GB2365197A - Effect unit for electric guitar and other electric instruments - Google Patents

Abstract

A device that imparts an effect to the sound of an electric guitar or other type of electric musical instrument. The device modifies the attack of the instrument by adding a signal burst, derived from the input signal, to that input signal. The burst may be added either in-phase or out-of-phase to provide a choice of sounds and the sensitivity and the volume balance of the burst signal to the original signal may be adjusted.

Description

<Desc/Clms Page number 1> Effect unit for electric guitar and other electric instruments Electric guitar players often use additional electronic effect circuits to extend the tonal colour and complexity of the sound of instrument, beyond those that can be obtained through playing technique and manipulation of the amplifier settings.

The problem has been that in the past few years no new methods for modifying the sound have been invented. Products from companies that specialise in this market have relied on variations, digital emulations and combinations of the existing basic effects.

The principle of this invention is to add an extra attack pulse, or signal burst, to the original electric guitar signal and as a result, to modify the attack of each note. This is a new effect and no previous effect has attempted to alter the note attack in this way. The new note that is produced sounds like a hybrid instrument that is related to the guitar. Because the signal burst is derived from and controlled by, the original signal, the resultant sound is natural, musical and responds well to the players fingering and picking. The signal burst may be added either in-phase or out-of-phase with the original signal, providing yet another variation in the final sound.

Drawing 1 is a simplified outline of the circuit functions required to produce the effect described.

Drawing 2 is of a fully working analogue design. For the sake of clarity, component values, power supplies and the bypass switching normally found on this type of effect, are not shown.

As outlined in drawing 1 the effect may be obtained by first buffering the signal from the instrument l and splitting the audio path. One branch (A) of the signal is left unaffected, or `clean', and passes straight through to an output mixing stage 5. The second branch (B) of the signal passes through a controlled amplifier or modulator 4, to a second input to the mixing stage, where the two signals are blended into one. The entire circuit can be set up to provide a modest amount of gain so that it can be used purely for volume boost. By applying a suitable control pulse to the controlled amplifier or modulator 4, the `B' branch of the signal can be reduced into a brief burst version of the original signal. When added to the clean signal, in the mixer stage 5, this provides the final output signal with a more percussive attack. By adjusting the relative signal levels into the mixing stage the output can go from clean to percussive or any balance in between.

The control pulse for the controlled amplifier may either be derived directly from an envelope follower 2, so that it follows the dynamics of the input signal or it may be a triggered pulse with an amplitude and duration that is not related to the input. In the design shown in drawing 2 the former method is used. Pulse shaping or generation is provided by section 3.

Although a fully functional, analogue design is described by the accompanying circuit diagram (drawing 2) this concept of adding a more percussive attack to the guitar note

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applies to any realisation of this effect using either analogue circuitry or digital circuitry including software emulation.

In drawing 2 the signal from the musical instrument is buffered by the high impedance input amplifier 1. This amplifier also provides enough gain to drive the attack pulse sections of the circuit. The output of the input amplifier then splits three ways. It passes directly (signal path A) to a rotary volume control that feeds one input to the output mixer 5. This control sets the level of the unaffected signal heard at the output of the device. Secondly, this signal, following path B, drives the input to the Controlled Amplifier (CA) or modulator 4. A variation on the circuit is to use a toggle switch to route this signal to either the non-inverting or inverting inputs of the CA to allow a choice of either in-phase or out-of-phase attack burst, as mentioned previously in this description.

Thirdly, this signal, again following path B, drives the input of the full wave rectifier that forms the first part of the envelope follower 2, via a second rotary control. This control sets the sensitivity, touch or response of the effect. The rectified signal passes through an integrator that forms the second part of the envelope follower.

The output of the envelope follower is then shaped into a narrow current pulse by the differentiator 3. This current pulse drives the CA or modulator and this produces a brief burst, typically from 10 milliseconds to 20 milliseconds in duration, of the original signal. Finally this burst from signal path B is mixed with the unaffected signal from path A.

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Claims (6)

1. CLAIMS 1. A device for altering the attack of an electric guitar, or other electric musical instrument, by adding a signal burst derived from the input signal to that input signal.
2. 2. A device as claimed in Claim 1 where the degree of attack alteration may be controlled by playing technique.
3. 3. A device as claimed in Claim 1 or in Claim 2 where the sensitivity to player control may be adjusted.
4. 4. A device as claimed in Claim 1, in Claim 2 or in Claim 3 where the balance of the added attack burst and the unaffected signal may be adjusted.
5. 5. A device as claimed in any preceding claim which is made in either analogue form, digital form or in the form of software emulation.
6. 6. A device substantially as described herein and illustrated in the accompanying drawings.