EP0732034B1 - Improvement to a power amplifier/loudspeaker interface - Google Patents

Abstract

A method for supplying power to a hi-fi loudspeaker unit comprising a speaker (Hp) supplied via a conductor (LA) connected to a positive pole of an amplifier, and a conductor (LR) connected to a negative pole thereof, and at least one filter mounted in parallel. According to the method, the filter(s) (Z1, Z2, Z3) is (are) connected to the negative pole of the amplifier via a conductor (L1, L2, L3) which is separate from the conductor (LR) connecting the speaker (Hp) to said negative pole.

Description

The present invention relates to an improvement to the interface "Power amplifier-speaker".

High fidelity loudspeakers generally have several channels to which a certain frequency band is assigned to reproduce. To do this, it is necessary to have filters on the enclosure supply circuit consisting of capacitors, reactors and resistors. While some speakers only have filter components in series, most, requiring more complex filtering, also have them in parallel. Such arrangements are described in FIGS. 1 and 2 of patent EP 0 485 010.

The diagram in FIG. "1a" represents such filtering on one channel of a multi-channel enclosure; this known arrangement comprises a loudspeaker "Hp" supplied by a circuit comprising two conductors 1 and 2, the conductor 1 being connected to the pole "+" of the amplifier via the conductor "LA" and the conductor 2 to pole "-" via the conductor "LR".

As is known, the conductor 1 comprises one or more filters "F" arranged upstream of the loudspeaker "Hp" and, between the conductors 1 and 2, one or more filters "Z" such as Z1, Z2, Z3.

These filters are arranged in parallel so that they bypass the speaker "Hp". The connection of these filters to terminal "E-" of the enclosure takes place via conductor 2.

A known variant of this wiring is shown in Figure "1b".

We note, and this is essential, that these different ways of wiring the speakers all have one thing in common: the return to terminal "A" of the amplifier is made from one and only one common terminal "E- "of the enclosure, via a single conductor" LR ".

In the case of multi-amplifications, there are as many "E +" and "E-" terminals and "LA" and "LR" connecting conductors as there are channels, but each channel is wired and connected to (or to) amplifiers according to a "1a" or "1b" type diagram.

The applicant has discovered that if, instead of connecting the elements in parallel Z1, Z2, Z3 to the single terminal "E-" as is known and shown in Figures "1a" and "1b", they were connected separately to the terminal "A-" of the amplifier by independent conductors L1, L2, L3, a considerable improvement in the sound quality was obtained.

Thus, several professional musicians, mainly violinists and cellists, were made to hear recordings highlighting their instruments, using either a pair of speakers mounted according to the diagram in Figure "1a" or "1b", or a pair of speakers mounted according to the diagram in Figure 2, the test being made "blind", that is to say without them knowing what was the pair of speakers used. Each time, they made the difference quickly and unambiguously.

Listening carried out on the speakers modified by the applicant was all very much superior to that carried out on conventional speakers: markedly improved dynamics, more natural and richer sound, completely realistic timbre of the instruments.

In a more subjective way, they noted that the artist's "play" was more emphasized and that the emotion became more palpable.

Otherwise, the sound has been described as more "flat", less rich with a very noticeable loss of details causing a loss of much credibility to the illusion of musicians in the listening room.

Other tests were carried out with high-fidelity amateurs and in 95% of the cases, the listeners considered that there was a marked improvement in the sound.

This result is unexpected and even contrary to the teachings of the technique, because for a person skilled in the art, it appears that the electrical assembly is the same since all the conductors L1, L2, L3 meet at the pole "-" of the amplifier. It therefore turns out that for unexplained and therefore in no way obvious reasons, the fact that the return of the shunt filters takes place separately for each filter and separately from the return "LR" of the loudspeaker circuit "Hp" produces a considerable improvement in sound quality.

In the example of Figure 2, there are shown three filters Z1, Z2, Z3 each having its independent conductor L1, L2, L3 but various variants are possible.

There can indeed be only one filter "Z": in this case, there is only one conductor "L" independent of the conductor "LR".

There can be two filters Z1 and Z2: in this case, two solutions are possible: there are two conductors L1 and L2 or there is only one conductor "L" for the two filters. It turns out in this case that if there is an improvement in sound, it is less clear than if each filter has its own conductor "L".

The same variants are possible if there are three or more filters: one can have an independent "L" conductor for each filter or group them. But we see that the best sound is obtained when each filter has an independent conductor, which clearly demonstrates the existence of a particular result.

Another attempt was also made to minimize the distance between the amplifier enclosure.

It is obviously not desirable to have the speakers on either side of the amplifier and a few centimeters from it. In this case, the desired stereophonic effect is greatly attenuated, which goes against quality listening.

However, the applicant carried out an assembly simulating a very small distance (a few centimeters) between the amplifier and the speakers. Indeed, by removing all the filtering from the enclosure and connecting it directly to the amplifier by a conductor as short as possible (a few centimeters), the desired experiment is carried out. In this case, the "Hp" speakers remain in place while the length of the "LR" and "L" conductors is reduced to a few centimeters.

This experience has shown that even in this extreme case, the wiring in FIG. 2 still gives superior results to those obtained in cases "1a" or "1b". The differences in reproduction quality are always of the same order and obvious when listening "blind".

One would have thought, however, that the improvement would have decreased in proportion to the reduction in length "LR" to become imperceptible for very short lengths. It is not so. It even seems that the improvement brought by this new link mode is almost independent of the amplifier-speaker distance.

Claims (3)

1. Method for supplying a high-fidelity speaker system comprising a loudspeaker (Hp) supplied by a conductor (LA) connected to the positive pole of an amplifier and a conductor (LR) connected to the negative pole and at least one filter (Z) mounted in parallel, characterised by the fact that the filter or filters (Z, Z1, Z2, Z3) are connected to the negative pole of the amplifier by a return conductor (L, L1, L2, L3) independent of the conductor (LR) connecting the loud-speaker (Hp) to said negative pole.
2. A method for supplying a speaker system according to Claim 1, characterised by the fact that as many independent return conductors (L, L1, L2, ...) are provided as there are filters in parallel (Z, Z1, Z2, ...).
3. A method according to Claim 1, in which certain filters (Z, Z1, Z2, ...) are grouped on the or one of the return conductors (L, L1, L2, ...).

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