mixer to an effects processor <NUM> with output <NUM> or provides a signal <NUM> as an output. In various embodiments, the crossfader has a built-in position or linear position sensor, for example a sliding fader control.

The crossfader device may be any know crossfader that provides outputs capable of selecting levels of two or more signals. For example, the crossfader may utilize a selector or continuous selector whose position determines a first signal level from a first curve relating position to level and a second signal level from a second curve relating position to level. The crossfader may be actuated by a physical slider or rotary device. The crossfader may be actuated by a touch sensitive device emulating a physical device such as a slider or rotary device. In some embodiments the crossfader output determines a first signal level and a second signal level based on actuator and/or touch position. In some embodiments the crossfader actuator and/or touch position is a crossfader output.

<FIG> shows another embodiment of the invention 100C. Here, a processor or microprocessor µP ("processor") block B is interposed between crossfader block A and audio signal processing block C. The crossfader <NUM> has an actuator such as a slider <NUM>. The crossfader is connected to the microprocessor <NUM> via a crossfader output <NUM> and the microprocessor is connected to the mixer <NUM> via a microprocessor output <NUM>. Note the microprocessor may create a set of PWM modulated digital signals which are made "analog" with RC filters (see https://www. allaboutcircuits. com/technical-articles/low-pass-filter-a-pwm-signal-into-an-analog-voltage/ incorporated herein by reference). These analog voltage signals then control the Voltage Controlled Amplifiers <NUM> in the mixer <NUM> which create the mix between the stereo audio inputs.

Other processor inputs <NUM> may include inputs for user selectable settings and/or other settings <NUM>. Other processor outputs <NUM> may include outputs for indicating status and data. In some embodiments the processor may include an output <NUM> to the effects processor <NUM>.

The audio signal processing block includes input signals such as first input <NUM> and a second input <NUM> that pass through a mixer <NUM> and produce an output <NUM>, <NUM>. In various embodiments, a selector <NUM> provides a signal derived from the mixer to an effects processor <NUM> with output <NUM> or provides a signal <NUM> as an output.

<FIG> shows an embodiment of the processor and its connections 100D. Main processor connections may include an input from the crossfader <NUM> and an output <NUM> to the mixer. Some embodiments may include a PWM to constant voltage converter <NUM> to <NUM> between the processor and the mixer. Some embodiments may include an output <NUM> to an effects processor <NUM>.

Pots <NUM>-<NUM> may be endless potentiometers with each pot also operable as a button when you depress the knob. Alternatively, some embodiments may include input and output volume knobs in addition to a set of four potentiometers or button potentiometers such as potentiometers rotatable from <NUM>-<NUM>% with a stop or stops therebetween.

Other processor inputs, for example settings, may include a mode input or settings configurator (i.e., settings config) <NUM>, one or more potentiometers (three shown) <NUM>, and various buttons <NUM>. Buttons may include plural potentiometer buttons (three shown), a mode input or mode encoder button, and edit button, a shift button, an expand button, a capture button, a fire button, a fine button, a hold button, a reset button, and a star button.

One or more of the potentiometers <NUM> may be any know potentiometer that provides or indicates level control. For example, the potentiometer may utilize a selector such as a <NUM> degree potentiometer whose position determines a signal level from a curve relating position to level. The potentiometer may be actuated by physical motion of the device. The potentiometer may be actuated by a touch sensitive device emulating a physical device such as a rotary device.

Other processor outputs, for example status and data outputs, may include output(s) for neopixel ring (three shown) <NUM>, OLED screen <NUM>, CV (control voltage) <NUM>, MIDI Out <NUM><NUM>, and MIDI out <NUM><NUM>. Note that CV output <NUM> may be replaced by CV Out <NUM> and CV Out <NUM>.

Signals passing from the crossfader <NUM> to the mixer <NUM> via the processor <NUM> are modified in the processor.

The architecture of the fader device disclosed in the figures above enables manipulation of the audio input signals <NUM>, <NUM> according to various inputs including processor <NUM> inputs such as those shown in <FIG> ("processor inputs"). For example, these manipulations may apply one or more of latency, acceleration, and quantization to the input signals. For example, latency and acceleration may be applied for controlling the gain of audio input signals. The figures below including <FIG>, <FIG>, <FIG> describe acceleration and latency features of some embodiments of the present invention.

<FIG> provides an overview of one embodiment of the latency and acceleration features <NUM>. Latent response is shown as a variable to the left of the variable acceleration with a null point in between. Latent response can be understood as playback that is delayed or a mimic of motion imparted to the crossfader actuator that is delayed. Alternatively, accelerated response can be understood as a prediction of future play or a mimic of future motion imparted to the crossfader actuator.

For example, turning a potentiometer or selector <NUM> to the left or counterclockwise may indicate or provide a setting that indicates latent playback. After the potentiometer or selector is set for latency, the crossfader <NUM> will interpret its actuator or slider motion as a delay. These actions will mimic a delay of the motion that is actually imparted to the crossfader actuator <NUM>.

Turning a potentiometer or selector <NUM> to the right or clockwise may indicate or provide a setting that indicates "accelerated" playback. After the potentiometer or selector is set to accelerate playback, the fade device may mimic a prediction of future (unknown) motion as if this crossfader actuator <NUM> motion had actually taken place.

In the present invention, prior crossfader slider <NUM> motion may be used predict or indicate future crossfader slider motion. For example, this future motion may be based on a second derivative (acceleration) of slider position versus time. In the present invention, this future motion is based on a third derivative (jerk) of slider position versus time. This future motion may be adjusted with a level device or rotary device such as a rotary encoder(s) or potentiometer(s) <NUM>.

In the present invention, a latency algorithm provides a crossfader slider motion indication that is delayed with respect to the actual crossfader slider motion. The amount of latency can be adjusted with a fade device potentiometer <NUM>.

<FIG> shows examples of latency and acceleration applied to signals from or derived from the crossfader slider control 200B. As mentioned above, latency and acceleration may be applied to slider motion for example by rotating a microprocessor connected potentiometer left of zero for latency, and right of zero for acceleration.

In particular, three curves describe an indicated slider position as a function of time a) when no latency or acceleration is applied, b) when latency is applied and c) when acceleration is applied. Note that the indicated slider position is not the actual slider position when latency or acceleration is applied. But, it is the indicated slider position or a signal derived therefrom which the microprocessor sends to the mixer <NUM>.

The central curve corresponds to a signal which is not delayed (latent) and which is not accelerated. Here, the actual slider position and the indicated slider position match.

The upper curve corresponds to the same signal after acceleration is applied. As such, the indicated slider position will be <NUM>% before the actual slider position reaches <NUM>%.

The lower curve corresponds to the same signal after latency is applied. As such, the indicated slider position will be less than <NUM>% when the actual slider position reaches <NUM>%.

The table below the figure shows how motion imparted to the slider is indicated for a) no latency or acceleration, b) latent motion, and c) accelerated motion. For example, a slider motion which takes <NUM> while moving <NUM>% indicates a motion of <NUM>% with no latency or acceleration. For example, a slider motion which takes <NUM> indicates a motion of <NUM>% at a selected latency. For example, a slider motion which takes <NUM> indicates a motion of <NUM>% at a selected acceleration.

<FIG> shows and another example of latency and acceleration applied to signals from or derived from the crossfader slider control 200C. Here, indicated slider motion is shown to vary with musical time such as <NUM>/<NUM> and <NUM>/<NUM> notes referred to here as a quantized version. As before, the central curve without latency or acceleration matches indicated and actual slider positions. As before, the indicated slider position will be <NUM>% before the actual slider position reaches <NUM>%. As before, the indicated slider position will be less than <NUM>% when the actual slider position reaches <NUM>%.

The table below the figure shows in this quantized version how motion imparted to the slider is indicated for a) no latency or acceleration, b) latent motion, and c) accelerated motion. For example, a slider motion which takes <NUM>/<NUM> note while moving <NUM>% indicates a motion of <NUM>% with no latency or acceleration. For example, a slider motion which takes <NUM>/<NUM> note indicates a motion of <NUM>% at a selected latency. For example, a slider motion which takes <NUM>/<NUM> note indicates a motion of <NUM>% at a selected acceleration.

<FIG> show sequential mixing of processed audio signals where some embodiments/applications emulate the transition from one audio source to another such as a Disk Jockey's transition from one turntable audio source to another turntable audio source (e.g., a turntablist practicing turntablism) 200D-E.

In <FIG> a crossfader <NUM> with a crossfader slider control <NUM> sends slider signals <NUM> to a microprocessor <NUM>. A master buffer <NUM> within the microprocessor may hold actual slider motion versus time information. Microprocessor outputs include an output <NUM> to a modulator <NUM> and an outputs 242a, 242b to voltage controlled amplifiers <NUM> (Gain <NUM>), <NUM> (Gain <NUM>) associated with a first voltage controlled mixer 104a. In various embodiments, a mix of signals derived from the gain adjusted inputs provides a mixed signal. This mixed signal or a facsimile may appear at the Mix <NUM> output <NUM>.

Microprocessor output <NUM> may be signal <NUM> with latency or acceleration applied. Microprocessor outputs 242a, 242b may be signal <NUM> with the same or different latencies or accelerations applied.

Signal sources for microprocessor output signals <NUM>, 242a,b may be via any of several buffers, for example three buffers <NUM>, <NUM>, <NUM>. Any of these buffers may contain a) a latent version of actual slider motion versus time information, b) an accelerated version of actual slider motion versus time information, or c) actual slider motion versus time information. These buffers may, as shown, be located in the microprocessor. Note that a latent signal buffer contains position versus time information where latency may be achieved by delayed recording. Note that an accelerated signal buffer contains position versus time information where acceleration may be achieved by a simulated version of recorded future movement.

As shown, the first mixer 104a receives audio inputs <NUM>, <NUM> from respective audio sources <NUM>, <NUM>. This mixer outputs audio signal <NUM> to a second mixer or voltage controlled mixer 104b. Mixer 104b may be controlled by a microprocessor signal 242c. Microprocessor signal 242c may be derived from any of the microprocessor input parameters or crossfader slider <NUM> position(s).

Cued audio from audio source <NUM>, audio source <NUM>, or mix <NUM> is received in a cued audio block <NUM> via a respective one of related signals <NUM>, <NUM>, <NUM>. A modulator <NUM> receives one of the microprocessor outputs <NUM> and a cued audio block output <NUM>.

Regarding modulation, in various embodiments the crossfader slider <NUM> motion signal with latency or acceleration applied may be used to produce microprocessor signal <NUM> which modulates the cued audio <NUM>, <NUM>, <NUM> to produce a modulated cued audio output <NUM>.

The second mixer 104b mixes the first mixer 104a audio output <NUM> and the modulator <NUM> audio output <NUM> to produce a sequential mixer output <NUM>. Signal <NUM> is a first mixer output and may be a copy of signal <NUM>.

The sequential mixer of <FIG> can be operated to produce a rhythmic cut between audio sources <NUM>, <NUM> at the Mix <NUM>104b output <NUM>. For example, application of acceleration or latency to a first mixer 104a audio signal <NUM>, <NUM> can produce a rhythmic cut at the first mixer 104a output <NUM>. And, a cued audio source <NUM>, <NUM>, <NUM> can result in a scratch sound (modulation of cued audio) at the output <NUM> of the modulator <NUM>. The second mixer 104b combines outputs <NUM> and <NUM> to produce a rhythmic cut combined with the scratch sound which introduces the transitioned audio source.

<FIG> shows an example of modulation 200E. Signals are traced for a) position versus time <NUM>, b) position interpreted as playhead position versus time <NUM>, c) an audio signal to be modulated <NUM>, and d) the audio signal after modulation <NUM>.

The trace of position versus time <NUM> relates crossfader slider <NUM> or buffer position and time with or without latency or acceleration applied. In some embodiments, the position and time relationship is from, or is derived from, one of the buffers <NUM>, <NUM>, <NUM>, <NUM> mentioned above.

The trace of time versus position interpreted as playhead position <NUM> is from, or is derived from, the trace of position versus time <NUM>.

The trace of audio to be modulated <NUM> is an audio signal such as the output <NUM> of the cued audio signal block <NUM>. In some embodiments, this signal is amplitude (vertical axis) versus time (horizontal axis).

The trace of the modulated audio <NUM> shows the audio signal <NUM> after it is modulated by the time versus buffer position interpreted as playhead position signal <NUM>. In some embodiments, this signal is amplitude (vertical axis) versus time (horizontal axis).

The modulated audio signal <NUM> that results from playhead movement <NUM> may be described as follows.

Playhead moves from B to E. As seen, the playhead position <NUM> signal guides the playhead from B to E which plays the audio signal <NUM> from B to E as shown in the modulated audio signal <NUM>.

Playhead dwells on E. As seen, the playhead position signal <NUM> is a vertical trace during time t1 resulting in a period of no modulated audio <NUM> from E to E.

Playhead moves from E to C. As seen, the playhead position <NUM> signal guides the playhead from E to C which plays the audio signal <NUM> from E to C as shown in the modulated audio signal <NUM>.

Playhead moves from C to D. As seen, the playhead position <NUM> signal guides the playhead from C to D which plays the audio signal <NUM> from C to D as shown in the modulated audio signal <NUM>.

Playhead moves from D to A. As seen, the playhead position <NUM> signal guides the playhead from D to A which plays the audio signal <NUM> from D to A as shown in the modulated audio signal <NUM>.

Playhead dwells on A. As seen, the playhead position signal <NUM> is a vertical trace during time t2 resulting in a period of no modulated audio <NUM> from A to A.

Playhead moves from A to E. As seen, the playhead position <NUM> signal guides the playhead from A to E which plays the audio signal <NUM> from A to E as shown in the modulated audio signal <NUM>.

Playhead dwells on E. As seen, the playhead position signal <NUM> is a vertical trace during time t3 resulting in a period of no modulated audio <NUM> from E to E.

<FIG> are flowcharts showing multiple steps, one or more of which implement an example of acceleration 300A-B.

In <FIG>, a fade device similar to the fade device of <FIG> is readied for operation. In this example, a potentiometer <NUM> is operated before the crossfader actuator <NUM> is operated <NUM>.

A selected potentiometer <NUM> is rotated clockwise which indicates acceleration <NUM> and provides an acceleration setting <NUM>. At this point, the signal may be quantized <NUM>.

Once the potentiometer <NUM> is set, the crossfader actuator may be moved <NUM>. An indication of crossfader slider motion and/or position is provided to the processor <NUM>. From the indication of position, the processor may determine a first signal decay curve value and may determine a second signal introduction curve <NUM>, <NUM>.

In step <NUM>, based on information which may include one or more processor inputs of <FIG> and which may include values or functions of the curves <NUM>, <NUM>, a signal is derived that provides mixer control <NUM>. In step <NUM>, based on information which may include crossfader slider position or the above, a signal may be derived that provides special effects control <NUM>.

The mixer <NUM> and optionally the effects processor <NUM> respond to signals <NUM>, <NUM> from the processor. And, as shown in step <NUM>, the audio signal processing block C outputs a modified audio signal <NUM>, <NUM>.

<FIG> shows additional processor <NUM> responses that may occur with crossfader actuator <NUM> movement(s) when the potentiometer <NUM> is set for acceleration, for example the acceleration of <FIG>.

In step <NUM>, the crossfader actuator <NUM> is moved or moving and in step <NUM> the processor receives an indication of the crossfader movement. For example, the crossfader may move through positions p1, p2, p3, p4. In various embodiments, the processor associates timing and/or time differences with the these positions, for example t1, t2, t3, t4.

Crossfader actuator <NUM> positions and times are used to estimate changes with respect to time. For example, calculations similar to or having a similar result to a divided difference table may be used to estimate derivatives of position with respect to time such as velocity, acceleration and jerk (first, second, and third time derivatives) <NUM>.

In step <NUM>, after jerk is calculated, it is adjusted according to the potentiometer <NUM> setting. This is followed by a mixer control output <NUM> that is a function of at least the adjusted jerk value which is provided to the mixer <NUM>.

Optionally, the effects processor <NUM> receives a control signal from the processor <NUM>. This effects processor control signal <NUM> may be a function of crossfader actuator position.

The MIDI (Musical Instrument Digital Interface) outputs <NUM>, <NUM> may be a function of the effects processor input <NUM> or a signal similar to the effects processor input. The CV (control voltage) <NUM> may also be a function of the mixer input <NUM> or a signal similar to the mixer input signal.

<FIG> are flowcharts showing an exemplary implementation of latency 400A-B.

A selected potentiometer <NUM> is rotated counterclockwise which indicates latency <NUM> and provides a latency setting <NUM>. At this point, the signal may be quantized <NUM>.

<FIG> shows how the additional processor <NUM> responses that may occur with crossfader actuator <NUM> movement(s) when the potentiometer <NUM> is set for latency.

In step <NUM>, the microprocessor <NUM> calculates a difference in times associated with crossfader actuator <NUM> positions. Delay is a function of this time difference. Notably, the difference in crossfader actuator times may be a difference in any two times corresponding to positions known to the processor, for example (tn+<NUM> - tn).

In step <NUM>, the magnitude of the delay is adjusted. The adjustment is a function of the potentiometer <NUM> setting and may be a function of the processor inputs of <FIG>.

In step <NUM> a processor mixer control output <NUM> is sent to the mixer <NUM>. This output is derived from the adjusted delay. Optionally, in step <NUM> an effects processor control output of the processor <NUM> is derived from the crossfader actuator position <NUM> and sent to the effects processor <NUM>.

The MIDI (Musical Instrument Digital Interface) outputs <NUM>, <NUM> may be a function of the effects processor input <NUM> or a signal similar to the effects processor input. The CV (control voltage) <NUM> output may also be a function of the mixer input <NUM> or a signal similar to the mixer input.

<FIG> are figures including block diagrams and flow charts that show various configurations, controls, operations, and functions of various embodiments of the fade device 500A-<NUM>. Each figure is intended to be self-explanatory and, as seen, each figure may refer to other figures in this application.

<FIG> show embodiments of buffers, controls, and functions associated with the fade device 500A-H. These figures are for reference as they are referred to by various ones of the figures which follow.

<FIG> show methods of scratching. For example, what a turntablist achieves with two hands, by moving a record platter or a CDJ (compact disk jockey) controller platter with one hand while manipulating a crossfader with the other hand can be achieved with this fade device using only hand. This is the ONE HAND SCRATCH. The steps taken to create a ONE HAND SCRATCH on a fade device can be represented by the following:.

Once one of the options for Step <NUM> has been chosen and a corresponding option has been chosen from Step <NUM>, a One Hand Scratch can be performed solely by performing Step <NUM> and sliding the crossfader. The fade device can be used to either time the "scratch" to match the cut or time the cut to match the "scratch".

<FIG> shows embodiments of the fade device as a linear position controller of MIDI and Effects parameters as subdivided from the full range of motion of the linear position controller into smaller divisions of the same range 500I. This is the MIDI/effects expander.

<FIG> shows an embodiment of the fade device configuration in block diagram form 600A.

<FIG> shows an embodiment of primary user control of the fade device 600B.

<FIG> shows an embodiment of quaternary user control for, among other things, choosing microprocessor parameters settings 600C.

<FIG> shows an embodiment of secondary user control for example via fade device knobs affecting acceleration, latency, and master volume levels 700A.

<FIG> shows an embodiment of acceleration/latency knob position settings affecting acceleration, latency, and easing 700B.

<FIG> shows an embodiment of motion easing settings including easing for speed and easing for acceleration 700C.

<FIG> shows an embodiment of tertiary user control for example via buttons for setting/interpreting various inputs <NUM>.

<FIG> shows an embodiment of the fade device microcontroller for interpreting mix position and inputs and for routing signals 900A.

<FIG> shows an embodiment for recording crossfader position data including a main motion buffer for recording position or position versus time of the crossfader control or slider position 900B.

<FIG> shows an embodiment for applying latency or acceleration with or without quantization and for loading affected motion buffers with this information 900C.

<FIG> shows exemplary master settings parameters and how these settings might be made 900D.

<FIG> shows an example of how a master tempo setting might be made 900E.

<FIG> shows an example of crossfader motion capture and fire operations 900F.

<FIG> shows an example of audio sample capture and fire operations <NUM>.

<FIG> shows exemplary MIDI output(s) where an expand function may be active or not, the MIDI outputs being a part of the master settings parameters <NUM>.

<FIG> shows an embodiment of the voltage controlled mixer with audio inputs processed and resulting in a master stereo audio output and a cue/headset stereo audio output as well as two channels of control voltage output <NUM>.

<FIG> shows exemplary audio effects processor controls where an expand function may be active or not, the effects processor controls being a part of master settings parameters <NUM>.

Claim 1:
A fade device (100C; 200D) comprising:
a crossfader (<NUM>) and mixer (<NUM>) interconnected via a processor (<NUM>; <NUM>);
a crossfader slider control (<NUM>) for generating slider signals (<NUM>) indicative of slider positions;
a rotary control (<NUM>) connected to the processor;
a first direction of rotary control movement for creating a delayed slider position signal;
a second direction of rotary control movement for creating a predicted future slider position signal;
the mixer (<NUM>; 104a) being configured to receive a first audio input (<NUM>), a second audio input (<NUM>), and one of a) the delayed slider position signal or b) the predicted future slider position signal, and
combine an audio signal derived from the first audio input and an audio signal derived from the second audio input to provide a mixer output;
wherein the gain of at least one of the derived signals is controlled by the delayed slider position signal or the predicted future slider position signal;
characterized by:
a processor main motion buffer (<NUM>) for indicating a sequence of actual slider positions and the times therebetween; and
the processor being configured to:
create a delayed recording of the actual slider position versus time in a delayed slider position buffer (<NUM>, <NUM>, <NUM>) to provide the delayed slider position signal; and
create a prediction of slider position based on third derivatives of actual slider position versus time to provide the predicted future slider position signal.