# How Many Pre-outs Do I Need?



## improvise (May 25, 2011)

Hello everyone. I am very new to car audio. I have purchased the following:

Front doors - JL Audio C5 components 6.5

Rear doors - JL Audio C5 Co-ax 6.5

Subs - JL Audio Stealthbox Dual 10w1

Amp - JL Audio HD900/5

Headunit- In progress

Which brings me to my question. I desire the Pioneer AppRadio. The problem is the AppRadio only has one set of pre-outs. 

My question is: If I am only using one amp, will one set of pre-out be sufficient enough? 

Or do I need a headunit with multiple pre-outs.

If I need multiple pre-outs, why?

Thank you in advance for your input.


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## seekingSQnirvana (Dec 21, 2008)

I personally like 3 pre-outs: front, rear, and sub. That gives you the ability to fade front to back, and the sub pre-out usually means the h/u has built in low pass filter (which is nice to have).


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## rain27 (Jan 15, 2009)

Are you using a processor? The MS-8 for example only needs one set of preouts from the head unit to create 4 sets out.


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## improvise (May 25, 2011)

The only processor I will be using are the crossovers that were included with the mids and highs.


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## prince427c (Dec 7, 2010)

Simply enough, only use the amount of pre-outs your amp needs. It looks like that amp accepts 3 pairs of inputs. If you can supply all 3 from your deck, awesome. Use ALL of them. If you can only supply 2, use y-splitters for one pair to the amp for the front/rear inputs(they are the same anyhow. This will prevent you from fading, though), and use the 2nd pair for the sub input. If you can only supply one pair(which is rare), you may have to split it twice per channel. Some amps only require you to have one pair of inputs on the front stage since it just duplicates it for the rear stage anyhow. More than likely, you will need separate inputs for the sub stage though. If you have less than 3 pairs of pre-outs on your deck, and you are not satisfied with these conditions, you will need a processor between your HU and amp to handle that.

Since you have the rare condition of single pairs of pre-outs, the signal might have to be split twice per channel. This is fine, but you lose a lot of flexibility. If you want more flexibility, see above about a processor.


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## improvise (May 25, 2011)

I think that was the answer I was looking for. Much appreciated!


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## TrickyRicky (Apr 5, 2009)

Not really. You want to have fade. Now for the sub you can use either front or rear (but rear being the optimal choice).


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## prince427c (Dec 7, 2010)

TrickyRicky said:


> Not really. You want to have fade. Now for the sub you can use either front or rear (but rear being the optimal choice).


You can't fade with one set of pre-outs though. You can control levels with say, a 3XS, in this regard. One set of pre-outs requires a processor for any fading ability.


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## improvise (May 25, 2011)

prince427c said:


> You can't fade with one set of pre-outs though. You can control levels with say, a 3XS, in this regard. One set of pre-outs requires a processor for any fading ability.



I have never used the fade function in my factory unit. I cannot envision a scenario that I will be using the fade function in an aftermarket install.


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## Angrywhopper (Jan 20, 2010)

3 preouts.


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## prince427c (Dec 7, 2010)

improvise said:


> I have never used the fade function in my factory unit. I cannot envision a scenario that I will be using the fade function in an aftermarket install.


I've never used it either, but I've often not had a rear set of speakers to fade to :laugh:


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## improvise (May 25, 2011)

prince427c said:


> I've never used it either, but I've often not had a rear set of speakers to fade to :laugh:


Hmmm, if I decide to purchase the Pioneer AppRadio (highly unlikely at this point) I guess I could go with a in-dash EQ/line driver like the Audio Control Three.2. 

Thoughts anyone?

Thanks!


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## Jericho941 (May 24, 2011)

improvise said:


> Hmmm, if I decide to purchase the Pioneer AppRadio (highly unlikely at this point) I guess I could go with a in-dash EQ/line driver like the Audio Control Three.2.
> 
> Thoughts anyone?
> 
> Thanks!


You might not need to have an eq as expensive as the one from AudioControl, but I would go that route if I were stuck with so little head unit pre-amp options.

As long as there are separate gains for the front and rear channels on the amp, you don't need a fader control, but it might be harder to get dialed in. Many here keep their rear speakers turned down a bit to prevent the front sound quality/imaging from being interfered with by the rear speakers. If you want to avoid having a separate eq, I recomend just getting the remote bass knob to go with the install. The main flaw I see with the single pre-amp output is that you'll have no sub adjustment from the front if you have a single set of RCAs split into six channels. The remote bass knob would be alot simpler than adding an eq.


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## Richardwr83 (Mar 10, 2019)

If you have 3 pre outs 
1 front 
2 rear 
3 sub

What do you do with the speaker wires on the stereo?


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## Redliner99 (Mar 26, 2018)

Richardwr83 said:


> If you have 3 pre outs
> 
> 1 front
> 
> ...




Nothing you won't be using them if your using an amp 


Sent from my iPhone using Tapatalk


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