Tannoy 800 user manual Sum of the parts

the emitted sound field, diffractions and reflections caused by the cabinet boundaries are too often overlooked although they are the cause of most of the irregularities heard and measured in the higher frequency areas.

In that respect conventional rectangular, sharp corner boxes perform especially poorly. On the other hand, the shape of the System 800 has been designed with careful attention paid regarding the sculptured front panel to provide smooth, rounded edges which minimise side diffractions.

Another problem involved in cabinet design is to ensure that the box will effectively behave as neutrally as possible, ideally without interfering at all with the sound field emitted by the drive unit and the port. There are two main ways the box can get into vibration. First there can be a mechanical transfer of energy between the drive unit and the cabinet front panel. Preventing this requires the use of a rigid and stiff front baffle, which is achieved on the System 800 by a very thick and compact MDF panel. The second way the cabinet can get into vibration is by transmission from acoustical to mechanical energy. Since high acoustic pressures are present inside the cabinet this is quite likely to occur if no attention is paid in order to minimise it. Here the use of rigid panels is also helpful but, since their stiffness cannot be infinite and therefore their resonances only shifted towards higher frequencies, enough damping has to be provided in the cabinet assembly, including panels and joints. Due to its octagonal shape and its cabinet construction, the System 800 perform very well in that respect. Its shape tends to decrease the largest dimensions of each side panel, which reduce low frequency resonances, while the doubled number of side provides additional damping.

In addition to the cabinet construction the volume and port tuning have been carefully calculated to give the best set of parameters for monitoring loudspeakers. There is a fundamental relationship in loudspeakers between efficiency, cabinet volume and low frequency performance given that minimal amplitude variations can be tolerated (as in monitoring situations). The set of parameters that are arrived at as a solution are inevitably a compromise and the skill of Tannoy has always been shown to be getting these particular parameters correct for the application.

The Sum of the parts.

The crossover is an important, sometimes difficult part of the design. However the use of an optimised, well designed drive unit makes the task easier and allows using simpler networks, which generally give better results.

It is also important to point out that a very important benefit of the Dual Concentric technology is in connection with the crossover. With conventional discrete multi- drivers speakers, the crossover has a dramatic effect on the speaker performance in the frequency range where the different drivers overlap, especially on off-axis response and on spatial dispersion. Actually, because of the detrimental effects resulting from the fact that they are non-coincident, the drivers should ideally work in completely split ranges of frequency. High order low and hi-pass filters are therefore required to reduce the overlap range. Apart from the fact that it makes the design more complex, requires more accurate components and increases the costs, a major drawback is that higher order filters involve increased phase and group delay distortion, which can be quite perceptible. On the other hand the low order filter used with Dual Concentric drivers achieve a smooth phase response.

The integration of all the features described above is what makes the whole loudspeaker system even greater than the sum of the individual parts.