Powered Sub connected to rear speakers

[Johnny Jeeper]

I just have a quick question...I want to hook a powered sub with crossover to an aftermarket head unit that does not have sub output, I have read you can splice from the rear speakers, my question is do I use + from left rear and - from right rear to go to the sub amp (sub has both high and low inputs) or just tap into either left or right only, and my second question is...does this change the ohm rating of the speakers being spliced or the subwoofer?

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[wew lad 5,000+ posts]

I just have a quick question...I want to hook a powered sub with crossover to an aftermarket head unit that does not have sub output, I have read you can splice from the rear speakers, my question is do I use + from left rear and - from right rear to go to the sub amp (sub has both high and low inputs) or just tap into either left or right only, and my second question is...does this change the ohm rating of the speakers being spliced or the subwoofer?

no no no, you have an aftermarket headunit, does it have RCA outputs? you can split RCA outputs if necessary to your powered sub, you want to avoid splicing into the rear speakers if you can because you already have an aftermarket headunit, which solves a lot of those problems. keep it easy on yourself //content.invisioncic.com/y282845/emoticons/fro.gif.c695f1f814b01c4ad99fe7f8cccadd29.gif

basically, need you to find out if you have RCA outputs

 

[Johnny Jeeper]

The head unit only has 1 set of RCA's just left and right out, I am going to hook up an amp from the head unit to the 4 speakers (2 front/2 rear) and want to connect the sub...if I have the 4 speakers hooked to the amp via the speaker wires (hi input connector to amp) can I then use the RCA on back of the head unit to run the sub?

 

[wew lad 5,000+ posts]

The head unit only has 1 set of RCA's just left and right out, I am going to hook up an amp from the head unit to the 4 speakers (2 front/2 rear) and want to connect the sub...if I have the 4 speakers hooked to the amp via the speaker wires (hi input connector to amp) can I then use the RCA on back of the head unit to run the sub?

use your RCA output with a y-splitter. it's always better to use RCA's if you can, the quality of signal is better, and its much easier and simpler to tune than a hi-input from your headunit. to clairfy what im saying, your 4 speakers eight wires total will go into the output of your 4 channel amp(you will often need to run a 9 wire cable if you're mounting the amp in the back to basically move your 8 speaker wires to where your amp is). the signal into the 4 channel amp will be RCA's from your headunit. the same RCA's will be split with a y splitter to your powered sub. 2 RCA's split to 4

what amp are you using? do your door speakers have passive crossovers or are they stock?

 

[keep_hope_alive Premium Member]

mitchell is right, stick with RCA. don't use high level downstream of another amp.

Y-splitters may not be needed. many 4 channel amps have RCA outputs for adding other amplifiers.

 

[Johnny Jeeper]

Good info thanks!!! now if the head unit only has the 1 rca (L&R) output how does it separate front/back speakers??? so if I run from the rca (L&R) output from head to amp that will give me the stereo out from the head unit but the amp has 4 rca's in how does that work?

 

[wew lad 5,000+ posts]

Good info thanks!!! now if the head unit only has the 1 rca (L&R) output how does it separate front/back speakers??? so if I run from the rca (L&R) output from head to amp that will give me the stereo out from the head unit but the amp has 4 rca's in how does that work?

what is the amp? often they will have a switch allowing you to use only 2 RCA inputs, but if not, use another y-splitter. this is why having a headunit with 2 or 3 (4 or 6 total) rca outputs is extremely helpful - if you have the cash buy one. you cant have front/rear fade with this set up though, but you can individually set the gain on the front vs the rear on the amp if you need to attenuate the rear to keep the sound up front (this is how its supposed to be for sound quality).

 

[Johnny Jeeper]

Sorry...the amp is a small Kenwood marine 50 watt per channel amp, the speakers are 4 Pioneer 6.5 3 way speakers rated at 300 watt max/ 50 watt rms I think they have built in crossovers for the tweeters...

 

[Johnny Jeeper]

I'm trying to set this up for a friend of mine that just got a new stereo for Christmas...I just did a system in my Jeep but used an Alpine head unit I already had around the house, it has 6 rca's on the back for the front, rear speakers and a sub, so it really wasn't very hard to set up I just added an amp for the 4 speakers and another amp for the sub and I was done but this doesn't have all the nice outs on it...lol

 

[wew lad 5,000+ posts]

verify they have passive crossovers in the door, and learn about how HPF's are necessary to attenuate sub bass, and how to properly use the HPF on your 4 channel amp, the rest is just wiring.

sounds too easy, but read the manual to learn about that amps HPF