BMW i3 Base Audio Upgrade

19.4.2022

This time we to dive into how to make BMW i3 or i3s base audio sound better. And better means even better that stock Harman Kardon sound system.

Previous blog about i3 Harman Kardon upgrade can be found -> HERE

i3 base audio is maybe one of the worst stock audio setups in modern BMW's. It includes 4" full range speakers in front doors and 6,5" bass speakers in footwells (4ohm) and no rear speakers. All four channels are powered with head unit that is located under the rear seat. Head unit is basically regular car stereo in terms of power output around 4 x 15W continuous and maybe 4 x 50W peak power. It doesn't matter if you have smaller business (6.5" screen) or Professional (10.25") head unit. With 12 Volts you just can't get more power than that without big power converter that won't fit inside regular car stereos, especially with all Navi and infotainment electronics that head unit is responsible of.

Good thing is that i3's rigid carbon fiber body is made for car audio and it is easy to get signals from the HU located under the rear seat.

Also like in live concert audio is better if it comes in front of you so rear speakers are not necessary. Sure they give some "airiness" to the sound, but in i3 adding those is not easy job as there are no wiring or grilles ready (there are places ready though inside door panels). Also adding rear speakers needs 2 more amp channels that are not provided from HU, so Fader would be "fixed" from the amp. So better focus adding good speakers to the front and put subwoofer in the trunk.

In this i3s base audio upgrade project we used components (link to product in website by clicking):

i3 Harman Kardon A-pillars
Ground Zero GZCS 100-BMW-SQ+A component speakers (discontinued, new -> https://www.audiokit.fi/tuote/ground-zero-gzcs-1002bmw)
- Good option also Audison K4E (need to remove crossover covers to fit inside A-pillars)
Match M 5DSP (new model M 5.4DSP) + URC.3 remote
PP-AC 13a T-adapter and PP-ISO 1 harness
Audison APS 8D subwoofer + 8L encosure (new better in link with angled rear wall)
+ power accessories incl. fuse box, power cables, speaker cables and lots of connectors

Full upgrade package is -> LINK and it is possible to also to upgrade kickwoofers for more upper bass punch and even replace bass adapters for HK size 6x9" kickwoofers.

Installing door speakers and tweeters

First we replaced 4" door speakers with Ground Zero component set mids. There are videos in Youtube how to remove door panels so we don't go into that. GZCS A-versions are identical to i3 stock speakers so it's basically plug&play. This time we didn't add sound deadening to the doors as in HK upgrade we noticed that it's not helping much to reduce road noise and 4" speakers won't give much bass that soundproofing would help.

Ground Zero vs. stock mids.

4" speaker installed.

Adding tweeter is more complicated but not hard. First you need to remove A-pillars by prying off airbag label and unscrewing T20 torx bolt under that. After that all you need is hard pull to the center of the car and two clips will pop out. Then just pull bottom part away from the corner.

Next is good to attach new GZ tweeters to the HK A-pillars and do wiring. As we didn't decide to swap kickwoofers in this install so we routed new tweeter wires to the rear seat. Wires can be routed to floor level and tuck under the door sills so they won't be visible. When swapping kickwoofers you might find speaker wires going to the door grommets and connect tweeter wires parallel to those, but as for now we don't have info or pictures of that.

Ground Zero tweeters has small crossovers in wire, so it's easy to find place to attach those.

Tweeters are always connected parallel with mids and all you need is check which wires are outputs from the amp and make Y branches. And of course know which wire is positive and negative. In all BMW's wire with brown stripe is negative. In this case Match PP-ISO 1m harness was responsible for all inputs & outputs so we made modification to that. Rule of thumb is that in all aftermarket car audio wiring is: white=FL, grey=FR, green=RL, purple=RR.

HK A-pillars installed.

Wiring and installing amplifier

First it's best to do all wiring ready for the amp and then find good place to attach amp and just plug it in. Audio signals are coming from head unit and for that PP-AC 13a adapter + PP-ISO 1 harness is needed. Audiotec-Fischers Match PP-AC 13a adapter is BMW specific and just routes audio signals to amp and back to speaker cables so no need to worry anything else. Simple plug in and route cable to a good location where amp is gonna be.

Next amplifier needs power and we don't recommend tapping to head units power as there's just 25A fuse and amp can take up to 50A max. Some people have strong belief that 12V needs to be taken out of 12V battery but this is not the case in i3. In upper part of the electric motor located under the trunk there is DC-DC converter that feeds small 20Ah 12V battery in the frunk (front trunk) with direct cables. Converter is capable providing around 170A constant power so this max 50A is no problem. Still we wouldn't recommend going much over 100A for audio setup as car accessories needs their own amount of amperage. But tapping to DC-DC converters +/- poles is the easiest way and actually those poles are meant for charging 12V battery. Also there's no need to drill any holes. Just route the cable going under the trunk's lid that covers the electric motor.

Match M 5DSP installed using STP Aeroflex 5mm as base and velcro to attach (now new version is M 5.4DSP with more DSP output channels).

Coding the Head Unit

Base audio speaker outputs from the head unit are heavily equalized to compensate low power and poor speaker. Coding to Harman Kardon makes signal better for adjusting with DSP. This procedure needs some hardware and software and maybe easiest app for that is Bimmercode. More info in Bimmercode website.

Once connected to the car you need to go inside Headunit and activate Expert mode. Then from search (magnifying glass logo) type "audio" and select AUDIO_SYSTEM and choose hifi_system_harmankardon. Then just press code button and you are done.

Adding subwoofer, remote and adjusting the amp

Connecting subwoofer is just routing speaker wire from amp to the sub. Match M 5.4DSP gives 160Wrms / 320Wmax @ 2Ohm from sub channel that isn't much, so speaker + enclosure needs to be selected carefully. In this case we used Audison APS 8D that can handle 250Wrms but does perform super nicely with 160Wrms even in tiny 8 liter enclosure.

Many try to preserve i3's small trunk by adding a flat subwoofer. We have tested some of those, but for real bass some sacrifices needs to be made so better to go for real wooden subwoofer enclosure. There is some room under the trunk lid in BEV where REX engine would be. So it is possible to make custom enclosure there, but we haven't done that at least for now.

Audison APS 8R + 8L enclosure.