Project Lowbucks 2: Civic 7G Sound System

Project Lowbucks 1 involved a hatchback configuration (US Model 2G Mitsubishi Eclipse). After getting better than expected results with the first car, I decided to try and replicate the results with a coupe. Project Lowbucks 2 came in the form of a 7th generation Canadian model Honda Civic Si. This was a limited production, custom ordered 2-door version of the ubiquitous Honda compact car. It came with full leather seating with color-matched stitching and a Canada-only Aztec Yellow (Gold) paint scheme with gold plated emblems.









The OEM sound was acceptable but nowhere as good as the OEM for the 2G Ford Explorer Sport (see Project overkill). It had 6.5 fronts and 6x9 rear pioneer paper cone speakers. These were complemented with a pair of tweeters on the door section of the A-pillar. The deck was made by Pioneer and was capable of playing regular audio cd’s. It wasn't capable of playing mp3s and lacked an external CD changer connectivity. It was also massively underpowered. Distortion and clipping was unavoidable even at moderate volume levels. Bass was totally non-existent.


(OEM Pioneer CD deck)





The deck of choice came in the form of a Sony CDX-GT 420IP. This unit has a front aux input and a single sub/preamp output at 2volts. This model also comes with an integrated ipod cable and controller. The menu controls for the ipod can be quite cumbersome to use but at least you do not have to spend more money to connect a current generation ipod and use it as your main music source.




(Rear output. For connecting an external amplifier, the rear output is switchable to subwoofer out mode)


(Detachable face for security)

Modestly rated at 52W x 4 (17W x 4 CEA), it is possible that this would be adequate amplification for the replacement speakers. Project lowbucks 1 and Project overkill used built-in (deck) amplification. Since the objective for lowbucks 2 was just improving existing sound and clarity – I did not expect any issues going this route. Best Buy had this deck on sale for about $90.



Initially, I was planning of keeping the OEM under-the-deck parcel shelf but after removing the entire dash assembly, I decided to just get an installation kit to keep things simple. A Bestkit stereo mounting kit and wiring harness was obtained from Future Shop for about $50. This made for a more seamless integration and OEM-like fitment. There are cheaper kits for a few dollars less but the bestkit seemed to be better constructed and made of better ABS plastic. The texture also complements the current dash better.


(420iP installed with Bestkit Model HONK809 and using the supplied Bestkit bezel)


(420iP installed with same Bestkit model and using the Sony Bezel)


(Completed harness assembly. A Bestkit BHA1721 mated to the Sony420iP harness. All connections were crimped, soldered and shrink wrapped. The White end connects to the factory honda plug while the Gray end plugs into the sony deck. The Blue butt connector is for the amplifier trigger signal and the black wire is an extra ground connection)

For the subwoofer, I actually had two Alpine Type E subwoofers available. These were obtained a few years back and were never used. After measuring the available trunk space (or at least the amount of space that I was willing to sacrifice for the enclosure), it was decided that 1 sub was the best configuration. Besides, I expected even a single 12 to be more than sufficient. (In comparison, Lowbucks 1 only had a single 10 ). Cost for the subs were $0




(Alpine SWE1241 Magnet assembly and stamped steel basket)

Amplification came in the form of a big Sony XM1600GSD class D amplifier. Although rated at 1200 watts peak, it had a more realistic 350W at 4Ohm output. This seems to be perfect for the alpine’s 250W requirement. Furthermore, this amp would provide enough gain for the deck's 2volt output. The amplifier was acquired the same time as the two subs. These components were never used and have been kept in storage for a few years. The amp was a little big for my preference (so finding a place for it was quite tricky) but since cost for it was $0, it fitted my budget perfectly.





The Civic is a vehicle with a trunk and the spare tire is covered by a flimsy and thin board barely a quarter of an inch thick. This means that I needed to reinforce the cover for it to support any additional weight. I also needed unhampered access to the spare tire with the subwoofer enclosure bolted down. A false floor was constructed out of 5/8 inch (0.625”) plywood and reinforced with 1 ½ wood slats. The cover was also “halved” and hinged to allow access to the spare tire (and whatever else was stored underneath).


(Original spare tire cover looks just like a thin piece of cardboard)


(Floor reinforcement, passenger side)


(Floor reinforcement, driver's side)


(The finished false floor is hinged and allows access to the spare tire)

A custom shaped enclosure with a final volume of about 1.6 cu in was made using heavily braced ¾ inch birch plywood. Birch was selected over MDF for its rigidity and strength. The front baffle board is 1.5 inches thick with another ½ inch carpeted trim panel over it. The amp is bolted to one side of the box and is concealed by the trim panel.


(Birch plywood is only slightly heavier than MDF but has a far higher elastic modulus than MDF. This means it is more rigid and allows less enclosure resonance)


(Mock-up of the setup. The red sony amp can be seen on the driver's side of the enclosure. This will eventually be hidden by another trim panel)


(The enclosure is not a simple box. Seen from this view is an angled cut on the back of the box that allows the enclosure to fit more flush with the rear speaker deck and seatback. At this point, the box is still lacking the baffle board and all internal bracing)




(Box is positioned so that amp fuses can be replaced without unbolting the enclosure)


(Finished enclosure)


(The heavy enclosure and amp assembly was bolted to the reinforced floor at 5 locations to prevent it from shifting and moving around in the trunk)

The entire assembly was covered in extra thick automotive grade black carpet and filled with 1 pound of polyester fiberfill.


Cost for the construction of the enclosure was around $40. This covered the cost of the carpet, glue, screws, caulk and poly-filler. Cost for wood was $0


(Finished assembly looks clean with none of the modifications showing. The trunk looks completely stock and everything can be reversed and returned to original if needed)

With total amplification duties assigned to the onboard head unit amps (for the multiaxial speakers) and a single amplifier for the single subwoofer, there was no need for large 0 or 4 gauge wiring. An 8 gauge Scosche kit was obtained from Walmart for about $30. This kit included everything needed to install the amp (wiring, trigger wire, fuse, fuseholder, terminals, etc).


(Inline fused battery connection. Since the Honda has a really small alternator and battery, recommended upgrades include better battery terminals, and possibly a battcap or a capacitor bank).

As with any late model vehicle, removal and replacement of parts is not a straightforward job. The 6x9 rear speakers were standard sized but removing them involves taking off the entire rear parcel panel as a single piece. In order to do this, however, the left and right rear side panels, both door sill plates and the entire rear seat assembly had to be removed.








(8 gauge power wire was routed under the passenger side door sill plate. The Signal wire was routed under the center console. Wire separation was important in order to prevent unwanted noise)



The replacement for the rear speakers were Best Buy in-house brand called Insignia. Model number NS-S6900. I have never heard of these models nor could I find any reviews on the internet but I decided to purchase them anyway since construction seemed to be solid and power handling was acceptable. At $39 for the pair, the price was on the spot as well.


(Comparison of the NS-S6900 versus the OEM pioneers)


(Power handling of the OEMs were doubled by the insignias)



Generally, with better 6x9 speakers came bigger magnets. The insignias have massive magnets and upon dropping them into the stock location, the magnets hit the rear trunk spring support. While this should not prevent the trunk from operating normally, it is possible to get some rattling between the spring and the magnets


(Comparison of magnet assembly and driver height. Insignia NS-S6900 vs Pioneer TS-09045)


(Magnet clearance. Rear OEM speaker)


(Insignia magnet resting on the trunk spring)

Perhaps an even better deal were the front speakers. Again, I opted for insignia 6.5 which were on sale at Best buy for $19 for the pair. What I did not expect was that I needed spacers to mount any type of aftermarket speakers on the Honda doors. After constructing the rings out of half inch plywood, the new speakers dropped in without any additional issues. It also fit well under the stock door panels without modification.


(Comparison of Insignia NS-S6000 and OEM Pioneer 6.5 inch magnet assembly)


(The driver of the OEM Pioneer has a magnet assembly less than an inch in size)


(NS-S6000 installed)


(NS-S6000 as seen throught the stock grill)

The entire setup allowed keeping the existing tweeters. Since the speaker placement on the door panels were below knee level, front staging did not have enough clarity without the OEM tweeters.

Summary:

Overall sound performance was a big improvement over stock. A better sound source, solid amplification, less distortion, thumping sub and the capability to play music from different sources (audio cd’s mp3 on cdr, songs from ipod, etc) were the enhancements achieved by the installation.




(The 420IP features a built-in ipod connector)


(First generation ipod Nano connected. The interface allows most ipods to be controlled by the Sony head unit)


(Unit displays "PD1" when accessing an ipod)




(System cost at time of installation - June 2008)

This has got to be the best sounding $300 investment for the car.

The Honda Civic was built as a light compact car. There is minimal sound insulation. The biggest issue at this point is that even with a single sub and moderate sound levels, the Honda needs a substantial amount of sound deadening to cancel sheet metal and plastic panel resonance. The door panels, flooring, roof panels as well as majority of the trunk area needs a substantial amount of some form of mass-adding acoustic deadener like Dynamat, FatMat, eDead or BrownBread.


(Gold on gold)