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Old 03-29-2005, 08:48 AM   #1
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DIY - Aftermarket Amp, Speakers, + Subs w/ Stock Head Unit (Make Sticky?)

This is a verbatim copy of a SUPERB post over at Roadfly made by William Quiles (who kindly allowed me to repost it here), describing the steps needed to replace the stock amplifier and speakers, while retaining the factory head unit. In my opinion, this is a must-read for anyone planning an audio upgrade to an E46, whether they plan on doing it themselves or having it done by a shop. It provides answers to a large number of the questions I see posted here daily, and can help demystify any misconceptions put forward by Mobile Audio shops trying to sell you extra equipment. Thanks again to William.

E46 M3 Coupe (with H&K, no NAV) Full Audio Upgrade
By William Quiles (


Thanks to those who came before me and shared their information with me. They are the ones who deserve credit as they discovered most all of the information presented in here. Please look at the references for some very good sources of information, most specially the post by David Bagby on his lessons learned. He has the CORRECT wiring diagrams, which I used during my install (Yes, my H&K system has wires where his diagram shows no-connection, but it did not mater during my install). NOTE: To preserve this data (since it is the ONLY post I found that has this information) I have copied his wiring diagram at the end of this post in case his post is ever lost – this information is very valuable!


I am not an audiophile, nor do I like very loud music, but I do like clear and quality sound of an stereo system, specially if I am listening to CD’s. When I ordered my M3 Coupe (2002, late April production) I figured that the H&K would have been good enough for me. I also though, getting the upgrade now meant that if I wanted to replace components if would be easier later on. I was unfortunately wrong on both counts.

Based on “unofficial” polls here on E46 M3 board, about half of the owners feel the H&K is pretty decent, although it lacks bass. I am on of the “other” half that thinks that the H&K is not good enough since I was not happy with the audio system on my car (specially the spatial button!), plus the more I listened to it the more I was convinced that the system just SUCKS big time!. I hesitated for a while about what to do, but eventually decided I could not live with the factory system (music simply did not sound accurate nor “right”).

This whole process took about 2 months or so, so I am hoping that by me sharing what I learned it will be easier for those of you who are considering what to do. This post shares what I learned through this process and what I did on my particular car.

When I started I had some simple goals (which might or might not match your own):

- system must sound clear, with good imaging, and slightly louder.

- good, decent bass, although not wanting to win SPL contests.

- retain OEM head unit – no exceptions!

- make the install look 100% factory.

- no significant trunk space loss – preferably none.

- try as much as possible to make changes reversible.

- spend the LEAST amount of money possible.

- try to do all of the work myself (also saves money!)

Not only did I wanted to save lots of money by doing the install myself, but I really wanted to make sure that everything was done as best as possible. While researching for this task saw some photos of installs that were done by local shops that were not done “right”, so I studied my options for several weeks until I felt I had enough information to get started (see references/links at the end). Also, by doing the install myself I can tune and balance the system and the stage to MY liking, not somebody else. Lastly, if something went wrong, I have only but ME to blame J

I first upgraded my rear stock OEM subs with the superb Kicker 6x9 Free Air replacements. Quite a few have replaced the factory subs for these for a “quick and dirty” upgrade on the bass department. For some, this will be enough and it will also be the least expensive and by far the easiest upgrade. However, if you are used to larger (10” or larger subs) with amps then this is not going to be good enough by itself. Although the new Kicker subs were a good improvement, I decided I wanted a little bit more “punch” so I decided to use an amp to give more power to my new Kicker subs.

Let me take a moment to say that adding a simple sub and amp for the subs is what most folks need – no more. If you have the factory CD-changer and new rear left panel you already have enough space for a decent, small, 2-channel amp to drive the OEM subs. You will need to add a thin layer of foam around the H&K’s sub housing to reduce/eliminate rattle (believe me, if it did not rattle before, it “will” after you use an amp!).

You do not need more than 40 “clean” watts for the factory subs as right now they have FAR less. In fact, just look at the active crossover/amp next to the sub housing and you will see what you can not possibly have much power there at all. It would also be best if you get a small amp that has a built-in crossover for the sub frequencies (150Hz or less) as it will make the install easier. You should also know that there is power and ground going to the sub amp/crossover so you could install the amp to the underside of the rear deck and wired it all there. Some of the links at the end do show some other posts about just adding a sub/amp, so please review those as well before proceeding.

You could wire the sub for the amp directly from the rear or the factory subs, but realize (as I will cover later on) that the OEM amp already cuts the frequency range of all outputs (as it has buil-in active crossovers on all outputs), so if you do not bypass the OEM amp you will not have the full frequency range to feed your aftermarket amp. Some have reported excellent sound by taking the rear speakers directly to drive the subs, so you can try it to see what sounds good to you - after all that is what really counts.

Since I decided that I needed an amp for the Kicker subs and since I wanted to replace the front speakers for better sound/image/bass I knew I would be better of by getting a multi-channel amp. After doing some research I found that a six channel amp would work great when configured in this way:

- channel 1 and 2 – front door separates (component speakers)

- channel 3 and 4 – rear fill (provides small ambience for rear passengers)

- channel 5 and 6 – drive the subs

So now I need a 6-channel amp and a good set of quality component speakers. After much research for the amp I realized that if the amp had a built-in crossover to make tuning and balancing the overall system, the install would be easier on me. As you will see in the references, the a/d/s amps came highly rated and always got high marks for being very clear and for having clean power (low distortion at their rated power output). From my research, and since I do not listen to very loud music I found that I only needed about 40-60 watts of “clean” power per channel. Given this I started looking for a 6-channel a/d/s amp and after a month or so I found an used a/d/s P640 (6x40 watts) on Ebay for $250. Amp down, speakers to go!

From my internet research I found that the front speaker is about 6 inches in diameter but that because of depth you can only fit a 5 and ¼”, so I concentrated on the 5 and ¼” speakers as I did not wanted to modify the front door. For the front speakers separates I found 3 speakers recommended (in order of preference):

1) a/d/s 235is or 345is (345 better woofer and crossover but same tweeter as in 235is)

2) MB Quart (although some consider them a little bit too bright)

3) Infinity Kappas

Out of these I was able to listen to both the Kappas and the MB Quarts, and although I took a risk and was not able to listen to them, I pick the a/d/s speakers as the always got rave reviews for being the most clear and accurate, plus the fact that I already had an a/d/s amp meant that the system will work together for sure. After a couple of weeks I found a new set of 345is on Ebay that came from a closing store’s auction so I had my front speakers. Now I needed to figure out how to wire everything together.

Last edited by Seth_Horwitz; 03-29-2005 at 09:03 AM.
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