Abstract: A heat sink alignment apparatus having an internal chamber with a plurality of heat sinks placed at an angled relationship to one another creating a tunnel through which air streams flows. At least one heat source is attached to a heat sink. A plurality of air streams enter the heat sink alignment apparatus through an ambient air intake and over a fan into the tunnel. The tunnel gradually narrows thereby increasing the velocity of the air streams which increases the cooling of the heat source. The narrowing shape of the tunnel creates turbulence within the plurality of air streams increasing the transfer of heat to various airstreams from the heat sink thereby lowering the temperature of the heat sources also.

Abstract: A heat sink alignment apparatus having an internal chamber with a plurality of heat sinks placed at an angled relationship to one another creating a tunnel through which air streams flows. At least one heat source is attached to a heat sink. A plurality of air streams enter the heat sink alignment apparatus through an ambient air intake and over a fan into the tunnel. The tunnel gradually narrows thereby increasing the velocity of the air streams which increases the cooling of the heat source. The narrowing shape of the tunnel creates turbulence within the plurality of air streams lowers the temperatures of the various air streams thereby lowering the temperature of the heat sources also.

Abstract: A circuit for increasing damping factor in an audio amplifier adapted to be coupled to a load by output feed and return leads and components having an impedance causing a reduction in the damping factor, employs a balanced feedback network having first and second inputs and first and second outputs. The first input is coupled to a selected one of the feed and return lead near the output terminal and the second input is coupled to the same lead remote from the output terminal to thereby establish a series impedance between said first and second inputs representative of impedance of the selected output lead. The first output is coupled to the non-inverting input of the amplifier and the second output is coupled to the inverting input of the amplifier. The balanced feedback network positively feeds back a representation of the impedance to compensate therefor and thereby raise the damping factor of the amplifier. In an alternative embodiment, an isolating transformer is employed in the balanced feedback network.

Abstract: In a power amplifier, a control device employing a dual ganged potentiometer is connected in the feedback circuits of successive amplifier stages to increase the gain of the front end stage while simultaneously reducing the gain in a subsequent stage when the control is turned down. A distortion circuit, such as a tube compression circuit, is coupled between the stages. When the control is turned down, the compression circuit is activated at a lower level that effectively reduces the output power of the second stage. Presence and resonance controls may be provided to tailor high and low frequency damping factor of the second stage and function until the compression circuitry is activated. A ripple reduction filter is provided in a filtered supply for the drivers in the second or power amplifier stage.

Abstract: A power amplifier has a distortion control circuit responsive to a clipping detector for loading said amplifier input with a signal sufficient to reduce the input to the tube grids to a level below clipping.

Abstract: A multi-stage solid state amplifier emulates the distortion associated with grid current flow in a multi-stage tube amplifier by means of a clipping device in the circuit between each series connected stage. In a particular embodiment, each stage includes a field effect transistor (FET) and the clipping device is a diode.

Abstract: A multi-stage solid state amplifier emulates the distortion associated with grid current flow in a multi-stage tube amplifier by means of a clipping device in the circuit between each series connected stage. In a particular embodiment, each stage includes a field effect transistor (FET) and the clipping device is a diode. In another embodiment, each stage includes a Darlington connected pair of transistors. An input diode and a multilevel biasing circuit emulates a tube circuit input.

Abstract: A solid state amplifier for emulating the compression associated with an overbiased class-B push-pull tube amplifier at high input signal levels due to the flow of current into the grid of the output tubes resulting in a desirable output clipping characteristic with crossover distortion is disclosed. The invention includes at least one pair of class-B connected solid state devices, each having an input circuit and an output circuit. The output circuits are connected for mixing. A biasing element in the input circuit of each paired solid state device establishes a clipping level offset at the input circuit and at the output circuit of each device. A clipping element in the input circuit and the output circuit clips the offset at the input circuit and clips the offset at the output circuit of each respective solid state device. A charging element overbiases the offset in the input circuit whenever the input signal is greater than the input clipping element.

Abstract: An amplifier switchably operative in a plurality of voltage modes depending upon the level of the input signal is disclosed. A circuit for each voltage mode includes a common driver for each level and a plurality of output devices arranged in parallel. Each output device is operative at a selected voltage level and is coupled to the common driver for the corresponding voltage mode. One output device of each level is coupled in series to an output device of the next lower level. A switching diode circuit is coupled between series connected outputs of each output device. In one embodiment, paired diodes are coupled to each level in a common terminal of the diodes are coupled to the input. A regulator is provided for causing the driver and the output devices of each next higher level to turn on prior to the input signal achieving a selected voltage level. The circuit thus provides smooth switching between levels with reduced distortion.

Abstract: In a particular embodiment, an audio amplifier drives a load in the form of a sound producing loud speaker exhibiting a frequency variable impedance characteristic over a range of audio frequencies. Voltage and current feedback circuits respectively establish a minimum voltage feedback and a feedback characteristic representative of the load. A presence feedback circuit couples the voltage feedback circuit to ground for reducing feedback with increasing frequency above a selected level whereby the damping factor of the amplifier is reduced. A resonance feedback circuit coupled in parallel with the voltage feedback circuit reduces voltage feedback with decreasing frequencies below the selected level whereby the damping factor is accordingly reduced. The amplifier is responsive to the reduced damping factor for increasing power to the load for enhancing the sound produced by the loud speaker.

Abstract: The present invention employs gain compensation such that when the amplifier is in the clean mode, the gain is at a selected level and when the amplifier is in the lead mode gain is decreased. In one embodiment a selectable brightness control is employed to raise the high frequency response in the clean mode. In another embodiment, a selectable gain boost control is employed to increase the gain in the lead mode. At least one frequency selectable means is provided in a post distortion stage output circuit for varying the frequency response of the output in the lead mode.

Abstract: An amplifier using vacuum tubes is mounted in a housing with a speaker in such a way as to minimize microphonics by having the speaker axis and all vacuum tube axes parallel.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels may also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: An amplifier circuit for use with a guitar. It has two modes, a "clean" output mode, and a "super-distortion" mode, which mode has independent gain control prior to a distortion stage. There is also post distortion gain control.

Abstract: Circuitry is provided for simulating a combination of vacuum tube clipping and soft cross-over characteristics in a transistor power amplifier circuit. A first circuit includes a biasing network for assuring that the transistor amplifier saturates in response to high level input signals. A second circuit includes a biasing network for providing sufficient bias current to maintain the transistor in an active, rather than cutoff, operating region when the first circuit fails to provide the needed bias at times when the instantaneous input signal level is low but average or peak input levels are high. A combining circuit provides the higher of the bias values to the amplifier, to assure that the amplifier saturates for particular high level inputs yet operates at a modified, linear mode for low level inputs, thus simulating a compression characteristic of vacuum tube amplifiers.

Abstract: Circuitry is provided for distorting an audio signal, useful in providing a "dirty" sound to an electric guitar simulating a vacuum tube amplification thereof. The circuit includes components for simultaneously changing the amount of distortion introduced by a clipping circuit and the amount of gain boost provided at a preselected narrow bandwidth. Addition of such gain boost leads both to increased clipping of the audio signal and to reduced frequency response, at both low and high frequencies. A separate volume control is provided for broad band gain adjustment. Independently operable control switches permit insertion or elimination of the distortion, and insertion or elimination of a brightness circuit boosting high frequency response of the circuit.

Abstract: A circuit for limiting transient intermodulation distortion in a amplifier system including an operational amplifier having a gain stage and a feedback network connected between the gain stage and the amplifier feedback port together with a pair of oppositely poled diodes, connected in parallel and coupled by means of capacitors between the amplifier output port and feedback port to limit the operational amplifier going to the supply rails under non-linear conditions thereby reducing the slew rate recovery time and therefore the amount of transient intermodulation distortion.

Abstract: An amplifier system with automatic distortion control including an amplifier provided with a detector between the amplifier output and feedback ports for detecting a nonlinear condition with a balanced differential circuit connected to the detector and feeding a full wave threshold detector which charges a storage capacitor proportionally to the percent clipping of the output signal of the amplifier. The storage capacitor is discharged into an input variable gain amplifier in the amplifier input circuit to reduce the gain for minimizing clipping.

Abstract: A high frequency roll-off circuit for a gain stage including an amplifier having a feedback network together with a dual potentiometer comprising two serially connected gang operated resistors connected between the amplifier feedback port and through a capacitor to the amplifier output port, one of the resistors forming a volume control and the other resistor forming a high frequency roll-off control whereby at high volume settings, high frequency roll-off is automatically provided.