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Mercedes SL500 Sound System
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Mercedes SL500 Radio

Radio and HVAC controls on 1997 SL500, same on SL320 and SL600. HVAC controls are the same from 1996 - 2002, radio is the same from 1993 - 1998.

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Care and Service

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Sound System

All the SLs, at least since about 1993 though at least 2002, have wonderful Bose sound systems. They were standard, never an option. Only the CD changer was optional. This is the first sound system in the history of the world to have been custom designed and voiced to fit a specific vehicle. The SL sound system uses multi-amplified subwoofers and sounds great at any level. Compared to a $25,000 home system the bass is a little boomy, but better than any other automotive system I've heard. The voicing is a little crisp around 8kHz, and this helps add clarity over the road noise. I think I'd prefer it a little flatter, but I suspect if it was I'd be less happy.

This system is designed to be loud enough to be heard at 155 MPH with the top down, which means it also can make you deaf. Playing a typical dynamically compressed FM radio station I measure 106 - 108 dBC continuous with slow weighting in the driver's seat, top down. This means it's loud enough to hear your music echoing back from under freeway underpasses, or as I said before, make you deaf. The U.S. Department of Labor's Occupational Safety & Health Administration's laws (OSHA) permits workers exposed to this noise level only one hour of exposure per day, and at that level you can expect some hearing loss. Here's OSHA's table. I measured dBC, OSHA looks at dBA, and both are similar at this level. Of course if you turn it down this is not a problem; just beware that it sounds so good that it's very easy to turn it up and not realize how loud it's gotten. I don't know it it's stupid-proof enough to prevent clipping if you turn it up too far.

Radio 1993 - 1998

AM, FM, Cassette and Weather band radio standard gets weather reports direct from NOAA in the USA. These radios are made by Becker in Germany. FM and cassette are stereo, AM and weather are mono. Earlier model year radios also provided AM stereo, as if anyone outside of broadcasting cares. Dolby B and C noise reduction for tape, none for FM.

The volume automatically varies slightly with speed. With the top down you'll still want to duck the levels when stopped to avoid sharing with the neighbors. It's effect is subtle. I hear it ramp up about 4 dB as I accelerate through 79 MPH. It ramps down a little at a slower speed to keep it from pumpiikng up and down. (Engineers call this hysteresis.) . This is great, it eggs you on to keep going faster! The faster you go, the louder it gets.

Early Radio: 1990 - 1992

These pre-dated the Bose system. They add Dolby C capability for playing tapes, variable scan sensitivity (the L-D button), and direct numerical entry for tuning the radio. Press * and 1043 to select 104.3 FM, for instance.

SL500 Radio

Early SL500 Radio: 1990 - 1992.

Late Radio: 1999 - 2002

The cassette player slot is hidden behind the folding screen!

1999 - 2002 SL500 Radio

Late SL500 Radio: 1999 - 2002.

This radio also has diect numeric station tuning, and integrates with the optional phone for dialing. For the first time the function buttons are variable: you'll see what they do over the buttons. This is more dangerous than eariler radios if you divert your attention fromthe road to see what the buttons do. Thankfully with practice it becomes easy to guess what they do.

For instance, to change thhe bass or treble, press AUD, which brings up the ability to adjust the bass. The left and right buttons become the + and - controls. Press AUD again to get to treble, balance and fade.

Amplifiers

The SL has a multi-amplified system. Bi-amping or multi-amping means that different amplifiers are used for different frequency ranges. Each speaker driver has its own amplifier. Different frequencies are sent to each amplifier and then these signals are connected directly to each speaker driver, exactly as in professional sound systems used in concert halls. This is standard procedure in movie theaters and concert sound because it allows much higher efficiency, power and freedom from distortion. Even better, if one amplifier distorts, clips or is overloaded it usually prevents the tweeters from burning out since in conventional systems all the distortion is sent to the tweeter. Home systems by comparison use a single amplifier is used to handle all frequencies and a network in the speaker cabinet attempts to divide the frequencies among the drivers, which is why the tweeters blow out when fed with high frequency and inaudible distortion products.

Speakers

The speakers and amplifiers are a 200 Watt Bose multi-amplified speaker system system with a 12 litre 5.25" Acoustimass subwoofer behind the driver's seat. Front speakers are two 2" tweeters and two 6.5" midrange/woofers. Rear speakers are two 2.5" in the back deck. Mercedes called the 6.5" and 2.5" mid-to-high range speakers "twiddlers" in the 1994 brochure.

CD Changer

6 disk trunk-mounted CD changer optional. It was standard on the SL600. The SL500 is prewired; today you can buy the same Alpine unit Mercedes used for about $250 and drop it in. My dealer installed an Alpine CHM-5630 at the recommendation of Mercedes' parts dept. in New Jersey in June of 2004. Mercedes no longer stocks the version with "Mercedes" on it. Later models (1999 and newer) have fiber optic digital connections to the head, my 1997 uses copper analog connections.

In 1992 my sales brochure tells me a 10-disc changer was optional. It took advantage of the 10 preset buttons on the 1990 - 1992 radio. I've never seen one of these changers.

In Japan the importer installed Japanese radios with changers behind the driver's seat (where the Bose woofer is on USA 1993 - 2002 models). The Japanese versions even came with remote controls! Only the Japanese know why they'd want a remote control in a two-seater. The Japanese versions also had capacities around 12 CDs.

Alarm

HISTORY and COMPARISON OF MODEL YEARS 1990 - 2005

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