# Will this LC2i work for wiring this?



## Acidtabvocab123 (Sep 19, 2017)

Hello everyone. New to the forum, and new to the car audio game (sort of). 

I hope this is posted in the right spot I think it is!

So I'll begin by saying I'm a driver of a 2017 KIA OPTIMA EX without the Harmon Kardon audio upgrade. The sound sucks so I have put in a pair of ARC audio 602 speakers in the front. Well it didn't change the sound so I learned I needed a LOC. So I did some research, but I don't think enough research. I have another pair of ARC 6.5s coaxials for the rear, as well as an MBQUART 4 channel 60w x 4 @ 4ohm amp, wiring kit, and LC2i LOC coming today and tomorrow in the mail. 

My question i could not find a clear answer to online; am I able to wire all 4 door speakers to the LC2i and amp, and later add a single 12" sub and mono amp? Or am I only able to wire 2 door speakers and a sub to the LC2i? Can I splice the 4 door speakers into two channels to put into the LC2i? 

I'm also a little confused that the Lc2i is rated up to 400w, that doesn't mean that if my four door speakers take up 200w that would only leave 200w left to add a mono amp to push a sub at only 200w? Or I think I am missing the point of that rating, can someone fill me in here? 

Like I said, new to the car audio game, please be forgiving! I'm just trying to learn, this is really cool stuff to me and I wanna know more. I have only ever wired a sub to an aftermarket HU before. So this is all new to me, but definitely something I'm interested in learning about now that I actually have disposable income. 

Thanks everyone looking forward to the knowledge. ?


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## xTHANATOPSISx (Apr 2, 2007)

The power handling of the LC2i is for the input power from the stock system you are adapting. Has nothing at all to do with the power from the amps you add.

The LC2i has two channels for speakers and two for sub. A left and right for each. If you really wanted to connect 4 speakers to a 4 channel amp getting signal from the "Main" outputs of the LC2i you could, but you won't have fader control for front to back. You'd have to set the relative level with the amp's gain.

If you really want to amp rear speakers get the LC7i and wire it to front and rear signal from the stock head unit to retain fader control.

Unless you're going to implement "proper" rear fill, I'd suggest using the LC2i and just upgrading the front speakers and adding a sub, assuming your rear speakers are properly functional. If the rears are shot, just replace them with some inexpensive coaxials and leave them powered by the stock system. The majority of your experience comes from the front, but rear speakers are nice to have when you've got someone riding in the back.


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## Acidtabvocab123 (Sep 19, 2017)

xTHANATOPSISx said:


> The power handling of the LC2i is for the input power from the stock system you are adapting. Has nothing at all to do with the power from the amps you add.
> 
> The LC2i has two channels for speakers and two for sub. A left and right for each. If you really wanted to connect 4 speakers to a 4 channel amp getting signal from the "Main" outputs of the LC2i you could, but you won't have fader control for front to back. You'd have to set the relative level with the amp's gain.
> 
> ...


Well all right! This is the answer I was hoping for.

-- My rears are fine, I have the fronts replaced with coaxials and for the rears I have new coaxials on the way as well. 

So if I DID bridge the two left front and back and two right front and back i would then connect them to the LC2i as per usual, and then I would just have equal sound coming from all 4 door speakers? Is that what you mean when you say "fader control?" I sort of jumped the gun, otherwise I'd get an LC7i. But I already have the LC2i, it actually JUST Showed up on my doorstep, and my 4 channel amp is showing up tomorrow I believe. 

So, hypothetically considering I have the amp, LC2i, and speakers already, I would be fine using all 4 channels on the 4 channel amp, and bridging connections from the 4 door speakers to power all 4 of them since I did after all buy a 4 channel amp. 

Or is there a way to only utilize only 2 of the 4 channels on the 4 channel amp I bought using only 60w RMS @ 4ohms? If so I'd prefer going that route instead of using all 4 channels since I'd lose fader control. But is losing fader control such a bad thing? Will It really make a big difference? Could I use the cars stock fader control?


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## xTHANATOPSISx (Apr 2, 2007)

Don't bridge anything to from the stock head unit. That won't do what you want and can damage the stock head/amp.

You're not getting fader control on the 4 channel with the LC2i. The end.

If fader is important, you want to leave the rear speakers on stock power.

You need a single pair of left and right, full-range channels to get signal to the LOC. Doesn't necessarily matter where you get that, provided it's full-range and stereo. Could be from front or rear channels, but then the output to the LOC will react the same as the speakers that were connected to those wires did when using the fade/balance of the stock head unit. Thus ideally you'll get front channel signal from front channel speaker outputs from the head unit.

LC2i will give you one L&R pair that's intended for full-range speakers or the like and one L&R pair optimized for sub-woofer signal. That's it.

You can run two of the 4 channels on the amp, or bridge the 4 channels to 2 channels. Either way works with a 4 ohm speaker. One gives you more power than you may need, but you could set the gain for the power you want and be fine, plus that leave headroom on the table so you don't get into clipping at high output levels. Headroom is always a good thing.

Depending on the crossovers in that amp, you could possibly run your component set active off the 4 channel, but you'd need to have some pretty high frequency high-pass filter options, like minimally 1.5khz and possibly much higher depending on the speakers.

It's worth mentioning that there's no difference between front or rear audio signals. They are the same left and right signals, just duplicated and with relative level adjustable via fader. All rear speakers do is reproduce the same sound as front speakers, but behind you where it doesn't really belong when listening to normal, stereo music mixes.


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## Acidtabvocab123 (Sep 19, 2017)

xTHANATOPSISx said:


> Don't bridge anything to from the stock head unit. That won't do what you want and can damage the stock head/amp.
> 
> You're not getting fader control on the 4 channel with the LC2i. The end.
> 
> ...


Wow lot of info! Thanks for helping me. 

So essentially I should bridge the right and left channels from the front to rear speakers, then run wire from the bridge to the amp/loc? 

I'm not TOO concerned about losing fader control, but then again I don't know what I'm talking about so I may end up caring later once I know how it sounds. 

So in the photo are the specs for the MB QUART amp I bought, so the speakers i bought in the front are rated for 75w RMS, the ones I bought for the rears are rated for 60w RMS, both 4ohm. (I ordered some CT sound speakers instead of the ARCs again they were cheaper) -- My plan was wiring all 4 speakers and powering them at 60w at 4ohm bridged. 

So that will work if I bridge the speakers not from the head unit, but from the actual speaker connections themselves? I.e. the front speakers are wired to the head unit, then I would wire the front L/R channels to the rear L/R channels then those connections go to the amp and LOC correct?

If I go the route of ONLY wiring the front L/R channel door speakers I would be giving them 180w RMS bridged according to the amp specs. But I think it would be 120w RMS actually correct me if I'm wrong). So that's almost twice the power they can utilize which again is 75w RMS. I feel like over powering it that much is almost dangerous even if I adjust the gain maybe I'm a noob but that doesn't sound right to me. 

Thanks for the help I should be installing all this Thursday!


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## Acidtabvocab123 (Sep 19, 2017)

Or if I am understanding this correctly, if I bridge all 4 speakers I would then drop down to 2 ohm correct? Which would give me I think 90w RMS per channel on the amp outputting t the 4 speakers. Or am I missing this entirely?


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## Acidtabvocab123 (Sep 19, 2017)

The amp has a mode switch for 2 and 4 channel. And the instructions say how to run the amp as a 2 channel bridged. If you run it 2 channel mode won't it be putting out 120w @ 4ohm?


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## xTHANATOPSISx (Apr 2, 2007)

Don't bridge anything on the stock system. Nothing. Don't do that. Just run front speaker wires to the LOC.

You can bridged the 4 channel amp to the component set if you'd like. It'll make what ever it's bridged power rating is, and that will be limited to no less than a 4 ohm load (the speakers are the load) most likely.

I haven't looked up the ratings for your amp and that pic isn't very readable.

Also why would you think the bridged power of the amp is 120 rms? If the specs in fact state 180, I would assume that's correct.

Amps don't just combine channels with you bridge them. Each channel of the bridged pair effectively "sees" half the load, so the power output is roughly the total of both channels at 2 ohms when bridged to single 4 ohm load.


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## Acidtabvocab123 (Sep 19, 2017)

xTHANATOPSISx said:


> Don't bridge anything on the stock system. Nothing. Don't do that. Just run front speaker wires to the LOC.
> 
> You can bridged the 4 channel amp to the component set if you'd like. It'll make what ever it's bridged power rating is, and that will be limited to no less than a 4 ohm load (the speakers are the load) most likely.
> 
> ...


 OK so, I think I'm going to go ahead and tomorrow just wire the front two speakers. Bridging sounds like not only it will be a pain, but I'll lose my fader control which I prefer to keep after thinking about it. 

So yes you are correct the RMS at four ohm would be 180 W. So the front speakers are rated for 75 W RMS, so should I just take a multi meter do my thing and figure out the correct voltage the speaker needs to be up and sent to gain accordingly?


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## xTHANATOPSISx (Apr 2, 2007)

Acidtabvocab123 said:


> OK so, I think I'm going to go ahead and tomorrow just wire the front two speakers. Bridging sounds like not only it will be a pain, but I'll lose my fader control which I prefer to keep after thinking about it.
> 
> So yes you are correct the RMS at four ohm would be 180 W. So the front speakers are rated for 75 W RMS, so should I just take a multi meter do my thing and figure out the correct voltage the speaker needs to be up and sent to gain accordingly?


I don't think you fully understand any of this.

I don't know how else to explain this, so I'm just going to pummel you with this as simply as I can.

The fader is a function within the head unit. It controls the RELATIVE level of the front and rear speakers. It makes one pair quieter than the other. This change happens within the head unit itself, and directly effects the output from the head unit. This is all a fader does.

The LOC takes the signal from the head unit and lowers the voltage to something an amp's inputs can work with. In the case of your LOC, it takes ONE PAIR OF INPUTS and steps them down. ONLY ONE PAIR. FRONT OR REAR. It receives high-level, left and right signal. Two channels.

You connect the LOC to either the front OR rear speaker output of your head unit. Just one pair. One left and one right. THAT'S IT.

The LOC will take that signal and do up to three things to it.

1. - Lower it from high level to low level so the amp can accept it.

2. - Apply some correction if needed for factory bass roll-off. This restores lost low bass if necessary.

3. - Split that signal to TWO PAIRS of left and right outputs that are at the same volume. One optimized for signal to interior, full-range speakers, one optimized for sub-woofer use.

If you connect the LOC to the front speaker wire, it will be effected by the fader in the same way as the current front speakers. If you connect the LOC to the rear speaker wires it will be effected by the fader in the same way as the current rear speakers.

If you have the LOC connected to the front speakers, and you fade to the rear, you will lower the output of EVERYTHING that gets signal from the LOC. Front speakers, sub, everything.

There is no way you will have any fader control between speakers connected to the amp. Ever. None. Your LOC can't provide that. Ever.

Bridging the 4 channel will never change that, because it wasn't possible either way.

If you want fader control, you'll need to leave one pair of speakers powered by the stock head unit or get a second LOC or a different LOC all together.

You could set the level of 2 channels lower than the others to have a similar effect, but you can't change this on the fly. You'd need to readjust the the gain at the amp to change the front to rear levels. The fader won't effect the levels between front and rear speakers connected to the amp any more. It will be done at the amp.

The only reason you have to bridge the 4 channel amp right now is to have more power for one pair of speakers (by bridging 4 channels down to 2 or to power one pair of speakers off 2 of the channels and power a sub with the other two bridged to a single channel.

Regardless of your amp's actual specs, these are examples of what you could do...

1. - 4 channels of 50 watts into 4 speakers of 4 ohm impedance.

2. - 2 bridged channels of 200 watts into 2 speakers of 4 ohm impedance.

3. - 2 channels of 50 watts into 2 speakers of 4 ohm impedance AND 1 bridged channel of 200 watts into 1 speaker of 4 ohm impedance.

4. - 2 channels of 50 watts into 2 speakers of 4 ohm impedance AND 2 channels not operating at all.

5. - 1 bridged channel of 200 watts into 1 speaker of 4 ohm impedance and 2 channels not operating at all.

6. - 1 channel of 50 watts into 1 speaker of 4 ohm impedance AND 3 channels not operating at all.

DO NOT BRIDGE ANY OUTPUT FROM THE STOCK STEREO. DO NOT COMBINE THEM INTO A SINGLE CONNECTION IN ANY WAY.

Is any of this not clear? I can't help you if you don't understand something so be honest if you just don't get it. However, if you still do no understand, you may be best served taking your equipment to a professional installer and explaining what your goals are.


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## Acidtabvocab123 (Sep 19, 2017)

xTHANATOPSISx said:


> Acidtabvocab123 said:
> 
> 
> > OK so, I think I'm going to go ahead and tomorrow just wire the front two speakers. Bridging sounds like not only it will be a pain, but I'll lose my fader control which I prefer to keep after thinking about it.
> ...


Excuse my ignorance, like I mentioned this is all pretty new to me so I'm pretty much in kindergarten at this point. 

That all makes much more sense. I understood what the LOC was for I was just unclear on the part of which connections would do what and how to do so. I want to do this myself as I am a hands on person and like to do things the hard way (i.e not paying to have this done) even if I don't know 100% what I'm doing. That's why I joined the forum to try and get some help and guidance so thanks for your patience. 

I understand what I need to do. You basically answered my follow up question in your last post.


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## xTHANATOPSISx (Apr 2, 2007)

Best of luck. You can obviously always make a post if you get stuck and need help.


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## Bstreet71 (May 26, 2020)

xTHANATOPSISx said:


> I don't think you fully understand any of this.
> 
> I don't know how else to explain this, so I'm just going to pummel you with this as simply as I can.
> 
> ...


Could you do everything you mentioned to do for the front speakers and subwoofer setup through the LC2i but then use the rear speaker wires from the factory unit and plug them into an additional amp with speaker level inputs to power the aftermarket rear speakers?


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