Choosing the right speaker is crucial to the sound of a system: It has a bigger influence on the sound than any other part of the chain, and you need to consider how a loudspeaker will interact both with your amplifier and the room in which it will be enjoyed.
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Floorstanding speaker (Quad 22L) |
Size
Floorstanding speakers were once the preserve of the well heeled, but low-cost models are now extremely popular. It's not hard to see the attraction compared with smaller stand-mounting or 'bookshelf' designs - a tall cabinet is generally much more aesthetically pleasing than a small box perched on a speaker stand, and it produces more if not higher quality bass.
On sonic grounds stand-mount speakers do have their advantages. While the greater volume of a floorstander makes it easier to achieve deep bass, it brings with it another set of problems with regard to controlling the resonances of the cabinet. Small speakers are inherently stiffer, and as a result are less susceptible to boxy colorations. There are, of course, excellent examples of both broad types, but as a general rule don't expect tight bass and great imaging from a sub £500 floorstander, unless it's tiny.
Construction
A speaker's cabinet needs to be more than merely pretty. The aim is to make it as inert as possible, so it has minimal effect on the actual sound. Choice of material is crucial - MDF is still the most common, but there are plenty of other examples around including various woods, metal and occasionally fibreglass and carbon fibre. Cabinets are often braced internally to make them more rigid; a variety of other techniques may be employed to reduce coloration further, like the use of wadding to damp resonance, or the avoidance of parallel internal surfaces to cut standing waves.
There are a variety of different styles of cabinet design including sealed box and transmission line, but the most popular is the reflex loaded infinite baffle. These speakers have a port or tube which acts as an air spring for the main drive unit(s). In practical terms reflex loading makes the speaker more efficient (easier to drive), it also has a secondary advantage in that it reinforces bass.
Drive units
Most speakers use dynamic drive units which consist of a magnet, a voice coil and a diaphragm (cone or dome). Size, excursion and diaphragm material all contribute greatly to a speaker's sound, as does the number of drive units, their configuration and the quality of the crossover (the circuit used to allocate different frequency bands to their appropriate drivers). It all adds up to a real balancing act for designers and the permutations are almost infinite. Ultimately you should judge a speaker by its sound and not the size or number of its drivers.
There are also panel loudspeakers that use electrostatic skins, aluminium ribbon or in the case of NXT vibrating plastic to produce sound. All of these work on different principles and offer alternative advantages but none can compete with dynamic drivers when it comes to bass reproduction.
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Bookshelf speakers (Monitor Audio Bronze B1) |
Power
People often ask, 'how powerful is that speaker?', or 'how many Watts is it?' A speaker doesn't generate any power itself, of course, but manufacturers often provide a power handling range - these figures should be treated as a minimum. You're more likely to damage a speaker with a low power amp than with a high power one because the latter are better able to control the speaker.
Arguably the two most useful figures when choosing a speaker are sensitivity and impedance. A model with high sensitivity will provide greater volume for a given amount of power, it will also tend to sound more dynamic. High sensitivity - say, 90dB or higher - is generally desirable but cannot be considered alone. Impedance relates to how tough a load the speaker presents to an amplifier. Most impedance figures are nominal and don't indicate ease of drive but note that 4 ohm loads are twice as hard to drive as 8 ohm ones.
Positioning
When it comes to placement of speakers, experimentation is the key. Some speakers benefit from being close to a rear wall, most prefer a bit more space, so start by siting them fairly close to the wall and gradually pull them towards you to get the optimum balance between bass control and extension. If you have to put them close to a wall avoid designs with rear mounted reflex ports, and bare in mind that few work well in the corner.
It's also worth experimenting with toeing or angling your speakers in towards the listening position - this helps improve imaging with some speakers, but the more directly a speaker faces you the brighter its balance.
Most floorstanding speakers come with spikes to provide a rigid coupling with the floor. These tend to give a tighter sound to the bass but can end up making the floor vibrate as well. Experiment with the effect they have but be careful on uncarpeted floors such as wood laminates.
Site smaller speakers on purpose-made stands that are the correct height for your speakers, the closer a speaker is to the floor the more bass reinforcement you get. Speaker stands are usually spiked at the bottom and often at the top but some prefer the calming effect of Blu-Tack between speaker and stand.
Room furnishings also effect the way a speaker sounds, in simple terms, lots of soft furnishings tend to soak up the treble so you get a more laid back sound whereas a sparse, minimalist room may have a relatively hard, bright sound.
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Subwoofer (Monitor Audio ASW100) |
Satellite & subwoofer systems
These consist of two or more compact so called satellite speakers which produce treble and midrange, combined with a subwoofer that produces bass. Subwoofers are often active (have built in amplification). Sat/subs systems are designed for situations where space is at a premium, they do not tend to compete with two box speakers at a similar price in terms of sound quality.
Subwoofers
Even quite large speakers have difficulty producing the truly earth shaking bass that's popular with home cinema enthusiasts and bass heads alike. This is where dedicated sub-bass speakers or subwoofers come in. For best results they should be adjusted so that they come in at the lower roll-off point of the main speakers' (the -3dB point in the specs). In home cinema systems you can usually tailor the signal being sent to a sub to achieve a seamless transition.
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Speaker cable (Supra Rondo 4mm) |
Cable
The effect that cables have upon the sound of a system cannot be underestimated, they can sometimes have more influence than major components. One reason for this is that they effect the way the amplifier and loudspeaker interact. Ideally cables should have a low inductance but the tradeoff for this is high capacitance which can upset some amplifiers so most cables tread a line between these extremes. Get the best speaker cable you can afford and keep the runs as short as possible, that way you make the amplifier's job easier. The majority of speakers these days allow for bi-wiring (connecting treble and bass drive units independently) but you are better off using one run of great cable than halving your budget to buy two sets because the speaker allows it. You can always get another set at a later point.
