Well, I decided this weekend to get the awful stereo sorted in the car. I have the basic, non DSP set with a cassette player!!! and CD Changer and after doing a little research, and from experience on my previously DSP equipped car, decided that the actual audio electronics were fine, it was the speakers that were of such poor quality.

I therefore decided to replace the front speaker with a component 2-Way set from Diamond Audio, an up-market manufacturer but using their entry level set, and add a subwoofer system. The components are Diamond Audio M3 series M361, 6.5" components and the subwoofer is a JBL, Northridge E250 Home Cinema 550 Watt Active sub.

"Hold on there", I hear you cry, that sub runs off 240V mains. Correct. I will get to that! Lets do the fronts first.

First thing we did was remove the door panels by detaching the top trim........



We had a slight hiccup trying to remove the lower screw as the door insert was spinning in the door, so a little stress on the panel by leverage as seen here, locked the insert up and allowed us to undo the screw and remove the panel.



The stock Mid-Bass unit is glued into this detachable housing and is destroyed in the removal process.......



The new 6.5" Diamond Mid-Bass driver is screwed into position in the original housing......



Wired with some new 1.5mm quality audio speaker cable and mounted on the door in the original position.



We now mounted the Diamond Audio Cross-over network in the available space above the Mid-Bass driver and wired the original speaker cables to the input of the X-Over, and then running wires from the X-Over tweeter output up to the top of the door panel.



We decided the best, and easiest position for the tweeters was in the same position as the DSP cars as the grille was already there.



And removing the grille revealed the foam already cut and ready to insert the Diamond Audio tweeters.......thanks BMW!!!



And that completed the front component install. Refit the door panels, fit some billet alloy door pins, see first pic, to match the other interior trim rather than them naff plastic buttons and on to the sub.

So why you ask am I installing a 240V home cinema sub in the car? Well, there are a number of reasons.
1, I have done it before very successfully
2, You get a complete dedicated package, with a (in this case) 12" driver in a purpose built, proper wooden cabinet, (no mdf here!) with a dedicated, designed for purpose power amplifier with all the control you expect from a high quality home audio system, specifically designed to produce quality sub-bass.
3, It's cheaper
4, It's removeable.

To get this sort of performance from a "normal" car stereo components you would need something like a JL12W6 sub, in a 19mm purpose built cabinet, with a Phoenix Gold or JL amp. There goes £600+. I paid £120 for this JBL Pro-Series sub which has a frequency response down to 25Hz!!!

A small 8" sub in the side panel where the factory subs go is neater, but a cabinet to fit is very expensive or takes a VERY long time to make and you will never get true Sub-Bass from a small, 8" sub and you still need to power it from a decent power monoblok amp.

So how is it powered? A simple 12V to 240V inverter is installed above the CD Changer. I used a 1Kw inverter so that even at maximum output, the inverter is only running at 50% output.



I previously learnt that using too small an inverter could cause problems, and I now also fit an anti-surge plug on the sub to protect it from voltage spikes when starting the engine. The on-off switch of the inverter is removed, and the wires reconnected to a 12V switched live in the boot of the car. The main power and earth use large 4 gauge cable, the live directly to the battery through an in-line 60A fuse and the earth to the existing earth point on the rear panel. The speaker is then plugged into the "mains voltage" supply with a 2-pin in-line rubber plug to facilitate easy removal.



To use a home cinema sub, it MUST have a high level speaker input unless you have a phono signal line from your head unit. I then spliced into the rear speaker input and ran an additional speaker cable back along the car and into the high level input on the sub. The sub is now switched with the ignition and ready to set-up.
To do this, I set the sub gain to zero, (volume), and put on a good quality CD with plenty of low, low bass and wound the volume on the head unit to the maximum volume I would ever likely use. You then slowly increase the gain on the sub until the "feel" matches the sound. You can then adjust phase to get the fullest sound and adjust the X-Over to get that real deep bass sound without booming. I ended up cutting the sub upper frequency ay 80Hz. You can then alter the orientation of the cabinet for the best sound, we found sideways firing to be the best.



I seldom take much luggage but should I need to, the sub can be removed completely in seconds. It fits unobtrusively under the screen shelf and I can always sell it later for pretty much what I paid for it, AND I have a 240V 1Kw mains supply in the boot for a hairdryer!!! He he.



How does it all sound??? Absolutely fantastic. The Diamonds up front have brightened and lifted the audio image up to screen level and are C.R.Y.S.T.A.L clear, and the sub shakes the car on bass heavy dance tracks, but on quality music CD's, the punch and attack of even the lowest bass is astonishing, and even on Reggae, it never boom, boom, booms.

You would need to spend a LOT more money to make improvements of any real consequence.

X5Girl, xxx