Sind Breitbänder optimal? specifications

Category : Lexicon

A wideband is more of a narrowband compared to multipath constructions. Although it is a minimum phase system, it is one with a very narrow quasi-linear transmission range. And it is also - at least on rough examination - a point sound source, but one with often very uneven radiation behavior. However, a broadband is free of the usual phase and impulse problems that otherwise occur in the transition areas of the chassis. There are limitations:

Widebands have great difficulties, especially at the ends of the transmission range. They are not real powerful bass speakers. The limited linear stroke and the relatively small diaphragm area rarely allow a significant expansion of the bass reproduction at low frequencies, especially not if you exceed the room volume. From a metrological point of view, the relationship to other "time-correct" concepts consists in the time-synchronous playing style. Within the transmission range, everything plays together to the point. There is a feeling of naturalness when listening. The highest sensitivity of our hearing organ is in the middle of the hearing spectrum and at the transients and can therefore be very well served with a broadband. The usable transmission range often ends at significantly less than 10 kHz. The amplitude values in the higher frequency range are then only a superposition of membrane resonances on the low-pass filter of the chassis, which cannot be corrected by filters. Occasionally, widebands are combined with another tweeter to improve tweeter reproduction. However, in principle, this is not possible at the right time, since in the case of the chaotic amplitude and phase behavior in the upper transmission range of a broadband, the addition and subtraction of the sound waves also takes place randomly and not according to the music signal. So-called "super tweeters" or coupled basses destroy the property of the point sound source, unless it is already limited by partial vibrations.

Wild Thing

Widebands usually have not only a strong drive, but also very light membranes. This results in the specified, very high efficiency at a certain frequency. However, when viewed over the entire bandwidth, the efficiency is already significantly lower! High efficiency due to often short voice coils and light paper diaphragms also leads to a nonlinear stroke with strong distortions and, due to the diaphragm, to an uneven drop in the dynamic phase at an early stage. Light membranes are also not very stiff, which creates the so-called partial vibrations. They are the result of partial membrane oscillations, in which the membrane breaks up into many small partial surfaces, each of which oscillates on its own. They all have their own acoustic center. So it is not a pure spot radiator. Due to these acoustic centers distributed on the membrane, which also vary in time, time-shifted, chaotic sound additions and subtractions are generated, which, as interference, lead to unevenness in the frequency response. Flat-diaphragm loudspeakers such as those in the Myro Spirit IV are still the most suitable for a broadband application. The resonance phenomena are in the upper treble range and are often perceived by the listeners "only" as living highs. On the other hand, the advantages of a much deeper coupling to the mid-woofers outweigh the advantages of the usual tweeters, which ensures a more good-natured vertical radiation behavior of the entire system.

ESS PS-61

The settling A wideband combines the characteristics of tweeters and woofers. Its transient response is thus determined by a high and a low pass at the lower and upper cutoff frequency. The transient distortions are thus present as well as with separate tweeters and woofers.

A speaker with the right timing should have a fast-resonating tweeter that can already reproduce the first half-wave correctly. This requires a high resonant frequency. So far, the Accuton diamond tweeters offer the best characteristics. But the broadband behaves the other way around. If you look at its frequency response, then in addition to a fairly smooth progression in the midrange, you can see increasing ripple in the high-frequency range. These are resonances that produce the high-frequency level. As with all resonances, it is an unmodulated sound that does not contain any music information. Therefore, widebands hardly play music in the tweeter, but a chaotically generated frequency mixture. The useful bandwidth available for the music is therefore much lower than the frequency response indicates! Accordingly, one has the impression that there is not a lack of high-frequency level, but a lack of resolution. It should be noted that the frequency responses shown in the data sheet have often been smoothed, so the ripple is much stronger in the real measurement. Due to the inertia of the membrane and the development of high-frequency resonances, a very poor reproduction of the first wavefront can be expected in the high-frequency range. On the other hand, the necessary membrane area is missing for the bass tone. In the steady state, the broadband thus becomes a chassis that provides correct reproduction only in a narrowband range.

Radiation at an angle Not only the direct sound, but also the reflections on the side walls are relevant for time-correct hearing in space. After all, reflections are also of different authenticity and contribute their part to the sound experience. Broad bands are usually extremely nonlinear outside the axis, however, and therefore there are no time-correct reflections in space. Filter s should only be used to correct non-linearities that do not occur only at certain angles. There are many resonances that lead to extreme elevations on the axis, for example, but form a depression at an angle, for example 30 degrees, because the partial vibrations are extinguished at this angle. Especially with chassis that are operated openly in their upper transmission range, i.e. with broadband, these problems are clearly evident. And they are also not covered by the sound component of a tweeter. If membrane resonances make up the frequency response at higher frequencies and these consist mainly of partial oscillations, then the time correctness under angle does not work.

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at maximum sound pressure
in the high-frequency range (cut-off frequency / fine resolution)
in the bass range (cut-off frequency / / stroke / harmonic distortion)
during pulse reproduction (The radiation resistance curve causes weak first halfwaves in the fundamental and especially in the bass range.)

Sind Breitbänder optimal?