A7.1. Admissible power of speakers (also referred to as “nominal” or simply “power”)

This order of magnitude is only an indication. The admissible power has no direct relationship with the acoustic power or the playback quality of the speakers. As a general rule, and for the safety of the speakers, their admissible power should be slightly greater than the effective (nominal) power of the amplifier. Otherwise, there is a risk of damage to the speakers. For a use without any care of the amplifier, or for the pop music or synthesizer, with very strong listening, it is recommended to choose 3 times the effective power of the amplifier.

A7.2. Performance of the speakers (efficiency or sensitivity)

A speaker transforms electrical energy into acoustic energy.

To obtain a higher volume of sound, the higher the efficiency of this transformation, the less power the amplifier has to provide. A high yield does not necessarily mean good playback quality. However, if high volume levels are needed in a large room, choosing high-efficiency speakers can reduce the power required for the amplifier.

The specifications regarding the effectiveness (in decibels), the sensitivity (in watts) or the efficiency (in %), which are usually displayed, are different measurement methods. They are practically unusable for laypeople; only the order of magnitude is important.

Supposed “comparison” of sound systems by listening to the same recording on different systems or speakers may be misleading. Without knowing what the original music sounds like, how is it possible to appreciate the “fidelity” of the “recording”?

The sensation perceived is related to:

• – whether or not the music is pleasing;
• – the ability of a given sound system to create the sensation of the presence of the musical group;
• – listening conditions which are rather different from the actual conditions;
• – the mood at the time and the influence of the seller.

Comparative listening necessarily requires an equivalent volume level between systems.

A7.3. Can we make judgments according to technical features?

The figures and curves are very explicit but are not directly usable for laypeople.

Each characteristic is only meaningful in relation to others, and in relation to certain listening conditions. Some of these data are used for commercial purposes and have no bearing on the choice to be made.

Any sound playback, however faithful, cannot claim make the listener perceive the reality of the original sensation.

The listening qualities of a “hi-fi” system depend on:

• – the type of music;
• – the ability of the channel to make the orchestra feel present;
• – the volume level;
• – the “quality” of the listener’s ears;
• – the acoustics of the listening room;
• – the ambient background noise;
• – the personal requirements.

Real listening tests with a jury, that meet the current requirements: a fairly large living room, coatings and ordinary installations, have been realized, a large enough living room, a good surface and the correct fittings.

A jury, containing a wide variety of “musician ears”, has assessed the differences between the sound made by the sound systems and sounds used as a reference.

A dozen different characteristic sounds, taken from various types of music, were recorded and used as the reference sounds: voice, contrabass bugle, gong, clarinet, saxophone, piano in the high registers, trio, applause, etc.