BMW M2: Sound System Upgrade
The BMW M2 series F22/23 is a fabulous coupe. However, it suffers the same audio fate as the rest of the BMW range: terrible music reproduction. Whether you have the base audio system or the ‘upgrade’ Harman Kardon ‘hi-fi’ the audio performance is bad. Generally, the sound lacks sparkle or dynamics with poorly defined stereo imagery and a very coloured bass performance.
The majority of the blame can be laid at the speakers. Like most auto manufacturers, there is always a drive to cut costs. These speakers that BMW fit are some of the worst, especially considering the cost of the vehicle.
The Original BMW Speaker
The standard BMW door speaker has a heavy cone and surround leading to a very low sensitivity. This results in a reasonable mid-bass but very poor higher frequency performance. Along with this, an inability to respond to delicate nuances and subtle tones. Even worse, this may be the only speaker in the door as tweeters are only fitted as part of the ‘upgrade’ pack. Unfortunately, the stock BMW tweeters are also poor. So even if you have them they contribute little to the audio performance.
This 12cm speaker is used in the front and rear of the car and of course cannot produce any bass at all. To compensate, BMW fit a pair of 20cm speakers under the front seats. These speakers are often referred to as sub-woofers but that is far from correct.
What’s wrong with them?
A picture cannot convey how cheap and flimsy these speakers feel. You could not compare these with any quality speaker let alone a sub-woofer.
The under seat speakers should not be classed as sub-woofers in the usual sense of the meaning. They are the bass component of the two or three way front speakers. The advantage of this speaker setup is that if we can control the frequency range going to each speaker in the component set then we can produce a full range and balanced sound. Unfortunately, BMW have missed that mark by a long way. Instead, the under seat speakers play full range along with the door speaker, leading to a very muddled, dull sound. Of course, mounting the speakers under the seat does not help from an imaging point of view either. However, that can be compensated for. Even if your car has the ‘upgrade’ system with an extra amplifier and some level of frequency control, the poor speakers and positioning add up to a very unsatisfactory performance.
So how can we make it better?
Let’s take the BMW M2 mentioned earlier. The owner had noticed all of the problems we have referred to here and was keen to make it a lot better, as he spent a lot of time commuting. We discussed his tastes and preferences so that we could determine the optimum system for him. We would normally recommend a proper sub-woofer for the boot. In this case we could not as the car was constantly full of equipment. That meant we would need to use the under seat speakers to generate the whole of the low frequency spectrum. This is possible as long as we have a tight control over the frequency and phase of the speakers.
As his was the base audio system with no tweeters, we obtained the appropriate covers from BMW. These are inexpensive and allow us to install a two way component set.
Sound deadening material is then installed behind the speaker. This further enhances the acoustic performance and all cables are carefully wrapped in cloth tape to eliminate the possibility of rattles.
The speaker set we chose for this customer was the Audison Prima BMW range. These speakers are excellent and of course cover the whole BMW range both door and under seat.
Under seat replacements:
The next task was to install the under seat replacements. This requires the seat to be removed along with the pod containing the BMW speaker.
The difficulty here is that the original speaker is glued into the pod. However, with careful application of heat this can be removed. Once the door cards, covers and seats are re-installed there is absolutely no indication that anything has been altered.
At this point we have dramatically improved the sound in the car. By just replacing the front door speakers and under seat drivers the system now sounds much more lively and punchy. For many customers that might be enough but this needed to be better. As mentioned previously, we were starting with the base audio system which has little power and no individual frequency control for the speakers. We could install passive crossovers to give frequency control, but this will do nothing to improve the standard output. We need an amplifier.
Our choice for this car was the brilliant Audison Prima AP8.9 Bit. This amplifier offers up to eight configurable, high power output channels with a very powerful digital signal processor on board. We could have chosen the AP4.9 Bit as we actually only needed four channels of output. However, by using the 8.9 we are allowing for future expansion. Another advantage of the 8.9 Bit amplifier is it’s small footprint, allowing us to mount it discreetly in the well next to the battery.
Like most of our installations, this is mounted on a carpet trimmed panel that is bonded to the car. This means it is secure but electrically isolated to eliminate any possibility of interference.
Tuning the system:
Once the hardware is installed we can move on to tuning the system. At this point, I like to take a break from the installation for an hour or so, as to approach the car fresh. The first task after making sure all tone controls are neutralised is to listen to some of my test tracks before any adjustments are made. This gives me a feel for the general sound of the car space and to anticipate any gross adjustments that need to be made. I know from experience that the 2 series BMW has a very bright acoustic performance, (meaning the tweeters need to be tuned down accordingly) but it always pays to listen to each install first.
Next, I like to measure the response with our real time analyser. This shows graphically the actual acoustic performance of a pink noise test track. I always want to know what medium my client uses for music (CD or streaming) so that I can tune it using the same medium.
Using the software for the amplifier, I can now start to equalise the car. It is important to note that this process is done to tune the system to the car and has nothing to do with music. The purpose of this is to optimise the installed components to the acoustic space. Once this is correct, the music will sound as it should with detail and authority. Meanwhile, stereo imagery will be right in front of you across the dash. The bass will not sound like a hollow afterthought coming from under the seat but will blend seamlessly with the rest of the sound for a full, rich performance that will greatly enhance driving pleasure.
Even without a boot mounted sub-woofer this BMW M2 sounded fantastic and played all types of music with energy and presence, the owner was delighted.
Want to know more?
If you would like to know more about how we can improve the sound in your BMW or indeed any car please give us a call on 01625 432707. Better still, pop into the shop on Sunderland Street, Macclesfield, where we can demonstrate these systems to you.