2008 Accord Coupe - factory upgrade

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llebcire

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Iowa
Upgrade build log – 2008 Honda Accord Coupe (EXL)

I am in the very early stages of an upgrade to my OEM system after recently joining the forums. Initially I needed to do a lot of research as although I’m not new to high-end car audio (I was an installer in the past) things have changed dramatically since I installed in the early 1990’s.

Here are the goals I have in mind:

• Low cost

• Stealth (in cabin)

• Utilize factory head unit

• Designed for sound quality

• Utilize factory charging system

I listen to a mix of music depending on my mood but typically fall back to something bass heavy. When I’m in the mood for Jazz I need a system that can reproduce vocals and saxophones without sounding harsh.

Regarding the factory HU, here’s my thought process: Obviously, its stealth as there wouldn’t be an aftermarket head unit and cars have changed – where we used to put a DIN (or double DIN) is most cars, factory head units have changed substantially making this difficult. Additionally, I have the upgraded audio system with external amp and in the Accord forums there’s an individual who competes using the stock HU as it provides a 4V balanced output that can be adapted to RCA. Using the stock HU would allow me the additional capability of balance, fader and subwoofer output as I have 5 channels coming out of the HU.

Here’s my plan: Factory HU converted to 5 channel balanced outputs. Mono block amp driving a single 12” subwoofer and 4 channel amp driving 6.5” components in the front (stereo) and rear in tri-mode mono. For the rear, I might use a coaxial 6.5” or possible a quality 6.5” mid bass driver than can make it to 5 KHz + for fill. I’m contemplating keeping an 8” OA solution and using it as a woofer from 50 Hz up. If I use a 8” woofer, I don’t know if I’ll need to enclose it but I haven’t done that in the past and without driving a few thousand watts into a 12” sub it shouldn’t be impacted. I spent time in August sealing off the rear deck with sound deadening to get rid of rattles and dramatically enhanced the sound of the factory sub – output decreased slightly but low end is crazy shaking the entire car and impacting the mirrors more than I’ve seen with a factory system. Many owners complain about this sub (Pioneer?) but Honda did a terrible job isolating the front from the back on the rear deck and the difference in sealing it is remarkable.

Along with the upgrades I need to get rid of some “rattles” and “buzzes” and will be adding more sound deadening to the rear deck as well as going through the doors. Not sure whether I’ll trim out the trunk (don’t planning on competing) or just keeping the install clean. I also plan on building (or buying) a standard enclosure for the sub (haven’t decided on sealed or ported) instead of removing the spare and using that space.

My plan is to use Zapco amps and still deciding on components. I have a friend that will sell me a new in box Alpine Type R 12” sub (old gray style) that he never used. I’m intrigued but it’s dual 2 ohm voice coils and while Zapco amps handle 1 ohm they prefer 2 ohm for efficiency. This isn’t as big of a deal on a sub so I might do it anyway. I lean towards a Class D mono block, i.e. ST-500XM II, producing 500 watts at 1 ohm and a Class AB 4 channel, possibly ST-4XSQ @ 70 watts x 4.

If I’m able to start soon, I’ll focus on the mono block, sub and sound deadening the front doors. I live in IA so installs aren’t popular in the winter and my garage is old (i.e. not heated) but it’s still comfortable outside right now. I need to tread lightly on the finances so my wife doesn’t freak out and currently have some unused electronics for sale to pay for stage 1. I also have some OCD and love car audio – it’s an addiction that I need to keep from getting out of control.

-Eric

 
Question on amp as I'm vacillating:

4 channel plus mono block or 5 channel?

Zapco make a 5 channel that produces 80 x 4 plus 350 x 1 watts into a 4 ohm load which would be ample power. I've always been under the impression that with an "all-in-one" option, when the mono channel needs additional power it could tax the mids and highs as they share the same power supply.

While this it theoretically possible, does this typically happen in a modern amp of decent quality? With multiple inputs and the controls built into the amp it seems like an ideal situation.

Thoughts?

-Eric

 
I haven't posted to this thread for a while and things are creeping along. In late November I got a great deal on a Zapco ST-5X rated at 80 x 4 plus 350 x 1 all into 4 ohms for $130 shipped from Woofers Etc. through Amazon. The amp was down to$199 after Black Friday and I took Amazon up on their offer to save $70 by signing up for (but not using??) their credit card that I cancelled shortly thereafter. Amp has what I need with built-in crossovers and high level inputs. Initially wired it to the factory speakers using Honda's HU.

Sent from my SM-G930R4 using Tapatalk

 
There wasn't anything special about my.install: 4 gauge, 100 amp fuse and high level inputs from fronts/rears and a DIY LOC for the sub input.

Instead here are some pics of the amp.
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quality amp.. how much u looking to spend on sub and amp? u like deals sundown 1200 is $231 bstock (all bstock works and looks great no one can even tell y it's bstock) car audio bargain, sundown Ev3 $95 bstock..

 
Think these pics were taken December 2nd and it didn't take long for me to want more low end.

I was able to get an older (grey) NIB 12" Alpine Type R dual 2 ohm sub for $50. As it was getting colder I went for a 0.96 cubic foot prefab sealed box from Amazon that was supposed to be 1" MDf. Turned out only the front​ was 1" so I internally braced, glued and sealed the box then stuffed it with fiberglass.

Whatever needed to fall in place did - the sound is amazing and incredibly low.

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Cost to this point: $249 (free labor)

Amp: $130

Amp kit: $20

Sub: $50

Box: $35

Speaker wire:$12

DIY LOC: $2

-Eric

Sent from my SM-G930R4 using Tapatalk

 
I would've used polyfil instead of fiberglass....but whatever...lol..
I know and that's been an ongoing discussion for years. I only use fiberglass in sealed enclosures and either here or another forum someone posted as link to a well executed comparison of fiberglass, rock wool and fiberglass. Last fall I had a conversation with one of the engineers who helped design the original Alpine Trype Rs who said fiberglass is still the best option with the new soft touch denim insulation being comparable.

-Eric

Sent from my SM-G930R4 using Tapatalk

 
Spent months researching budget 6.5" components going on what I read from others​ who own them or have heard them. Not easy but there doesn't seem to be many car audio shops around any more. Initially wanted to find a pair of Oz Audio 180s from the 90s (Superman) but there didn't seem to be any around. Was leaning towards a $130 set of Polk Audio or possibly Silver Flute woofers with Seas tweets when I got back into the Oz kick with their new Vector series components. After talking with one of their engineers (Atrend) pulled the trigger but they were out as they're revamping the line.

Back to square one and I purchased a set of Morel Maximos from Crutchfield for $150 shipped and they included mounting rings and wire harness adapters. I will use both and I'm going to use the factory wiring and replace the factory crossovers with the Morels.

Using ideas from KHA (Rich) I'll be deadening the doors and adding a layer of compressed fiberglass sealed with plastic. With the trim rings I'll be using non-hardening model clay to seal and isolate the speakers so the trim rings will just be holding the speakers in place.

Tweeters posed a challenge as they don't fit in the factory location easily but I have a plan.

Sent from my SM-G930R4 using Tapatalk

 
Here's a pic of the factory tweeters - my goal is to be able to easily return everything to stock if I trade the car:
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What I decided to do was create a new grill leaving this one untouched. The factory tweeter (metal) snaps out of the back then the grill pushes out the front.
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Started by copying the grill with 1/4" ABS and I may redo them with 1/8" as I thought I'd need the extra depth for the protective dome on the tweeter.

Cut approximately a 29mm hole for the tweeter, rounded the edges to minimize defraction, flushed 2 6mm machine screws in and used ape tape (hanger strap) to secure the tweeter.
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