Trying to Understand Bose Sound System

neoskunk

So just a little background as this is my first post. About a month ago I totaled a 300zx when I hit a patch of ice and slammed into a guard rail. Being a Z enthusiast I decided it was time for a 370z. Long story short I ended up buying a 2009 touring edition. However, the 370 I purchased has had some audio work done to it.

The current setup has an Alpine iXA-W407 headunit, an Alpine PDX 4.150 amp, and an Infiniti Kappa sub along with some sort of dynamat all over the trunk. This is all I have been able to see and not sure about the speakers.

I am not a fan of subwoofers for a few different reasons and as such have decided to remove it. Upon removal of the sub and box I found the amp in the area pictured below.



I have a few questions....

1. The foam from this area seems to be missing. This probably wasn't a problem for the previous owner as the sub was covering this area but I'd like a stable trunk area. Do you guys know of anywhere / anyone with the foam? Will the foam fit over this alpine amp?

2. What is this gray box on the right? It says Visteon voice technology on it. From what I have found its the stock bose systems bluetooth unit. Is this correct and if so can it be removed as I do not have the stock bose system anymore?

3. After some research, from what I can tell my alpine amp now sits where the stock bose amp used to sit. Is this true? Related to this but more of a preference question, if I remove the subwoofer how necessary is the amp? Do the stock bose speakers NEED an amp driving them? Previously an after market head unit driving the speakers has been plenty for me.

RonRizz

are you sure the original owner left the bose speakers in the car? doesn't seem likely. If they are still there, hooking them up directly to your headunit would be questionable, and risky, IMO. The impedance would not match, and may damage your head units internal amplifier. I believe more research will be required on your part.
as far as the foam goes, I doubt that it will fit over the alpine amp, but it can easily be modified to do so. also, Im sure someone on the forum can help you out with where to get the piece you need. Post it in the WTB thread.
I cant speak of your Bluetooth box, being that is a factory piece, Im not familiar with it, or how it is wired into the whole system.

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P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

So after further investigation you were right RonRizz, all the speakers have been changed out. In the doors there are MB Quart ONX169 and not sure about the tweeters but they are definitely aftermarket.

My plan is to replace the speakers all the way around with some Infinity Kappas. This will include adding the two speakers in the back. My question now is what is the best way to drive this setup with the headunit and amp that I have. The headunit is rated at 50W x 4 and the amp is rated at 150W x 4.

I'm thinking drive all of the speakers off the amp. The rear channels to the rears and the front channels to the door speakers and tweeters with a passive crossover. Although I've read a lot on this forum and many think adding rear speakers can overpower the fronts so I was considering driving the rears off the headunit and then driving the door speakers and tweeters off their own channel on the amp, active crossover to split the signal.

Thoughts?

RonRizz

You can hook them up as you described, and use the fader to cut power to rear speakers. All off the amp.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

Ok. What power rating should I go for on these speakers? How does a passive crossover affect the power ending up at the speakers?

neoskunk

Also it seems like the only speakers that will fit in the rear of the Z are 3.5 inch. I can't find any speakers of this size with an RMS rating of over 70W. Can these be used with a 150W amp like I have?

RonRizz

Sure, you can use them. You will need to set your gain on your amp with a multimeter, so you don't overpower them. Assuming this amp has a gain control for both channels 1 and 2, and 3 and 4 separately. (Which it should)

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

I thought you were supposed to match the gain to the head unit preouts? My amp has gain adjustment from 0.2V to 4.0V and the head unit has 4.0V preouts.

Can you explain the procedure for setting the gain with a multimeter?

RonRizz

You are correct. You are matching them to get the most out of your amplifier. But in this case, we want to lower the amps output to the rear speakers. To do that, we use Ohms law, where Voltage is the square root of Power (watts) times ohms.
4 ohm speaker, 70 watts......4x70=280 square root of 280 is 16.7332
get a cd with a 80 hertz test tone, or download one onto a disc.
set your amp gains at their lowest point.
turn your head unit volume to 75% of max
test for voltage at speaker outputs, and adjust gain until you hit the required reading.....
16.73 volts for rear speakers (70 watts)
24.5 volts for front speakers (150 watts) This is as close as you can get without an oscope.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

Thanks Ron! Super helpful! Just out of curiosity why do you use 80Hz test tone and 75% volume? If I run components off the front channel that are rated at 100W RMS do I need to do a similar procedure or can they handle the full power from my amp?

RonRizz

75% is sort of an industry standard. Most of your distortion will be at volume levels above that point. Keeping it at or below means a cleaner signal to the amp.
I would do the same for the fronts as well just to protect them from being overpowered.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

So does this mean you are saying I shouldn't ever turn the volume above 75%?

Also is the process for setting the gain on the front channels the same as the rear even though the signal will be split by passive crossover?

RonRizz

Yes, the process is the same. And yes, I'm saying it is wise to keep your volume knob below 75% in a high powered system. Necessary?? No. Wise?? Yes.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

neoskunk

Hey Ron had another quick question. I ordered my speakers and am trying to plan out the install. I can't decide where to put the crossovers for the front speakers. Does crossover proximity to the speakers matter? If possible I'd like to mount the crossovers in the trunk area near the amp. Will this affect sound quality or cause interference?

RonRizz

Not at all, just more wire to run

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals