The previous owner of my car had an aftermarket stereo system installed; at first glance it looked like a pretty clean, decent install as it was clean and properly mounted.

However, upon closer inspection, it was the most random set-up ever, consisting of:
  • Clarion Head Unit
  • Pioneer 4ch 300W amp powering:
    • Front MTX 5.25" Coaxials and OEM Tweeter wired to coax via a bass-blocker/capacitor (via high-level input)
    • Rear Bose OEM-type 6x9 via MTX crossover with tweeters mounted on the rear deck (via line-level RCA)


So, over the past few months of my ownership, step by step I changed the setup and re-wired it to the setup I currently have now, which I am very happy with:
  • Wired front speakers (coax and OEM tweeter) directly to head unit, freeing up a set of amp outputs
  • Hooked up an old 10" MTX sub and ported box I had lying around to the amp (shared input with the rear speakers)

  • Got rid of MTX tweeters and crossover on the rear deck, hooked up 6x9's directly to the amp (which then I found out they were shitty paper-coned Bose)

  • Replaced rear 6x9's with a set of Infinity Kappas

  • Rempved OEM tweeters in door pods and retrofit the aftermarket MTX tweeters

  • New deck! JVC KD-R800 with iPod Control and Integrated Bluetooth and TI/Burr-Brown DAC
  • Ran another set of RCA's to amp, so that the rear speakers and sub will have dedicated inputs/channels for better fine-tuning between the sub and rear speakers.

  • Took the crossover from earlier and totally re-wired the fronts properly, snipped the tweeter leads off the coaxial speakers so it sucks less juice from the head unit amp, making it a true 'component' system.

Current setup:
  • JVC Head Unit powering front MTX component system
  • Pioneer 4ch 300W amp powering:
    • 10" MTX sub (via line-level RCA)
    • Rear Infinity Kappa 6x9's (via line-level RCA)


Tweaking:
  • LPF: 80hz at the amp, off at the head-unit
  • HPF: Off. I toyed with it, but found that at low volumes the HPF made the music sound 'thinner'.
  • EQ: +5 at 100Hz (this REALLY helped the mid-bass dip I had, reading a comment from Luke that the frequency dynamics of the E30 cabin)

Future Upgrades? For now I am very happy with the setup, but the sub is probably the weakest link right now, I want something tighter and more musical, less boomy.

Anyways, that's my audio journey for my E30! I am more a headphones/home theater/home audio guy, but for what it consists of and what I started out with, I am very happy with the setup.

Comments or suggestions on how to make it better?