Input Voltage vs Speaker Level Outputs

[OldFartAudio]

I have a 2018 Ford Focus and I would like to add a subwoofer and amp. I already own an xtant 3150c that works and thus would be the cheapest route to bass. A new HU would be nice but the freaking dash kits are outrageous and if I want to do iData it is like $350 on top of the HU so that is out. My Focus is the SE and has 6 speakers, not Sony. I have no idea what the HU puts out but I have heard that the rear channels have less power than the front. The 3150 can take up to 8 volts on it's inputs. I don't have any clue what kind of voltage high level lines carry and I am wondering if a line level converter is a must have. Also, if I use an LLC I am thinking it would be best to run speed wire from the HU to the rear of the car and then convert the signal so I am using a higher level signal for the long runs of wire. Any help will be greatly appreciated.

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[Lasherž]

I have a 2018 Ford Focus and I would like to add a subwoofer and amp. I already own an xtant 3150c that works and thus would be the cheapest route to bass. A new HU would be nice but the freaking dash kits are outrageous and if I want to do iData it is like $350 on top of the HU so that is out. My Focus is the SE and has 6 speakers, not Sony. I have no idea what the HU puts out but I have heard that the rear channels have less power than the front. The 3150 can take up to 8 volts on it's inputs. I don't have any clue what kind of voltage high level lines carry and I am wondering if a line level converter is a must have. Also, if I use an LLC I am thinking it would be best to run speed wire from the HU to the rear of the car and then convert the signal so I am using a higher level signal for the long runs of wire. Any help will be greatly appreciated.

You'll want a Line out converter to interface between the car and the 3150c, even if your system is so low power that it can be within 8v (it will be very close if those speakers are 4ohms) even if it's only producing 15W per channel. √(15Wx4ohms)=7.75V

The main reason you'll want an LOC is because your car very likely doesn't send the same EQ to your speakers at high volumes. Newer cars like that focus will adjust the bass range downward so that the head unit and the speakers won't be damaged. The way around this is to get an active LOC (never buy a passive one, they're trash) like the AudioControl LC2i, which can amplify the bass signal back up to what it should be before the car's head unit toned it down. Also that LOC can produce up to 9.5V preouts which is enormous, you'll have no signal integrity loss at all with it.

Importantly before you do this you need to do a tone test on your system. Play a 50hz test tone over the speakers in your car and use the fader to adjust between the front and the back. Don't tap any speakers that can't play that note audibly. On my car the rears don't play it at all so tapping them would be a mistake but the front ones play it loud and clear so they'd make a great candidate for tapping an LOC into.

 

[OldFartAudio]

You'll want a Line out converter to interface between the car and the 3150c, even if your system is so low power that it can be within 8v (it will be very close if those speakers are 4ohms) even if it's only producing 15W per channel. √(15Wx4ohms)=7.75V

The main reason you'll want an LOC is because your car very likely doesn't send the same EQ to your speakers at high volumes. Newer cars like that focus will adjust the bass range downward so that the head unit and the speakers won't be damaged. The way around this is to get an active LOC (never buy a passive one, they're trash) like the AudioControl LC2i, which can amplify the bass signal back up to what it should be before the car's head unit toned it down. Also that LOC can produce up to 9.5V preouts which is enormous, you'll have no signal integrity loss at all with it.

Importantly before you do this you need to do a tone test on your system. Play a 50hz test tone over the speakers in your car and use the fader to adjust between the front and the back. Don't tap any speakers that can't play that note audibly. On my car the rears don't play it at all so tapping them would be a mistake but the front ones play it loud and clear so they'd make a great candidate for tapping an LOC into.

Thanks for the info! I appreciate it. I won't need to do the test tone if I use the line out converter as the two I am interested in are both 2 channel so I would only be using the front out. I like the Audio Control unit and NVX makes one that is probably a clone of it. They both have bass restoration, distortion lights, and a second set of outputs for a subwoofer channel that has a remote gain control option. That LC2i looks really nice but a little more money.

 

[Lasherž]

Thanks for the info! I appreciate it. I won't need to do the test tone if I use the line out converter as the two I am interested in are both 2 channel so I would only be using the front out. I like the Audio Control unit and NVX makes one that is probably a clone of it. They both have bass restoration, distortion lights, and a second set of outputs for a subwoofer channel that has a remote gain control option. That LC2i looks really nice but a little more money.

I have no experience with NVX but I'd say those features are pretty identical, just make sure it outputs a strong signal. Anything over 4v preout is good.

You do still need to do the test tone for best results. I would do the test tone if you're tapping any speakers at all, even if you intend on tapping all of them. A poor bass response can be a good reason to say screw the fader functionality and instead use a single pair of speakers' signal for all of your speakers including the part of the car that you didn't tap. Sound quality > fader

 

[OldFartAudio]

That's what I was saying, I know the fronts get full range so I use them for the LR inputs on the LC2, then I use both outs on it to go to the front and rear of the amp. That gives me one stereo pair for the front channels and a second stereo pair with level control for the Sub channel. I have several options as far as rear speakers but I honestly don't even need them. The more I think about it the more I like the options that little LC2 would give me. This is cool, the xtant 3150 is a 3 channel amp rated at 25 x 2 and 100 x 1 but it also has outputs for rear speakers that are in parallel off the front channels and they have attenuation controls that let you dial in your rear fill. I could use these for the rear, or I could leave the factory stuff alone for the rear, or I could replace the rear speakers and wire them in from the amp or the factory HU. Lots of options.