New wheels

So, as promised, here's an update on the new car.

The car itself is great. An update from the previous model, it's a 2014 Audi A4 Quattro with a diesel engine. The engine produces 190hp and 400Nm of torque. It has a 6-speed manual gearbox. And it's in a rather fetching metallic blue, with a pale grey leather interior. That's right, I finally own a car with an interior made from peeled cow.

It's a 4th generation A4, post-facelift, usually referred to as a B8.5 series. It has hard disk based sat-nav, however it didn't include the B&O audio system. From what I was able to find on various Audi forums, this is no great loss. The standard system is fine given a few 'tweaks'.

One forum post described the setup as "pretty ass". In its factory condition I'd describe it as "barely adequate".The problem with the 'stock' system is twofold. Firstly the factory-fit speakers are not exactly great:

Secondly, because the factory speakers are so absolutely average, Audi attempted to compensate for this by applying EQ. Fortunately this is easy enough to solve. Hook up your laptop to the diagnostic port on the car, fire up VCDS, go into "Radio (56)" then "Long Coding" and change byte 4 from '01' to '00'. This disables the 'sound profile', setting it to 'Off (External amplifier)'.

Even with the factory speakers, this gives a massive boost in audio quality. The lack of bass is gone, the shrill treble is tamed. I tried this whilst sat in the car with music playing through the system, the improvement was instant. Unfortunately there's still a resonant peak at around 500Hz.

In the old car, I had an aftermarket head unit with a decent digital EQ. I was therefore able to 'dial out' the resonance by applying a -3dB cut at 500Hz with a 3dB/octave slope:

Unfortunately with the factory setup this wasn't possible, as the EQ can only be set to a preset 'sound profile' and can't be tuned. One option would have been to buy a mObridge unit (£850) to connect to the MOST fibre-optic bus and provide a 6ch analogue out, then fit an aftermarket 6ch amplifier (another £500), but this seemed particularly expensive for what's basically a fancy DAC. Again, checking the Audi forums determined that the best course of action after disabling the 'sound profile' was to uprate the door speakers to something better. Focal seemed to be a popular brand, but were relatively expensive (£200+ for just the speakers, without any adapters etc). And that's just for the fronts, another set are required for the rear doors.

I've previously used speakers from Vibe Audio, which are good value and a big step up from the factory units. So I ordered a couple of sets of those, an 8" set for the front and a 6.5" set for the rear. Both sets come with a 1" soft dome tweeter and the appropriate crossover components. This came to £120 for the fronts, £40 for the rears, and £40 for the adapter rings and wiring adapters, totalling £200 - less than half the price of the Focals.

So, the new front bass-mid speaker is a bit of a beast:

Despite the massively larger magnet, this does fit in the space where the original speaker was installed. Firstly a bit of preparation:

A quick explanation: The black plastic connector fits onto the factory wiring in the door. The length of thinner cable has an inline capacitor and feeds the door tweeter.

So firstly remove the door panels. I won't go into details on how to do this; there are instructions on several Audi forums and in the Haynes workshop manual.

Now, another problem. The non-B&O system doesn't have tweeters in the front doors, only in the dash. The B&O system does. So as I'm fitting door tweeters, I had to scour eBay for a pair of B&O tweeter trims. The Audi part numbers for these are 8K0035423A and 8K0035424A for the left and right doors respectively - note the 'A' suffix, the non-suffixed part is for the non-B&O system which just has blanking plates (styled to look like grilles) over the tweeter locations.

Before fitting the adaptor ring, it is necessary to cut a small slot at the top to allow the cables to be routed:

Now the adaptor ring can be bolted back into the door, and the new speaker secured to it:

Now the door trim can be re-attached, leaving the door looking absolutely factory (apart from the B&O tweeter cover of course). Rinse and repeat for the passenger side:

Again, once the trim is refitted, the interior looks absolutely stock apart from the B&O tweeter trim - normally the bass-mid speaker has an aluminium trim as well when the B&O system is factory-fitted.

Next, I'll move on to the rear door speakers. These come with a crossover unit to roll off the midband to the bass-mid driver, required as the 6.5" driver will otherwise extend too far up into the midrange. This isn't required with the 8" driver as this rolls off naturally at around 500Hz.

The crossover as supplied has a long flying lead for input and two shorter leads for output, one for the bass-mid and one for the tweeter:

Before fitting this into the car, I'm going to open it up, remove the long flying lead and attach the Audi speaker adapter lead:

Now to remove the door trims from the rear door:

After removing the factory bass-mid driver, the replacement is easily fitted:

At this point I hit a minor problem. The factory tweeter in the rear door is clipped in using a custom mounting. I couldn't figure out an effective way of mounting the aftermarket tweeter into the door trim, so eventually I just left the factory tweeter in the rear door and replaced only the bass-mid. This actually works fine, as the mid-band resonance comes from the factory bass-mid speaker. The replacement doesn't have this problem, and has a crossover to properly roll off the midrange. The 'spare' pair of tweeters can be re-purposed and used to replace the factory ones in the dash, giving a further improvement.

Having replaced all the trim, I tested out the system. The improvement was nothing short of dramatic. It turns out the electronics that Audi fit in the B8 (DAC, DSP, amplifier) are actually pretty decent. Yes, if I was going for absolute sound quality I'd fit a mObridge and separate amplifier, but any improvement would be drowned out by road noise. This setup gives me proper bass, clear mids and a nice sparkling treble, and goes loud enough to cover wind and road noise at motorway speeds.

All that's left to do now is spend a few hours copying all my favourite music to the built-in hard drive.