E30 ICE

E30 ICE Written by Paul Lacey

1   Definitions 

2 The factory setup 3 What's wrong with the factory setup? 4 A little about sound 5 Truisms 6 Some questions you need to answer 7 So you want to upgrade? 7.1 The head unit 7.2 The front speakers 7.3 The rear speakers 8 I want more! 9 Cabling 10 Door builds 11 Amplifiers 12 Bass 13 I want more still! 14 Some good advice...

1. Definitions

Baffle - Board that a speaker driver screws to and sits on

Concourse (D'elegance) - competition/show for the most truly amazing condition/original vehicles

Crossover - device that splits incoming frequencies into two or more signals for different speakers

DIN - ISO standard that refers to the size of hole for a head unit - the e30 dash hole size is 1 DIN high. A 2 DIN hole is twice the height but the same width.

Gauge - a measure of cable size - 1 gauge being larger than 2 gauge and so forth OR a beautiful porn star - please forward contact details if known

Head Unit - the piece of sound making equipment that sits in the hole in the dash above the heater controls

ICE - In Car Entertainment

On-axis - speaker driver positioning so that each driver points and fires towards the opposite side head rest, thus allowing all passengers to hear sounds as if they are situated exactly in the middle of the speakers. Which of course they are not.

RDS - Radio Data System. Allows information to be transmitted alongside the audible broadcast.

SPL - Sound Pressure level - a measure of volume in decibels.

2. The factory setup

By now you'll be very lucky to come across an e30 with a factory original head unit. Most will have had at least 1 owner try their hand at 'upgrading' with varying degrees of success. The factory loom as provided terminated in a multi-pin plug that can be connected to many after market head units using adapters (where necessary) available from any ice dealer. Just as likely however, is a spaghetti jumble of wires with varying degrees of termination hanging freely from your dash. Even if your car is factory original and unmolested, the improvements made in head unit design and manufacture mean that even todays inexpensive units are far superior to what was available in the eighties - and unless yours is a concourse entry you're probably looking to take advantage of this fact.

E30s came with either 2 or 4 speakers from the factory, 2 in the front and (possibly) 2 in the back. All front speakers are located in the 'kick panels' i.e. behind the trim that sits in front of the front doors. Saloons had their rear speakers on the rear 'parcel shelf' behind the back seats, convertibles rears were placed in the rear 'quarter panels' to the sides of the rear seat and the tourers were in their own black plastic enclosures behind the carpet covered side panels.

An electric aerial was provided on the near side rear wing, except on some M3 and motorsport models where it was re-located to the front centre of the roof.

3. What's wrong with the factory setup

Eighties head units are more than likely to be cassette based, a medium that can still work very well but is now becoming increasingly seldom used. If the unit still works well (because some very diligent owner has cleaned the tape heads properly and regularly all these years) then you can listen to all your favourite tapes. More likely however is that your collection has migrated to CD or MP3. A modern tape based head unit will be superior in performance to the factory supplied one. The factory unit will also be supplied with a radio - but probably not with RDS. You'll be hard pushed to find a modern unit without RDS these days.

Early eighties design thinking was that the human ear is positioned on the top of the human shin. That's why the front speakers are positioned pointing to front passenger's shins. More likely is that this was the cheapest place to fit them as part of the manufacturing process. Speaker sizes (all round, in fact) are 5 1/4 inch or 13 cm, thus by design limitation these speakers will only be able to reproduce sound down to upper mid-bass frequencies. More of this later. The speakers as supplied were Blaupunkt 'IC 107's with the not so earth shattering nominal current handling of 15W or 40W peak. I suspect that BMW hunted quite far and wide but could not find anything cheaper, enough said.

Conversely the factory supplied aerial - if extended - was very good. This however, is quite likely to be inoperative or replaced (maybe with something not very aerial like e.g. a coat hanger) at some point during the car's life.

4. A little about sound

Sound is made up of waves of varying frequencies that your brain interprets through your ears. Without getting bogged down in science suffice to say that these frequencies can be divided into highs, upper mids, mids, mid-bass, bass and sub-bass. The general idea for a car is to have the high to mid-bass sounds from the front to give detail and soundstage with the bass/sub-bass provided from the rear, mainly down to logistics of speaker sizes but also because bass is generally thought to be omni-directional i.e. the human ear cannot tell from which direction it emanates. (although some studies have disputed this)

High frequencies do the window breaking for you - but when distorted (sibilance) ruin music enjoyment like nothing else. Smooth, detailed and clear highs are a must and not difficult to achieve.

Mid-range frequencies make up the bulk of pre-recorded and broadcast sound and give the listener the detail required for soundstage (instrument/vocal positioning) and detail. These can be accurately re-produced without a great deal of time/expense/effort in the e30 and will produce a very pleasing listening experience.

Mid-bass is what gives music its 'kick' or 'feel in the chest' quality and if reproduced well will have the less experienced passenger asking where your subs are but....

Sub-bass is generally rare among pre-recorded music - except for the classical and Drum'n'Bass genres. That doesn't necessarily mean it isn't there - often it is engineered out of the sound as producers know that the average system won't be able to reproduce it. (your average teen fan of Britney doesn't have subs in their bedroom - for good reasons when you're a parent!) Sub bass is what makes your nose itch and eyes water...

5. Truisms

Every car hi-fi install is, to a greater or lesser degree, an experiment.

Garbage in gives garbage out (GIGO). The only way to a quality sound is to feed a quality recording into a quality head unit through quality cables into quality speakers. You get out of a system what you put into it.

Average components fitted with thought and care always sound better than quality components thrown in the car from the other side of a workshop.

One man's meat is another man's poison. What sounds marvellous to me may suck to you.

It doesn't matter how loud or how good it sounds - after a while you'll want more.

PPPPPPP - Prior Preparation and Planning Prevent Piss Poor Performance. Plan any install carefully. It's no good spending a week making and trimming a custom speaker mount and then realising there's no cable there to connect it up with.

6. Some questions you need to answer

Now before you go rushing out (or to the internet) to buy loads of kit you need to be honest with yourself with some very key questions. Honesty now will save a broken heart later...maybe a scowling bank manager too.

What do you listen to? (1) Do you have 2000 tapes at home and 1 CD that you don't know how to play? Better buy a tape based head unit then.

What do you listen to? (2) Only ever radio 4 as a background sound? or do you want everyone in the High Street to share your love of music? Don't bother putting together a 140db+ system if you're the former - you're wasting your money.

What are you looking for the system to do? Entertain you for long journeys? You'll be needing some sound quality so the listening experience doesn't become tiring or abrasive. Wake up the neighbourhood? You'll be needing some proper power and be fitting as many components as possible then. Entertain the offspring in the back while you relax with radio 2 in the front? Some multi-media is a coming... Impress any mates that jump in for a lift? You'll be needing some flashy lights then, maybe a screen up front.

How much money can you spend on your system? This answer may well cause you to re-visit the questions above. Generally you can estimate what you think it will cost and add another 10-50%.

How much time can you put into installation?

Are you willing to modify the car to achieve your aims? If so then how intrusive are you willing for the system to be into your cabin?

How much installation work can/will you do yourself? Further - how many tools are you short for the tasks you foresee? (add these to the cost)

How much learning is required before you undertake any improvements?

7 - So you want to upgrade...

The following words of advice will have to be general as no two after-market installations are the same. Take what you need and discard the rest...

7.1 the head unit

Probably the easiest and quickest of all the upgrades to complete this, it can be done in minutes if you're practiced and less than an hour all in if you're not. It can also go wrong and cause damage so take care. Make sure you start with a clear dash i.e. any old equipment removed and any wiring that doesn't end somewhere taken out. Now if you're lucky all the wiring you require will be terminated in a multi-plug which will plug straight into your replacement head unit, frankly though, life is not like that so...

Let's start with the power side of things - you'll need to identify three wires using a multi-meter or test bulb; a permanent live, switched live and earth. For the e30 they should be present and the following colours: (it's worth checking these out to be sure)

permanent live - grey/red - set your multi-meter to measure volts and check for +12 with one probe on the wire and the other earthed to a chassis point. Check for a fuse in this wire - if your head unit has a fuse then don't worry too much but if it doesn't now's the time to find and fit one. switched live - violet - the same as above but check it goes to 0v with the ignition off. Consider fusing this too. earth - brown - set your meter to resistance (ohms) and check for continuity with your known earth point.

If any of these are not present you'll have to put them in from scratch.

Now if you're unsure about these ask advice or get someone else to do it because a jolt in the arm is worth another head unit or a small under-dash fire... disconnect the battery if you feel it would be safer. Anyways bare back the permanent live wire and ensuring it doesn't then come into contact with any earthed point (or anything else for the matter) connect it to the (usually) yellow wire of your head unit wiring loom using your favourite connection method, crimped connectors being favourite, similarly connect the switched live to the (usually) red wire of your head unit wiring loom. Connect the earth wire to the (usually) black wire of your head unit wiring loom and assuming you didn't disconnect the battery you can now plug your connected multi-pin plug into your head unit, turn the ignition key and it should at least turn on. Okay so it's still hanging from the dash like a cartoon popped out eyeball but it works. If it didn't turn on re-visit your wiring and check your connections - there's something amiss. If it popped and started to smoke be assured that it's not the fault of this guide.

There's two more 'power' connections that you may or may not wish to utilise - the (usually) blue cable from your head unit goes to the trigger wire for the electric aerial (white in the e30 from memory) - don't worry about this if your aerial doesn't raise itself upon command. (Consider at this point adding a switch somewhere in this wire so you don't have to have the aerial extended when listening to a source other than the radio.) The blue/white cable needs to be connected to any external equipment you wish to trigger at power on time - amplifiers and the like If you're intending to run more than three amplifiers consider connecting this via a relay. Make these connections at this point.

Now connect up any speakers that will be driven by your head unit. Head unit manufacturers have different colour code so consult your manual but the e30 side colours are:

Right Front (+) Grey/White Right Front (-) Grey/Brown Left Front (+) Grey/Red Left Front (-) Grey/Violet Right Rear (+) Black/White Right Rear (-) Black/Brown Left Rear (+) Black/Red Left Rear (-) Black/Violet

The aerial plug should simply push home either into the back of the head unit or into a female receiver that's part of the head unit loom. Any pre-out or line level signal cables push home in a similar manner and any external sources such as a CD changer need plugging in also - these will be specifically designed plugs and if they don't match up they are not meant for joining. To run any cables away from the head unit and into the car remove the lower centre console trim pieces and put your hand up under the left hand side of the heater controls and you'll be able to see your fingers in the head unit dash slot.

To fit the cage simply pull all the wires that you've connected through the centre of it and then push the cage into the dash slot until it's flush at the front. Now, using a flat bladed screwdriver, bend back as many tabs as necessary to ensure a firm, no movement fit.

Now connect all your cable plugs to the head unit and put your left hand up behind the cage and gently pull the cables back as you push the unit into the slot with your right hand, thus ensuring that no cables are pinched or disconnected in the process. There's plenty of room behind there - they go into the void behind the ashtray. You're done!

7.2 the front speakers

To replace the front speakers you'll have ready a pair of 5 1/4inch / 13cm drivers, a Philips screwdriver, some Dynamat with a heat gun, roller and a blade and some MDF with a jigsaw. Firstly peel back the furflex door rubber where it overlaps the kick panel trim, then undo the single Philips screw holding the trim in place. If on the nearside of the car undo the bonnet release lever too and pull away the trim panel. Remove the three remaining Philips screws holding in the driver and lift it away, storing it carefully for replacement when the car moves on. Now reach down inside the speaker cavity and remove the black plastic tray that sits down there - this rattles in sympathy with the driver and frees up more air for the driver to work with. Now clean the rear of the enclosure carefully and cut to size some Dynamat, heat it, peel off the backing and stick it down. Get as much in there as possible, rolling it flat and removing any air pockets with a blade while it's still warm.

Notice that the mounting plate for the driver is not flat - there's a recess for cables to enter the enclosure. This is bad news for 'return waves' - waves that the driver fires forward only to have them find their way to the back of the cone to muddy the sound. Consider at this point trying to seal this recess - some inventive work with gaffer tape, expanding foam and glass fibre will do the trick. To ensure that it can all be removed later on, tape up the wiring loom first.

Now clean and Dynamat the front mounting panel in the same way as the rear of the enclosure. Carefully expose the driver hole and fixing holes with a blade when done. Consider at this point Waxoyling everything reachable with a flexi pipe. Consider also Dynamatting the trim panel, a marginal benefit but if you have Dynamat left over then why not?

At this point there's a choice to be made. Mounting the driver with an MDF ring between it and it's mounting points will increase sound quality but will push the height of the driver out towards the trim panel. The way round this is to cut the trim panel carefully around the driver hole and mount it first, marking and drilling the three remaining holes for the speaker screws. Then place the driver upside down on the MDF and draw round it, making a circle with four 'ears'. Draw a circle within that to match the cone and cut this first, then cut to the outside line. It should now sit flush at the back of the driver enabling marking and drilling of 4 mounting holes. It will need colouring to match the trim or driver colour - black works well. Connect the cables to the driver and place the driver and MDF ring in position and using 4 longer screws than BMW provided screw it all home tightly. Fit the speaker grill and stand and stare, marvelling at the quality of your work. Revisit to retighten the mounting screws after 5 - 10 listening hours.

If it was decided not to cut the trim then re-fit the driver into it's recess and screw it home using three screws then re-fit the kick trim using the fourth, longer screw. Stand back and wonder how it would look and sound if you'd used a bit of MDF....

7.3 the rear speakers

The principles in upgrading the rear speakers are the same as the fronts - it's a simple case of removing the old, preparing the area with Dynamat and some MDF if possible and re-fitting everything. To remove the rear deck trim however it's necessary to pull out the rear seat squab, undo the rear seat back securing bolt/screw things (one each side at the bottom), undo the lower seat belt mounts (two 17mm bolts) and pull the seat back upwards to unhook it. Remove it from the cabin and store it carefully. Lever up the inertia reel plastic trims and gently pull the shelf trim upwards and forwards until it's free, then manoeuvre the seat belts through the holes as it comes away. This will expose the rear deck ready for cleaning and Dynamatting. There's no need to Dynamat the whole thing as it's fairly rigid back there but some deadening of the speaker mounting areas will make a considerable difference. Consider Dynamatting the underside too for double deadening.

Chances are that the shelf trim is now discoloured or damaged from a previous install attempt. It can be re-coloured with brush on dye or if it's already been hacked then ensure that the speaker hole mates with the actual speaker position, push out the four air vents at the rear and using trim adhesive (available from car parts factors) re-cover the whole shelf with acoustic carpet - available from any decent car stereo dealer or Maplin store at £20 per roll (one roll is easily enough.) Cut out the seat belt and air vent holes carefully with a sharp blade. This ensures a neat finish and completely invisible install while allowing sound to travel unimpeded into the cabin.

8. I want more

More sound quality, volume or both? If you've got here then you're probably ready to spend some serious time fussing over an e30 cabin and boot or pay someone else to do it for you.

The basic principles of a quality sound are to have the main volume, detail and clarity from the high to mid-bass frequencies at the front of the car and the bass at the rear. Any speakers mounted in the rear that aren't producing bass are 'rear fill' and mainly for the benefit of rear seat passengers who may otherwise suffer an all out bass assault with little reaching them from the front.

So let's consider the fronts for a moment - to get that mid-bass (very important, you don't want subs trying to re-produce mid-bass, they have enough to do) it has to be 6 1/2inch components as 5 1/4inch mid drivers just don't have sufficient cone area to reproduce frequencies lower than upper-mid-bass. Separate tweeters allow custom positioning for the best sound in every cabin and don't interfere with the mid drivers action. Decent quality here starts at about £100 retail. Also it's necessary to get them as close as possible to on-axis so that both front passengers hear the sound as if they are in the middle of the speakers - this really means door builds as by the time you put 6 1/2inch drivers on axis in the factory kick panel locations they stick out too far. It is possible to fit 8inch drivers or even 9s in the doors but it's not really necessary and probably for SPL monsters only.

That then puts the rears into perspective. If they are there for fill they don't have to be 1) as full range or 2) as loud as the fronts. therefore 5 1/4inch drivers will do their job (as a part of the whole) quite adequately. If volume is the aim however, 6 1/2inch drivers in the rear would be slightly preferable but require more work in the e30.

The basic principle of SPL systems is doubling up - fitting more speakers powered by more (and bigger) amplifiers. The sound quality principles above still apply. If you're serious about creating an SPL monster you're probably not reading this and finding anything new however, so I won't give more detail than that at this point.

So now it's all about making a plan. This probably involves some kind of build for the front speakers, an amplifier or two in a rack somewhere and a bass driver in the boot. What you want really comes down to how the questions in section 6 were answered.

9 - Cabling

So far cabling hasn't been touched in this article - but it's pretty vital to get it right. Let's start with power cabling - for without it nothing else ever seems to work quite right...

A word of warning here - before connecting any length of cable to a car battery ensure that there are no bared parts of cable touching anywhere on the car so that current can flow to earth. It may make for some pretty sparks at first but seeing adults cry at watching their e30s burn is not clever and more times than not - not funny either.

If running one low to medium sized amplifier than a length of 8 gauge cable should power it. Any more however and fit 4 gauge cable. Connect a proper ring to one end (soldered if possible) and ensure that it reaches the positive battery terminal, but don't connect it yet. Obtain a proper fuse holder and mount it as close to the battery as possible, this protects the car should anything go wrong. Then run the cable to where the amplifier(s) will be/are mounted and fuse the cable again - this protects the amplifiers in case anything goes wrong. If more than one amplifier is to be used a combined fuse and power block can be used to run separate, fused 8 gauge cables to each amplifier. If it is intended to run power caps they need to be fitted in series at this point - but bear in mind that a power cap can only re-charge at the same rate as the battery can supply it (and they have their own over-head) so use with caution. I have heard more than one person in the industry laugh at them as a great con, conversely some swear by them. At around £100 each it's worth trying any install without them first.

If the battery is under the bonnet run the power cable down the drivers side of the car. It can be tucked inside the inner sill area behind the black trim with a little patience. Only connect the cable to the battery when all the connected length is terminated securely. If necessary leave out the battery end fuse until the rest of the install is ready.

The same gauge earth cable as power cable needs to be used - if three amplifiers are used and fed from one 4 gauge cable split into three 8 gauge runs then use 8 gauge earth cables into a block exited by a 4 gauge cable - terminate this in a ring (soldered if possible) and earth this using a nut and bolt to a decent thickness metal part of the car frame as close as possible to the amplifiers. The inner rear wing or seat back is fine for this - drill a hole and bare back the metal both sides and bolt the ring using two washers - one each side. Roof bolts are good as they have a small profile for re-fitting trim onto. Waxoyl or paint after.

All signal cables from the head unit need to be run down the passengers side of the car - as far away from the power cable as possible. Again they can be clipped into the inner sill section and be trailed over the rear seat hump and into the boot if that's where they need to go. This can be done by removing the door sill trims and lifting the carpet.

Any speaker cables for front speakers that need to run from the boot area to front speakers however need to run down the centre of the car away from everything else. This requires the removal or all the seats, rear quarter panels, lower seat belt mounts, centre console and carpet. This is a marvellous opportunity to inspect and clean the floor pan from the inside, Waxoyl the sills and layout the cables in neat lines with perpendicular crossover points all held down with gaffer tape. Consider also Dynamatting the entire floor pan and rear seat area at this point - not only will it acoustically deaden the cabin it will keep out loads of road noise. Increased weight is the only downside for all you racers out there.

A word on quality - there's no need to spend hundreds of pounds on cables unless it's your thing. Basic cables these days do a good job. Do however plan a little bit for the future - it's most frustrating to have to remove your entire trim just to upgrade one cable later on - I speak from experience.

10 - Door builds

Door builds are excellent - end of story. They are light, strong, easy to make and the difference in sound is unbelievable - like night and day. To live with them however they require purchasing/making and fitting:

Purchasing: There are two manufacturers that I know of that make door builds for the e30 - Audiosport (www.audio-sport.co.uk) and Audioscape (www.audioscape.co.uk). I have not used either product but have heard others say that they work extremely well.

Making: This is relatively cheap to achieve and has the added advantage that any design can be made to suit any installation requirements. The basic principles are:

First strip the door card from the door and work out your design and where the speaker will fit ensuring that the magnet will clear everything with the window in all positions. You'll look pretty stupid if the window stops with a thunk half way down because it won't clear the magnet when it's all back together.

Next cut 2 pieces of MDF - 9mm is fine but no thinner - one for the base and one for the baffle. Once happy with the base shape mark on it where the door skin bars run and cut an appropriate hole in the base to allow the driver to breathe using the air inside the door. If this is not done the drivers will not give any real mid-bass (one half of the point of this exercise) and will lose all their 'warmth' in sound reproduction.

At this point consideration has to be given to the speakers being on-axis. (The other half of this exercise) This means that the drivers side speaker points straight towards the passengers side head rest and vice versa, this is vital for sound stage and imaging. To check for this cut a square of board about the same size as the driver to be used and fix a straight pole perpendicular to it in the centre. Now it's possible to trial fit the build and adjust the baffle to be on-axis while holding the crude but effective pointing stick against it - it is amazingly obvious where the sound will travel. The reality of the e30 cabin is that exactly on-axis speakers stick out a mile - so a compromise between usability and on-axis orientation must be made - unless you're aiming to win sound quality competitions whereby no compromise will be even considered.

Then measure carefully how high the baffle has to be in a few key places and cut some small pieces of MDF to raise the baffle from the base giving the correct angles and fit to the door handle - trial fit often here as this part is crucial - and ensure that both builds give the same relative angle into the cabin using the pointing stick. A spare pair of hands is very helpful for this. Glue/screw the box frame together.

Use some aluminium mesh and tacks to 'fill' the gaps around the build then fill with glass fibre. Finish with p38 easy sand filler and sand it all down to a pretty exact shape. Then trim to your preference - paint, cloth, vinyl, leather whatever floats your boat. Bear in mind at this stage that if you take your door handle to a trimmers or cloth shop and try to match the colour it's pretty near impossible to get it right. I don't know why this is so - it just is. Take the old door pocket too and the door card if possible and match any samples in daylight. A good trimmer will charge around £50 to supply the material and trim the build - it's money well spent. A poor trim job will ruin what is otherwise good work.

Mark the hole at the rear of the build behind the drivers magnet to the door card and cut. Then cut again through the Dynamat into the door - thus using the door as an enclosure - bass!! Now glass fibre a rim about 1 inch deep into the back of the build so that it extends into the door - thus preventing water running down the inside of the door and getting into the build. Make the rim deeper at the top than the bottom.

Now fix the build to the door card using several screws. Now mount the door card to the door and drill through the build base, door card and inner door skin and either bolt or screw the whole thing home, this should then be very solid indeed. Now connect up your speaker cables and screw the driver home. Re-visit and tighten all screws after 5-10 hours listening.

Consider also making covers for the builds to hide them from thieves when parked. These will also protect the builds and speakers from careless feet when entering and exiting the car and keep the rain off them when entering/exiting in the wet. If some really crappy grills with something equally crappy writing on them e.g. Saisho Max Power 100 watts (in gold) can be found and stuck to the covers then all the better!

There are several considerations when designing and fitting door builds (oh what a surprise!)

The e30 cables into the door design i.e. the rubber boot will not accept a great deal more than what was put in there from the factory (particularly the drivers side) without fouling the furflex door seal and letting in water. Therefore any crossovers need to be placed in the door or thin speaker cables used (which is a compromise.)

Glove box opening width is compromised on the passenger's side unless the design takes this into account. Probably ok with both the Audiosports and Audioscape designs.

If sports seats are fitted the side front adjustment lever only just clears the original door pockets - it looks like it will foul the Audiosport pockets - thus anyone shorter than about 5'4" will be unable to fully depress the clutch with the seat as far forward as it will go. Short partner anyone?

Just about any mid on the market is designed to work with some air behind it - thus needing to use the air in the door. This requires cutting the rear of the build and the door card and preparing the door itself. Firstly remove the weather strip and clean everything thoroughly, inside too. Then Dynamat the outer door skin. Then Waxoyl everything thoroughly. Then seal every hole with templated plastic sheet and clear silicone, this is time consuming work but essential. Then Dynamat the inner door skin. Then cut the dynamat to match the build hole. Then glass fibre a protective weather strip to the rear of the door card to prevent water coming into the back of the build if this has not been added to the back of the build. The two aims of free breathing driver and waterproof door take some effort to achieve but cannot be stressed enough.

If it's desired to put the car back to original at any time it's worth sourcing some replacement door cards. The rest of it will simply peel off and clean up.

It's also worth making sure all the inside door components are extremely healthy while in there - so as you don't have to peel all your careful Dynamatting away next month to fix a central locking or window problem.

A word on tweeter location - the closer they are placed to the mid drivers the smaller the soundstage will be but the more coherent the music will sound. Move them apart and the soundstage will broaden but the whole sound may become disjointed. (There's more to it than that but for the sake of simplicity...) No two manufacturers tweeters and woofer combinations will work the same in the same places - so I suggest that before screwing everything home run the front speakers alone with the tweeters loose on a decent length of wire. Move the tweeters around the cabin and listen carefully for where they sound best. You may be surprised - it could be right next to the mids, in the kick panels, on the dash or in the door window triangles... blue tack and insulating tape are handy for temporary locations.

11 - Amplifiers

Hmmmm my favourite. I don't know what it is about them but I can't get enough of these heat sink covered circuit boards. Strange.

Anyway - the amplifier provided in a head unit is only really there for the convenience of Mr and Mrs average that doesn't want to take their car apart. Anything more than 7 or 9 real watts per channel is an absolute lie. Disagree? If you can explain to me how to fit a true 40 Watts per channel amplifier inside a head unit that also has a CD transport and RDS radio chip and display circuitry then you're either deluded or a genius and shouldn't be reading this but working for an electronics giant. If you're asking a head unit to power speakers then a lot of its current draw will go towards this and not towards reading all the musical detail it can from the chosen source, not good. Separately amplify every pair of speakers. Please. You know it makes sense.

Amplifier mounting is straight forward enough - they require fixing to some kind of board which, in turn gets fixed to the car. There are only a few considerations - can you get to any adjustments easily enough once it's all in place; ensure there's sufficient cool air around it to stop it overheating and shutting down and never mount it upside down.

As for locations well - take your pick. The obvious place in the e30 is in the boot bolted to the rear seat back panel - both enough out of the way and accessible at the same time. Other contenders are behind the rear quarter panels in a 2 door car, under the front seats, in the seat backs (requires considerable work but possible), under the spare wheel or on the boot floor to name a few. Never leave an amplifier connected but unsecured though - for if it comes loose it's a heavy article to be moving around inside a car and an unprotected power supply cable can become dangerous very quickly.

Channels - as a general rule 1 channel is required for each speaker or crossover. If planning to bridge more than one set of speakers from an amp impedance issues are encountered - take advice first. A basic 2 channel amp will run either a pair of front speakers or a pair of rears. These days just about every amp is bridgeable - so a 2 channel amp will run 1 sub when bridged, usually via a switch on the amp itself. I've seen up to 6 channels in one amplifier box - so 1 amp can run a large system say fronts, rears and 2 subs. It's often better however to leave the job of bass amplifying to a separate amplifier. These days there are a plethora of dedicated bass amps on the market - so you're not paying for circuitry to run anything other than bass.

Power ratings, as with all car hi-fi figures, are quite often meaningless. More useful is to check for the size of fuse fitted in the amp casing. A 20amp fuse means the amp designers realistically expected the amp to draw 17 or 18 amps sometimes, a 40 amp fuse means more! Also feel the weight - the components required to deal with the best part of 40 amps weigh some. A light box with a 10 amp fuse and 1000Watts emblazoned across its cover should be treated with some suspicion. Conversely don't be overly concerned with big power amplifiers. A large amplifier is much much less likely to blow speakers - for it can deliver clean signals. It's small amplifiers that deliver 'clipped' or distorted signals when pushed hard that blow speakers. Your 15Watt factory speakers are safer on the end of a 200Watt Kicker amplifier (turned down!!) than on the end of your head unit... Still think your head unit amplifier is 40Watts per channel? Go check the fuse on it...

12 - Bass

Big bad bass comes from big bad woofers. This is not always true but in the main it holds fast. Focal make some 5inch woofers mind - now that gives some mounting flexibility! Ok they'll never deliver bass that sets off shop alarms as you drive down the high street but they're not half bad either!

So let's consider sub-woofers (subs) for a minute. There are two types of sub - infinite baffle and sealed enclosure. Infinite baffle (often incorrectly referred to as 'free-air') subs require minimal air pressure behind them to work - hence they are happy mounted straight into a boot or in a 'ported' (vented) box. These subs give what many consider to be the best sound quality, high volume per input current when in a ported and tuned enclosure and are ideal for sustained low end frequencies such as those found in Drum'n'Bass. Their downsides however include limited power handling ability, a certain slowness to react to quick bass (often sounding 'loose') and an absolute requirement to be return wave sealed i.e. sealed from front to back - often difficult to achieve from an installation point of view. Sealed enclosure subs are virtually the opposite - they require a defined amount of air pressure behind them (achieved by varying the size of the enclosure or box they sit in) and this controls the cone - preventing (to a large degree) over-travel at full excursion. This enables large amounts of power handling and quick motor response times but a struggle to accurately portray prolonged bass notes due to a need for the cone to keep travelling quickly, hence eating amplifier power and a compromise in sound quality. Modern sealed enclosure subs work in very small boxes (unlike days gone by) and have, to large degree, overcome the problems of reproducing all but the slowest of bass notes.

It is a widely held belief that bass in an e30 is difficult to achieve. Although this is true - it's pretty much true for cars in general. There are nearly always other noises to overcome and being inside a pressed and welded steel box is hardly an ideal listening environment. It is perhaps more accurate to state that getting bass from the boot into the cabin of an e30 is difficult to achieve. All you tourer owners can rejoice (start now please) but convertible owners can look forward to some difficult maths and installation problems.

There are two commonly used solutions to getting bass into the cabin - the first of which is to use a huge amount of power to drive the sub(s) hard enough to create sufficient sound pressure that it travels through the metal and trim and into the cabin. The sledgehammer approach. The second is to punch out the ski hatch (behind the rear seat back in the centre) and mount the sub(s) in the boot firing through this hole. It's almost as if BMW made the hatch for this very purpose.... These are by no means the only solutions however - I've seen subs mounted in rear quarter panels and both infinite baffle and sealed enclosure subs slung under the rear deck firing into the cabin. For the truly dedicated try removing the rear seats and filling the space with as many subs as possible.

As for installation - given the above it's very much a case of a car-by-car solution to suit the owner's needs. The lazy amongst us will swing by the local ICE dealer and have a pre-made box slung in the boot with an amp screwed to the side - the dedicated will take a fortnight off work and make a work of art boot build.

Infinite baffle subs for the E30 are going to be rare - I have done them so if you really want a step by step guide mail me or post in the forum and I'll give some pointers. To build a box for a sealed enclosure sub or two is relatively straight forward however and deserves some thought:

First off, as always, have a definite plan. It may change as the installation progresses but at least you know where you're heading. First up decide where the sub box is to be bolted. Don't consider not bolting it in for the same reasons as given above for amplifiers. If the firing through the ski hatch solution is decided upon then remove the rear seat and rear boot trim and cut an MDF board - 12mm is fine - to fit to the rear seat end of the boot. Mark out the ski hatch aperture and some suitable bolt holes and cut and drill your markings into the backboard. It's a nice idea to finish the ski hatch with a boot seal off-cut round about now. Now take two straight edged MDF off-cuts and place one upright on the boot floor and the other upright against your backboard (bolted in place). Mark the line of intersect of these two - thus you know the angle required for the box sides. Also mark on the backboard the height of the boot floor with a piece of 18mm MDF on it. The backboard can now be removed from the car and a box constructed using these lines and you know it'll fit perfectly when it all goes in. (This doesn't excuse many trial fits along the way however)

Make your box from 18mm MDF. If you can't cut straight MDF then mark out your cuts and take it to someone who can. For the sake of a couple of quid in B&Q it's not worth having wonky edges. Using your maths skills work out the size of the box required for the sub(s) to be used and get it all cut out. Ensure that the rear of the box is not parallel to the baffle. Glue and screw it all together and reinforce every joint with glass fibre. Make a brace for the rear of the box too and don't forget to take this into account in your maths. To wad or not to wad? I'd probably wad the box - but be aware that it will fool the sub into thinking the box to be slightly bigger than it really is as the rearward waves take longer to return to the cone. Affix the driver to the baffle using glassed in T nuts and bolts and don't forget to run the cables in there too! Done that before! Seal the cable entrance point with glass fibre. In fact seal everything with glass fibre - the whole point of the box is an airtight seal behind the woofer cone. Also don't forget to run the cables into the box somewhere sensible - out the back will most likely show, underneath will cause it to sit crooked so to the sides or top somewhere near the amplifier(s) powering it. really think about how the box will bolt to the car as part of the design - for our ski-hatch example it becomes simple to extend the four sides of the box forward and seal them to the backboard to push all the sound into the cabin, holding the sub box securely in place too. An added bonus is that the backboard either side of the box can act as amplifier mounting points. Trimming the box and board is very simple and should be done at home rather than handed to a professional, simply wrap around the chosen material and glue it in place. Or paint it or whatever...

Now as with all speakers a re-visit to tighten the mounting bolts/screws after 5-10 hours listening time is vital - so if you can run your sub at home for this time it saves pulling half the car to bits later on...

13 - I want more still

So you've done all the above and you're still not happy. Well all the above will have taught you all the skills required to move on and achieve bigger and better installs - it's just a case of time and money now. Fitting screens into headrests, for example, is just a case of cabling, mounting and trimming, the same skills learned before applied in different areas. Upgrading the wiring and alternator under the bonnet is only a case of nuts and bolts, cable terminating and soldering - there's nothing more you can learn from me and an article like this....

14 - Some good advice

Keep your stereo to yourself - never ever demo it within a mile of your abode - for that's where it's likely to be nicked. For the same reason turn it off at least a mile before your destination unless you know you're going to stay with the car for the duration of your stay. People get to know cars - just think how many people you recognise by their car....

Along the same lines make your installation stealthy too - don't parade from the car into your house with a dozen boxes proclaiming Genesis or Alpine or Rockford Fosgate or the like. Your friendly neighbourhood thief knows what car you drive... Put them in a bag (but not a Sextons carrier!!!) or throw a cloth over them at least.

Make your cabin as factory looking as possible. Contrasting trim colours for door builds may look lovely but they only highlight what's there. If someone doesn't know it's there they're not going to try to steal it. If your car lives in a garage then you may think it doesn't matter - but you'll leave it somewhere when it goes out...

If you don't have a garage then all installation work will have to be done away from home for the same reasons. Multi-storey car parks are good for inclement weather but bad for light. School car parks are good for evenings and weekends. A mate's garage with a decent stereo is perfect!

When cutting or sanding MDF wear a suitable fine filtered mask. Similarly when working with glassfibre wear rubber gloves. Glass fibre caught just before it finally hardens can de shaped easily with a sureform tool.

Double check all wiring without fail. You'll only get it wrong once. Don't work with live cables from the battery unless you really can't think of another way, it's asking for trouble.

When screwing into the side of an MDF board always pilot the hole to the same width as the shaft of the screw so that only the thread of the screw bites, this way the board won't split. (too much) Similarly always tighten screws into MDF by hand and not with a drill driver - that way you'll feel when they are tight and won't split the wood. (too much)

The rear deck of an e30 saloon can be cut away virtually to your heart's content. Don't cut away the rear seat back though - it's structural.

Never let anyone tell you what sounds good. If it sounds good to you then it is good. End of discussion.

When in a dealers the next model up is always so tempting. Catalogues have this affect too - that's why dealers give them out! When you get the unit that you need for your requirements home it always looks good. Rarely does one regret not getting that extra feature.

By the same token for 99.9% of the time it's used the equipment purchased will be re-producing sound. Only 0.1% of the time will it be fiddled with. Personally I'd like a CD player that has on/off and volume and no more. That would do me. I'd rather my money was spent on sound quality as opposed to features. Therefore if you're not using a feature turn it off. That's why music with a flat EQ will always go louder than music with the bass turned up. Think about it - if you disagree with that and have got this far then you need to read this article again.

Listen to the installer in the dealers - he's the guy doing it all day every day. Push past the salesman to get to him if necessary. Ask the installer if you can see his car - that way you'll learn a lot about him. (or her but unlikely) If you don't rate it then move on to the next dealer. An installer that takes a pride in their car will take a pride in their work.

Be wary of pile it high mail order firms. There's reasons why they sell cheap and customer service is not one of them. You get what you pay for in this life. I'm not running them down - just advising caution.

Be wary too of eBay. Check out sellers feedbacks carefully and make sure they've not been purchased. Collect any goods in person that you're unsure of.

If buying used equipment take a battery, some cables, clothes pegs and a speaker and connect up any potential purchase and check it works before parting with any money. Don't blow it up or short it out though!!

Above all - enjoy. Unless it's your profession it's only fun - don't lose sight of that.

Paul