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.

Installation Spotlight : An Engineer’s Perspective

This week at Car Home Stereo, we’re joining resident audio expert Tim on his mission to make the Land Rover Discovery 4 sound great. Tim has kindly taking the time to talk us through the process from his perspective, giving us audio enthusiasts an opportunity for rare insight into the sound engineer’s process!

 

The Process

This is the latest demonstrator for car and home stereo, the Discovery 4 commercial.

The challenge in this vehicle is the basic Harman Kardon system installed by the factory, the sound is flat and dull with poor separation and awful bass performance.

While we could have left the standard head unit in, I wanted the benefits of Apple Car Play. That meant mounting a unit discreetly into the dash screen location. There is very limited depth available, but fortunately the Alpine ILX-700 is perfect at just over 75mm deep. An original Discovery screen surround was purchased and modified to accept the Alpine unit.

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The original screen and controls had to be retained as the date and time adjustments are accessed from these. The answer was to relocate them to under the passenger seat.

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The original control button location proved an ideal position for the Audison Bit controller so an Alcatara trimmed panel was constructed. This allows quick access to all the amplifier settings as well as equaliser presets.

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I knew I was going to use the Audison Voce 5.1K amplifier and Bit 1 DSP and wanted to install them on show but without losing boot space. The solution to this was to mount the two units in a carpet trimmed panel in the existing boot panel recess.

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The same solution was applied for the sub on the opposite side, this time creating an enclosure in the storage pocket for the Hertz Mille 8 inch sub.

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Our speaker choice was the magnificent Hertz Mille 1650.3 two way components. These are absolutely amazing, offering a detail and clarity at any power level that is breathtaking. These were sited in the original door locations on custom built mountings. The door panel had full deadening treatment of course.

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It is difficult to describe how good this system sounds,it has to be heard. We love to show it off and would welcome you down for a demonstration.

The Art Of Tuning

We go to great lengths at Car and Home Stereo to find, test and install the best audio equipment available. Leading brands such as JL Audio, Audison, Rainbow and Hertz are all companies at the top of their game and are producing world beating equipment. An example of which is the new Profi range from German manufacturer Rainbow. Their T28 tweeter is one of the best speakers in the world right now.

 

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Car interiors have never been better, but unfortunately they are not the ideal acoustic environment. There are steps that can be taken to improve this and this should always be done before embarking on a serious upgrade. However, the (small) vehicle space still contains lots of soft and hard surfaces creating absorptions and reflections not to mention the fact that the speakers  and the listening position may not be in the ideal location.

 

Let’s imagine a fictitious “perfect” speaker. This unit has been designed to produce a perfect range of frequencies for a totally flat sound. This can be measured and verified. Now, let’s place it in a car in the typical location in the door. Allthough this is the same speaker the environment has had a dramatic effect on the sound output. To compound this our brains are very good at judging where sound comes from and the  speaker location will be very obvious. Our carefully designed and very expensive speaker has been severely compromised.

 

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So how do we fix this? We could re-engineer the speaker for the new environment but of course that is not practical. Fortunately the answer lies in digital signal processing. A modern, state of the art processor like Audison’s Bit 1 has the power to solve all the installation and acoustic problems we find in car audio. Of course, it requires a great deal of skill to set up properly but the results can be astonishing.

 

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All the issues of frequency cancellation or addition can be solved by using the powerful on board graphic equalisers. Positional issues can be solved by applying time delays to any of the speakers which will make it appear that the sound is coming from a different location. This will have the effect of making the sound stage wider and more dynamic, more like a live performance. Individual speaker level controls will ensure the sound is perfectly balanced for the driver or both front seats as required. We even have the ability to program multiple adjustments and to save them in up to four presets. This is especially useful for convertible cars so the sound can be adjusted for ‘top up’ and ‘top down’ at the touch of a button.

 

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Of course we have all the latest technology and tools to ensure the perfect sound for you.

 

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Our latest demonstration vehicle features this processor and we have built in the capacity to bypass it, it really is an ear opener to hear the difference a well set up processor makes.

 

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If you are interested and would like a demonstration of how good car audio can be, please call us on 01625 432707, we love to show it off!

Selecting a Subwoofer : The Nitty Gritty

Most music consists of a full range of audible frequencies, from low bass (bass guitar, cello etc) to high treble (cymbals, piccolo) although a notable exception is John Cage’ Four minutes and Thirty Three seconds. In simple terms – the lower the sound, the longer the sound wave and the more energy required to generate it. In practical terms – bigger speakers and a more powerful amplifier.

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“Bass is an essential part of music and is the part that adds the drive and excitement, try to imagine Michael Jackson’s Billie Jean or Prodigy’s Fire Starter without any bass, for example.”

“Can’t we just use a more ‘bassy’ speaker?”

To explain why this is not really the answer we need think about what a speaker is doing. In its simplest form a speaker is a vibrating membrane that is generating sound (pressure) waves and to produce lower sounds, the speaker cone has to move more slowly and further. This is no problem on its own but at the same time we need it to produce the mid and treble frequencies. These sounds require a very quick response and result in a very complex vibration pattern. Expecting a speaker to do both low and high frequencies inevitably ends in a compromise of both. The practical result of this compromise is at best a muddled, less defined sound and at worst a distortion that will lead to the destruction of the speaker. The only solution is a dedicated bass speaker, a subwoofer.

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Fortunately there are a wide range of compact, high performance woofers on the market now. Speakers that will operate in very small enclosures and take up minimal space. In a lot of cases, where I’m upgrading a factory Bose or Meridian system, I can use the existing bass speaker location for a completely stealth installation. In many cases I can use wheel wells, under seat locations or custom build enclosures in boot recesses. Even when none of this is possible there are woofers from Jl Audio and Hertz that offer spectacular performance from a unit little bigger than a couple of shoe-boxes.

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At Car and Home Stereo my system designs are always sympathetic to the vehicle but most of all it is my passion for music and great sound that drives my recommendations.

Pitch Perfect – Rainbow’s Profi Line

Here at Car & Home Stereo Macclesfield, we’ve fallen head over heels for the Profi brand.

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Uncompromisingly brilliant, these incredible pieces of equipment embody the precision and passion of real expert craftsmanship. The sound is so crystal clear, that you feel as though you’re at a live performance. Our resident car audio system expert and musician Tim described the sound as ‘utterly transparent’, and when you hear what these speakers can do when installed with precision – you understand why.

 

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We’ll be honest, Profi line is not the cheapest way to get your hands on an audio system for your car. However if you want the best possible quality of sound, we think the Profi kit is worth every single penny. In common with all high end car sound systems, proper installation is vital to getting the quality of sound that you’ve paid for. Here at Car & Home Stereo of Macclesfield, we have a trained musician and qualified sound engineer with a passion for crafting perfect audio environments. Tim Campling offers a bespoke and comprehensive instillation service, tailoring each of his creations to the requirements of your vehicle and sound system – achieving perfect harmony between the two.

 

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Our doors on Sunderland Street, in the Heart of Macclesfield, are always open – so if you’d like to come by for a chat, look or a listen – make sure to pop in!

We look forward to seeing you.

Why Sound Deadening?

In the pursuit of great sound it is essential to consider all aspects of audio reproduction. JL Audio, Audison and others make tremendous speakers which have been carefully designed for accurate music reproduction, unfortunately we have to fit them into less than perfect environments!

The average car door is an acoustic nightmare. A thin, unsealed metal enclosure fronted with hard plastic fittings, often with a loose polythene moisture barrier as well.car-door- explodedCrucially, we want the full, uncoloured response from the speaker we are installing. Unfortunately the design of the door is working against us. Fundamentally, a speaker is a transducer converting electrical signals into pressure waves. Sound is generated from the front of the speaker and from the back.

This is important as the sound from the back of the speaker is playing into the car door. Some will be reflected back into the speaker cone causing distortion of the front signal. Some will be reflected into the door card creating unwanted resonance and annoying vibrations. The louder you want to play it, the worse it will be. speaker distortion

 

Some car manufacturers do apply a token amount of damping but this is just to prevent the panel from rattling, we want to optimise the enclosure for sound reproduction.

The answer is sound deadening. Quite different from sound proofing, sound deadening is about the control of pressure waves inside the door. By applying special materials we can eliminate unwanted resonances and reflections.

There are lots of different products out there but by far the best are Dynamat and Skinz. Dynamat Xtreme is the lightest and most efficient panel treatment I have ever used. It’s damping properties are second to none meaning less needs to be applied. All sound being radiated from the back of the speaker is absorbed and converted into low level heat. This of course stops unwanted vibrations and ensures that you only hear the sound from the front.dynamat door A liberal application of Dynamat behind the speaker prevents reflections.

I believe that it is essential to consider sound deadening whenever a speaker upgrade is installed. Otherwise you will never achieve the full benefit.