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Discussion Starter · #1 ·
Hello, I had a couple questions if anyone could provide some feedback, I would appreciate it. I have attached a screenshot of some wiring diagrams to help understand that were provided by rockford fosgate wiring wizard. except Fig 3, which I added.

I have 2- 12inch subs, they are both 2ohm dual voice coil subs. I want to have them in separate boxes, as I am limited on trunk space. My goal is to be able remove 1 sub/box on the fly, when I need extra room in my trunk, while keeping 1 of them still working.

Fig 1 - shows 1 sub wired at 4 ohms. my amp is 450 RMS x1 @ 4 ohms

Fig 2 - shows 2 subs wired at 2 ohms - my amp is 900 RMS x 1 @ 2 ohms

Fig 3 - my edit where it shows the subs going directly to the amp. If you compare to Fig 2 it looks like the subwoofers are connected to eachother before going to the amp?

My questions:

1. Can I connect sub 1 and 2 directly to the amp, as shown in Fig 3?

2. If i am adding and removing 1 sub on the fly, it would be swapping between 4ohm and 2ohms loads, which is fine because it would have my amp automatically output the required wattage but would this require me to adjust my gains each time I remove/add a box, or leave as it?

Thanks!
 

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Figures 2 and 3 are the exact same thing, both are wired in parallel to the amp.

You can wired them in parallel like that for a 2 ohm load on the amp, and if you remove one sub, then the amp will see a 4 ohm load. You may need to adjust your gain every time you remove, or add the second sub back in, but you'll have to give it a shot to know for sure.
 

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1. Yes no problem.
2. No gain adjustment will be needed. Just pull one out and put something over the wire ends to keep them from touching each other and rock on:)
 

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Discussion Starter · #4 ·
Had another question , does it matter which direction the subs are facing? My seats don't fold down and airflow to the cabin will have to go through the rear deck, right above the subs. Wondering if i face them normal when you open the trunk and you see the subwoofer cone. or lay them down, so the subs cones are facing up forwards the deck ?
 

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Discussion Starter · #8 ·
i see. thanks.

one last question. i hope

reviewing the enclosure specs. should i go for .5 cu ft or 1 cu ft for the internal vol of the box? here is the subwoofer requirements

will i see much difference?
 

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I'd split it down the middle at .75 and then stuff each with about half a pound of polyfil.
 

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Discussion Starter · #12 ·
A couple more follow ups. I can create a new post if required.

but attached are a couple pics.

1. battery - will this battery be okay while adding a 1000d amp to the mix?

2. ground - this device is attached to my battery ground, unsure what it is. i can google it, just thought i would ask

3. radio - these mercedes have a radio feature where you can turn the volume up full blast but it won't go past a certain loudness level, so speakers would "never" blow. anyone familiar with setting amp gains using this type of volume control? i am going to give it a shot but tough to find out the clipping point.

thanks
 

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That battery should be fine. The radio part I'm not 100% sure. I would just turn the volume to 75% and set gains there. If for some reason it's not loud enough maybe revisit setting the gains again.
 

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Discussion Starter · #17 ·
yeah that is the tough part, again with this radio, you can keep turning the dial , it will just spin and spin. and there is no info on the screen, so its tough to gauge what is 75%. lol

ill figure it out though
 

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yeah that is the tough part, again with this radio, you can keep turning the dial , it will just spin and spin. and there is no info on the screen, so its tough to gauge what is 75%. lol

ill figure it out though
Got ya. What are you using to set gains? If you have a scope or something turn it till you know it's all the way up. Like 100 times. See if you have clipping. If not use that to set it. Or turn it 100 times and then back it off to what 75% sounds like to you.

Also. Does the stock stereo apply volume dependent eq. If it does that's a whole new battle.
 

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yeah that is the tough part, again with this radio, you can keep turning the dial , it will just spin and spin. and there is no info on the screen, so its tough to gauge what is 75%. lol

ill figure it out though
Or if you have a multimeter (or buy an inexpensive digital multimeter), take a measurement of the voltage output from your deck to the amp and then use 75% of that, again specified by measuring the output. That would be pretty exact.:)

Edit: it’s best to play pink noise or a test tone (100 or 1,000 Hz) when taking the measurement.
 

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Discussion Starter · #20 ·
yes i will use a multimeter to determine the voltage to set the gain.

another question. i plan to use Audiocontrol LC2i as i am keeping my factory radio. I watched a million videos and they all seems to connect all 4 speaker level inputs on the LC2i. as shown in my pictures. is that required? or can i tab into my factory sub and just use two inputs?

If look at my diagram, showing my cars internal system. i plan to remove the back subwoofer and surround speakers. i can tap into those two surround speakers for L/R, if needed. but could I just use the subwoofer ? it would only be 2 speaker wires, instead of 4. hope that makes sense
 

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