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Top Down Sound, Part 2: Installing an audio system in a convertible

Chrysler Sebring disassembled

The big day has arrived. In the first installment of this 3-part series, we planned out the system for my convertible. Now we'll take a long look at the installation process.

A system of this magnitude is completely out of my league, so I turn to Ben and Wayne, two ace installers who also maintain Crutchfield's car fit database. I pull into their installation bay at 9:00 a.m. on a Friday morning, put the top down, and within an hour my car is completely disassembled - door panels and rear side panels removed, dash taken apart, three out of four seats pulled out, and trunk liner detached. They remove the entire factory Infinity system, including the receiver, three sets of speakers, and the amplifier under the passenger's seat.

The system

Here's a list of the equipment we'll be installing today:

  • Eclipse CD7200 MKII CD receiver
  • Boston Acoustics S35 3.5" speakers
  • Boston Acoustics SX95 6"x9" speakers
  • Boston Acoustics G108 8" subwoofers
  • Boston Acoustics GT-50 5-channel amplifier
  • AudioControl DQXS 6-channel digital equalizer
  • Dynamat Xtreme door kit
  • Dynamat Xtreme bulk pack
  • StreetWires 4-gauge amp wiring kit

Lay out the wiring

Once the interior is stripped out, Wayne and Ben run the wiring. Ben readies the StreetWires 4-gauge power wire for connection to the battery, and runs the cable down the driver's side of the car to the trunk. Wayne routes a 6-channel patch cable and the turn-on lead from the dash down the passenger side to the trunk.

Next, Ben runs 14-gauge speaker wire from the trunk under the carpet to the passenger seat where the Infinity amp used to live. He thinks that the Chrysler speaker wire looks pretty decent, so he taps into the factory speaker wires that went from the Infinity amp to the door and dash speakers. A big time-saver.

Speakers into placeInstalling Boston Acoustic speaker in door

Next, the two installers surround the dash speaker openings with Dynamat, and totally cover the door panels with the sound killing material. This material kills any resonance in the metal dash or door panel, so the speakers can play loud without compromising the sound.

Wayne uses Crutchfield's Chrysler speaker harnesses so he won't have to cut the factory plugs. Each harness plugs into the Chrysler plug that was attached to the factory speaker, then clips onto to the new speaker. This saves time and allows you to pop the factory speakers back in the car if you decide to sell it later.

 Wayne installs the 3-1/2" speakers (possibly the heaviest 3-1/2" speaker ever made) in the dash and the 6"x9" speakers into the front doors. He replaces the door panels, but leaves the dash uncovered as we still have a lot of work to do up there.

8" subs in 6"x9" openings?Boston sub mounted in Chrysler side panel

My friend Jeff, who's an experienced car audio guy, talked me into trying to put 8" subs in the rear 6"x9" speaker locations. He shows up to measure the Sebring's rear side panel openings, and determines that the 8" Boston subs will indeed fit. We've got 3-1/2" of depth in those rear speaker openings and the subs measure 4-1/4" deep, so the trick will be to lift the subs up out of the mounting location a little bit. 

Jeff makes two subwoofer baffle boards in the general shape of the Chrysler speaker grilles from 1" thick MDF (medium density fiberboard), then cuts a 7" round opening in each board. He covers each baffle board in black vinyl, and then screws the Boston subs into place in the cutouts.

We've removed the plastic trim pieces from the rear side panels. Now, we cover every inch of the uncovered metal panels with Dynamat Xtreme, so we get the best possible performance from the Boston subs. These subs have fairly large magnets, so they won't quite fit through the holes that used to accommodate the magnets on the factory 6"x9"s. Jeff uses a power jig saw to enlarge those holes a little bit so the Boston subs will drop all the way in.

Jeff replaces the Chrysler's plastic side panel trim pieces, then attaches the 14-gauge speaker leads from the trunk to each sub. He uses extra-long screws to attach the baffle boards holding the Boston subs into the metal panels that originally held the 6"x9"s. The subs are ready to rock.

The system commander

Up front, Wayne uses a Crutchfield Chrysler harness to supply power, ground, and other leads to the receiver. He plugs the 6-channel patch cable into the receiver's preamp outputs, and attaches the turn-on lead that powers up the amp and EQ when the receiver is turned on.

Wayne connects the included iPod® cable to the receiver's USB input, then routes it into the Sebring's glove compartment to an iPod adapter. He runs the microphone that's used for Bluetooth hands-free calling up through the dash trim, and attaches it to my rear-view mirror. He then slides the Eclipse most of the way into the dash opening. He won't click it into place until everything's been tested.

Meanwhile, back at the trunk

Ben cuts a board for the amp and equalizer, and covers it with dark carpet. He screws the amp and equalizer into place on the board, places the board in the trunk, and connects all power, ground, and speaker wires to the amp. He connects the 6-channel patch cable to the AudioControl, then runs three short patch cables from the EQ to the amplifier. Now he connects the StreetWires 4-gauge power cable to the battery. We are ready to test the system.

The golden rule: stay calm

Here's the #1 thing to remember when you're installing a big system: it usually doesn't sound too great when you turn it on for the first time. So don't panic, because it can take hours or even days to get everything tuned properly.

In fact, my system sounds pretty awful when we crank it up, but I notice that nobody seems overly concerned. First, Wayne and Ben set some reasonable crossover points for the front and rear speakers and the sub, then they check to make sure that all speakers are operating properly. It's approaching five o'clock, so their day is done. They tell me to play a lot of bass-heavy music this weekend to break in the speakers.

The fun part

Now comes my favorite part of this process - tuning the system. Over the weekend, I play a lot of familiar music, and make some adjustments. The installers set the Boston 3-1/2"s to handle everything above 400 Hz, but I think they sound much better when I drop the high-pass filter down to 150 Hz. I drop the high-pass filter on the 6"x9"s from 125 Hz down to 80 Hz, and raise the low-pass on the subs from 80 Hz up to around 120 Hz.

Get the bass in phase

I work the subs pretty hard to break them in, but by late Sunday they still don't seem to be connecting with the rest of the system. I try the phase control, but the bass doesn't really sound better with the phase reversed. I'm still thinking that the subs are out of phase with the door speakers. I access the time alignment feature on the Eclipse, and delay the dash and front door speakers by a millisecond. Nothing. Two milliseconds. Nothing. At three milliseconds, kaboom! The bass jumps up maybe 15%. And now, the kick drum and bass sound big as life right in front of me, and I can't even tell that the 8" subs are working back there. I couldn't do that with a lesser head unit.

Easy adjustment from the Eclipse

We set the receiver up to control a 4-speaker/subwoofer system, which gives me access to a 7-band EQ. I was worried that the lack of global tone controls (treble, midrange, bass) would be trouble, but the Eclipse makes it easy to adjust my system for sonic changes from disc to disc. If a CD sounds a little thin, I can bring up the subwoofer level with just a couple of clicks. If it's too bright, I can lower the level of my dash speakers and bring up the midrange-rich 6"x9"s. And, if I'm not hearing enough detail, I just bring the dash speakers up a little to add some sparkle. And it's easy to make quick changes with the Eclipse's EQ -- so easy you don't even have to look at the screen.

What a good system should do

Any good car sound system should do three things:

  1. create an exciting "live" feel with strong bass response
  2. present a focused soundstage in front of you with all instruments arrayed right to left in the stereo mix
  3. overcome road and wind noise so you can hear the details in your music.

This system is succeeding on all counts. We're going to tune the system in a week or two, but it already sounds better than any system I've ever had before. I'm pulling out recordings I haven't heard in years to see how they sound, and I'm hearing things I've never heard before in songs I've listened to hundreds of times.

In my previous life as a musician, I became very familiar with the technology of sound reproduction. I put together PA systems for my bands and spent a lot of time in recording studios, so I know how equalizers and crossovers work, and I understand gain structures. So I thought that the lessons I'd learned at the University of Rock'n'Roll would serve me well in getting my new system to sound its best. But, as you'll see in the next installment, I was wrong.

Check out Part 3: Tuning up the audio system in a convertible, and watch the video "High-quality sound in a convertible."

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