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Old 03-29-2005, 09:49 AM   #2
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Join Date: Aug 2004
Location: NYC
Posts: 801
My Ride: 330ci, 911 Turbo X50
In case you were wondering about the rear “fill” speakers, my research (and emails to a/d/s technical support) revealed that the OEM speakers are good enough for fill duty as long as you take the very low end frequencies (feed those to the sub) and the high frequencies (only the front speaker set gets these as to not to confuse the imaging/staging). So far this is working great, although I can always upgrade those in the future if I want something with higher quality.

So I started looking in the Internet for audio upgrades for BMW’s and I soon found that late model BMW head units work hand-in-hand with the H&K OEM amplifier. Unfortunately, the H&K amp (and I am talking here about the “main” amp, not the Mickey Mouse, tiny amp for the subs) uses built-in crossovers, which means that the amp and the speakers are matched to each other and that the outputs of the amp already have reduced frequency range. This means that if you take the output of the OEM amp to an aftermarket amp to drive your speakers you will never have a “pure” signal available. This is not terrible (it is actually a good design from BMW and H&K) but means that once you decide to upgrade your system you HAVE to replace the main amp as well.

I also learned (and this is REALLY important) that the OEM head unit in our cars does not use the “standard” RCA signals prevalent in aftermarket stereos, but the much better differential output signals. This means that you “CAN’T” directly connect the outputs from the head unit into an aftermarket amp – you need a converter. There are a few recent aftermarket amps that can take the diff signal directly, but most can’t (check BEFORE you get your amp). My amp is one of those that does not, but luckily for me Peripheral makes one that works perfect with my a/d/s amp, the Vendetta 4 (also called VEN4 for about $40). I am using it and I can tell you it works!

My a/d/s amp is driving speakers with the following frequency ranges, plus I am using a “relative” scale of 1-10 for power:

- front speakers: power 6, high pass at about 50Hz or so

- rear “fill” speakers: power 2-3, high pass at about 150Hz and low pass at about 2KHz or so

- Kicker subs: power 8-10, low pass at about 150Hz or so.

The system is predominantly front staged (driver and passenger, which is what I wanted) and just with enough fill from the back. Since I am only feeding limited spectrum to the subs, they of course have to get much more power to “balance” out with the rest of the system. Yes, there is a little multi-coverage on the low frequencies, but I adjusted the a/d/s crossovers until the system sounded good, seating in the front and the rear or the car. This part takes a while (since you have to go back and forth the trunk and the seats many times) but the results are worth it!.

As for the sources from the hear unit:

- front and rear channels use the OEM front signals, so the balance of front to rear is done at the amp since my amp has adjustable gain for each pair of channels.

- the subs use the OEM rear signals so this allows me to change the relative power going to the subs by simply using the FADER control on the OEM head unit.

NOTE: Some aftermarket amps (like my a/d/s) have a remote BASS adjustment that could have been used instead of the fader, but I wanted the stock look and did not wanted extra knobs in the front of the car.

Components/pieces that I used for the installation:

1) a/d/s P640 amp (6 channel x 40W, built-in crossover) = $250 (used on Ebay)

2) a/d/s 345is Separate Component Speakers = $245 (new, super deal on Ebay)

3) Kicker 6x9 Free Air Subs (now discontinued) = $150 for the pair (new)

4) Peripheral Vendetta 4 = $40 (new – search Internet for it)

5) Cable Ties, High-strength Velcro, labels, etc. = $20-30 (Radio Shack)

6) Amp Installation Kit (ground, Power, and in-line fuse) = $30 or so (but came free from the same guy who sold me the P640)

7) OEM CD install kit with new rear panel = $100 or so with BMWCCA discount.

So I spend about $850 on parts and since I did all of the installation (about 9-10 hours worth) myself I saved about $400-500 on the install. I estimated that retail-wise, my install (if done by any good local shop) would have cost me over $2K – easily. In fact, if I would have saved the $600 for the H&K upgrade I would have only needed an extra couple hundred to have a system worth a couple thousand!.

It is VERY important to have a reference CD to compare your system before and after, especially if like me you are changing the main speakers. I made a new CD with different songs to test the system before and after, plus I took the same CD every time I went to listen to speakers – something has to remain constant so that you can really make comparisons!. Pick music from various sources (not just from one CD nor author) so that you can “really” test different aspects of your system. I have hard rock, rock, pop, classical, soft-rock, etc. on my CD so pick something you listen to. Just in case you are curious these are the songs on my “test CD”:

- Hybrid Theory - Linkin Park

- December - Collective Soul

- You Oughta Know - Alanis Morissette

- Call Me - Blondie

- Sunglasses at Night - Corey Hart

- Drops of Jupiter - Train

- Meet Virginia - Train

- Home - Sheryl Crow

- Hold On - Santana

- Don't Do Me Like That - Tom Petty & the Heartbreakers

- Refugee - Tom Petty & the Heartbreakers

- Time and Tide - Basia

- Last Chance - Shooting Star

- Brand New Day - Sting

- Love Theme from "The Saint" Soundtrack

- Devil Inside - INXS

The “new” system is completely unbelievable: clean, sharp, great bass and superb imaging. A couple of co-workers (one of them a jazz musician, another a guy with an M3 like mine but with “stock” H&K stereo) have listened to the system and cannot believe how different and improved the music now sounds. It is like night and day – this is the way the H&K should have sounded when we got it. The new system is so impressive (specially with CD’s) that you can now listen to music louder and your ears do not hurt after a while, plus with the VEN4 there is absolutely ZERO hiss/noise when the engine is running.

Lessons learned:

- Research, and then do more research before you start. Look at the references I list below as a staring point. Those guys figured out what worked and what did not – lets leverage what they learned.

- YES, you can do the work yourself. As I will show you in the pictures below, there is a great deal of work involved to wire the amp to the OEM harness, but it is doable. Take your time – it pays.

- Make sure your amp can take the diff signals. I am exchanging email with another guy who tried without the VEN4 adapter and the noise was far too great once the engine was started that he had to shut down the radio. He is now in the process of buying the adapter.

- The H&K system is adequate, but not even close to being decent (in my opinion, of course). You can spend “relatively” little money and get a really good upgrade.

- The OEM head unit is very good. Certainly not the best, but good enough for most all stereo upgrades. Plus, keeping it means that the steering wheel controls DO work after the update.

- NO, you do NOT need special, pricey, super-duper speaker wires. The OEM wires are more than adequate and are already twisted which minimizes noise pickup.

- Yes, you do loose the speed sensitive and “spatial” mode – and I am VERY happy I did J

- NO, getting the H&K system upgrade hoping that will make upgrading easier later is not true (what was my hope and I was wrong). There is nothing in the H&K system that makes the upgrade easier. The ONLY thing I am re-using is the H&K sub housing, but to pay $600 for that is insane!

- For those of you who like the H&K but want extra bass, just get a 2 channel amp, the adapter (if needed), and drive your subs with it. You can also try to fit aftermarket 6x9’s (the subs I got are now discontinued) and just use the built-in crossover to give the subs only the lowest frequencies (100-150Hz is a good place to start).

- It is worth to get a quality amp and quality separates – my system sounds awesome and it is because of the items that I selected. Even if you are on a budget (like I was), remember that you can replace stuff later, but it is cheaper to put good stuff the first time around!

OK, so here are the install pictures.

Getting access to the OEM amp:

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