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Thread: Planning a mobile sound system upgrade for my '03 G35 coupe

  1. #1
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    Planning a mobile sound system upgrade for my '03 G35 coupe

    Hey guys,

    I'm new to the forum and looks like I'll be spending a lot of time reading the threads here on the site. Anyway, I've been doing some research and here's my game plan for upgrading my OEM sound system.

    Right now I've got a 2003 Infiniti G35 coupe with the Bose amplifier/OEM speakers. I replaced the HU with an Eclipse AVN5435 three years ago. It's been working great. But now I'd like to upgrade my sound system, bit-by-bit.

    I've ordered a set of Infinity Kappa speakers to completely replace every OEM speaker in the car right now. Because the OEM Bose amp runs at 2 ohms, I decided to go with the Kappas. I've heard them and like the way they sound. Anyway, here's what I've ordered:

    • Front doors: Infinity Kappa 60.9cs component speakers (w/ tweeter)
    • Rear sides: Infinity Kappa 62.9i 6.5" speakers
    • Rear deck: Infinity Kappa 692.9i 6"x9" 2-way speakers


    For now I'll just utilize the OEM speaker wiring coming from the Eclipse HU. In the future, however, I'm going to want to get an amplifier and a subwoofer to round out the system.

    As for the amplifier, I'm targeting the Alpine PDX-5 (5-channel). I plan to run my front Kappa component speakers of two of the channels (75wx2@2ohms). I'll also run my Kappa 6x9's off two more channels (75wx2@2ohms).

    I can then run a sub (300wx1@4ohms) of the remaining channel. I was looking hard at the JL Audio Stealthbox (10" W1v2 subwoofer) for the G35 coupe so it'll sit tucked away. I have very limited trunk space and would like to preserve it if at all possible. The woofer in that Stealthbox is rated from 75-300w, I believe, so would it work well with that amp?

    Lastly, I really don't want to run more than one amp since my car's space is very limited. That said, I am planning to power the Kappa 62.9i 6.5" rear side speakers using the factory wiring directly from the Eclipse HU. I've read that those speakers are really just for "filler" noise, especially considering I hardly ever have anyone in the back seat.

    My goals with this system are to provide a completely upgraded sound system that will create a dynamic audio experience inside the cabin. I am not into excessive bass, and just want a little punch to match up with the other upgraded speakers that will be putting out more power. Does this sound like a good approach? I welcome your comments/advice.

    Thanks!
    B

  2. #2
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    No comments or advice, guys?

  3. #3
    Maximum Bitrate bratnetwork's Avatar
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    I love the infinity speakers for their power and clarity and I use them personally, but i think once you put them in you are going to want to add the sub in a lot sooner.

    They are really clear and sound great but lack in the mid-bass department. In my opinion they are perfect with a sub, but on their own they just cant produce the low notes enough for satisfying sound across the the spectrum.

  4. #4
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    Thanks! I'm hoping they'll at least be a step up from the OEM speakers. Looks like I might be getting that amp a bit sooner than I originally thought!

    What do you guys think of this amp instead of the Alpine PDX-5 for this setup?

    http://www.polkaudio.com/caraudio/pa...rview#pa1100_5

  5. #5
    MySQL Error soundman98's Avatar
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    I really don't think that getting 2 ohm speakers is ever a really good idea--your primary reason is because the factory system was 2 ohm. my car also had 2 ohm speakers too, but i changed them for 4 ohm speakers--overall, i feel that 4 ohm speakers are more realiable and easier to power(there are more options for amps), and don't tax the amp as much, leading back to realiability.

    sadly, the 300 rms watt output lines up with the max rating on the jl sub, so depending on who you talk to, this can be fine(more control), or horribly wrong(your going to murder the sub w/ too much power). if you really crank it, this setup will probably end up blowing the sub, but kept to lower levels though, it should be ok.

    the most dramatic statments i have heard on the pdx series is that it lacks balls, and has no puch on the low end, on the other side most say that they sound fine.

    if you are looking for a alternative, i heard a rumor that jl will be coming out with a 5 channel hd series amp in the near future, with the biggest complaint on those being the price.

  6. #6
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    Thanks this is good info. I like the way the Infinity's sound so hopefully I'm not going to have any issues powering them. Looking at that Polk amp, it seems to certainly have more punch. Of course while the Polk's main channels might provide plenty of power to the full-range speakers 125-250w@2ohms), the sub channel runs around 600w@4ohms so I'd need to super careful not to destroy that little 10" woofer!

    I'm hoping power is not an issue as I do have an Optima Yellow Top...

    Quote Originally Posted by soundman98 View Post
    I really don't think that getting 2 ohm speakers is ever a really good idea--your primary reason is because the factory system was 2 ohm. my car also had 2 ohm speakers too, but i changed them for 4 ohm speakers--overall, i feel that 4 ohm speakers are more realiable and easier to power(there are more options for amps), and don't tax the amp as much, leading back to realiability.

    sadly, the 300 rms watt output lines up with the max rating on the jl sub, so depending on who you talk to, this can be fine(more control), or horribly wrong(your going to murder the sub w/ too much power). if you really crank it, this setup will probably end up blowing the sub, but kept to lower levels though, it should be ok.

    the most dramatic statments i have heard on the pdx series is that it lacks balls, and has no puch on the low end, on the other side most say that they sound fine.

    if you are looking for a alternative, i heard a rumor that jl will be coming out with a 5 channel hd series amp in the near future, with the biggest complaint on those being the price.

  7. #7
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    You shouldn't worry much about running the rear speakers. In the G35, the rear deck speakers are Bose 6x9 dedicated subs and the rear side 6.5" speakers are mounted free air, meaning they do not have any enclosure for the backwave. Its a small cabin as well, you can get away with running just fronts, besides, I doubt you ever have rear passengers. If you do decide to run the rear speakers, I would install one or the other (rear deck / rear sides) but not both.

    The stealthbox is pretty expensive for what you get. You can find a used 4080 enclosure with a JL10W6v2 for pretty cheap on g35driver.com.

    Seeing how you are already an owner of the Kappas AND are happy with them, I wont comment on them

    The PDX series has balls, you could destroy the Kappas if you wanted to.

    Power will not be an issue, the G35 has a 110amp alternator.

    You can tell when you are exceeding the mechanical limits of your speakers and you should not be so concerned with running more power than the RMS of the speaker.

    Have you considered deadening your doors or any other treatments?

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    This is awesome feedback, thanks! That 4080 box looks really nice, I wonder if it's worth the time/effort to try and build my own ... even if I just buy that one, it's much cheaper than the Stealthbox. And it accomplishes my goal of keeping my trunk space; heck, it even looks like I won't have to sacrifice my "grocery" net either!

    I'll probably run speakers all the way around since I've already purchased the entire set. Based on your suggestions, I guess it's perfectly fine to just power the rear sides off my HU. I'll save the amp for the other Kappas and the sub!

    As for "overpowering" my speakers/sub, you're saying that I don't need to worry about that, right? I guess the way I interpret your statement is that I will hear when any of the speakers are starting to become distorted and not turn up the volume anymore (makes perfect sense actually)! Well, now that I think about it, I have a question about my configuration that relates to this topic. If I've got the front components, rear deck 6x9's and sub all running off the amp, and then I've got the rear side 6.5's running off the HU, I assume they'll all be controlled by the same volume function. My thought is that all the speakers running off the amplifier will sound pretty good as they're all getting a decent amount of power to run. However, won't the rear side speakers be the bottleneck of the system? Meaning, as I turn up the volume won't those rear sides, powered off the HU not the amp, have less power and thus not be able to "hang" with the rest of the system? It just seems that I will be limited on how far I can crank up the volume because those 6.5's will only have watts going to each. Is this accurate?

    And lastly, regarding the sound deadening or other treatments, I hadn't really considered anything yet. I like the performance aspect of the vehicle (I'm building out my motor and putting on twin turbos this year), so my preference is to maximize acceleration by keeping the weight of the vehicle down if possible. That said, since I am investing some money into the sound system, I am open to suggestions on how to optimize the experience.

    The interior of the cabin already rattles from the OEM Bose system/Eclipse HU, so I know I'll probably have to deal with even more rattling after the audio upgrade is completed. Do you recommend Dynamat (or something similar) to improve the acoustics in the cabin?

    Thanks again,
    B

    Quote Originally Posted by Sponge View Post
    You shouldn't worry much about running the rear speakers. In the G35, the rear deck speakers are Bose 6x9 dedicated subs and the rear side 6.5" speakers are mounted free air, meaning they do not have any enclosure for the backwave. Its a small cabin as well, you can get away with running just fronts, besides, I doubt you ever have rear passengers. If you do decide to run the rear speakers, I would install one or the other (rear deck / rear sides) but not both.

    The stealthbox is pretty expensive for what you get. You can find a used 4080 enclosure with a JL10W6v2 for pretty cheap on g35driver.com.

    Seeing how you are already an owner of the Kappas AND are happy with them, I wont comment on them

    The PDX series has balls, you could destroy the Kappas if you wanted to.

    Power will not be an issue, the G35 has a 110amp alternator.

    You can tell when you are exceeding the mechanical limits of your speakers and you should not be so concerned with running more power than the RMS of the speaker.

    Have you considered deadening your doors or any other treatments?

  9. #9
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    Quote Originally Posted by shdowflare View Post
    This is awesome feedback, thanks! That 4080 box looks really nice, I wonder if it's worth the time/effort to try and build my own ... even if I just buy that one, it's much cheaper than the Stealthbox. And it accomplishes my goal of keeping my trunk space; heck, it even looks like I won't have to sacrifice my "grocery" net either!
    Unless you have expert skills with fiberglass, you simply will not beat the fit and finish of the 4080 enclosure (no, I do not have any ties to the company). The glass is laid in a mold and the enclosure fits like a glove. If you want to be adventurous, you can build an enclosure into the area to the left of the spare tire. Under that plastic piece is the 5lb bose amp for the rear deck subs, remove that and you have room to build a decent sized enclosure (just like the JL stealth).

    Quote Originally Posted by shdowflare View Post
    As for "overpowering" my speakers/sub, you're saying that I don't need to worry about that, right? I guess the way I interpret your statement is that I will hear when any of the speakers are starting to become distorted and not turn up the volume anymore (makes perfect sense actually)! Well, now that I think about it, I have a question about my configuration that relates to this topic. If I've got the front components, rear deck 6x9's and sub all running off the amp, and then I've got the rear side 6.5's running off the HU, I assume they'll all be controlled by the same volume function. My thought is that all the speakers running off the amplifier will sound pretty good as they're all getting a decent amount of power to run. However, won't the rear side speakers be the bottleneck of the system? Meaning, as I turn up the volume won't those rear sides, powered off the HU not the amp, have less power and thus not be able to "hang" with the rest of the system? It just seems that I will be limited on how far I can crank up the volume because those 6.5's will only have watts going to each. Is this accurate?
    Correct!
    You are also half correct with the rear speakers 'hanging' with the amplified speakers. You will most certainty want to attenuate the rear speaker output. This means you will want to turn down the output on the rear speakers for a couple of reasons. First, you will have twice as many speakers behind you as in front of you which will give you a 3db gain over the front... assuming that all of your speakers are fed the same signal. Second, you do not want the music to sound like it is coming from behind you, but rather in front of you. Finally, you will want to minimize the effect of path length differences and multiple point sources. Having three left and three right speakers outputting the same signal at the same amplitude can really mess up the way you perceive the music. Again, I would only run one set of rear speakers and have them turned way down in your situation. By the time you max out the head unit power on the rears, your front speakers should be plenty loud.

    Quote Originally Posted by shdowflare View Post
    And lastly, regarding the sound deadening or other treatments, I hadn't really considered anything yet. I like the performance aspect of the vehicle (I'm building out my motor and putting on twin turbos this year), so my preference is to maximize acceleration by keeping the weight of the vehicle down if possible. That said, since I am investing some money into the sound system, I am open to suggestions on how to optimize the experience.
    You can capture most of the advantages of vibration dampening material with just a few square feet on each door. You would place the dynamat/raamat/edead/damplifier/fatmat on the center of the inside of the door sheet metal. More is better with dampening, but the law of diminishing returns takes effect quickly after the first square foot is added. There are two large empty voids in the chassis located behind each of the rear side speakers. You can fill these with polyfill or housing insulation to cut some noise. Polyfill is polysester fiber that is used to stuff pillows. It can be found for ~$3/lb at a craft store. Here are some very good links to read up on the topic:

    http://g35driver.com/forums/audio-vi...adening-g.html
    http://www.sounddeadenershowdown.com/products/cld

  10. #10
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    This is lots of great info. Thanks again. Looks like all my speakers are here, next up - amp and sub. That might be another few months before I buy anything. But I'm going to look into the sound deadening while I'm inside the door. Oh, BTW, where would I insert the filler insulation behind those dead spots on the rear sides?

    Now, time to read up on your links.. thanks.

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