Adding a real subwoofer w/amp to your Mach-E

[Hammered]

I was considering building a box for a 15" sub -- Quite a bit of space under the floor shelf. Great spot to mount amps and DSP.

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[ElectrikPony]

I have the JL, so I wouldn’t. But I am curious as to what you could fit there. Stock location is free air and tiny.

I don’t know yet. I’ll have to get into the stock space to take measurements. The enclosure will most likely be sealed.

 

[Mach1E]

I don’t know yet. I’ll have to get into the stock space to take measurements. The enclosure will most likely be sealed.

Let us know what you find out, but I don’t think much if anything will fit.

The stock sub is a tiny odd shape too (like 6x9). I doubt even an 8” sub would fit.

some more info and pics of the sub

https://www.macheforum.com/site/threads/can-someone-explain-this-odd-subwoofer-design.5409/

 

[ElectrikPony]

Thanks @markboris . Really detailed write up. This combined with https://www.macheforum.com/site/threads/official-instructions-to-replace-the-12v-battery-lvb.3882/ made installing the sub super easy for me.

the only not fun part is reaching to the firewall to feed the wire through the grommet, but that never is a fun task in any car.

For the time being I used spare equipment I had on hand. Installed a vintage SAS bazooka tube. Still figuring out the final design. This will do for now. Certainly can’t argue with the “free” aspect.

 

[markboris]

Thanks @markboris . Really detailed write up. This combined with https://www.macheforum.com/site/threads/official-instructions-to-replace-the-12v-battery-lvb.3882/ made installing the sub super easy for me.

the only not fun part is reaching to the firewall to feed the wire through the grommet, but that never is a fun task in any car.

Another way to get to the firewall without reaching would be to remove the left front wheel and inner fender liner then it can be more easily accessed but of course lifting up the car and removing the wheel might be a pain too.

 

[Mach-Jay]

I seriously don't understand why everyone it so set on going to the LVB through the firewall. I've been running off the 12v in the back for 6+ months and have zero regrets. If I ever blow the fuse, I will report back.

 

[markboris]

I seriously don't understand why everyone it so set on going to the LVB through the firewall. I've been running off the 12v in the back for 6+ months and have zero regrets. If I ever blow the fuse, I will report back.

Well, it all depends on the subwoofer amp you are using, how you use the sub and if you want to follow manufacturers recommendations.

I don't know exactly what sub amp you are using so not sure what the recommendations are for power requirements. I also don't know how you are using the sub but here is what I do know....

I'm using the JL Audio sub I mentioned in my first post. Whether you use the 10" or 12" version of that sub, the amp recommendations by the manufacturer are the same. JL specifically states to wire the 12V+ directly to the battery with a minimum of 8ga wire with a 30 amp fuse not more than 18" from the battery connection. They also state to use 8ga wire for the 12V- and not longer than 36" from the amp. I tend to follow manufactures recommendations but yes I have been known to wire things my way.

If I were to wire this particular sub for my 92 year old mom in her Volvo, I might wire it to an available 12V+ that does not carry a 30 amp rating like the one in the rear of the Mach-E knowing she would never turn that sub up to high levels for sustained periods of time. However, not only do I listen to music (all kinds) at high levels from time to time but also for sustained periods of time and THAT is why JL has these power recommendations. Turing up the sub for 20-30 seconds is no problem. Listening to music with lots of bass at high levels for several minutes or more will heat up that thin 12+ power wire at your connection and either melt it or blow the 20 amp fuse for that circuit. I have seen this happen more times than I can count when I use to install car audio way back in the day.

Bottom line, there really is nothing wrong with connecting a sub amp to the 12V+ outlet in the rear of the car as long as you don't use that amp to its fullest potential.

 

[Ride_the_lightning]

I seriously don't understand why everyone it so set on going to the LVB through the firewall. I've been running off the 12v in the back for 6+ months and have zero regrets. If I ever blow the fuse, I will report back.

I am also using the one in the back, but I specifically chose a 150w sub / amp for that reason. Amperage is only one criteria. The lower gauge wire will have a much larger dynamic voltage drop (the amp may draw way more than 30 amps for a second or two), which can also impact the amp and even cause it to shutdown momentarily. 30 amps through that stock wiring will cause at least a 21% voltage drop. It wouldn’t surprise me if you could run an 250watt amp without blowing a fuse, but end up with random shutdowns or issues as the voltage drops down to 7 or 8 volts during some songs. You may be able to mitigate this with a large external capacitor but I haven’t done the math to see what size cap I would need.

edit: I have actually had some undervoltage shutdowns even on on my small kicker occasionally. I think it may be a poor ground connection, but it may be due to that small wiring. I may need to add a capacitor. Too cold in my garage to deal with it right now.

 

[Mach-Jay]

Bottom line, there really is nothing wrong with connecting a sub amp to the 12V+ outlet in the rear of the car as long as you don't use that amp to its fullest potential.

I've got the JL 12" per your amazing suggestion - the thing sounds so clean and adds so much to the sound of so many songs.

Turning this thing up past 5/10 rattles the car - I am sure I would have when I was a teenager, but 44yo me doesn't like it up that loud.

I have yet to hear the sub cut out or make any odd noise.

 

[mkhuffman]

Yesterday I installed a Infinity Baselink mini under the driver seat. Sort of. I don't think this is a good permanent location, as people who sit there will have to put their feet on the subwoofer and I had to remove the floor mat. I am using Velcro (the hooks) to get it to stick to the carpet.

It sounds great, and I especially like how it vibrates the seat. That is why I wanted to put it under the seat. Ideally I will find a way to mount it under the front of the seat, but I have not figured that out yet.

By the way, I was using the front speaker outputs to drive the subwoofer and there must be a serious low frequency cutoff happening to protect those speakers. So I ran a new wire from the subwoofer output and it sounds much better. I should have known better than to use the front speaker outputs, but in case someone else thinks to do the same thing, don't. Use the subwoofer output.

 

[GCC_mtl]

Read the thread and I'm confused about the RCA wiring.

If I pull from the green/violet + and grey - before going into the stock amp, isn't that signal digital? Why wouldn't I just grab the signal out of the stock amp before going to the stock sub ( off that green Metra plug) when it's now analog?

Let's say I do use the digital input by splicing the green/violet and grey before the stock amp.. how do I feed my amp those 2 wires into 2 females RCA (which would be 4 wires since there are two per RCA). Do I use a Y cable or did you guys only feed one of the RCA inputs?

 

[markboris]

Read the thread and I'm confused about the RCA wiring.

If I pull from the green/violet + and grey - before going into the stock amp, isn't that signal digital? Why wouldn't I just grab the signal out of the stock amp before going to the stock sub ( off that green Metra plug) when it's now analog?

Let's say I do use the digital input by splicing the green/violet and grey before the stock amp.. how do I feed my amp those 2 wires into 2 females RCA (which would be 4 wires since there are two per RCA). Do I use a Y cable or did you guys only feed one of the RCA inputs?

Those wires (green/viloet + and gray -) are not going into the stock B&O amp. They are coming from the stock B&O amp going into the OEM sub. They are the high level analog audio signal needed for the JL Audio sub amp or whatever amp you may be using that has a high level audio input.

 

[GCC_mtl]

Those wires (green/viloet + and gray -) are not going into the stock B&O amp. They are coming from the stock B&O amp going into the OEM sub. They are the high level analog audio signal needed for the JL Audio sub amp or whatever amp you may be using that has a high level audio input.

So the metal block next to the sub, with 2 harness connections (speaker wires of multiple colors) is not an amp?

Is there something incorrect with simply swapping the green Metra harness cables from the stock amp / subwoofer into my subwoofer instead ? I'm asking because I would either purchase or 3D print a harness and plug into the existing wiring This would make the install on my leased Mach E very reversible.

Once tapped, no matter the source wire, how did you lead the RCA into the sub? Mono or stereo? If mono how do you chose which of the 2?


Thanks again

 

[markboris]

So the metal block next to the sub, with 2 harness connections (speaker wires of multiple colors) is not an amp?

Is there something incorrect with simply swapping the green Metra harness cables from the stock amp / subwoofer into my subwoofer instead ? I'm asking because I would either purchase or 3D print a harness and plug into the existing wiring This would make the install on my leased Mach E very reversible.

Once tapped, no matter the source wire, how did you lead the RCA into the sub? Mono or stereo? If mono how do you chose which of the 2?


Thanks again

This is the stock B&O amp above the OEM sub

This is the OEM sub and the green connector at the top of the sub that I tapped into

If you want to unplug the green connector at the sub and make your how harness to go from there to your amp that would work. You do not tap into or connect anything at the stock B&O amp. RCA inputs are for a low level signal. Since we are using the audio signal that is going into the OEM sub, that is a HIGH LEVEL signal so it does not use the low level RCA inputs of any amp.

If you are using the JL Audio sub amp, it has two sets of inputs. RCA low level (not used) and speaker wire/connector high level inputs (use). The OEM sub only has a mono audio input so on the JL Audio amp, connect it to either the left or right input.

You can see below on the JL Audio amp, there is a connector with 4 white wires. This is the high level audio input. I have two wires from the OEM sub going into just two wires of that connector.

 

[GCC_mtl]

Thank you for clarifying everything, it's greatly appreciated.
I just finished the job and it's fantastic!!!!
I'm using a Rockford Fosgate p300 8 inch. I decided on this sub vs others because it runs on 15A and, as such, I connected it to the 12V lighter plug that's in the trunk.
It won't turn off though.. ?

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