DE3144579A1 - Low-frequency power amplifier system - Google Patents

Abstract

Published without abstract

Description

Description:

The invention relates to a low frequency power amplifier arrangement, especially for an active loudspeaker box, with at least one power supply unit, one at least the power resistors and connections for those in thermally conductive connection with heat sinks standing power transistors having printed circuit board as well with at least one driver stage.

In any low frequency power amplifier arrangement occur in context not inconsiderable with the potential connection and the cooling of the power transistors Problems arise when the goal is to be pursued, the power amplifier arrangement to be interpreted in such a way that the input signal is only amplified, but not falsified will. In the case of active loudspeaker boxes as electroacoustic transducers, these exist Problems to a greater extent because of high quality loudspeaker boxes demands that they do not measure or

produce audible coloration of the sound. It is also desirable for the external ones Dimensions of the cabinet next to the speaker chassis for each speaker need to include a power amplifier as much as possible. Conventional amplifier arrangements, in which several output stages are connected to a power supply unit on a circuit board are, generally have the disadvantage that due to the low cross-section Conductor arrangement for the potential connection of the transistors a coupling of the Output stages occur among each other, which means that low frequencies are coupled into high frequencies and vice versa and the distortion factor increases disadvantageously. High quality and Correspondingly expensive boxes therefore use a separate power supply for each output stage, through which not only the manufacturing costs, but also the housing dimensions grow. In particular, the use of several power supply units results in increased assembly costs tied together.

The invention is based on the object of showing ways and means which allow low-frequency power amplifier arrangements in their constructive and to simplify mechanical effort, while at the same time improving the electrical values should be achieved.

This object is achieved by the invention essentially in that the Power transistors in groups according to the potentials applied to their housing are arranged separately and the power transistors of each group on one metallic profile rail can be attached, which the circuit board with a heat sink mechanically and the potential connection of the power transistors with the power supply output electrically connects.

The separation of the power transistors according to those applied to their housing Potentials (+ or - to earth) electrically isolate the transistors dispensable from one another, since the potentials are now managed separately.

The arrangement of each group of power transistors on each one metallic profile rail that connects the circuit board with a heat sink-mechanically and the potential connection of the power transistors to the power supply output electrical connects, it allows the on the circuit board as a low-cross-section conductor track to keep the potential connection located very short, while the profile rail a large cross-section conductor is available, the resistance of which is extremely low is. The beneficial consequence of this is that the coupling is drastically reduced. the potential-wise separation of the power current transistors also prevents mutual Influencing of the potential lines through vt) n these generated magnetic fields. The breakdown of transistors is particularly important in so-called symmetrical push-pull output stages, in which a group of p-n-p-trans and storen urici ane r ## dert 'group n-p-n transistors is extremely advantageous. Since the profile rail in the rest establishes the mechanical connection between the circuit board and the heat sink, a very compact structure can be achieved, with the length of the profile rail by appropriately shortening the respective size ratios can be customized. Because the power transistors are on the rail can be fastened, which is mechanically connected to the heat sink, the large cross-section is used Profile rail at the same time for improved heat dissipation from the power transistors to the heat sink.

Since the potential is directly transmitted to the housing of the Power transistors can be performed, I made the mechanical and electrical Connection of the potential connection pin of the transistor to the circuit board. There a single output stage can have ten power transistors, for example It is clear that this effect already results in a considerable saving in assembly work can be achieved.

Within the framework of the invention principle described with its advantages Numerous further refinements and advantageous developments are possible. So it can be continuously moved and fixed along the profile rail the power transistors of each group as well as the heat sink and the printed circuit board be arranged. For the infinitely adjustable and definable arrangement of the power transistors, of the cooling body and the circuit board on the profile rail are preferably T-slots provided in this or in the heat sink, angular in the widened section Nuts or screw heads as fastening elements cannot be rotated storable are. Are the profile rails and, if applicable,

the heat sink from shortened sections of an extruded profile especially light metal - also copper or some other material with high electrical and thermal conductivity would come into consideration - formed, these profiles also need no processing whatsoever when cutting to the desired format.

In particular, it is not necessary at specially determined points To make mounting holes including thread. If in the extrusions the T-slots are taken into account, one is in the choice of the assignment between the Profile rail, the heat sink and the circuit board completely free within wide limits, so that, if necessary, an asymmetrical structure of a power amplifier arrangement can also be used can be achieved if this is advantageous for reasons of space, e.g. in a loudspeaker box were.

Another feature of the invention is that the electrically Conductive connection between the conductive track on the printed circuit board that carries the potential and the profile rail by placing the conductor track directly on the profile rail or is created by a bridge formed by the fastening members. This is easily possible, since the profile rail is attached to the circuit board anyway is. Special supply lines, in particular by means of cables with a large cross-section, can be circumvented.

With regard to the design of the profile rail, there is another Advantageous feature is that they have a, an insertion step for on the long side has the edge region of the conductor track forming web strip, in the profile rail side Means for fastening the circuit board are arranged. That way it is E.g. it is possible to place the circuit board in one level above the radiator level to be arranged, whereby a particularly compact structure can be achieved.

An advantageous arrangement and assignment of the power transistors for Circuit board is given according to a further feature in that the component side the printed circuit board is facing the web strip and on the side with respect to the component outwardly facing surface of the profile rail, the transistors can be fastened. Then the connecting pins running parallel to the plane of the circuit board can Power transistors via solder pins running across them with the conductor tracks connected to the printed circuit board. In particular, it is not necessary to use the connector pins of the power transistors as in itself Ubl bend around ~ 90 () 9 <> anyway. This also makes the replacement of a defective power transistor, for example, significant facilitated, since only the connection between its connecting pin and the soldering pin must be separated, but it is not necessary, spatial access to the soldering side the circuit board, so that the required soldering work exclusively can be done from the component side of the circuit board.

In order to be able to achieve a particularly variable structure, is still provided that the profile rail is transverse to which the holding means for the power transistors and the circuit board having legs extending additional legs for the alternative Attachment, the heat sink has. In this way, an arrangement can be made with each heat sinks attached to the outside of the conductor plate can be reached; it arises a power amplifier arrangement with a very flat design.

The profile rails carrying the groups of transistors can be attached to each other arranged opposite side edges of the circuit board and each with one or be connected together with a heat sink. Regardless, it usually is required to electrically isolate the heat sink (s) from the profile rails.

As part of the target direction, with simple and few resources after To be able to build different sized power amplifier arrangements, further features of the invention gain in importance. Such is a power amplifier arrangement according to a further development, characterized in that it has a plurality of amplifiers comprising a single power supply, with the same groups of transistors all amplifiers are arranged on a common rail. At this In the design, the problems of coupling and potential magnetic fields mentioned at the beginning do not arise because the potentials on the large cross-sectional profile rails that are separated from one another are led. The profile rails therefore primarily offer favorable conditions for a power amplifier arrangement with high performance, compact structure and Component-wise to manufacture with little effort, without electroacoustic disadvantages such as especially having to accept a high distortion factor.

In connection with the desired compact structure of the invention Power amplifier arrangement is provided that the arrangement has a first printed circuit board includes, with the power supply unit, the power transistors and the resistor resistors can be equipped for several amplifiers, while the driver stages on further circuit boards are arranged in the arrangement area of the transistors and resistors each Amplifier can be connected to the first printed circuit board, in particular plug-in connection are. The connections for the components of the individual amplifiers on the first printed circuit board on one or both sides of the power supply unit in blocks one behind the other arranged and the blocks be galvanically connected to each other that by Cutting the circuit board to length an integer multiple of connection blocks can be separated is. The arrangement of the driver stages on other, specifically pluggable Circuit boards shorten the space required by the first circuit board - which is also known as the "mother card" could call - considerable. The block-by-block arrangement of the connections for the Components of the individual amplifiers on the first circuit board h; & t with the Cut to length: The result is that the circuit board as well as the profile rails and which the heat sinks can be "cut" to the respective conditions. For example, active loudspeakers of different sizes are sufficient for a complete program a single first printed circuit board that fl '# r the. Box designed with most power amplifiers is. The connection blocks that are not required are used to equip a smaller box simply removed by a separating cut. Sneezing way of creating a printed circuit board for smaller power amplifier arrangements is considerably more economical than for to make its own lyre plate for each type of power amplifier.

The invention is illustrated below with reference to one in the drawings Embodiment explained in more detail.

The drawings show: FIG. 1 a schematic end view of a Power amplifier arrangement FIG. 2 is a partial plan view of this and FIG. 3 is an approximate view on a scale of 4: 1 enlarged partial representation of an edge region according to the arrangement Fig. 1.

The schematic structure of a power amplifier arrangement shown here should have several amplifiers, results from Fig. 1 as follows: It is one first printed circuit board 10 is provided, the power resistors 11 and connections 12 for power transistors 13, 14 has. In addition, e.g. on one end (not shown) is provided with the component arrangement for a power supply unit. In addition to power resistors, each amplifier in the amplifier arrangement has 11 and power transistors 13, 14, a driver stage. This is on one labeled 14 and arranged schematically indicated second circuit board 15, which with the first Printed circuit board 10, standing on this, can be connected, in particular can be plugged in. The arrangement has the effect that each amplifier has a delimited block B or

forms. There are therefore so many blocks on the first printed circuit board 10 B, B '... arranged like amplifiers are provided.

The illustrated schematic embodiment includes pre power amplifiers two complementary transistors 13, 14, one of which, for example, in a p-n-p circuit and the other is provided in an n-p-n circuit. Depending on the power of the power amplifier this can of course also be an integral multiple of two transistors 13, 14 have. For the formal differentiation of the components of those shown in FIG Amplifiers 15 and 15 'are these with the same, only differentiated by Provided with reference numerals.

I) ie power transistors 13, 14 or 13 ', 14' of each amplifier 15 and 15 'are in groups - on different sides of the first circuit board 10 arranged. In the exemplary embodiment, however, each group of transistors includes just a transistor. It is essential that the transistor 13 (or 13 ') have a different one Has potential connection than the transistor 14 (14 '). All transistors 13, 13 '- 14, 14 'of all amplifiers 16, 16' etc. are in groups on a common profile rail 17 or 18 attached. The two rails 17 and 18 are identical, only arranged in mirror image on one and the other side of the first printed circuit board 10 and consist of an electrically and thermally conductive metal, e.g. Aluminum, copper or the like. The Transistors 13, 13 'or 14, 14' are in direct electrical contact with their housing on the profile rail 17 or

18 attached, while each rail with the appropriate potential of the power supply output is connected.

In addition to the transistors 13, 13 'and 14, 14', there is also the first printed circuit board 10 and finally at least one heat sink 19 with each profile rail 17 or lS connected.

Each profile rail 17 or 18 therefore provides the mechanical connection between circuit board 10 and heat sink 19 as well as the electrical connection between the power supply output and the housing of the power transistors 13, 13 'or 14, 14 '. To attach all parts to the respective profile rail 17 and 18 has these T-slots 20, 21 and 22, with which screw fasteners 23, 24, 25 cooperate. The way in which this is provided is best illustrated in FIG. 3 with reference to FIG Profile rail 17. This is (as well as the identical profile rail 18) around an extruded profile in which the grooves 20 and 21 are molded directly. The groove 20 is used for longitudinally displaceable but non-rotatable accommodation of a polygonal Head 26 of a screw 27 as a fastening member 23 for holding the first printed circuit board 10 on the profile rail 17. The screw shaft of the screw 27 extends through it a corresponding hole in the circuit board 10, which by means of a nut 28 and a washer 29 is fixed on the profile leg 17. An analogous arrangement is provided for attaching the transistors 13 (and of course 13 ', 14, 14'). With regard to FIG. 3, there is an upside-down T-slot in the profile leg 17 intended. Here, too, the head 30 is mounted in a non-rotatable but longitudinally displaceable manner Screw 31 as fastening element 24. From the top is the fastening foot 32 of the transistor 13 by means of nut 33 and washer 34 on the contact side 35 for the circuit board 10 facing away from and parallel to her system side 36 provided.

Relative to the profile rail 17, both the circuit board 10 as well as each power transistor 13 steplessly move independently of one another and attach where required.

The electrically conductive connection between the corresponding Potential leading conductor track 37 to transistor 1 happens via the as electrical Fastening member 23 serving the bridge. Deviating from this, it would also be conceivable and possible that the first printed circuit board 10, the potential conductor 37 on the top with respect to FIG. 3 carries. Then this conductor track 37 would come on the one hand through direct installation and the housing of the power transistor 13, on the other hand, on the profile rail 17 the electrically conductive connection is established.

For the infinitely adjustable fastening arrangement of the cooling body 19 there is a T-slot 22 in this. To completely: any and freely selectable Can make a threaded hole in the profile rail (with reference to F .. 3 from below) 17 are introduced through which the head 38 in the dswr groove 22 cannot be rotated held screw 3 <) reaches through with its shaft. On the top 36 A nut (Fig. 2) is then screwed onto the Profilsc'.iene. To make things easier the required through-hole of the profile rail 17 is in this during manufacture a grain groove 41 already formed.

With an insulating strip 42 is designated, which the bar 17 opposite electrically insulated from the heat sink.

As can be seen, the profile rail 17 is in the vicinity Circuit board 10 has a web strip 42 of tapered cross section, so that an insertion step 43 for the printed circuit board 10 including the screw arrangement 27, 28 and 29 is created. This makes it possible, in particular, for the heat sink 19 to be in a parallel envelope below the circuit board 10 - in close association with (this - can extend.

When it comes to the exemplary embodiment shown in the drawings intended to use a heat sink for the entire Lf 1 power amplifier arrangement, on which the two profile rails 17 and 18 are arranged. But of course two separate heat sinks can also be used in the same place. As each Profile rail 17 is provided with an additional leg 44, can each have a heat sink also on the outside of this additional leg (here too there is a center groove 41 ' prepared) as an alternative. As can be seen, a very low construction.

For the electrically conductive connection of the connecting pins 45 and 46 each power transistor 1: 3, 13 ', 14, 14' is on the first printed circuit board 10 one soldering pin 47 is fastened with a soldering eye 48 in each case. The solder connection 49 between the connecting pin 45 (or 46) and the soldering pin 47 can therefore be on the component side the first circuit board 10 can be made. The same is also true the replacement of a transistor easily possible, because only the the component side of the circuit board 10 her freely accessible soldering points 49 released Need to become. Since each profile rail 17 or 18 is the transistor group-specific Carries potential, the electrical connection of the respective third connection pin is omitted 50 of the transistors. These connection pins 50 can therefore also be removed.

It is now readily apparent that in a simple manner Use of the same basic elements from a manufacturing point of view, simple power amplifier arrangements different Size can be produced. Depending on the number of required E: ntl:; tufen value ztlnachtìt in the event that fewer power amplifiers are provided are as it corresponds to the maximum design of the base circuit board 10, of this along a straight line 51 as many blocks B are separated as amplifiers do not are needed. According to the space requirements of the individual transistor groups the sections for the profile rails 17 and 18 are made of a long profile bar cut to length, as well as the required length of the profile for the heat sink 19.

For fastening these parts to one another, including the stung transistors only need the screw connections in the T-slots 20-22 provided for this purpose to be introduced. Due to the infinitely variable displacement of the fastening means connected elements, these are aligned with one another in a simple manner and then fixed the fastening elements.

Thus it has succeeded with the means of the invention, a simple ~ Modular system "for the construction of compact power amplifier arrangements in proposal bring to. The structural design as well as the mechanical play a decisive role in this unti electrical arrangement, the profile rail 17 (or 18), d: trl their use however, it is not only the structural design effort that is low in a space-saving manner can be kept, but which also changes the electrical properties of the Let the power amplifier arrangement improve significantly.

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Claims (15)

Low frequency power amplifier arrangement claims: 92J low frequency power amplifier arrangement, ins-especially for an active loudspeaker box, with at least one power supply unit, one at least the power resistors and connections for the in thermally conductive Connection with heat sinks standing power transistors having printed circuit board and with at least one driver stage, characterized in that the power transistors (13, 13 ', 14, 14') separated in groups according to the potentials applied to their housing (13, 13 '/ 14, 14') are arranged and the power transistors (13, 13 '- 14, 14 ') of each group can be attached to a metallic profile rail (17 or 18) are that mechanically connect the circuit board (10) with a heat sink (19) and the potential connection which electrically connects the power transistors to the power supply output. 2. Power amplifier arrangement according to claim 1, characterized in that that the power transistors (13, 13 '- 14, 14') of each group in the longitudinal direction the profile rail (17 resp. 18) can be continuously moved and fixed along this. 3. Power amplifier arrangement according to claim 1, characterized in that that the heat sink (19) in the longitudinal direction of the Profile rail (17 and / or 18) can be continuously moved and fixed along this. 4. Power amplifier arrangement according to claim 1, - characterized by ## darms along the printed circuit board (10) in the longitudinal direction of the profile rail (17 or '8) this is infinitely adjustable and fixable. 5. Power amplifier arrangement according to one of claims 2 to 4, characterized in that for the steplessly displaceable and fixable arrangement of the Power transistors (13, 13 '- 14, 14'), the heat sink (19) and the circuit board (10) on the profile rail (17 or 18) continuous T-slots (20, 222) in this or are provided in the heat sink (19), angular in the widened section Nuts or screw heads (26, 30, 38) of the fastening elements (23, 24, 25) cannot be rotated are storable. 6. Power amplifier arrangement according to claim 1 or one of the following, characterized in that the electrically conductive connection between the relevant potential leading conductor track (37) of the circuit board (10) and the profile rail (17 or 18) by placing the conductor track (37) directly on the profile rail (17 or 18) or created by a bridge formed by the fastening elements (23) is. 7. Power arrangement according to claim 1 or one of the following, characterized characterized in that the profile rail (17 or 18) and, if applicable, the heat sink (19) formed from shortened sections of an extruded profile, in particular from light metal are. 8. Power amplifier arrangement according to claim 1 or one of the following, characterized in that the profile rail (17 or 18) on one Long side one, one insertion step (43) for the edge area of the circuit board (10) forming web strip (42), in which insertion step (43) the profile rail side Fastening members (23) for the circuit board (10) are arranged. 9. Power amplifier arrangement according to claim 1 or one of the following, characterized in that the component side of the printed circuit board (10) of the web strip (42) and on the one facing outwards with respect to the component side Surface (36) of the profile rail (17 or 18) the transistors (13, 13 '- 14, 14') are attachable. 10. Power amplifier arrangement according to claim 9, characterized in that that the connecting pins (45, 46) running parallel to the plane of the printed circuit board Power transistors (13, 13 '- 14, 14') across soldering pins running transversely to these (47) are connected to the conductor tracks of the circuit board (10). 11. Power amplifier arrangement according to claim 1 or one of the following, characterized in that the profile rail (17 or 18) has a transverse to which the Fastening members (24, 23) for the power transistors (13, 13 '- 14, 14') and the circuit board (10) having legs extending additional legs (44) fi for has the alternative attachment of a cooling body. 12. Power amplifier arrangement according to claim 1, characterized in that that the profile rails (17, 18) carrying the groups of transistors lie opposite one another Side edges of the circuit board (10) arranged and each with one or together with a heat sink (19) are connected. 13. Power amplifier arrangement according to claim 1, characterized in that that it comprises a plurality of amplifiers (16, 16 ') with a single power supply unit, being the same groups of transistors (13, 13 '- 14, 14') of all amplifiers (16, 16 ') are arranged on a common profile rail (17, 18). 14. Power amplifier arrangement according to claim 13, characterized in that that it comprises a first printed circuit board (10) which is connected to the power supply unit, the power transistors (13, 13 '- 14, 14') and the power resistors (11) for several amplifiers (16, 16 ') can be assembled, while the driver stages on further circuit boards (15, 15') are arranged in the area of the transistors (13, 13 '- 14, 14') and Resistors (11) of each amplifier (16, 16 ') can be connected to the first printed circuit board (10), in particular can be plugged in. 15. Power amplifier arrangement according to claim 13 or 14, characterized characterized in that the connections for the components of the individual amplifiers (16, 16 ') on the first printed circuit board (10) on one side or on both sides of the power supply unit are arranged in blocks one behind the other and that the blocks (B, B ') are so galvanically are connected to each other that by cutting the printed circuit board to length (dividing line 51) an integral multiple of connection blocks (B, B ') can be separated.