The loudspeaker: a bassists supposititious child?

For many bass players their instrument is the most vital part of their appearance, and rightly so. But since many bass players need some kind of electronic amplification to do the job it’s obvious that the quality of that amplification does matter. Ergo: a good bass and moderate amplification make a moderate sound.

half-speaker

As it happens, the amplifier got most of the attention, and the loudspeaker is a matter of minor importance. So let’s see if that is self-evident. Well…. It’s not.  In the end, it is the loudspeaker that makes the transition from an electric signal to moving air (= what you hear). But pity about the loudspeaker, the amp is much more attractive because of its knobs and connectors and leds. So let’s turn to the loudspeaker.

Without any doubt the bass loudspeaker has the greatest influence on your bass sound. Of course there are (cheap) bass amps that colour your sound without your permission, but bass loudspeakers always have a major influence on your sound, the extend of that influence depending on speaker brand and type. Sometimes , it results in a characteristic sound that is typical for a certain particular brand, but many bass players want loudspeakers to reinforce their natural tone of their bass guitar or double bass with as little as possible additonal colouring.

Bass loudspeakers come in many different sizes. The most common sizes of loudspeaker for bass players vary from being between 10″ to and 15″, although some companies use other sizes too as well. Hevos uses also 6” and even at request 18”. In general small loudspeakers and cabinets have difficulties with reproducing sub-bass tones, but are good in reproducing mid-high to high tones. For large loudspeakers the reverse is often common. That is due to the fact that large loudspeakers have large cones that have a large moving mass, this being the weight of the cone plus voice coil.

loudspeaker

The cone must be rather stiff and therefor should not be too thin, otherwise cone breakup spoils your bass sound. The magnet also plays a very important part in the control of the cone movements. Not only is the magnet the motor of the cone movements, but it also controls these movements so that these movemenmts won’t become too extreme. This control and drive function can only be guaranteed with a heavy magnet structure. Heavy in the sense of magnetic flux, the strength of the magnetic field, rather than the weight of the magnet.

Smaller loudspeakers have lighter cones which can move faster and follow the signal easier. Bass players that slap a lot (= mid tones) are usually fond of 10″ loudspeakers because of that ‘quick’ response. But if you want massive sound pressure levels, you have to use a large loudspeaker or several smaller ones. Small and large loudspeakers are supplementary to each other. That is why many bass stacks consist of a cabinet with small loudspeakers (for instance 2×10″) and a cabinet with a large one (usually a 15″). For that matter, differences between loudspeakers of the same size are just as common as between speakers of different size, depending on their electro-mechanical parameters. Hevos 10″ loudspeaker handles a low B as easy as many 15″ of other brands do. And we even have 6” loudspeakers that can handle a low E.

A good bass loudspeaker has a stiff structure, which prevent unwanted movements. In the first place that concerns the chassis or frame, which are nowadays often made of aluminium in stead of the old fashioned steel sheet chassis of years ago. Cheap loudspeakers often have steel sheet chassis. Suspension need to be stiff as well, because bass signals are very impulsive and should move the cone too extreme.

As far as bass loudspeakers are concerned, there are two types of power handling that are important. The first is the thermal power handling, in AES (or wrongly RMS) Watts. That is about heat dissipations, because about 96% of the electrical signal in the loudspeaker is transformed into heat. The diameter of the voice coil is important for that reason: the larger that is, the better a speaker can get rid of the heat. This type of power handling is important but not the most important.

The second type of power handling has to do with the maximum peak lineair excursion of the voice coil in the magnet structure. When using heavy magnets it is possible to use long voice coils in loudspeakers. The result is a high sensibility combined with a large Xmax. ( the maximum or peak linear excursion of the loudspeaker). It is usually defined as the distance the voice coil can travel in one direction and still maintain a constant number of turns in the gap of the magnet. This definition yields the maximum excursion before distortion occurs. These loudspeakers can work at high power levels without distorsion.

The reason why not every company uses long voice coils, is because they only work with enough sesitivity (98-100 dB/W/m) in very large magnet structures. And magnets are very very expensive! So the Xmax is a very important loudspeaker parameter for bassists, because a signal from a bass guitar or double bass is very irregular, impulsive. A bass signal will hardly ever reach the thermal edges of the loudspeaker, but can easily bring the loudspeaker to and even over its maximum excursion. That is why many bass loudspeakers sound lousy when you play your bass a bit louder than normal. It is just a matter of money.

2x10-liggend

Hevos uses only loudspeakers with long voice coils and strong magnet structures. That is why Hevos bass cabinets sound clean, even when they are pushed to the edge of their thermal power handling. Cheap but excellent loudspeakers do not exist. So it is silly to go for cheap loudspeaker cabinets.  And if your financial space is limited and you have to choose between an exellent amp with moderate loudspeakers, or a moderate amp with excellent loudspeakers, go for the latter. Or better: save up for an Hevos amp and cabinet. Take your time!