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alpha17

Adding a relay and subwoofer connection

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Hello guys,

Finally ordered the Bose spare tire subwoofer and it’s on the way. Can’t wait for it:D. Since it originally came with Mazda 6 and Nissan Murano, we have to do a little amount of extra work when wiring. The sub has a 100watts amplifier inbuilt with a 6.5’ subwoofer. Only problem is that it has four wires coming out, one for +12v, ground,signal input +,signal input - . It doesn’t have a remote input. So I plan to add a relay and connect the car’s dvd player’s remote switch to the relay. So I have these problems.

1.Do I need to find a specific relay for the task? What is the most suitable type?

2.Can the subwoofer be wired from the fuse box rather than from the battery, since it’s not a huge amplifier?

3.Is there any way to run wires without piercing the firewall?

4.I heard that the wire can be run through the fender. Is it possible?

Electrical experts please help me. I want the system to be installed without ruinning the original condition of the car and that’s what I chose this sub. It looks completely like an OEM unit. Another fact is that I don’t want thumping bass like a private bass. Just a nice bit of low end to my existing system. Also I don’t trust mechanics around this area due to past experiences I had. So help me with your knowledge.

I will do a review of the unit after installing it, since it would be helpful to people around here.Thanks for reading

Cheers!!!

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This is what i have done to my under-seat sub. Im no electrical expert but it is better to have an aftermarket sub wired directly to the battery as 100W is a considerable amount of power and wiring it to existing fuses will only strain the car's electrical system as it was not designed for it.  Also the sub might not work to it's potential due to power restrictions when coupled with a existing fuse. The wire from the batter can go to the dash from inside as illustrated. No modification is required.

image.thumb.png.643343d571a3600d64710bc16e78c0ad.png

 

 

 

image.thumb.png.f0278af0ad6a028e7b4b1b2465df39ca.png

image.thumb.png.21d192dcc6d81e03dabc204bae940f16.png

image.thumb.png.751c040b6b2934270442f7da2ee9cb39.png

 

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28 minutes ago, TheFlyingFox said:

This is what i have done to my under-seat sub. Im no electrical expert but it is better to have an aftermarket sub wired directly to the battery as 100W is a considerable amount of power and wiring it to existing fuses will only strain the car's electrical system as it was not designed for it.  Also the sub might not work to it's potential due to power restrictions when coupled with a existing fuse. The wire from the batter can go to the dash from inside as illustrated. No modification is required.

image.thumb.png.643343d571a3600d64710bc16e78c0ad.png

 

 

 

image.thumb.png.f0278af0ad6a028e7b4b1b2465df39ca.png

image.thumb.png.21d192dcc6d81e03dabc204bae940f16.png

image.thumb.png.751c040b6b2934270442f7da2ee9cb39.png

 

In my previous 121 it was wired like this. Direct line from the battery. Can I make a new connection by adding a new fuse to the fuse box? A power wire running from a battery kinda destroy the original look😁

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4 hours ago, alpha17 said:

Hello guys,

Finally ordered the Bose spare tire subwoofer and it’s on the way. Can’t wait for it:D. Since it originally came with Mazda 6 and Nissan Murano, we have to do a little amount of extra work when wiring. The sub has a 100watts amplifier inbuilt with a 6.5’ subwoofer. Only problem is that it has four wires coming out, one for +12v, ground,signal input +,signal input - . It doesn’t have a remote input. So I plan to add a relay and connect the car’s dvd player’s remote switch to the relay. So I have these problems.

1.Do I need to find a specific relay for the task? What is the most suitable type?

2.Can the subwoofer be wired from the fuse box rather than from the battery, since it’s not a huge amplifier?

3.Is there any way to run wires without piercing the firewall?

4.I heard that the wire can be run through the fender. Is it possible?

Electrical experts please help me. I want the system to be installed without ruinning the original condition of the car and that’s what I chose this sub. It looks completely like an OEM unit. Another fact is that I don’t want thumping bass like a private bass. Just a nice bit of low end to my existing system. Also I don’t trust mechanics around this area due to past experiences I had. So help me with your knowledge.

I will do a review of the unit after installing it, since it would be helpful to people around here.Thanks for reading

Cheers!!!

Get a pro to do the installation, and no you don't need a relay.

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18 minutes ago, Twin Turbo said:

Get a pro to do the installation, and no you don't need a relay.

Why no relay? Then how can I get it synced with the head unit? Please explain

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What you mean by relay is not what is used to connect to the head unit,..

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4 hours ago, Twin Turbo said:

What you mean by relay is not what is used to connect to the head unit,..

The sub has no remote turn on wire, since it originally came intergrated into the  Bose system in Mazda 6. So I have to connect it through fuse box to sync it with ACC turn on. Or else I have to use the direct line from the battery and use a relay to connect the remote turn on wire of my head unit and then the sub can be connected. Also many people recommend using a relay to stop a “pop” the device makes when turning on. But no ond has clearly mentioned about the power line.

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1. You need a regular 4 pin relay with 30, 85, 86 and 87 pins. 30 is directly wired to the battery (preferably through an in line fuse). 85 is ground, so you can connect it to a bolt that has a good connection to the chassis. 86 is the switched 12v pin. This needs to be connected to the fuse box (the same fuse that powers the head unit). And finally, 87 goes to the + terminal of the sub woofer/amplifier. 

2. Don't. The load will fry the fuse when the volume is increased. 

3. There's no need to pierce the firewall. You can pass the wire into the car through an existing rubber grommet in the firewall. Find one that's closest to the internal fuse box. 

4. This will involve more work and not worth the effort IMO when you can neatly route the wire into the car from the engine bay like TheFlyingFox has shown above. 

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3 hours ago, Davy said:

1. You need a regular 4 pin relay with 30, 85, 86 and 87 pins. 30 is directly wired to the battery (preferably through an in line fuse). 85 is ground, so you can connect it to a bolt that has a good connection to the chassis. 86 is the switched 12v pin. This needs to be connected to the fuse box (the same fuse that powers the head unit). And finally, 87 goes to the + terminal of the sub woofer/amplifier. 

2. Don't. The load will fry the fuse when the volume is increased. 

Thanks @Davy.So I have a few questions.

1. About the relay, what is the type I should use? Is there a specific number, voltage or amperage? Please recommend me one.

2. I watched a review about one installed in a Civic. He has mentioned in the comments that he used the cigarette lighter to get the 12v. Is it possible?

3. Can I use a piggyback (add-a-circuit) fuse holder to form a new line from the car’s fuse box? Is it safe to use?

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Posted (edited)
2 hours ago, alpha17 said:

Thanks @Davy.So I have a few questions.

1. About the relay, what is the type I should use? Is there a specific number, voltage or amperage? Please recommend me one.

2. I watched a review about one installed in a Civic. He has mentioned in the comments that he used the cigarette lighter to get the 12v. Is it possible?

3. Can I use a piggyback (add-a-circuit) fuse holder to form a new line from the car’s fuse box? Is it safe to use?

1. For a regular amplifier, a regular 4 pin relay would do. You should be able to find them in any auto spare parts shop. They're called SPST relays (Single Pole, Single Throw). 

However, depending on how much power draw the amplifier has, you might want to install a better relay meant to be used with high powered audio systems. The relays mentioned above typically handle 30A to 40A. But since you said that your sub woofer is 1000w, you might want a better relay (assuming that 1000w is RMS and not peak power).

If it's RMS, you can just do P = VI (Watt's law) which is 1000 = I x 12 = which is around 80A. So if you use a relay rated for 30A in the circuit, it will just fry before you can even make it through one song. So your relay needs to be able to handle it as well as the inline fuse. Best thing is to take the car to a good car audio place and get them to do the job if you are not sure.

2. Yes, it's possible. Usually accessories like the lighter and audio system are wired through the same fuse if not fuses that get power when the key is in ACC or ON positions. 

3. No, you should not use the car's fuse box as the power source of your amplifier. That is a recipe for disaster. Running a line to the battery and switching it on through a relay is your best bet IMO because you want the subwoofer and amp to power up when the head unit gets power.

Again, I think you should take the car to a reputed car audio place. They will have the correct fuses, relays and even the high tension leads to wire it up properly. 

Edited by Davy
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6 minutes ago, Davy said:

1. For a regular amplifier, a regular 4 pin relay would do. You should be able to find them in any auto spare parts shop. They're called SPST relays (Single Pole, Single Throw). 

However, depending on how much power draw the amplifier has, you might want to install a better relay meant to be used with high powered audio systems. The relays mentioned above typically handle 30A to 40A. But since you said that your sub woofer is 1000w, you might want a better relay (assuming that 1000w is RMS and not peak power).

If it's RMS, you can just do P = VI (Watt's law) which is 1000 = I x 12 = which is around 80A. So if you use a relay rated for 30A in the circuit, it will just fry before you can even make it through one song. So your relay needs to be able to handle it as well as the inline fuse. Best thing is to take the car to a good car audio place and get them to do the job if you are not sure.

2. Yes, it's possible. Usually accessories like the lighter and audio system are wired through the same fuse if not fuses that get power when the key is in ACC or ON positions. 

3. No, you should not use the car's fuse box as the power source of your amplifier. That is a recipe for disaster. Running a line to the battery and switching it on through a relay is your best bet IMO because you want the subwoofer and amp to power up when the head unit gets power.

Again, I think you should take the car to a reputed car audio place. They will have the correct fuses, relays and even the high tension leads to wire it up properly. 

Thanks @Davy. The amplifier is 100 watts.Not 1000 watts.

How to wire it from the lighter or the audio system?Is it safe?

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5 hours ago, alpha17 said:

Thanks @Davy. The amplifier is 100 watts.Not 1000 watts.

How to wire it from the lighter or the audio system?Is it safe?

Oh. I swear I saw another zero there before. 🤓

As I said before, wire it through a relay. The relay is connected to +12v (using high tension lead with inline fuse). The trigger for the relay can be any ACC signal (cig lighter, head unit) circuit. You should find the corresponding fuse in the fuse box and use a fuse tap to wire up the line to the relay. 

Here's an example:

images?q=tbn:ANd9GcQ7VuX_8AqOTMtdybeZP5V

The circle marked "Lights" will be your amplifier. If your head unit already has an amplifier trigger line (corresponds to the switch in the diagram), you can use that. Otherwise you will have to go with the fuse tap on the fuse box. The example here uses a 5 pin relay with a 87a pin which is unused. The fuse ratings in the figure are indicative only. 

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Thanks @Davy. I decided to take a line from the battery without destroying the original look of the car. The I’ll add a relay. The head unit has the remote turn on wire. Also plan to add just plain black wire for the battery power line to make it look more original-like😁

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6 hours ago, alpha17 said:

Thanks @Davy. I decided to take a line from the battery without destroying the original look of the car. The I’ll add a relay. The head unit has the remote turn on wire. Also plan to add just plain black wire for the battery power line to make it look more original-like😁

Good choice. As for the colour of the wire, you can still keep it red and run it through a black conduit. What TheFlyingFox has shared above looks pretty clean. 

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@Davy Today I checked the car’s owner’s manual. So according to the manual on the interior fuse box there is a 15A Fuse for the Heated Seats. Since my car has no such option can I start a new line from there? According to most owners the a 10A fuse is sufficient for the sub. 15A is recommended by some owners. Can there be a line from the battery to the exact empty fuse slot? Is it okay to form a new line?

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@Davy I checked the car's fuse box and it's a little bit different from the one shown in the manual and have no extra lines for power seats. So I should focus on getting an independent line from the battery.

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