Simon Says? Speakers Please!

For this instalment let’s look at speaker installation. The speaker is the last piece of hardware between your music and your ears and as such has an awful lot to do with the sound you hear.

The science behind the speaker is extremely simple; pass an electric current through a wire that sits inside a magnetic field and the wire experiences a force, vary that current and you vary the force. Of course this demonstration produces no sound but if we attach the wire (or coil) to a diaphragm (or cone) we have the nucleus of a working speaker. The electronics in the amplifier produce the varying electrical current and the speaker responds, creating the highly complex vibrations in the air that we hear as music.

The above description is of course highly simplified and in reality there are many more aspects to speaker design. We have to consider the weight of the moving parts, the resistance to movement within the materials themselves, the linearity of the magnetic field, the quality of the coil wire, the damping to prevent uncontrolled excursion, stability of the frame and so on and so on! Fortunately all of these considerations are engineering problems and this means that better engineering will lead to a better product.

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When Mr. Ford or Mr. Audi or even Mr. Porsche are told that they have to put speakers in their cars their first consideration is not about quality even when they enlist the help of respected Hi-Fi companies. Their overriding concern is one of reliability. A blown speaker is a warrantee issue and that costs money. The trouble is that a speaker that can survive heavy metal hard core country rap at full volume has to be made super resilient. This speaker is not going to be able to respond to the subtle nuances of any quality musical performance.

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At Car and Home Stereo we are always going to install a high quality speaker, carefully selected to match the vehicle and musical tastes of the customer. This is where our installation skills are needed. The average car door is a challenging place for a speaker. It is a steel box that is often wet inside, can be freezing one day and very hot the next. There are moving parts within it and it is subject to a large amount of vibration and noise. Let’s look at a typical installation addressing each point.

First of all we carefully remove the inner trim making sure that all clips and seals are retained. After this the next job is to treat the metal skin with sound deadening material which will absorb road noise and any vibrations within the door.

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Particular attention is paid to directly behind the speaker as this will absorb the sound generated by the back of the cone and prevent reflection back into the door panel.

Once the outer skin has been treated we apply a foam barrier to the inner skin. This forms a watertight seal and acts as a thermal and acoustic barrier. This keeps the car warmer in winter, cooler in summer and again reduces road noise. The difference these treatments make to a car is astonishing.

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Now we come to installing the speaker. The factory units are often built to fit so we must make panels and collars to allow a perfect fit to the door.

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It is very important that no moisture gaps are left as it may come as a surprise to know that doors are designed to let rain flow through them. Any gaps could lead to a wet floor so we make sure everything is sealed with high quality silicone, both the collar and the speaker, this also ensures no air gaps to compromise the speaker performance.

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Quite a lot of work but absolutely worth it. These Audison APK speakers sound great anyway but by treating the door they are at least 30% better.

If you would like to know more about how we can improve the sound in your car please call Tim on 01625 432707.

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