Both of these change the way the loudspeaker driver reacts with the enclosed volume, mainly at or near the speaker's resonant frequency. If packed in tightly, the enclosed volume is smaller. When these materials are added loosely, the effect is to make the enclosure acoustically larger. You'll find claims (well, perhaps not quite) that only virgin yak's wool should be used, because man made fibres 'sound bad'. The air within the box can be made somewhat acoustically dead by adding damping material - fibreglass 'wool', or any number of proprietary filling materials that are designed to absorb the sound inside the enclosure. The enclosed volume should never have two internal dimensions the same (such as top to bottom and front to back) as that will usually reinforce standing waves at certain frequencies. While the panels may be acoustically dead, the air space within is not. The cabinet shape can make a difference, even if the enclosed volume is exactly the same. Differences are due to resonance(s), meaning that one or more panels are not dead at all. Once something is acoustically dead, it doesn't matter what it's made from - dead is dead. If one box sounds different from another (identical other than material), then the material is not damped properly. Different types of plywood are used (and no, birch ply (for example) should not sound different from some other tree species). It may or may not be possible to refill the panels after the sand has settled or the panels have expanded as the sand compacts and tries to force the panels apart.Ĭoncrete has been used, sometimes with tiny pellets of expanded polystyrene foam to reduce the mass (so the box can actually be moved), sometimes only the baffle may be concrete. These are certainly likely to be acoustically dead, but are difficult to make. At one stage, hollow, sand filled panels were popular. How you get there depends on the philosophy of the designer.
Very few loudspeakers have a truly flat frequency response, and the way the system interacts with the listening room also changes the sound.įew hobbyists today would argue that enclosure panels need to be rigid and acoustically 'dead'. Some of these differences will be due to the way a system has been 'voiced' - a term that means adjusting the response so the system sounds balanced and 'right' from the designer's perspective. There are several things that can change the sound of a loudspeaker system, even when using driver components that are identical to another system.
This is often not the case with loudspeakers. While CD and SACD players (as well as DVD players) definitely sound different from vinyl, blind testing the preamp-amp combinations will most commonly result in a 'null' outcome - it's usually not possible to correctly identify amp 'A' from amp 'B' with a statistically significant result. Amplifiers and preamps are routinely so close to being a 'straight wire with gain' that measurements can be difficult. Loudspeakers are the most subjective component in any audio system. It can be very difficult to work out just why (and how) two apparently near identical designs can sound different.
This is often despite the fact that many will show frequency response (both on and off axis) to be very similar, with many sharing one or more of the same speaker drivers as used by other manufacturers. There aren't many 'real' audio brands that will be truly awful, but there will be differences. This is reflected in commercial offerings as well. We can be fairly certain that some of the published designs will sound very good, and others awful. It's highly likely that most of these will sound different from the others, although it's almost guaranteed that the designer will claim that his/ hers is 'better' in some way. A web search will reveal literally thousands of different designs, a great many of which are (at least superficially) quite similar. One of the most popular pastimes in the DIY audio world is building loudspeaker systems.