Omega Help Area > Omega Electrical and Audio Help

Speaker Buying Guide


Dave DND:
From the number of questions I get asked on a daily basis with regard to upgrading speakers, it is very clear that there is a lot of confusion out there over some of the terminology that is used and the suitability of the products available. So I have written a few notes that will probably muddy the waters a little further.

The answer to the most commonly asked question:
What size speakers do I need in my Omega? Speakers are usually referred to by the physical size of the hole that is left when you take them out. Generally speaking, the front doors of the Omega use a 16.5cm speaker with a separate tweeter, (although you will often find these referred to as 17cm components), and 13cm Coaxial ones in the rear doors – but check as there can be a few exceptions.

Speaker Adapter Rings:
These specially shaped adapters will allow the fitment of a standard shaped aftermarket speaker into a non standard shaped hole left by the removal of the original speaker. You may also find that by using adapters from a different vehicle (that effectively move the speaker away from the door a little), that you can then use a speaker with a much larger magnet without the problem of the deeper speaker fouling the window mechanism. Both Vauxhall Cavalier and Corsa adapters have been very popular for this.

Speaker Types: Co-Axial Vs Components
The larger part of the speaker cone will produce the deeper Bass sounds, and the smaller speaker, (or Tweeters) will reproduce the higher treble sounds. Now if you think of a car speaker, it will generally fall into one of two types, either a big speaker with a smaller tweeter placed in the middle (Co-Axial) or a big speaker with a small separate tweeter (Components).

Co-Axial speakers will reproduce sound in the same direction that the speaker is pointing, and if the speakers are low down in the doors, then that is where your sound will stay.

The advantage of a Component speaker is that you can relocate the tweeter, and with a bit of careful positioning, this is enough to make the sound appear as though it is coming from much higher up, and not low down in the kickwells. Tweeters are traditionally placed near the tops of the doors or the base of the “A” post, as making the sound appear nearer your head can really bring the sound “alive”.

Part II to Follow

Dave DND:
Power ratings:
This is a minefield, and I hate this one, as what I am going to explain here in basic terms, makes no sense and has no bearing on sound quality or performance. A speaker needs to physically move air, and the more air it moves, the more power it needs, that is generally understood. BUT that does not mean that a higher power speaker is louder nor more efficient. Power is measured in Watts, and this is where the manufactures have decided to confuse us further.

There is an RMS power rating, which is generally only ever referred to by audiophiles using the more expensive stuff, but to be fair, this is the true figure that should be used, but it isn`t. However, RMS figures are often low in value, not understood very well, and as far as the manufacturers are concerned, they don`t appear sensational enough to sell speakers. So with a bit of a recalculation, the manufacturers then turned our RMS figure into a MAX POWER figure. Now the clue is in the word MAX. It is not a figure that the speakers can endure for any length of time, it is the level at which they will expire. In other words, if you put 200W into a 200W speaker, it will go pop. The MAX POWER figure is the one you will often see on the side of a speaker box in the shops. However, in order to appeal to the mainstream market and sell more speakers, the manufacturers of car audio decided to then double this figure and call it “Ultimate MAX POWER”, (or often referred to as “Max Bullshit Power” by the retailers), and if you see a figure of 1000Watts against a speaker the size of a fag packet, then you must realise that this is a poor quality product and will not perform as well as the packet artwork states.

If you are actually attracted to and have reason to believe this 1000W figure is true, then please switch off your computer now and go and join your Chav mates in the local Mackie D`s car park – as this forum is obviously not for you.

It is important therefore, to make sure that you know which band of figures you are referring to, and to stick with them when deciding on power ratings. Most of you here will be using the MAX POWER ones. So what power figure should you be looking for? Well, as a general rule of thumb, the power output of a speaker should be at least double that of the head unit driving it, but not too much more. If you have a head unit, of say 50W per channel, then 100 ~ 150W speakers would be ideal. If your speakers are rated too low, then the stereo may exceed the power rating and burn them out, and if you go too high, then your stereo may not be able to power them at all.

If we consider a 50W head unit and 500W speakers, then running flat out, the head unit will only provide 10% of what the speakers can take. By now, you should be able to understand why your OEM 15W head unit is never going to power your 100W speakers, and why your aftermarket 50W head unit is going to instantly blow your 25W OEM speakers.

Part III to follow

Dave DND:
This is the resistive “load” that is seen by the equipment, and is measured in Ohms. The standard speakers in the Omega are industry standardised 4 Ohms, and 99.9% of vehicle manufacturers have also stuck to this with a few exceptions. Some of the older USA vehicles use 8 Ohms, but the main problem is that of the BOSE system in the Omega, which uses a much lower 2 Ohms impedance. It is important to replace your speakers with like for like Ohmage – so if a 2 Ohm BOSE speaker has blown, it MUST only be replaced with a 2 Ohm replacement. There are still some 2 Ohm speaker manufacturers out there, but it is highly unlikely that you will find these stocked as an “off the shelf” option, and they may have to be specially ordered.

The crossover is simply a filter to ensure that the correct sounds go to the correct speakers. You do not want the bass coming through the tweeters any more than you want the high end frequencies coming out on a large bass speaker. A crossover may consist of nothing more than a capacitor glued to the side of a tweeter, and may also appear as a separate hideaway box when you start playing around with some of the more expensive speaker sets.

These are the speakers that produce the really low down bass notes, and are often very badly fitted by the younger generation resulting in a “Boom Boom Boom” noise that overpowers everything else. If you think that this is all subwoofers are for, then please think again. The reason that the BOSE, and indeed the earlier Philips systems made such a difference to the sound in the Omega was the addition of subwoofers in the rear shelf or boot. A subwoofer (set up correctly) can add a real depth to the sound and warmth to the music, and as such is probably one of the most important audio upgrades that you can ever make. Jazz, and the spoken word of Radio 4 can sound unbelievable with a subwoofer set at a very low volume in the background. Subwoofers can also vary dramatically in size from the small drivers on the rear shelf, to the tiny shoebox size units that fit under the seats. But if opting for a large box in the boot, please note that size is not everything and you may find that a slower 12” sub will add more depth to a bass guitar than a 10” sub that will often respond faster to an electronically produced beat. It really depends on your choice in music, but the golden rule remains, if you can hear the subwoofer over the top of the rest of the speakers, then turn it down as your system is unbalanced – it will sound better as a result.

Part IV to follow

Dave DND:
Speaker Ranges and Models available:
Speakers will generally come in one of four price brackets / performance groups and you need to understand that you are only ever going to get what you pay for. If budget is paramount, then look at an older model of speaker from a better range rather than the latest model speaker from a budget range.

Budget / Entry level speaker range: £20 ~ £45
This range of speakers are best avoided. Often found piled high in Car Accessory shops and shagged out on the Internet, buying here will often lead to disappointment as with very large claimed power ratings and very distorted sounds, these will offer no real improvement over the speakers you are replacing, irrespective of which brand they are from.

Mid level speaker range: £50 ~ £85
If you are running an OEM stereo, or a reasonable aftermarket head unit of around 4x30W, then this range, also found in the larger Car Accessory shops, Specialist Car Audio shops and even the Internet, is a far better range to look at, as will offer a decent level of sound reproduction, and will make the effort of removing all of the door cards to fit them, worthwhile.

Upper Range: £90 ~ £140
If you are running a good brand of aftermarket head unit of around 4x50W, then you should consider looking here. Rather than being constructed from Polymers, you will probably find that the speaker cone construction is fibreglass or similar for better sound reproduction. You generally won`t find these in Halfords or the like, and are usually only found with a visit to your local audio specialist who should advise you that running these is going to be just on the limits of your head unit, and that an external amplifier should be considered in the future, should you ever decide that you need a bit more grunt. Speakers bought here will certainly take the power of an external amp should you choose to upgrade at a later date.

Semi Pro range: £150 +
These speakers will not usually be found on the net, and are generally restricted for sale by a “Good” Car Audio specialist, as you will certainly need extra amplification and advice on how best to set up your system. But Beware - This range is expensive, and exceptionally addictive !!

Buying Secondhand:
A word of caution here. Speakers do not have an infinite life, and they do perish and wear out over time. Paper cone speakers, used on the Omega are starting to Bio-Degrade around the edges, and the foam surrounds are starting to break up, so a visible inspection is essential if you are buying here. But the rear danger is the state of the internal voice coil, that’s the wound copper wire ring that moves in and out, as you have no way of testing to see how hard it has been run. If it has been overpowered, the voice coil heats up, boils its glue and then expands ever so slightly and starts to rub against the magnet internally. This can lead to a loud (and often expensive) audible “Crack” from the speaker, and if you are unlucky, it can damage your head unit very quickly. Although not conclusive, there is a basic test that you can perform. With a very light and even pressure applied to the speaker cone, it should move freely in and out. If there is any sort of resistance or “gritty” fell, then the speaker is probably blown and should be discarded.

Part V to follow

Dave DND:
It should be remembered that distortion is not our friend, and if you are experiencing distortion in any shape or form, then something is wrong and must be remedied before any long term and expensive damage is done. Seek advice from a specialist immediately if you do not know why this is happening.

Very Important:
A speaker has a Positive (+ve) and a Negative (–Ve) connection, and it is very important to connect these the correct way round. If connected incorrectly, you will still get audio, but the sound waves in the car will be out of phase and fighting against each other, and this can sound like there is a hollow “echo” somewhere. When people complain about fitting aftermarket speakers that do not sound right, in 99% of the cases, it is because somewhere there are a pair of wires that have been connected the wrong way round. It cannot be stressed how important this is.

Stick to one brand:
To prevent any overlapping and imbalance of frequencies, it is often advisable to stick to a same brand of speaker throughout the car rather than mixing and matching. However, the speakers do not have to be from the same range, but always put the best ones in the front, as that’s where you will spend the most time listening to them. Omega owners will always point out how good the BOSE system sounded, and that is because the system design was very balanced with an unobtrusive bass, but more importantly, utilised the same brand of speakers and the best quality materials that were available at the time. Apply the same logic to a good aftermarket system and the result should certainly not disappoint.

Go Compare:
Now go and have a listen to what is currently available and suits your audio requirements, but make sure your comparisons are on a level playing field. You would probably not rush out to buy an Omega just because you had a fabulous test drive in a VXR8, yet they are both made by Vauxhall, so don`t assume that the BOSE system in a 2011 Audi A3 means that the BOSE from a 1999 Omega will sound the same – it won`t. Find a good Car Audio retailer and have a listen to their display stands, but a tip here is to take your own music along on a genuine CD (not a compressed MP3 file) and ask to listen to it with the Bass and Treble all set to Zero. The differences in the display speakers will then be easier to hear as you select between them.


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