07 g35x factory amp need to be modded to add subs?

[farhanashraf]

Question 07 g35x factory amp need to be modded to add subs?whats up guys,

i have a 07 g35x and i wanted to add a couple of 12" subs in the rear. i wanted to find out first

- where the factory amp is in my car,

- is the amp used only for the sub in the back or for all speakers?

- do i haveta mess with the amp to hook up another amp and pair of 12" subs

- if so, what is the right kind of amp i should get? mono or what not?

i am looking to get a good package, like more than 300w rms...

i basically want to run an external amp for my 2 12" aftermarket subs, i am trying to figure out whats the best way to hook them up, thanks.

[pfarmer]

Question 07 g35x factory amp need to be modded to add subs?whats up guys,

i have a 07 g35x and i wanted to add a couple of 12" subs in the rear. i wanted to find out first

- where the factory amp is in my car,

- is the amp used only for the sub in the back or for all speakers?

- do i haveta mess with the amp to hook up another amp and pair of 12" subs

- if so, what is the right kind of amp i should get? mono or what not?

i am looking to get a good package, like more than 300w rms...

i basically want to run an external amp for my 2 12" aftermarket subs, i am trying to figure out whats the best way to hook them up, thanks.

I suggest you go to the av section of the factory service manual for the 07. The amp is located behind your cd changer in the trunk however........ if you look at the FSM for the 07 you will notice that there is an amp on signal that comes from the factory Bose amp to the woofer. What does this tell you about the woofer? Sounds like it is a powered woofer. Haven't check this out on my car but otherwise it would seem odd to have an amp power on supplied to the unit.

This tells me the most grease free system for installing an after market sub may be to tap into the sub woofer speaker leads (actual speaker leads on the woofer itself). Going this route however may present an issue depending on the characteristics of the woofer amp which may well be tailored to the installed woofer. Tapping into the other speakers may have similar issues since each speaker is powered from the Bose amp. The possible exceptions are the front center and two rear door speakers.

Perry

[farhanashraf]

thanks for the advice, somebody was telling me to:

"tap into the audio signal before it goes into the Bose amp. If the 07 sedan Bose amp is anything like the 03-06 Bose amps, the amp will roll off the bass once you reach a certain volume level, presumably to keep from damaging the stock speakers. You don't want that rolloff to go to your subwoofers. that would be counterintuitive."

what do u think?

[pfarmer]

thanks for the advice, somebody was telling me to:

"tap into the audio signal before it goes into the Bose amp. If the 07 sedan Bose amp is anything like the 03-06 Bose amps, the amp will roll off the bass once you reach a certain volume level, presumably to keep from damaging the stock speakers. You don't want that rolloff to go to your subwoofers. that would be counterintuitive."

what do u think?

You could tap into the signal to the Bose amp but keep in mind that these are not RCA with a ground and a positive. They have a negative (not ground) and positive. This means you should have either a device to convert these to RCA (such as a differential amp). Typically I would suggest against an adapter that is inductor based like most seem to be, but that may work as well. Some amps have differential inputs but most of these are speaker level inputs and I believe most will be inductor based.

But this may not solve your possible issue with the equalizing that may take place. The reason is on many factory units this actually takes place in the head unit, not the amp.

If you do go with a total amp replacement you may want to consider something like the 'bit one' (www.audison.eu). This is just one example of similar units that can sit between your head unit and an amp and allow you to custom tailor your system. Many connect to your pc through a USB or other port to fully set the system up. Some also have a display that can be mounted in your car for on the go changes.

I am also looking at still others that are similar to home units that put out a video signal that would allow connection through your aux inputs.

Perry

[farhanashraf]

i dont want a total amp replacement, i just want to add an amp for my subs that i will install...

[pfarmer]

i dont want a total amp replacement, i just want to add an amp for my subs that i will install...

Again you could try tapping into the woofer speaker leads (not the same as the leads to the woofer itself which appears to be powered). The issue of course is if equalization is taking place for the woofer. If you grab the center front speaker and rear doors that may work for speaker level inputs. One thought here would be the concept of using sub woofers with two voice coils. One connected to the front center input, the other to the rear doors. I don't know what the actual frequency response these speakers have so don't know what the amp is supplying to them. It is possible that the lows you are really interested in are absent.

So.................maybe for now what you could do is check what is being supplied to the existing rear woofer. A cd that sweeps the low frequencies may allow you to decipher this. If all goes well then tap into the signals to the woofer.

Perry

[farhanashraf]

tap into the signals to the woofer before it goes to the stock amp or after?

thanks a lot, i really appreciate the help.

[joe603]

Hi! I have the exact setup you're looking for...you just need an aftermarket amp that takes high-level input. (I have an MTX 7801 superamp) I used the rear seat, factory "subs" as the amp source. Just pull the speaker leads off and solder on RCA type connectors.

Here's a pic



My Bose amp was mounted here:

[farhanashraf]

wow thats a sick setup!

i haveta custom make the bottom piece i guess...

[pfarmer]

Hi! I have the exact setup you're looking for...you just need an aftermarket amp that takes high-level input. (I have an MTX 7801 superamp) I used the rear seat, factory "subs" as the amp source. Just pull the speaker leads off and solder on RCA type connectors.

Here's a pic



My Bose amp was mounted here:

The only difference I see would be that it appears the 07 and up have a separate amp for the woofer whereas it appears tha the 05 only uses the Bose amp. At first I thought the 07 and up had a two coil sub but then that did not explain the amp on signal sent from the Bose amp to the woofer.

If this is the case (I need to verify this by going out and looking, then you may need to make sure that you tap into the actual speaker leads.

Perry

[farhanashraf]

please let me know what you find out...

[farhanashraf]

also, one more question, i am trying to figure out how hooking up an aftermarket sound system is going to mess with my bumper to bumper warranty,

any possible scenarios where i could be screwed besides maybe the battery goes down??

[joe603]

You will be fine. Unless it causes a fire due to faulty wiring your warranty will not be affected.

This goes for any mod. The best way to explain how it works is this: Lets say you install an aftermarket cold air intake. 2 months later your drivers seat won't move. The seat is covered under the warranty because the CAI has nothing to do with a seat problem. However, if you damaged your MAF sensor during the install that might not be covered since its not in an OEM intake.

[pfarmer]

also, one more question, i am trying to figure out how hooking up an aftermarket sound system is going to mess with my bumper to bumper warranty,

any possible scenarios where i could be screwed besides maybe the battery goes down??

This may depend on the size of the aftermarket amp. You have a fairly wimpy size alternator when it comes to some of the common amps. On the other hand plenty of capacity for others. It is rated at about 110 amps and I believe from what I see it may have close to a 30 percent or so 'fudge factor' added in.

The maximum draw I have seen with the car running was about 40 or so amps. However if you add in some enhanced lighting, toss in another 900 watts (of load, not amp rating) then you would be at the factory rating. Many recommend that you consider the amp maximum load at about 40% over the rated rms output value. This would then mean somewhere in the area of 650 watts.

The second thing to keep in mind is to make sure you get the input level setpoint correct. This can be especially important with a sub. While listening to vocals, etc. setting the levels too high will usually be somewhat detectable in the way of distortion above about 1-2 percent. With a sub this becomes a little bit blured. The importance is that many amps will simply put out more power once the waveform moves into the area of a square wave (the reason many blow their speakers). It is easier with a sub for users not to notice that they have introduced 'clipping' into the mix. With the increased output levels comes increased power requirements.

If you go to another alternator keep in mind that your stock wiring has a fuseable link of about 140 amps. You may need to upgraded the wiring to and from the alternator. Your car runs on the alternator, not the battery.

If you decide to upgrade battery cables keep in mind that your charging circuit on an 07 (and up) uses a current sensor that the negative lead of your battery cable passes through, probably not a good idea to defeat it by installing a larger negative lead either around it or as a replacement without somehow incorporating it into the enhancements.

Perry

[farhanashraf]

well this is the set up i was looking into:

Two 12" Kenwood subwoofers. 1000W Kenwood amp. Sub box included. Perfect condition. (only used 3 months).





and i have a 1 farad capacitor that i would hook it up to, if that makes any difference.

[pfarmer]

well this is the set up i was looking into:

Two 12" Kenwood subwoofers. 1000W Kenwood amp. Sub box included. Perfect condition. (only used 3 months).

and i have a 1 farad capacitor that i would hook it up to, if that makes any difference.

1000 watts peak, peak to peak, or rms?

(RMS x 1.414) x 2=P-P

If this is peak then it is 707 watts rms. If peak to peak then 353.5 watts.

The capacitor is for transients and is very short term. If this is the peak to peak value then you should be fine, but if it is either peak or rms, then it sounds like you may exceed your alternator 'rated' value at times. A common rule of thumb is to estimate your maximum draw for input power at about 40% over the rated rms output power.

800 watts of additional load over my observed 40 amps would mean that an amp of 700 watts rms would put you over the rated output of the alternator by 100-150 watts at about 13 system volts.

Perry

[farhanashraf]

subs: http://www.justkenwood.co.uk/s...2.asp

amp: http://www.onlinecarstereo.com...17789

[pfarmer]

subs: http://www.justkenwood.co.uk/s...2.asp

amp: http://www.onlinecarstereo.com...17789

Being a class d amplifier it should have a draw of about 550-575 watts with a 500 watt output. These are widely used for subs but probably not preferable for wider frequency applications. You should be good to go with your stock electrical system as long as you don't have something else in the picture such as some super high powered lights.

Perry

[farhanashraf]

naah, havent got any of those, i was thinking of putting HIDs for my foglights though...