Head unit 1 output rcas, to 5 channel amp, LOC or 1 set off HU

[RyanJ0022]

Hi guys, been a while since I did any car audio but my buddy ordered equipment (not sure how he picked out what he did but)
HU is JBL R3500
Amp is JL M700/5
Three sets of 6.5 M3 JL speakers and a prefab 10" sub box (hasn't told me the specs of this)

I was going to help him install and my 2 questions. Do I convince him to buy a new HU (he's really fighting me on this) or will a LOC work. My concern is using the 4 channels on the amp for his six speakers, running channels 1 and 2 to the fronts at 4ohm (75rms) and the back four on channels 3/4 at 2ohm (50rms per speaker) with also adding a LOC to get the sub output just doesn't sit right.

Even with doing that, would I use the LOC for the fronts and the one rca output for the rears? Fade and balance isn't a priority, just sound quality. Not sure if running the four speakers at 2 ohms off channels 3/4 should get the LOC.

Another option is running the fronts off the HU, and adding the loc for the rear 4 speakers to get the subwoofer rcas. I am just unsure of how to get this decent without swapping the head unit.

Looking for advice thank you

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[RyanJ0022]

Hi guys, been a while since I did any car audio but my buddy ordered equipment (not sure how he picked out what he did but)
HU is JBL R3500
Amp is JL M700/5
Three sets of 6.5 M3 JL speakers and a prefab 10" sub box (hasn't told me the specs of this)

I was going to help him install and my 2 questions. Do I convince him to buy a new HU (he's really fighting me on this) or will a LOC work. My concern is using the 4 channels on the amp for his six speakers, running channels 1 and 2 to the fronts at 4ohm (75rms) and the back four on channels 3/4 at 2ohm (50rms per speaker) with also adding a LOC to get the sub output just doesn't sit right.

Even with doing that, would I use the LOC for the fronts and the one rca output for the rears? Fade and balance isn't a priority, just sound quality. Not sure if running the four speakers at 2 ohms off channels 3/4 should get the LOC.

Another option is running the fronts off the HU, and adding the loc for the rear 4 speakers to get the subwoofer rcas. I am just unsure of how to get this decent without swapping the head unit.

Looking for advice thank you

I left a detail out, this is for a 24 foot Bentley legacy pontoon.

 

[maylar 10+ year member]

You don't need an LOC. Just use Y adapters and plug the rear HU channels into the amp's sub inputs.

 

[Doxquzme Premium Member]

A set of these at the amp

https://www.amazon.com/dp/B08669YZDJ/?tag=caraudiocom-20

Then the sub out to the amp. Important that you are using 4 ohms speakers as the JL is 2 ohm stable and you have the 2 sets of speakers at 4 ohms, it will be a 2 ohm load to the amp on that channel. If you purchased 3 ohm speakers, it will cause the amp to go into protect mode or damage the amp altogether.

 

[RyanJ0022]

Hi guys, been a while since I did any car audio but my buddy ordered equipment (not sure how he picked out what he did but)
HU is JBL R3500
Amp is JL M700/5
Three sets of 6.5 M3 JL speakers and a prefab 10" sub box (hasn't told me the specs of this)

I was going to help him install and my 2 questions. Do I convince him to buy a new HU (he's really fighting me on this) or will a LOC work. My concern is using the 4 channels on the amp for his six speakers, running channels 1 and 2 to the fronts at 4ohm (75rms) and the back four on channels 3/4 at 2ohm (50rms per speaker) with also adding a LOC to get the sub output just doesn't sit right.

Even with doing that, would I use the LOC for the fronts and the one rca output for the rears? Fade and balance isn't a priority, just sound quality. Not sure if running the four speakers at 2 ohms off channels 3/4 should get the LOC.

Another option is running the fronts off the HU, and adding the loc for the rear 4 speakers to get the subwoofer rcas. I am just unsure of how to get this decent without swapping the head unit.

Looking for advice thank you

I left a detail out, this is for a 24 foot Bentley legacy pontoon.

A set of these at the amp

https://www.amazon.com/dp/B08669YZDJ/?tag=caraudiocom-20

Then the sub out to the amp. Important that you are using 4 ohms speakers as the JL is 2 ohm stable and you have the 2 sets of speakers at 4 ohms, it will be a 2 ohm load to the amp on that channel. If you purchased 3 ohm speakers, it will cause the amp to go into protect mode or damage the amp altogether.

so with one set of outputs off the head unit, I can y split these for the rca outputs for the speaker channels and sub channel?

I did a bad job of explaining. The HU has one set of RCAs total, there are no sub RCAs off the back of the HU. I'm trying to hook up a sub and 6 speakers off the 5 channel amp, with just one set of RCAs off the head unit. That can be done?

That can be done without a LOC?

 

[Doxquzme Premium Member]

I looked up the HU, one set R/L outputs. Since it's a boat and considerations for fading are moot, then yes, a set of RCA to the amp, splitters at the amp to fill all four inputs. That amp has a set of RCA outs, run an RCA cable from those to the sub amp's inputs, good to go.

One set of speakers will get a dedicated lead from the amp, one set will have the other four, wired in parallel on each side. Adjust the gains so output is where you want it be, good to go. Might have to set the gains a little in favor of the set that will be a regular 4 ohm load as the sets in parallel will draw more output from the amp then the other set will.

 

[dragon.breath 10+ year member]

It would also be easy to add an equalizer to have individual rca inputs for all of the channels. A decent one can be had for less than $40.

CT-7EQ // 7 Band 1/2 Din Parametric Car Audio Equalizer with AUX Input

The CT Sounds CT-7EQ is a 7 band 1/2 din parametric car audio equalizer designed to divide and enhance the segment of frequency for your car audio application. The car audio equalizer features 7 bands that divide 20Hz - 20kHz into 7 segments.

www.ctsounds.com