WO2013008260A1

WO2013008260A1 - Distorting device with dynamic correlation for electric music instruments

Info

Publication number: WO2013008260A1
Application number: PCT/IT2012/000197
Authority: WO
Inventors: Giuseppe Marineo
Original assignee: Giuseppe Marineo
Priority date: 2011-07-13
Filing date: 2012-06-26
Publication date: 2013-01-17
Also published as: ITTO20110612A1

Abstract

A distorting device with dynamic correlation for electric music instruments is described, comprising at least one pre-amplifying and buffering means (2) of at least one input sound signal (1), at least one clipping circuit (4) comprising clipping means of a signal output from such pre-amplifying and buffering means (2), at least one differential amplifier ( 7 ) having as input at least one signal output from such pre-amplifying and buffering means (2) and at least one signal output from such clipping circuit (4), at least one analogue-digital converter, ADC (8) of a signal output from such differential amplifier ( 7 ), and at least one analogue pre-amplifier with variable gain (6) having as input at least one signal output from such clipping circuit (4) and at least one signal output from such analogue-digital converter, ADC (8).

Description

DISTORTING DEVICE WITH DYNAMIC CORRELATION FOR ELECTRIC MUSIC INSTRUMENTS

The present invention refers to a distorting device with dynamic correlation for electric music instruments.

As known, the distorting device consists in an electronic device employed when using music instruments of the electric type, whose purpose is generating particular types of sound by clipping the input signal, starting from the more classical effects of simple amplifier saturation till a decidedly more aggressive sounding, like those deriving from the actual squaring (clipping) of the input signal.

The above device, widely known and used in modern music, so that it represents its most widely used effect type, is usually employed with reference to electric guitars, namely basses, though it is possible to use it also with reference to different types of sound sources, provided that they are equipped with microphones, namely pickups .

Even if different type of distorting devices are currently available, they have however in common a quite similar operating system: a pre- amplifying system with variable gain is usually present, aimed to amplify the input signal and afterwards transmit such signal to the clipping circuit, typically made by using a pair of silicon diodes in counter-phase (though it is possible to use different solutions, such as transistors or other) . In a similar situation, clipping starts when a signal reaches the threshold value for conduction of the silicon diodes, approximately equal to an amplitude of 0.5 V. After having reached this point, since the diode behaves as a Zener, the voltage can be increased only by a very small margin (typically not more than 0.6 V), and this in spite of the amplitude increase of the input signal. This is in practice the greatest limit of what is currently available in the art: it is in fact clear how, when reaching the above limit, unavoidably a flattening of the dynamics is reached for the signal subjected to the distortion itself, with detectable consequences in terms of prejudice of the yield of the final sound.

Essentially, it appears that, the stronger the required distortion, the more limited the consequent dynamics: this in addition is a widely felt problem by the musicians, because, since a sound is derived that is not any more under a condition for wholly follow the input signal dynamics, the final yield of the technical skill of a musician is strongly impaired. In music, in fact, it is not enough that the adopted solutions are able to be satisfactorily implemented from the technologic point of view, since it is also necessary to have a good yield from the sound point of view.

Many attempts have been made from the most known manufactures in the field, in order to provide solutions that, as a minimum, were able to solve the above problems, among which:

the use of a consistent supplementary amplification of the output signal that, though not increasing the dynamics, is however able to strongly increase the sound volume when the effect is inserted; the use of more or less complex equalizers: these latter ones in fact make it possible to reach a supplementary gain, giving thereby the idea of a dynamics increase next to certain frequencies.

Having said this, it must be stated that none of the solutions proposed in the prior art can be effectively complete, regarding the problem of limiting the dynamics that remains nowadays essentially unsolved. It must be further noted that, though it is theoretically possible to use a digital system that is able to sample the input signal and therefore re-build, through a suitable software, the desired distortion in the output phase, such possibility would necessarily require the use of high-performance microprocessors, being however scarcely efficient from the sound point of view .

Therefore, object of the present invention is solving the above prior art problems by providing a distorting device with dynamic correlation for electric music instruments that allows satisfactorily comply with the need that the sound distortion is not at the same time deprived of its related dynamics. Another object of the present invention is providing a distorting device with dynamic correlation for electric music instruments of a completely analogue type as regards the step of transmitting the audio signal, and of a partially digital type with reference to some specific computation supports, made for such purpose by an hardware architecture (known as "analogue computer") .

The above and other objects and advantages of the invention, as will appear from the following description, are reached by a distorting device with dynamic correlation for electric music instruments as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention as appears from the enclosed claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

Figure 1 shows a block diagram of a generic operating scheme of a distorting device according to the prior art;

Figure 2 shows a block diagram of a generic operating scheme of a preferred embodiment of the distorting device according to the present invention.

As anticipated, the basic operating scheme of a distorting device according to the prior art, like the one for example shown in Figure 1, is essentially based on a circuit comprising a preamplifier 20 operating with a variable gain 30, aimed to amplify the input signal 10 till the clipping circuit 40 is reached, necessary to obtain the distortion of the final output sound 60.

In order to solve the described problems related to the flattening of the dynamics of the signal subjected to distortion, common to what is currently available in the art, the present invention proposes a distorting device for electric music instruments of the analogue type in transmitting the audio signal, implemented, as regards the computation supports, by an analogue computer: this latter one bases its own operation on the use of operational amplifiers and the functions that, under a digital context, are commonly performed by suitable software programs, in this case are implemented through specific hardware configurations that, in association with the value of the components inserted in the network, are wholly able to perform the necessary computations in times that are substantially equal to the speeds of the operational amplifiers being used, thereby generating essentially neglected time delays.

Therefore, with particular reference to Figure 2, it is possible to note that the distorting device with dynamic correlation for electric music instruments according to the present invention comprises:

at least one pre-amplifying and buffering means 2 of at least one input sound signal 1;

at least one clipping circuit 4 comprising clipping means of the signal output from such pre- amplifying and buffering means 2; at least one differential amplifier 7 having as input at least one signal output from such pre- amplifying and buffering means 2 and at least one signal output from such clipping circuit 4;

at least one analogue-digital converter (ADC) 8 of the signal output from such differential amplifier 7; and

at least one analogue pre-amplifier with variable gain 6 having as input at least one signal output from such clipping circuit 4 and at least one signal output from such analogue-digital converter (ADC) 8. The output of the analogue preamplifier with variable gain 6 is therefore composed of the final output sound signal 9.

Possibly, the pre-amplifying and buffering means 2 can cooperate with gain-varying means 3. Preferably, the clipping means are composed of at least two diodes 51, 52 arranged in parallel.

Through the distorting device according to the present invention, a dynamic correlation in amplitude is generated with a 1:1 proportion between the input sound signal 1 to the clipping circuit 4, non yet subjected to distortion, and the output signals 12, with variable distortion depending on the gain 3 of the pre-amplifying and buffering means 2.

As can be seen in the example scheme shown in Figure 2, the input sound signal 1 is first of all pre-amplif ed and buffered in the pre-amplifying and buffering means 2, with the chance of performing variations at gain level through the gain-varying means 3 in order to reach the desired level of distortion, in addition to the progressive clipping of the signal 1 itself; similarly, a portion of the signal 1 that drives the clipping circuit 4 is sent to the differential amplifier 7, having the other input 9 connected to the output signal 12, already clipped by the two diodes 51, 52: in this way, at the output 10 of the differential amplifier 7 there is the amplitude related to the missing dynamics that needs to be re-built.

The thereby-obtained value is converted by means of the analogue-digital converter (ADC) 8, that is able to provide as output 11 the binary signal that is mandatory for the analogue pre- amplifying means with variable gain 6, digitally controlled, and also preferably made by using the operational amplifiers.

Obviously, the above-described functional blocks composing the distorting device according to the present invention allow for various solutions, operating differently, according to different parameters that are able to affect the quality of re-building the dynamics in compliance with performed design choices, such as:

- accuracy in re-building the dynamic range, depending on the resolution of the ADC converter 8, depending on which a minimum resolution is advisable that is not less than 8 bits;

- delay in re-building the dynamics, depending on the speed of the ADC converter 8, which should be like the one used in high-fidelity audio applications;

- amplitude of the dynamic range, that mainly depends on the dynamic capability of the analogue amplifier with variable gain 6 and only partially on the choice of the ADC converter 8 and its working point;

- linearity of the dynamic reconstruction, that essentially depends on the linearity of the analogue amplifier 6 in addition to the conversion error of the ADC converter 8.

Depending on these latter statements, it is therefore clear how the distorting device according to the present invention also allows adopting different solutions for each block, in compliance with the needs of a user in terms of audio quality and manufacturing costs.

From the preferred embodiment of the distorting . device according to the present invention, as described above, a linear increase of the dynamics has been measured that is equal to 500% correlated to the input signal 1, though it cannot be excluded that further implementations can be reached.

Claims

1. Distorting device with dynamic correlation for electric music instruments, characterised in that it comprises:

- at least one pre-amplifying and buffering means (2) of at least one input sound signal (1); at least one clipping circuit (4) comprising clipping means of a signal output from said pre- amplifying and buffering means (2) ;

- at least one differential amplifier (7) having as input at least one signal output from said pre- amplifying and buffering means (2) and at least one signal output from said clipping circuit (4);

at least one analogue-digital converter, ADC (8) of a. signal output from said differential amplifier (7); and

at least one, digitally controlled analogue pre-amplifier with variable gain (6), having as input at least one signal output from said clipping circuit (4) and at least one signal output from said analogue-digital converter, ADC (8) .

2. Distorting device according to claim 1, characterised in that said pre-amplifying and buffering means (2) cooperates with gain-varying means (3) .

3. Distorting device according to claim 1, characterised in that said clipping means are composed of at least two diodes (51, 52) arranged in parallel.

4. Distorting device according to claim 1, characterised in that said pre-amplifying and buffering means (2), said differential amplifier (7) and said analogue pre-amplifier with variable gain (6) are analogue computers composed of operational amplifiers.

5. Distorting device according to claim 1, characterised in that a dynamic correlation in amplitude between said input signal (1) to said clipping circuit (4), non yet distorted, and an output signal (12) with variable distortion depending on the gain (3) of said pre-amplifying and buffering means (2) has a 1:1 proportion.