GB2308515A - A pulse pattern generator for a musical sampler, with continually variable repetition rate - Google Patents

Abstract

A punched card is moved in reciprocating fashion past an optical detector which generates trigger pulses for an adjustable monostable (figure 5) that enables a musical sampler. The card is moved by a rod connected to a geartrain (figure 2) driven by a reversible electric motor. The motor speed is varied by an adjustment knob 16 (figure 6). There may be a plurality of such generators connected to a sampler via a multiplexer such as a keyboard decoder. There may be a further manual control to provide a velocity note-on/note-off mode. In an alternative embodiment, a disc-shaped punched card may be rotated past a detector (figure 4). In further embodiments, the pulses may be generated in software.

Description

PULSE GENERATOR The present invention relates to a pulse generator. The invention further relates to an apparatus comprising a plurality of such pulse generators connected to a multiplexer. The invention further relates to a musical source comprising such an apparatus and in particular to a sampling or sequencing apparatus.

In music, the use of sequencers and samplers is widespread. In a sampler, a musical extract known as a sample is played for a predetermined period of time, for example one second, and repeated at predetermined intervals, either regularly, for example every two seconds, or with some other repeat pattern. Typically, the musician has a library of samples available to him such as an extract from the playing of a musical instrument, a note or phrase sung by a singer, or an extract from a piece of music. Selected ones of these samples from the sample library are then played through a plurality of channels. The framework of pulses which are used to trigger each of the selected sample channels is typically preprepared by programming the desired samples into a computer. The music is then reproduced by retrieving and running the program.

A sequencer operates in a similar manner with the activation of a switch, which is often the key of a keyboard, initiating the reproduction of a predetermined sequence of notes, the sequence having been programmed in or otherwise defined at an earlier stage.

Present day samplers and sequencers are thus controlled by means of programming. Furthermore, the framework of pulses which serves as the basis for sampled music can only be generated within the constraints of the software provided, such as the MIDI clock time, thus limiting the scope for creative input into the sampled music. The net effect is that sampled music often appears to the listener to lack originality over previous sampled music, despite different attempts at programming, this being at least partly due to the same or conceptually similar software being used.

The programming needed to generate the sequence of pulses for the sampler effectively limits its potential for use as an interactive component during live performances. For example, other musicians such as guitarists and vocalists must subordinate themselves to the sampler output. For example, the sample output cannot be changed in response to spontaneous improvisation by other musicians or to crowd response to the music.

Aspects of the invention are defined in the independent claims.

Modification and variations are detailed in the subordinate claims.

Aspects of the invention include a pulse generator and various musical sources, such as a sampler and a sequencer.

With the invention it is possible to provide an interface between a musician and a library of stored sound that overcomes the inherent limitations of conventional computer interfacing.

Rhythms and melodies can be constructed architecturally in real time by layering samples or sequences on top of one another. These are then effectively looped either electro-mechanically or by some other way such as electronically or via programming. Systems can thus be constructed which are ideal for live performances of an ambient-techno-dance nature and the system can be used at the heart of a multi-media system driving not only sound but also images, lighting effects etc. as well as custom software, computer animation, real-time video footage of performances etc.

In such a multi-channel system, all the channels are repositionable in real time relative to one another with the subtle resolution that is possible in analogue systems. The musician can therefore interact fully with other musicians such as guitarists, singers and the like in real time. A sound system in accordance with the invention can in one example be applied for use in poly-rhythmic percussion. For example, a loop of three sampled percussive sounds will be reinterpreted in much the same way as in polyrhythmic music and the point at which bars begin and end becomes irrelevant.

The system can be deliberately designed such that the outputs from each of the individual channel units drift relative to each other over longer periods of time. The original, perhaps coordinated "sound" will then slowly break up and then subsequently begin to recreate itself with virtually infinite compositional possibilities.

For example, when using signal generators in accordance with some embodiments of the invention, the electric motor, the servo-controller, the mechanical drive-train components, the punch card and the multivibrator are all capable of being designed to introduce long term drift to ranging degrees as described.

During a live performance, drift can be arrested via the possibility of activating the optional master/slave relationship between separate channel units as defined in claim 22.

The present invention therefore makes it possible to design instruments which take modern electronic music into a different dimension, one that is more organic, and less sterile and metered. For the first time, the musician is provided with an interface for performing live digital music which values and preserves the skills traditionally associated with the playing of conventional musical instruments and, in the case of a sampler, provides transparency between the musician and his library of sound.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a schematic illustration of a first embodiment of the invention; Figure 2 is a schematic exploded perspective view of the arrangement of the motor, transmission and piston-cylinder unit of the first embodiment; Figure 3 is a side view of a punch card and associated opto-switches of the first embodiment of the invention; Figure 4 illustrates a punch card and the associated opto-switches of a second embodiment of the invention; Figure 5 is a schematic circuit diagram showing a circuit portion of the first or second embodiment of the invention; Figure 6 is an illustration of a control panel according to the first or second embodiment of the invention; Figure 7 illustrates a rack assembly in which twenty pulse generators according to the Figures 1 to 6 and a unit containing the power supply and a fan-in multiplexer are mounted; Figure 8 is a block diagram illustrating a musical reproduction system in accordance with an aspect of the invention; Figure 9 is a schematic circuit diagram showing a circuit portion of a third embodiment of the invention; Figure 10 shows a pulse timing diagram illustrative of Figure 9; Figure 11 illustrates a routing unit according to a fourth embodiment of the invention.

Figures 1 to 6 show schematically a manuallycontrollable pulse generator suitable for producing a MIDI output signal to drive a sampler.

In figures 1 and 2, a 24V DC electric motor 14 is connected via a primary drive shaft 31 and gearing to a drive wheel 30 and via a reduction gear to a gear wheel 35. The gear wheel 35 forms one half of a crankshaft, the other half being formed by a disc 37 positioned facing the gear wheel 35 separated by a distance therefrom and sharing a common axis of rotation therewith. The gear wheel 35 and disc 37 are joined by a pin 39 which extends across the gap separating the wheel 35 and disc 37 and which is positioned out of their common axis of rotation. The pin is connected to one end of a connection rod 32 which at its other end is connected to a piston or slider 34 which reciprocates within a sleeve or cylinder 36 as the gear wheels rotate. The various gear wheels, pin, connection rod and piston-cylinder unit thus form part of a device in the form of a reciprocating beam engine which converts rotary motion to linear motion. The end portion of the piston 34 remote from the connection rod 32 is connected via an actuation bar 40 to a punch card 50 so that the reciprocating motion of the piston causes the punch card to move to and fro in unison.

As an alternative, the piston and punch card so could be connected in a hinged manner to the actuation bar which, intermediate its connection with the piston and the punch card 50, is provided with a pivot point.

The ratio of the travel of the punch card to that of the piston could thus be chosen by appropriate placement of the pivot point along the length of the actuation bar 40.

In Figure 1, the punch card is illustrated from above. An opto-switch unit 60 is arranged in the manner of a yoke over the punch card 50.

In this embodiment, the opto-switch unit 60 remains in a fixed position as the punch card moves to and fro. Alternatively, the relative motion between a sensor unit such as the opto-switch unit 60 and the card 50 could be provided by moving the opto-switch unit 60 to and fro and mounting the punch card 50 statically.

The punch card 50 and opto-switch unit 60 are illustrated in side view in a schematic manner in Figure 3. The opto-switch unit 60 comprises a first opto-switch Ol and a second opto-switch 02. These two opto-switches each comprise a light emitting device, such as a light emitting diode, positioned on one side of the punch card and a light sensitive device, such as a PIN diode situated on the other side of the punch card facing the light emitting device. When one of the punch holes, e.g. 52, lies near to the line of sight between the light emitter and light detector of a given opto-switch Cl or 02 the opto-switch is closed, whereas when a punch card hole is not in the vicinity of the line of sight between light emitter and light detector the opto-switch is open.

The output pulse from the opto-switch Cl can be passed through a Schmitt trigger circuit to ensure that a clean output trigger pulse at correct voltage levels is provided.

Figure 2 indicates schematically the bidirectional servo unit 12 used for driving the motor 14. The servo unit 12 is controlled from the controller 10 which incorporates means in the form of a potentiometer 17 directly controlled by a knob 16 for allowing a continuous manual adjustment of the rotational speed and of the direction of rotation of the DC motor 14. As an option, there may be a sync-to master switch 13 as illustrated in figure 1. In one position of the switch 13, the controller 10 controls the servo unit 12 as described above. In another position of the switch 13, the servo unit 12 is controlled by a signal from a master controller, which may be another generator of the form shown in Figure 1.

The switch 13 is actuated by a button 20 on the front panel of the controller 10.

Figure 1 also illustrates speed and direction status lights 21 & 23. These lights are light emitting diodes (LEDs) of different colours and are mounted on the front panel of the controller 10 as illustrated schematically. The LEDs 21 and 23 are responsive to signals indicative of the direction of rotation of the motor. These drive signals can be derived from the servo, the motor or any of the rotating transmission parts. In figure 2, it is evident that the drive wheel 30 is rotating in a clockwise direction as shown by the curved arrow and, as a result, the LED indicator light 21 labelled FWD (forward) is illuminated. The LED indicator light 23, labelled BACK, illuminates when the drive shaft 31 and wheel are rotating in an anticlockwise direction.

Figure 3 illustrates in side view the punch card 50 shown in plan view in Figure 1. The punch card 50 has an elongate strip-like form and is perforated by holes 52, 54, 541, 542, 543 and 544. The holes 54, 541, 542, 543 and 544 are positioned along a line and form a sample trigger track of the punch card. The opto-switch Cl is arranged with the line of sight between its light emitter and light detector also intersecting the line on which the above-mentioned holes lie. A signal line 67 leads from the opto-switch Cl to the input of a monostable multivibrator circuit and carries trigger pulses which are generated as each hole successively passes through the opto-switch 01.

In Figure 2, the punch card has a total of 5 holes in the sample trigger track thus producing a total of ten trigger events for each complete revolution.

It is noted that, when the motor is running at a constant angular speed, the punch card will be continuously accelerating and decelerating between its two end stationary points. Consequently, if for example pulses are desired at regular time intervals when the motor is running at a constant angular speed, then the holes in the punch card will be spaced in a non-equidistant manner with a logarithmic offset as illustrated schematically in Figure 2. In addition to the sample trigger track 61, the punch card also has a set-to-trigger track 62 having a single hole 52 which is positioned slightly offset by a distance 6 in the direction of back-and-forth motion of the punch card 50 from the primary sample trigger hole 54. When the setto-trigger hole 52 aligns with the line of sight between the light emitter and detector of the optoswitch 02, an LED 64 marked SET is illuminated so that the user can see that a sample trigger pulse will follow if the punch card is moved any further, since, after transit through the offset 6, the primary sample trigger hole 54 will align with the line of sight between the emitter and detector of the opto-switch Ol thus producing a trigger signal on the signal line 67.

The provision of the set-to-trigger hole 52 and the associated indicator light 64 therefore allows a user to position the punch card shortly before the primary trigger position by manual control of the knob 16 of the controller 10.

Figure 4 illustrates a second embodiment of the invention which uses a different system for generating the trigger signals. This embodiment is based upon rotary motion of the punch card instead of the reciprocating motion of the first embodiment.

In the second embodiment, the punch card 50' has circular tracks and is driven directly or indirectly via reductions gears from the drive shaft 31 of the motor 14. The holes 54', 541', 542'... are positioned at equal distances from the centre of rotation of the punch card 50', with an angular distribution corresponding to the linear distribution of the holes 54, 541, 542... of the first embodiment, thus forming the sample trigger track 61'. This sample trigger track is served by the opto-switch Ol' in an analogous manner to the first embodiment. However, in contrast to the first embodiment, there are two sets of trigger tracks each having a single set trigger hole 52A' and 52B' respectively.

When the punch card disc 50' is rotating in an anti-clockwise direction as illustrated in Figure 4 by the curved arrow, the set-to-trigger track with the hole 52B' is activated by a direction sensitive switch (not shown) and the set-to-trigger LED is connected to the opto-switch 02B' associated with this anticlockwise set-to-trigger track.

When, however, the direction of rotation is clockwise, the set-to-trigger track is switched to that containing the hole 52A' and using the opto-switch 02A'.

Punch cards according to the first or the second embodiment can be provided with only one sample trigger hole 54, 54'. One, two or more auxiliary sample trigger holes may be provided as desired. Furthermore, the spacing between the sample trigger holes can be selected as desired to give any desired pulse pattern e.g. regular pulses, bunched pulses etc. The punch cards are designed to be easily fitted and removed thus providing further variation in the sound envelopes which can be created by allowing the musician to select different punch cards. The musician is even be able to design and make his own punch cards by punching holes into blank punch cards or punch cards supplied with only the primary sample trigger hole and the set-totrigger hole prepunched.

Instead of using holed cards, cards otherwise corresponding to those of the first or second embodiments could be provided with reflective dots or strips and the light emitter and detector of each optoswitch would then be positioned on the same side of the punch card 50. Moreover, instead of using optoswitches, a magnetic pick-up system could be used with the card being provided with pieces of magnetic material in place of the holes and inductive pick-up coils being used in place of the opto-switches.

In further embodiments, the pulse generation functions provided in the first and second embodiments by the mechanical and optoelectronic components could be generated either wholly or partly in hardware, software and/or firmware.

Figure 5 illustrates a monostable multivibrator circuit 70 which receives the trigger signals from the signal line 67 shown in Figure 3 and outputs a voltage pulse having a duration which is controllable by means of a variable resistor-capacitor (RC) network. In Figure 5, a single variable resistor R (e.g. a potentiometer) and a single variable capacitor C are shown. A further indicator light 65 is illuminated when a voltage pulse is currently being output, thus giving further information to the musician. The musician can therefore, for example, adjust the resistance R or capacitance C via a front panel knob or the like and thus adjust the pulse length of a forthcoming pulse.

Figure 6 illustrates the front panel of a channel unit 100 incorporating the features illustrated in Figures 1 to 5 and described above. Some further features are also evident from this front panel.

The knob 16 actuates the potentiometer 17 shown in figure 1 thereby controlling the speed and rotational direction of the motor. When the knob is positioned at 12 o'clock, the motor is halted, at which position neither of the indicator lights 21 and 23 is illuminated.

When the knob is rotated in a clockwise direction from the halted position, the motor is driven with increasing speed with clockwise rotation. Rotation of the knob in an anti-clockwise direction from the halted position effects anti-clockwise rotation of the motor in an analogous manner, i.e. with increasing speed. In Figure 6, the knob 16 is in a position resulting in relatively rapid anticlockwise rotation of the motor and causing the red indicator light 23 to illuminate.

Clockwise rotation is indicated in a similar manner by the green indicator light 21.

A sample width adjuster 120 is provided for actuating the variable resistor VR1 shown in figure 5 and thus adjusting the width of the pulses which are output from the channel unit whenever a pulse is triggered by the punch card. A twin-position switch actuator 122 is provided for actuating the double pole double throw switch (DPDT) shown in Figure 5. This feature provides for discrete adjustment of the possible range of sample widths. For example, sample widths in the range 0.3-3 and 3-10 seconds are producible when the switch is in the lower and the upper position respectively.

The indicator light 64 labelled SET is the indicator light associated with the set-to-trigger track of the punch card 50 and is illustrated in Figure 3. The indicator light 65 labelled PULSE is shown in Figure 5.

The upper portion of the front panel includes holes 102 and 104 for the finger and thumb which facilitate the insertion and removal of the channel unit from a rack unit or the like. They also serve the function of allowing air to be drawn into the channel unit during operation by cooling fans mounted to the rear of the channel unit. An illuminated momentary switch 110 is positioned in the middle of the upper portion of the front panel to show the channel number assigned to that particular channel unit, it being appreciated that in applications of the channel unit as part of a sampling system there will be many channel units mounted together. The button 110 is provided with a further function of triggering a single shot from the monostable multivibrator when it is depressed.

(The circuit elements associated with the single shot function are not shown in Figure 5).

There is also a peek hole 106 in the front panel through which the musician is able to view the drive wheel 30 or some such other of the moving parts. The gear wheel visible through the peek hole is preferably illuminated from within the channel unit 100 by a high power LED. The musician is thus able to check and view any creep or dead-slow movement of the motor and also look through the peek hole when bringing the motor to a halt via adjustment of the knob 16.

On the front panel there is illustrated a sync-tomaster button or lever switch 13. When the sync-tomaster button 13 is activated, an LED indicator light 9 illuminates and the servo unit 12 of the channel unit 100 is bypassed, so that the channel unit operates as a slave channel unit, typically then being driven from the servo unit 12 of another channel unit, designated as a master channel unit.

In applications using a plurality of channel units, it is convenient to designate channel number 1, as defined by the dual-function indicator and single shot button 110, as a or the master channel. If for example twenty channel units are incorporated in a single sampling system, then channel number 1 may be the only master channel unit or the channels may be grouped in subgroups of for instance 5 channels, with channel numbers 1, 6, 11 and 16 being master channel units for selectively controlling each of the subgroups containing the channel numbers 2 to 5, 7 to 10, 12 to 15 and 17 to 20 respectively.

Figure 7 illustrates a 19 inch rack unit having 20 channel units. The channel unit on the top-left, channel number 1, is configured as a master channel unit, it being wired to the sync-to-master socket at the back of each of the other channel units visible in Figure 1. It is noted that a master channel unit does not require a sync-to-master switch. The channel units are wired such that, when the master activation switch is activated, each of the motors of the channel units 2-5 are driven from the channel unit number 1.

In Figure 7 there can also be seen a rack unit situated below the block of channel units. This unit houses a power supply, a MIDI trigger board and a fanin multiplexer (e.g. a keyboard decoder) and has a MIDI output socket at its rear. Each of the channel units is wired to this rack unit, signals from each channel unit being supplied to the input side of the multiplexer.

Figure 8 illustrates a sampling system utilising a plurality of units 100 as previously described and including for example a rack assembly according to Figure 7. There are N individual channel units labelled 1, 2, 3.... (n-l), n which are fanned into a multiplexer 1300, the output of which is supplied to a MIDI trigger board 1400. The MIDI trigger board 1400 is clocked for example at 4 MHz and generates MIDI datastream at 31.25 kHz. There is also provided a microprocessor with a universal asynchrous receiver transmitter (UART) which can conveniently be mounted in the same unit as the MIDI trigger board. The output from the MIDI trigger board 1400 is supplied to a sampler 1200 via an opto-isolator 1420 provided for the isolation of surges, spikes and the like and for the prevention of earth loops. The sampler 1200 contains a sample library and adds the musical sample component to the rhythmic framework generated by the preceding stages. The music output from the sampler is then supplied to a mixing desk 1500 and then channelled as desired to reproduction and/or storage devices such as a digital audio tape 1600 (DAT), a monitor unit 1100, amplification systems etc. The unconnected arrows in Figure 8 schematically indicate vacant docking positions for further connections to the mixing desk 1500.

Figure 9 illustrates a circuit portion of a third embodiment of the invention. In the third embodiment, the circuit portion illustrated in Figure 9 is provided in addition to the circuit portion of the first embodiment illustrated in Figure 5. The trigger input is branched off the trigger input to the first circuit portion.

The additional circuit portion of the third embodiment provides additional output signals emulating the so-called velocity signals of an electronic keyboard which are conventially used to change the timbre of the triggered note or sample according to the speed of the key press both on depression (NOTE ON) and release (NOTE OFF). The circuit portion illustrated is specifically designed for use in conjunction with an ESO1 or compatible MIDI trigger chip. It is noted that the E501 was originally designed as an interface chip for electronic keyboards and has an internal timer with a facility for automatically calculating the velocity of key movement on depression (note-on) and release (note-off). The velocity values are calculated from two control signals input to the E501 chip, the timing intervals being triggered by rising and falling edges in two control signals input to the chip.

In the circuit portion illustrated in Figure 9 the trigger pulse is handled initially in a similar manner to the first embodiment with the trigger pulse being supplied to a "555" chip configured as a monostable multivibrator. A pulse is output from the "555" chip and has a duration which is dependent on the setting of a variable resistor VR2 and on a capacitance C. The variable resistor VR2 is actuatable from the front panel of the channel unit via a knob 8 which is visible in Figure 6 in a manner analogous to the actuation of the variable resistor VR1 of the first embodiment via the front panel knob 120. The output from the "555" chip (velocity OUT) is then supplied to the logic device 705. The logic device 705 conditions and processes the input signal and outputs two control signals on two control lines which can then be supplied to the velocity inputs of an E501 chip.

The MIDI velocity information is thus set to a value determined by the manually controllable position of the velocity actuator knob 8 on the front panel.

The third embodiment thus utilises the velocity function already built into an E501 chip to provide a further manually controllable parameter to allow variation of the timbre of samples generated by a sampling system comprising a plurality of channel units of the kind described above.

Figure 10 shows in more detail the control signal pulses outputted from the circuit portion of Figure 9 (two lower traces) as well as the pulse output from the circuit portion of Figure 5 (upper trace). The rising edge of line 710 occurring at time tl triggers the internal timer of the E501 chip. The subsequent falling edge on the other control line 712 at time t2 then stops the timer with the time btA = t2 - t1 being proportional to the "velocity of note ON" in a conventional keyboard application, but in this case, being proportional to the setting of VR2 controlled by the position of front panel knob 8. The pulse output from the circuit portion of Figure 5 on line 708 is initiated at some time intermediate t1 and t2 although the relative timing sequence between the line 708 on the one hand and lines 710 and 712 on the other hand is not crucial.

Similarly, an input corresponding to the note-off of a key, is provided at times t3 and t4 which are separated by an internal btB = t4 - t3. The interval btB will equal btA when the circuit portion of Figure 9 is used.

It is noted that the time between associated rising and falling edges of the control signals is much shorter than the pulse duration (upper trace). In one example, the respective times are 256 microseconds and 32 milliseconds.

Figure 11 illustrates the front panel of routing unit 80 according to a fourth embodiment of the invention. One routing unit 80 is provided for each channel unit 100 and has the function of associating a particular sample in the sample library with that channel unit. This function is conventionally performed by the computer used to control the sampler.

A rocker switch 82 allows channel numbers in the range 0 to 99 (1 to 20 for the system illustrated in Figure 7) to be displayed on the two-segment LED display 84. A further rocker switch 88 allows note numbers in the range 0 to 999 (typically one number for each key of a keyboard) to be displayed on the threesegment LED display 86. In this way any channel unit 100 can be linked to any desired sample manually thus changing the basic correspondence between samples and channel units. For example, in the system shown in Figure 7 the twenty routing units can be fitted into the power supply/multiplexer unit illustrated in Figure 7, with the front panels of the routing units being integral with the front panel of the power supply/multiplexer unit.

Although the embodiments have been described with particular reference to samplers, the channel units can be employed for any application, and not just musical ones, for which a large degree of flexible manual control is required for pulse generation, and in particular when the precise phase of pulse generation relative to some other events perceived by the user are required to be synchronised.

Claims (56)

1. A device for generating pulses, a pulse being triggered by triggering means which produce a triggering event at a primary point in each period of a repeatable cycle, wherein adjustment means responsive to manual input are provided for allowing continuous acceleration and deceleration of the cycle.

2. A device according to claim 1, wherein the adjustment means are capable of setting the cycling running both forwards and backwards relative to real time and of stopping the cycling, wherein phase registry is maintained even when such stopping has been effected.

3. A device according to claim 1 or 2, wherein indicator means are provided which cause a userdiscernable signal to be produced at an offset point in each said period which is slightly offset from the primary point in the cycle, whereby a user is able to adjust the adjustment means in response to said userdiscernable signal, thus allowing user control of the phase relationship between the cycling and real time.

4. A device according to any one of the preceding claims, wherein at least one auxiliary point is provided in each period the triggering means producing a triggering event at each such auxiliary point, thus triggering a pulse.

5. A device according to claim 4, having a number of auxiliary points selected from the group one, two, three, four and five.

6. A device according to any one of the preceding claims, wherein control means are provided for allowing continuously variable adjustment of the duration of the pulse caused by each said triggering event.

7. A device according to claim 6, wherein the control means can be adjusted such that a pulse duration of zero is set, thereby disabling pulse generation, even when triggering events occur.

8. A device according to claim 7, wherein indicator means are provided which cause a user-discernable signal to be produced when pulse generation is disabled by the control means.

9. A device according to any one of the preceding claims, wherein range control means are provided for allowing discrete adjustment of the duration of the pulse caused by each said triggering event.

10. A device according to any one of the preceding claims, wherein indicator means are provided which cause a user-discernable signal to be produced when a pulse is being output from the device.

11. A device according to any one of the claims 2 to 10, wherein each or any one of said indicator means produces its user-discernable signal as a visual signal.

12. A device according to any one of the preceding claims, wherein the repeatable cycling is driven mechanically.

13. A device according to claim 12, wherein each said period of the cycle is associated with a period of a cyclical movement of a body and wherein the primary point in each period is associated with a feature positioned at a specific location on said body, with a triggering event being caused by the passage of this feature past a predetermined position in the cyclical movement of the body, adjacent which position pick-up means responsive to said passage are arranged.

14. A device according to claim 13, when appended to claim 4 or claims dependent thereon, wherein each auxiliary point in each period is associated with a feature positioned at a specific location on said body, with a triggering event being caused by the passage of each such feature past said predetermined position in the cyclical movement of the body.

15. A device according to claim 14, wherein said pickup means comprise a light-emitting device and a lightdetecting device and, when said feature is in a position adjacent to the pick-up means, the light flux passing from said light-emitting device to said lightdetecting device is modulated.

16. A device according to any one of claims 13 to 15, when appended to claim 3 or claims dependent thereon, wherein the offset point in each period is associated with a feature positioned at a specific location on said body, with said user-discernable signal being produced by the passage of this feature past a further predetermined position in the cyclical movement of the body, adjacent which position further pick-up means responsive to said passage are arranged.

17. A device according to claim 16, wherein said further pick-up means comprise a light-emitting device and a light-detecting device and, when said feature is in a position adjacent to the pick-up means, the light flux passing from said light-emitting device to said light-detecting device is modulated.

18. A device according to any one of the claims 13 to 17, wherein said feature or features are selected from the group of a through-hole in said body through which light can pass and an area on the surface of said body of enhanced reflectivity.

19. A device according to any one of the claims 13 to 18, wherein the cyclical movement of the body is reciprocating.

20. A device according to any one of the claims 13 to 18, wherein the cyclical movement of the body is rotary.

21. Apparatus comprising a plurality of devices according to any one of the preceding claims and a fanin multiplexer to which each of the devices is connected.

22. Apparatus according to claim 21, wherein one of the said devices is configured as a master device and the other or selected ones of the others of said devices are configured as slave devices, with at least the slave devices each comprising actuation means for selectably allowing the adjustment means of the master device to bypass the adjustment means of each such slave device, thereby allowing a selected plurality of said device to be driven in unison.

23. A musical source comprising the apparatus of claim 22, a midi unit and a sampler.

24. A musical source according to claim 23, comprising a sound mixer.

25. A musical source according to claim 23 or 24 selected from the group: sampler and sequencer.

26. A trigger card substantially as hereinbefore described with reference to Figure 3.

27. A trigger card substantially as hereinbefore described with reference to Figure 4.

28. A device for generating pulses for use in activating samples of an electronic music sound generator, the device comprising means controllable to generate a sequence of pulses and a manual control means for the generating means to vary the pulse repetition rate of the sequence, the manual control means comprising a displaceable actuating member which has a null position in which the pulses are not emitted and from which position the actuating member can be displaced in opposite directions in each case to increase the repetition rate as the displacement from the null position increases.

29. A device according to claims 28, comprising indication means for indicating the current direction of displacement of the actuating member.

30. A pulse generator comprising means for generating a controllable pulse train, manually operable adjustment means for accelerating and decelerating the train to adjust the repetition rate of the pulses resulting from the operation of the generating means, and means for giving to the' user an indication defining predetermined phase positions non-coincident with or intermediate to the pulses in the train so that controllable phase adjustment can be made by control of the acceleration and deceleration.

31. A pulse generator according to claim 30, wherein the generating means comprise means for defining a pulse sequence and means for operating the defining means cyclically so as to generate the pulse train as a cyclical repetition of the pulse sequence.

32. A pulse generator according to claim 31, wherein the indication giving means comprise means defining a predetermined position within the sequence, that portion thus recurring in each cycle.

33. A pulse generator according to claim 30, 31 or 32 and wherein the train can be decelerated to zero.

34. A pulse generator according to claim 33, wherein the train can be reversed relative to real time.

35. A pulse generator according to claim 34, wherein the adjustment means comprises a displaceable actuating member which has a null position in which the pulses are not emitted and from which position in which the pulses are not emitted and from which position the actuating member can be displaced in opposite directions in each case to increase the repetition rate as the displacement from the null position increases.

36. A pulse generator according to claim 34 or 35, comprising indication means for indicating the current direction of displacement of the actuating member.

37. A pulse generator comprising means for generating a train of trigger pulses and means coupled to receive those pulses to generate therefrom a series of pulses of manually adjustable durations, the generating means comprising a shift means for shifting a bit or bits along the shift means either in recirculatory or back and-forth fashion, the bit or bits being arranged to generate the trigger pulses when they reach a predetermined position or positions in the shift means, and the shift means being manually controllable to control the rate of travel of the bit or bits.

38. A pulse generator according to claim 37, wherein the rate of travel of bit or bits can be slowed to zero, thus halting the said shifting.

39. A pulse generator according to claim 38, wherein the direction of travel of the bit or bits can be reversed, intermediate the ends of travel in the case of a back-and-forth functioning.

40. A pulse generator according to claims 37, 38 or 39, wherein there is a marker bit which is arranged to travel with, but offset from, the said bit or bits, the marker bit being arranged to provide an output to the user when it reaches a predetermined position in the shift means in order to assist the user in phase control of the pulses.

41. A pulse generator according to any one of claims 37 to 40, wherein the shift means comprises bit detecting means for producing the trigger pulses and a member carrying a portion or portion (providing the bit or bits) readable by the detecting means, and means for driving one of the detecting means and member relatively to the other such that the portion or portions is or are driven repetitively past the detecting means to produce the trigger pulses.

42. Apparatus comprising a plurality of pulse generators, each pulse generator including means for allowing continuous manual adjustment of the pulse repetition, and a multiplexer to which each of the said pulse generators are connected.

43. Apparatus according to claim 42, including means for allowing continuous manual adjustment of the pulse duration.

44. Apparatus according to claim 42 or 43, including means for allowing continuous manual adjustment of a velocity signal to be input into a keyboard specific controller.

45. Apparatus according to any one of the claims 42 to 44, comprising a MIDI unit which is connected to the multiplexer.

46. Apparatus according to claim 45, comprising a sampler which is connected to the MIDI unit.

47. Apparatus according to claim 46, comprising a mixing desk which is connected to the sampler.

48. Use of a device, pulse generator or apparatus according to any one of the preceding claims for a musical performance.

49. Use of a device, pulse generator or apparatus according to any one of the preceding claims for recording music.

50. Method of playing a sampler comprising continuous manual adjustment of the repetition rate of at least one sample channel.

51. Method according to claim 50, comprising continuous manual adjustment of sample duration of the said at least one sample channel.

52. Method according to claim 50 and 51, wherein the sampler is played live.

53. A device comprising an interface for connection with a pulse generator output and an interface for connection with a plurality of sample channels of a sampler and means responsive to manual control for associating any one of said plurality of sample channels to said pulse generator output.

54. A device according to claim 53, comprising a display for indicating the one of said plurality of sample channels currently associated with the said pulse generator.

55. A device according to claim 54, comprising a display for indicating information identifying the said pulse generator.

56. A device according to any one of the claims 53 to 55 in conjunction with a device, pulse generator or apparatus according to any one of the claims 1 to 47.