Coupe Stereo Upgrade

November 1, 2002

By: Douglas Lindqvist

1.9 Sound System Upgrade

I’ve wanted to upgrade my Z3 sound system for a while. I found that the stock system simply wasn’t good enough to support a convertible. I started looking around and came to and looked at Robert’s 1.9 (Non-HK) Stereo Upgrade. This article helped me A LOT during my search for a better sound system. Now was the time to see where I should get it done. The first place I went to was Audio Excellence. It looked very professional and some of my friends suggested it. I also went to Audio Extreme and Sound Advice but out of the three Audio Excellence was at the top.

I wanted to upgrade the front speakers first. I looked at JL Audio and was impressed by their clarity. I also wanted to get larger speakers and I ended up with 6 ½” JL Audio XR650-CS (with tweeters and crossovers).

I realized that I needed a much better amplifier because the stock amp (non HK) was pushing around 20-25 watts per channel. I decided to go with the Orion Cobalt CS200.4 (Which later changed to the CS500.5) I was also looking at the Alpine V12 models but their prices were too high.

Audio Excellence told me that I might be able to put 5 ½” in the rear to replace the 4″ speakers. This luckily didn’t work out and I got a free pair of 4″ speakers.


The installation took around 7 hours. I took it in at 9 am at brought it home at about 4 pm. I was very happy with this installation because everything seemed to go my way. First they tried fitting the 5 ½” in the rear. These didn’t fit so they decided to leave the stock 3 ½” in there. The install for the tweeters and XR650-CS went fine but the amp didn’t. They put the CS200.4 in and it blew my rear speakers due to a short. They gave me a CS500.5 instead and replaced my rear speakers with JL Audio XR400-CX.

So the price of the JL Audio XR525-CX was cut from the bill and I upgraded to 4″ rear speakers and a 5-channel amp for free! Total cost was about $750.

Turning up the new system loud would guarantee to make your ears bleed. All that was coming out of it was highs. There was more bass than stock but it wasn’t enough. I decided to get a subwoofer.

The first place I wanted to put one was in the trunk. I planned on putting a 10″ sub opposite the side of the trunk with the CD Changer. Audio Excellence told me that in front of the trunk was a metal wall separating the cabin from it. Porting to the cabin would have to go through the boot of the convertible and with the top down bass would be nonexistent. I also wasn’t too happy with the idea of cutting a whole in my BMW.

My other idea was to put an 8″ or a 10″ in the spot where the HK Sub is. My idea was similar to where the Dodge Viper has its subwoofer. Audio Excellence looked at the area (where my storage compartments are) and told me that it would mess with the structural integrity of the car because the roll bars came down into there. I decided this idea was a no-go also.

They came up with an idea that I was trying to avoid. They wanted to put the sub below the dash on the passenger side. They did this to a member of N’Sync’s Superformance Shelby Cobra. Even though I was disappointed because doing this would take up legroom I decided to go along with this idea.

They ended up making a custom box and putting a JL Audio 8W3 subwoofer in my car. This ended up costing $350 and took about 13 hours (11 hours one day, 2 hours the next). It turned out well and sounds amazing!

Is it worth it?

Yes, I think that it was worth it. I love being able to hear music without distortion at 60mph with the top down. It turned out to be much cheaper than I thought and sound better than I imagined. Even though the subwoofer installation took forever I think that having that extra bass really makes the sound fuller.

Pros – Awesome Sound, Not very expensive

Cons – Lost passenger legroom, No more stock look

Cost – About $1,100

4 Inch Rear Speakers

In the continuing quest for better sound in a Z3, I decided to replace the stock rear 3″ speakers in my 99 2.3 with 4″ speakers, or possibly 4×6″. Model year 2000 and newer have 4″ speakers, so I knew that in theory at least, I should be able to fit a decent set of 4″ co-ax’s back there. The stock 3″ speakers are pitiful single paper cone drivers, “designed” for “filtered” midrange sound from the factory amp. I found their sound lacking, even annoying. They did not add anything to my audio experience. I am cheap, …..let’s say cost conscience,…… so I am always looking for more bang for the buck and aftermarket speakers have always provided more satisfying sound over stock OEM drivers. The first step was to see what kind of volume and interferences I had to work with. I popped out the little hatch, shown in first photo, but even with a flashlight it was difficult to get a clear view. The 3″ speakers are held in place by a threaded collar, essentially a giant knurled nut. If you take a large screwdriver and tap the knurls through the little hatch counter clockwise with a rubber mallet to start, it then unscrews easily. The speaker pulls out to reveal a circular hole with a chord (flat spot), that is supposed to prevent the speaker from spinning. This allowed a better view and some discouraging news as well.

There’s a bunch of stuff in there…the seat belt retractor, the structural steel for the roll hoop and the re-enforcing cross member that goes across the vehicle. The steel is a problem because it is so close to the plastic trim housing. This limits where the speaker can be placed, because either the driver basket or magnet will hit something. Depth is about 2 ½”, but variable because the housing slopes. In addition, the 3″ speaker opening is located far to the outside, because the tiny magnet does not interfere with anything. It is actually easier to install a new speaker if you have NO rear speakers; ie. you can cut a new hole farther inboard without worrying about the existing hole showing beyond the coverage of the speaker trim/grill.

Luckily, 4″ speakers are strange creatures, many appear to have grills with trim that increases the coverage area. This was critical in this case; if the trim were any smaller, it would not have been possible to mount the speakers and avoid interference, and still cover the existing opening. The last photo shows the grill coverage outline (courtesy of dirt sticking to Armorall……will stop using that stuff!). I looked at installing a 4×6 speaker, but quickly found that only Blaupunkt 4×6 seemed to come with grills! The other manufacturers assume you are replacing an OEM installation and do not include them. I was not impressed with the Blau 4×6 specs, so I decided to go 4″.. Based on listening and a car audio store recommendation, the speakers I installed were Pioneer TS-A1086. They had nice plain black grills, and once I dremeled off the Pioneer name and made a P-touch label that spelled “BMW” to put in its place, it really looked stock. They have a cut out requirement of 4 1/16″, and a magnet diameter of 2 3/4″ . The trim and grill actually covers a diameter of about 6″.. I also looked into installing Infinity 452i speakers which are a “plus one” 4 inch size; ie the cone is 30% larger for the same cutout. It has a magnet that is ½” larger in diameter and ½” deeper, so it would be trickier to fit, but has a rubber surround, silk tweeter, and higher power handling capability. It would be easier to install the 452i, if there had not been any rear speakers. And since they were out of stock at the time, I went with the Pioneers. My cutout (from the outside edge of the hole, closest to the measuring point) ended up being 3/8″ vertical down from the upper trim piece end that starts the groove (leaves about 1/8″ left in bottom trim piece TO the groove) and 1 5/8″ horizontal from the center trim piece. This allowed the magnet to clear (actually JUSTS touches the carpet over the cross member), the speaker trim to cover the old opening, and still contain the plastic cut within the lower trim piece. I was afraid that cutting into the upper trim piece would cause the assembly to be too flimsy and buzz or rattle. There are also some interference issues, if you feel up under and into that area. The upper and lower trim pieces snap together, and I wanted to try to avoid breaking that connection for aesthetic and structural reasons. The plastic is thick, about 1/8 to 3/16″ and is ribbed on the backside for more support. I used a Dremel tool with a cutting blade that resembles a tiny circular saw. It cut through the plastic like butter, but it is CRITICAL that you tape the surrounding area, as it is VERY easy for the saw to jump and instantly mar the surface for good. It is easier to work the saw with the seats removed but I actually only removed the driver side; once I had my measurements I did the passenger side with the seat moved all the way forward, but then I also have a flexible extension that really helps…YMMV.

The pictures are pretty self- explanatory. There was a very noticeable increase in clarity and volume with the new speakers, even hooked up to the stock amp. I ended up running dedicated, unfiltered speaker wires directly from my Toronto head unit under the center console to get full range (for a 4″, anyway) sound, which sounded MUCH better than the stock amp connection. Even firing into the back of the seats, they are so close to you that they provide significant “top down” midrange and high sound. I find the stereo sound similar to that of wearing headphones; it is as if you are “in” the sound, not “in front” of it. Some people don’t care for that…I like it. Another idea to try instead of the Infinity co-ax’s, would be to use a 4″ component set and locate the tweeters up and outboard in the upper trim unit for better separation and directionality. I found the Pioneers to be a significant upgrade to the sound system for very few dollars. Now if I can just find a way to put in a powered subwoofer and lose no legroom or storage space……..

Sound System Upgrade for a ’98 HK Equipped Z3 Roadster

Pros: Unimaginable sound improvement, Maintains factory look
Cons: Limitations in sub woofer design is prevalent in terms of frequency response
Cost: Professionally Installed at $1500

Anyone who has visited the Z3 message board has come across many discussions and complaints about the stereo system in the Z3. One would think that for the money (and the fact that its a convertible) it would have a decent sound system. My ’98 roadster came equipped with the Harmon Kardon upgrade which offers a few more speakers and the infamous sub-woofer system. I like having the BMW head as it has a proper fit and finish to the rest of the interior, and helps keep an untouched look to curious passers-by.

Upon reference of a good buddy of mine who is an absolute nut when it comes to auto and home theater systems, I went to CAPS Audio which is an operation run by two brothers, Danny and Frank. They exclusively handle car audio for the Ferrari dealership down the road. (check out pg. 3 of their photo gallery!) After a preliminary visit, Danny gave me the plan of action: We are going to open up the car and see how the stereo is arranged, I offered Robert’s “A stereo upgrade to learn from” which seemed to spell it out to me, but that was not sufficient. “I’ll tell you what you have, then we can figure out what we can do.” Hey, what can I say, the man is thorough and I don’t pretend I could do their work. He explained in great detail about how proprietary the BMW systems were and that if the project either became too costly for me, he promised to reassemble the system to a level that BMW would not know anyone had touched it.

The design constraints were as such:

* Keep the factory head unit as I like the matched looks to the rest of the dash and provides a “stealthy” approach towards the stereo upgrade. Since I separately purchased the CD unit, I felt even more committed to this. If I could have started all over, I would consider an alternate head unit that would match up nicely.

* Minimal trunk (what trunk?) obtrusion. I actually attempt to use it.

* Keep the factory speakers, but drive them with clean power. I felt that the sound system was acceptable for almost all driving, the speakers are fine (with the exception of the sub). The only time where I was dissatisfied with the performance of the stereo was when driving at highway speeds with the top down. I could hear the amplifier weaken after 20 minutes down the highway as the factory amp would start warming up, and the bass became easily distorted. Notably absent was a full range of sound under these driving conditions.

* Some sort of flexibility towards future applications, in case I should want to redo the entire car. (Not for a long while)

After some time they had figgered it out and offered to install the following (You can see that I obviously went with it.) The installation of two amps as such:

# The red one is a Sony Xplod which drives everything but the subs. 40Wx4 Ch, 4 Ohms at 0.04% THD, 5 Band ±12dB Adjustable Equalizer, 50/200/800/3.2k/12.8kHz Frequency Centers, Level Indicator LED’s, Regulated MOSFET Power Supply, F & R 50-200Hz Variable Hi/Lo CROSSOVER, Recessed Control Panel with Clear Cover, Separate RCA & Speaker Inputs, Peak Power 80W X4Ch, Signal to Noise Ratio 100 dB, Fan Cooled, Gold Plated Terminals and RCA connectors and a power level meter.

# The Silver is an Alpine Flex4 which drives the subs exclusively. MAX POWER (EIAJ), 75W x 4 (4 Ohm Stereo), 180W x 2 (Bridged 4 Ohm), RMS Continuous Power (Watt) (at 14.4V, 20-20 kHz): 4 Ohm Stereo (0.08% THD) 30W x 4; 2 Ohm Stereo (0.3% THD) 40W x 4; Bridged 4 Ohm (0.3% THD) 80W x 2, S/N Ratio 100dBA, Frequency Response (+0, -1dB) 10-50kHz, 4/3/2 Channel Operation, MOSFET Power Supply, DC-DC PWM Power Supply, Double Buffered Pre-Amp Input Circuitry, Discrete Pre-Amp Stage, Darlington Bi-Polar Outputs, STAR Circuitry, Duo (Beta) Feedback Circuit, Solid Copper Bus Bars, MultiMode, Top Mounted LED Power Indicator, Fixed Crossover (HP/LP), Continuously Adjustable Gain Control, Both sides Terminal Layout, Gold Plated RCA Input Connectors, Speaker Level Inputs, Gold Plated Power Screw Terminals, Gold Plated Speaker Screw Terminals, Noise Elimination Coil, Non-Fading Pre-Amp Output

As well, I required a few crossovers and the infinity Kappa crossovers were suggested. I have heard the Kappa series for home audio, so I felt confident in their suggestion. The crossovers were installed in the tower section where the original amplifier lived.

The installation took almost 10 hours from end-to-end. They cranked it out! I would walk back and check on the car on occasion to see the progress of the install. Danny was a little nervous about me looking over their shoulder, mentioning something about people being nervous about seeing someone rip apart the car, well hey if I could, I would have installed it myself! I did my best to stay out of their way so that they could complete their job.

Of course, this installation was quite timely and thus costly, as they spent quite a bit of time adjusting and tweaking to the oddities of the BMW system. It was pointed out that to me that I was taking a more expensive route in terms of my installation due to this, but they were both willing and capable of building to my wishes. Also the quality in their work is quite impressive.

Here’s a close-up of the wiring work.

Result: WOW! I had some expectations on how the system would sound, but DAMN! I never expected it to sound so great! This baby behaves like a Z3 should, with plenty of clean power for your entertainment.

The Test: Two days later, I put the car to the test with a trip to Syracuse and back (about 600 miles altogether) to add to it, I crammed every last inch of trunk space with stuff for the weekend journey.

Outcome: No Problem! It was wonderful to be able to hear the music so well while driving with the top down! I notice that I spend more time adjusting the bass & treble since the amps are capable of overdriving the subs if I don’t pay attention. The other thing I notice is that the speed sensitive volume has different nuances to it, as it seems to be adjusting the bass amplifier only – which probably has a lot to do with why I keep adjusting so much. I pulled from the instructions from Message Board Archive on adjusting the sensitivity of the amplifier will make that adjustment. Notably, the limitations of frequency response in the sub-woofer is present, but what it does handle is amazing. I’m sure that one-day, its day shall come for replacement.

Overall, I am excited with the outcome and performance of the stereo. If you have the opportunity to catch up to me on a cruise, you’ll be able to hear it for yourself. You won’t believe its the OEM speakers!

1.9 (Non HK) Stereo Upgrade

Pros: Factory Look, No Visual Changes, Much Better Sound
Cons: Still not much bass sound, Not BMW parts (warranty?)
Cost: $500

Radio: BMW AM/FM Cassette

CD: BMW 6 disk CD Changer

Amp: Precision Power 100iX

Spkrs: Boston Accoustic 6.4

Crossovers: Boston Accoustic

Most Z3 owners will agree that the factory stereo just does not cut it. Unfortunately, BMW has done a real bang-up job in deterring owners from upgrading by mixing in some proprietary technology in the stock stereo system. Any owners not happy with the performance with the stock stereo system (which is most) were left with minimal alternatives.

One alternative surfaced when BMW responded to the numerous complaints by offering a “Stereo Upgrade” that could be added to any roadster built before June 1997. This option added two small 3 inch speakers behind the seats, a sub-woofer between the seats, and all the brackets and mounting hardware needed. The down side(s) to this “upgrade” are

1. You loose the storage space behind the seats because that space will be used for the subwoofer (subwoofer is optional).

2. The replacement amp is better than the stock amp, but still not up to aftermarket standards.

The upside to this option is that the price is very reasonable. BMW sells the upgrade (without the subwoofer for $150). For many, this was the best solution available.

A second alternative usually surfaced after talking to a car stereo shop: “Scrap Everything and Start Over”. Several roadster owners took this route rather than give BMW even more money, especially after the BMW “Stereo Upgrade” started getting mixed reviews. These owners usually started by trying to replace the factory speakers, only to discover that the factory amplifier has a non-adjustable internal crossover that is matched to the factory speakers. So if the speakers were replaced, the amp should be replaced. Once the stereo salesman got on a roll, the roadster owner was then informed that the stock radio has a proprietary plug that would not connect to after-market amplifier, so a new head unit (radio) would also need to be purchased. To finish the domino effect, those roadster owners that purchased the optional BMW CD-Changer then found out that it has a proprietary connection to the factory head unit (radio) so the CD-Changer would need to be scrapped as well. Roadster owners that took this alternative usually ended up dropping some serious cash but left with an outstanding stereo system (and a box of slightly used, expensive BMW stereo components). This option (although expensive) was usually a good value and was the best alternative for those roadster owners who did not purchase the BMW CD-Changer.

Neither of these alternatives fit my situation, so I starting researching for another alternative. I started by creating a list of rules for myself to stick to. Hereafter referred to “Robert’s Rules of Stereo Replacement”.

1. Had to keep the factory BMW CD Changer. I fought very hard to get this thrown in with my roadster purchase and was not about to throw it away.

2. Had to keep the factory BMW head unit (radio). Turns out the head unit is an Alpine-made radio that is quite good. It also has a few really nice features that I wanted to keep (speed sensitive volume, CD changer controls, built-in code alarm with flashing red light).

3. No loss of trunk space.

4. No visual changes.

It took me a lot of research, but I finally found a solution that I would be happy with that didn’t violate any of “Robert’s Rules”. The breakthrough came when I found a way to connect the stock BMW head unit (radio) to an aftermarket amp. This is accomplished by using a device called a “Line Leveler”. This device enabled me to keep the factory head unit and connect it to an after-market amplifier. Best of all, it only cost $20. The factory head unit puts out a low, 2.5 volt signal, but this device increased the voltage and adapted the connection to industry standard RCA plugs. Now I could keep the BMW CD-Changer and BMW head unit.(Robert’s Rules #1 & #2)

The next step was to pick a replacement for the factory amplifier. Before I tell you about the amplifier I purchased, I have to tell you about the factory amplifier. This amplifier was the definite weak link in the stock stereo system. Documentation claimed that this amplifier produced 20 watts per channel into six channels for a total of 120 watts. In the fine print of that documentation it is revealed that the distortion (THD) at that output level was a whopping 10%. In comparison this is 200 times the distortion level of the amplifier I purchased as a replacement. First of all, it is my opinion that this amplifier could not produce 120 watts, even if lightning struck it. It would probably be rated as a 20-25 watt amplifier at 0.05% distortion (the semi-standard after-market amplifier distortion level). The other questionable move on BMW’s part is the fact that only 4 of the 6 channels are even used, so while it might be true that the amplifier could produce 120 watts, only 80 of those watts would be sent to the speakers. The last comment I’ll make about the factory amplifier is that there was absolutely no name, label or identifying mark on it (I guess no one would ever claim to have made it).

Okay, back to picking out a replacement amplifier. To keep from breaking Robert’s Rules #3 & #4 I decided I needed to find a replacement amplifier that was at or near the same physical size. This would enabled the installer to put the new amplifier in the same location without any loss of storage space. As luck would have it, I found an amplifier that was roughly the same size, of high quality, two channel @ 50 watts per channel (0.05% THD), and best of all it was on sale for $149. It was almost a perfect fit; I could have gone with another lesser-amplifier that would have been a perfect fit but this one was close enough. For those willing to sacrifice Robert’s Rule #4, you can get an even more powerful amplifier that is rated for four channels and through the third and fourth channel add rear speakers or a subwoofer.

The final step was to pick out replacement speakers. Stock, the roadster has six speakers (2 woofers, 2 midrange, 2 tweeters). I first started looking for an after-market three-way component speaker set but quickly found out that these are rare and I would have better selection, performance and value if I looked for an after-market two-way component speaker set. Three brands quickly jumped to the forefront. (Let me qualify that statement: hundreds of speakers are available, but I had found a car stereo shop that had worked on roadsters before. I really wanted them to do the work so I was limited to the speakers that they offered). The brand I wanted to purchase was Polk, since all my home stereo speakers were Polk. Unfortunately, the only place in town that sold Polk I wasn’t comfortable with in the installation area. I reluctantly ruled the Polk brand out. The two that were left were a/d/s and Boston Pro. Both sold for the same price so it came down to the sound show-down. Both speakers sounded good but the Boston Pros were just a little too shrilly (the salesman nicknamed them diamond cutters). The a/d/s sounded much deeper (ie lower bass), so I chose them. However, once the install was complete, these speakers sounded horrible in the roadster. All the sound seemed to come from the floor and it was horribly muddy. These were excellent speakers; they just didn’t do well in the unique locations in the roadster. So out came the a/d/s and in went the Boston Pros. The overly high ended Boston Pros suddenly became perfect once installed in the roadster. The extra high end is especially appreciated with the top down. The other bonus with the Boston Pros was that a 6.5″ driver fit into the factory position. The new speakers had external crossovers, but these we were able to hide under the amp.

Let’s review: new amplifier, new speakers, old head unit, old CD-Changer, no visible signs of a stereo upgrade, tons of audible signs of a stereo upgrade, and most important, Robert is happy.

This information isn’t really important, but some readers might find it interesting. The install process was done by Earmark Audio in Dallas. Very nice guys, but I did have to yell at them a little (okay, for awhile it turned ugly). Initially, I was sold 6.5″ a/d/s speakers and when they didn’t fit, Earmark swapped down to the 5″ driver without telling me. After the install I caught it and the finger pointing started. I never really resolved who did what, and if it was on purpose or not because I ended up with the Boston Pro 6.5″ speakers. The second trouble I had was leaving with a rear tail light not hooked up. After a friend almost rear ended me he informed me of the non-functioning tail light so I returned a little pissed to Earmark. They apologized and quickly hooked up the brake light, perhaps a little too quickly because when I left Earmark (turning right out of their parking lot) I discovered my right rear turn signal didn’t work (they busted the bulb). I stormed in once again and they quickly found out that they had busted the bulb re-installing the tail light assembly. I drove down to the local auto parts store, bought new bulb, and replaced the busted one in the parking lot.

Hold on… I’m not done yet (not even close). Over the next couple of days, I noticed a high pitched sound; this is commonly referred to as alternator whine. I returned once again, and they blamed the sound on the gain control (adjustment on the amp). They turned the knob down and it went away. However, the next morning I heard the whine again but rather than drive across town so someone else could turn a knob, I crawled into the trunk, peeled back the carpet and turned the knob down myself. That is when I saw it. A screw hole through the wheel well. Needless to say I hit the roof. It was a bright sunny Saturday morning and Earmark was packed with customers when I entered took one step inside the store and loudly asked “Who’s the Ass-Hole in Charge!” (which produced a manager quite quickly). He initially took a defensive stance and escorted me outside to discuss the situation. The conversation pretty much ended when he saw the hole himself. He promised a serious ass-chewing and monetary loss for the individual involved. He also was pissed when he heard the alternator whine (which ended up being that the speaker crossovers were too close to the amplifier). The final nail was when I told him of the brake light, turn light, and speaker swap .

The entire install process spanned two and a half weeks which is totally unacceptable, but the end result is exactly what I was wanting. The stereo is clearly audible top up or down, at any speed, and there is no visual indication of any upgrade. The final install is very clean, very professional looking. I think I just had a run of bad luck at Earmark. I almost can’t believe I’m saying this, but if the situation arises I might even give them my repeat business.