KEF Audio Your Guide to Selecting and Enjoying KEF Uni-Q Speakers

KEF LOUDSPEAKERS

What to look for when choosing your speakers

Of all the elements in your audio system, changing your speakers can make the biggest difference in sound quality. As a rule of thumb, the speakers in a basic two-channel hi-fi system often account for about a third of the total system cost.

Speaker quality has a lot to do with size and the number of drive units; but ultimately what matters is how well they reproduce

your kind of music or film soundtrack in your room at the volume you most enjoy. Although technical specifications are helpful, you can only find which model best suits your personal preferences by hearing them in action. These are some of the things you should be looking for...

Measuring performance

The smoother a speaker’s frequency response, the more faithful its reproduction

of the audio signal.Transient response is also important, reflecting the speaker’s

ability to respond quickly to any sudden change in the signal without blurring

(smearing) the sound. How loudly a speaker plays depends on its sensitivity,

maximum output capability and power handling. Low sensitivity speakers require

larger

amounts

of

amplifier

power

to

reach

a

given

loudness

level.

High sensitivity

speakers

require relatively

less and

SPL(dB)

Ci Reference 2000

110

can be used to compensate for low amplifier power.

100

When

compensating

for low

sensitivity

speakers

90

80

remember that a 10dB increase in sound pressure

70

level, which sounds twice as loud, requires 10 times

60

more power.

20

200

2k

20k

FREQUENCY(Hz)

Always look for a wide dynamic range in a speaker -

Ci Ref 2000

Ω

the range of sound intensity that can be reproduced

31.6

without distortion. It’s

expressed as

a

ratio

in

10

decibels. In speech, this

is rarely more

than

40dB;

3.16

in orchestral works, it

can be

as much

as

75dB.

20

200

2k

20k

FREQUENCY (Hz)

Judge whether loud passages sound appropriately louder than quiet ones. Can you hear subtle changes when something else is playing loud? Does music

come to life at high volume, or blur?

Ask yourself also whether the sound picture is complete at the frequency extremes. Or has bass, for example, been sacrificed to midrange clarity? Accuracy is a matter of how closely the speaker reproduces live sounds. How much detail can you hear? Do individual images sound separate from each other, or are they like highlights in an acoustic soup?

Neutral balance gives the human voice a natural timbre, without distortion at frequency extremes. Listen for colouration - do voices sound strange? Is there too much sibilance? Can you differentiate the sound of similar but different instruments? Or does a violin sound like a viola, a Stratocaster like a Les Paul?

Drive units

Hi-fi drivers are dedicated to different parts of the frequency spectrum. Bass units reproduce sound between 20 to 500Hz, midrange drivers (carrying most of the identifying tones of music or speech) usually from 200Hz to 4kHz, and HF drivers (tweeters), from 2kHz to above 20kHz. Long-throw drivers allow a large amount of cone movement, and therefore generate higher sound pressure levels. A strong chassis such as cast aluminium provides a rigid platform for the moving coil/cone assembly and avoids

the energy being drained from the cone into the cabinet itself. Some form of mechanical decoupling between the chassis and the cabinet can greatly reduce the transmission of this vibrational energy to

the cabinet walls.

Cone materials vary.Tweeters are usually made from metallic or fabric materials

-the former tend to be very revealing and detailed; the latter, a more reserved sound.

Components

Crossovers act as the brains of a speaker, allocating the various frequency ranges to the appropriate drivers, with filters to stabilise impedance loads and shape frequency response.

The quality of the components (such as polypropylene capacitors and air-cored inductors) directly affects acoustic fidelity.

Setting up

High performance speakers usually have dual sets of connectors (binding posts) and crossovers with separate sections for low and high frequencies. This is to accommodate bi-wiring (using two sets of cables to improve resolution) and bi-amping (in which each set of connectors is wired to a separate amplifier for optimum response across the frequency range). KEF’s new Reference Series even features 3 pairs of connectors for tri-wiring or tri-amping. Most speakers sound better after a few hours use.All you have to do then is sit back and enjoy.

Imaging

Stereo imaging is the illusion of a realistic 3D presence that seems not to come from the speakers themselves, but a virtual sound stage in which different instruments or sound effects are localised. With conventional speakers (as opposed to KEF Uni-Q), this illusion only occurs in a relatively small area - the ‘sweet spot’.

To test speaker dispersion characteristics, move around the listening area. Does the sound fade as you move away from the main axis of the speaker? Do central images stay centrally located at some frequencies but not others?

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