Combining 3 signals into 1 to get full range for aftermarket sub

amurciano

Senior Member
First Name
Aaron
Joined
Jan 23, 2020
Threads
14
Messages
241
Reaction score
105
Location
Fort Lauderdale, Florida, USA
Vehicle(s)
2019 Honda Civic Type R FK8
Country flag
I have a wiring question for you guys, I have mixed answers from people and would like to know the right way or at least a way that is pretty safe for doing the following:

I am trying to wire up my factory head unit's amp's output signals to my LC2i then to a monoamp then to an aftermarket sub. I will be keeping my stock factory speakers except for the factory sub which will be wired up to the monoamp.

I have been told that it's better to get signals from both left and right main door speakers which contain low to mid frequencies, on top of this I have been told to get the sub signal as well in here to get the really low lows. In total 3 signals that I would need to input into the LC2i which only has 2 inputs, L and R.

1. Is it possible to tap into these 3 signals and combine them all together into 1 input to the LC2i?
2. If I do this, will my existing door panel speakers (Left and Right) get affected by this wiring, essentially im shorting all 3 signals together? Will the speakers be loaded way too much due to varying signals from the factory amp?
3. Do I need to wire in some sort of passive mixer circuit to help the original signals going to Left and Right speakers get back to normal, putting a 10k ohm resistor on each tapped line before it combines into 1 line?
4. Does it make a difference if the input impedance of the LC2i is 20k ohms when adding these resistors?

Thank you for the help in advance.
Sponsored

 

shoegazer

assistant to the assistant manager
Joined
Sep 5, 2018
Threads
7
Messages
1,415
Reaction score
715
Location
Raleigh NC
Vehicle(s)
2018 Civic LX Coupe 2.0 (CVT)
Country flag
Hmm...

The LC2i is just two channels. What it's doing is more than just twisting wires together. I think your factory head unit would not be happy with the impedance/resistance (and cause damage) even if you could get the LOC to work this way.

Technically... if you could a second LOC to handle the sub signal; you could then take all three line level signals and connect them to a mixer which would then give you a single line level output to an amp.

If this were me... I'd just take the two door speakers signal into the loc and ignore the sub signal.

Good luck.
 
OP
OP

amurciano

Senior Member
First Name
Aaron
Joined
Jan 23, 2020
Threads
14
Messages
241
Reaction score
105
Location
Fort Lauderdale, Florida, USA
Vehicle(s)
2019 Honda Civic Type R FK8
Country flag
Hmm...

The LC2i is just two channels. What it's doing is more than just twisting wires together. I think your factory head unit would not be happy with the impedance/resistance (and cause damage) even if you could get the LOC to work this way.

Technically... if you could a second LOC to handle the sub signal; you could then take all three line level signals and connect them to a mixer which would then give you a single line level output to an amp.

If this were me... I'd just take the two door speakers signal into the loc and ignore the sub signal.

Good luck.
Thank you for the help, in your opinion do you think that the 2 door speakers have the same low frequencies as the sub? Or does the sub get the frequencies below the cutoff for the 2 door speaker?
 

shoegazer

assistant to the assistant manager
Joined
Sep 5, 2018
Threads
7
Messages
1,415
Reaction score
715
Location
Raleigh NC
Vehicle(s)
2018 Civic LX Coupe 2.0 (CVT)
Country flag
Thank you for the help, in your opinion do you think that the 2 door speakers have the same low frequencies as the sub? Or does the sub get the frequencies below the cutoff for the 2 door speaker?
Scopesys measured all this in a thread over in the electronics section. But I would think that the sub would get the lowest of the low. Or the sub would get *just* the low instead of the fuller range of the door speaker channels.

Just LOC'ing the sub channel and using an aftermarket amp and sub would preserve your control from the head unit. And if you used a powered sub with a LOC built-in (or a speaker level input option to the powered sub's amp); that's even more simple.

I'm a sound guy/electronics guy but not a car electronics sound guy. There's a bunch over on the Electronics section, though. Maybe I'll see ya' there.
 

ebatr24

Senior Member
Joined
Jan 20, 2018
Threads
10
Messages
974
Reaction score
730
Location
Oregon
Vehicle(s)
2017 Civic Type R, 2018 Civic Si Coupe
Country flag
What you would want is the LC7i, and you can take signal from the doors, and the sub directly at the amp by the passenger footwell. You will be able to sum the two signals, then use your sub amp crossover to eliminate the higher frequencies you don't need. I am currently running my system this way.
 


OP
OP

amurciano

Senior Member
First Name
Aaron
Joined
Jan 23, 2020
Threads
14
Messages
241
Reaction score
105
Location
Fort Lauderdale, Florida, USA
Vehicle(s)
2019 Honda Civic Type R FK8
Country flag
What you would want is the LC7i, and you can take signal from the doors, and the sub directly at the amp by the passenger footwell. You will be able to sum the two signals, then use your sub amp crossover to eliminate the higher frequencies you don't need. I am currently running my system this way.
WIth LC7i, do I use main inputs for right and left door panel speakers, and chanel 2 for bass, how do I know which output is for Bass? the lc2i has a bass output and main output, but lc7i just has "main" output and "channel 2" and "channel 3"?

Have an idea Using LC2i, what if I just used the sub signal for left input and right signal for right input leaving the left signal out of the picture? I would think that music rarely has varying lows for left and right, I would think music only uses the left and right variations for higher and mid sounds? I could be wrong though. what do you think? that way I can include the sub signal and at least use one of the door panel speaker signals.
 

ebatr24

Senior Member
Joined
Jan 20, 2018
Threads
10
Messages
974
Reaction score
730
Location
Oregon
Vehicle(s)
2017 Civic Type R, 2018 Civic Si Coupe
Country flag
WIth LC7i, do I use main inputs for right and left door panel speakers, and chanel 2 for bass, how do I know which output is for Bass? the lc2i has a bass output and main output, but lc7i just has "main" output and "channel 2" and "channel 3"?

Have an idea Using LC2i, what if I just used the sub signal for left input and right signal for right input leaving the left signal out of the picture? I would think that music rarely has varying lows for left and right, I would think music only uses the left and right variations for higher and mid sounds? I could be wrong though. what do you think? that way I can include the sub signal and at least use one of the door panel speaker signals.
You use the corresponding inputs, meaning the sub goes to the sub input and the doors to the others. You set the jumper to sum all signals which will be summed on the first channel and use that as your signal for your sub amp. I don't recommend what you're wanting to do as you will lose the ability to properly turn up the gain, and use the bass feature to bring back the lost bass from the stock dsp roll off.

Don't take offense to this but you strike me as a bit of a novice with these things. You're asking the LC2i to do something it's not intended to do. Have you heard a sub+amp going off the sub signal properly set up with the LC2i? I think it provides a sound that would satisfy most people.
 
OP
OP

amurciano

Senior Member
First Name
Aaron
Joined
Jan 23, 2020
Threads
14
Messages
241
Reaction score
105
Location
Fort Lauderdale, Florida, USA
Vehicle(s)
2019 Honda Civic Type R FK8
Country flag
You use the corresponding inputs, meaning the sub goes to the sub input and the doors to the others. You set the jumper to sum all signals which will be summed on the first channel and use that as your signal for your sub amp. I don't recommend what you're wanting to do as you will lose the ability to properly turn up the gain, and use the bass feature to bring back the lost bass from the stock dsp roll off.

Don't take offense to this but you strike me as a bit of a novice with these things. You're asking the LC2i to do something it's not intended to do. Have you heard a sub+amp going off the sub signal properly set up with the LC2i? I think it provides a sound that would satisfy most people.
Its my first time setting up an audio system, but I have enough knowledge of the principals to understand most of it.
And No offense taken at all, my issue is I get so many different answers from so many different people claiming all sorts of things. One person says one thing and other says opposite. I also over analyze things way too much so I am probably overthinking it, but overthinking combined with confusion is making me go crazy, I also have OCD in the sense that I can't stand to do thing the wrong way. So I end up asking so many in depth questions and my whole thought process makes it sound like I have no idea what's going on, but I Just want to do it the best and proper way with what I got (using LC2i).

My issue is that my sub is rated for 30-200hz, and I feel like I am not using my sub to its fullest potential by not getting the higher lows from main speaker signals. I feel like the main sub output only goes to like 45hz or something and I am missing out on the 45-80hz or something along those lines.
My thought process was that the LC2i can take 2 input signals and take in everything its getting and output the entire signal the way I want it, and I haven't heard what it sounds like going off just sub signal, so your right, I may be satisfied with doing off just the sub.
I'm going to go as far as using an o-scope to measure signals from factory amp, lc2i and lastly the amps output and I guess learn what the car can give me. I'll start off like you said just using sub signal and if I'm satisfied ill just end it there.

As the backup, why wouldn't doing what I said before work with LC2i? Originally I was going to connect the sub output signal to just the Left LC2i input, so why would adding another signal to right LC2i input be bad?? is it hard for LC2i to process 2 inputs with different frequency ranges on a single channel and give out a clean signal to amp?
 

ebatr24

Senior Member
Joined
Jan 20, 2018
Threads
10
Messages
974
Reaction score
730
Location
Oregon
Vehicle(s)
2017 Civic Type R, 2018 Civic Si Coupe
Country flag
Because that's not what it is intended for. The LC7i is intended for what you're trying to do. It will allow you to set the proper gains of each signal and still use the accubass for help with the bass roll off. Do as you wish though man, you know what the right way to get a full range signal is now.
 
OP
OP

amurciano

Senior Member
First Name
Aaron
Joined
Jan 23, 2020
Threads
14
Messages
241
Reaction score
105
Location
Fort Lauderdale, Florida, USA
Vehicle(s)
2019 Honda Civic Type R FK8
Country flag
Because that's not what it is intended for. The LC7i is intended for what you're trying to do. It will allow you to set the proper gains of each signal and still use the accubass for help with the bass roll off. Do as you wish though man, you know what the right way to get a full range signal is now.
Thank you for the help in understanding better, I now understand that the gains control the inputs and not the outputs, before I thought the gain controls the output level of the signal when it is actually controlling how much to amplify the input signals and if they are different then I may be increasing one signal too high. This makes so much more sense now.
Sponsored

 


 


Top