Free Shipping on Everything.
60-Day Money-Back Guarantee | Lifetime Tech Support

Help! 5 channel amp with only 1 preamp

Car Audio, Video, & GPS

Car Audio, Video, & GPS
Talk about stereos, navigation, amps, subs, and all things car audio

Help! 5 channel amp with only 1 preamp

This question is answered

I currently have a boss ce2505 amp with 4x 150 rms and one 500 rms for the sub. The speakers need 65 rms each and the subs 150 rms each. The problem is that I only have 1 set of RCA outputs on my HU and am not sure how to set it up. I initially had the system set up by a local shop and then connected all four speakers to 2 channels on my amp and the subs to the sub channel instead of using all 5 channels. This caused lots of distortion on my speakers no matter what gain setting they were on, however my sub sounded fine. I'm assuming using all 5 channels would stop the distortion and am trying to do it myself. On the back of my HU, they said they were going to use Y connectors but instead they used one of the RCA outputs and then a whole bunch of little colorful wires on my HU are hooked to a PAC LOC and then the other RCA is coming from that. I'm not completely sure what I'm doing.. help!



[edited by: nikkx323 at 3:56 PM (GMT -5) on Sat, Feb 11 2012]
Verified Answer
  • Wow, that looks like a mess indeed.

    I have no idea why they wouldn't have capped of loose unused wires like they did, not very professional I must say.

    Truth be told, without actually being there to see everything first hand I'm not entirely sure how much help I'll be, but...

    In your first photo you say those wires you're holding are wired to channels 1 and 2 on the amp? Why the **** would thay have wires coming from an amp's speaker outputs just loosely lying about in the trunk?! Sorry, that's just a little frustration towards whomever wired up your system.

    Now you said all speakers play, but I only see two sets of wires coming off the amp from channels 3 and 4 that would be used to power your full-range speakers. This has me wondering if they have all four of the speakers wired to the amp in parallel to the two channels being used somehow.

    In your second photo I believe I see three wires being held, a white, white/black, and purple/black. The White and white/black would be front left speaker outputs from the HU and I have no idea why they wouldn't have capped them off as that could lead to shorting out he internal amp if they were to make contact to something. The Purple and black wire is the ground to the rear right speaker, again, not sue why they just left it hanging.

    Are there any more unused wires behind the HU?

    As for the wires on the LOC, without knowing the model of the LOC I couldn't begin to tell what they are for sure.

    Lastly, in your last photo I see you do have the plugs for the high level inputs on the amp (glad they didn't toss those, at least they did one thing for you), but I see you have one set of RCA cables lying next to the amp. Are those the only two you have to plug into the amp coming from the LOC? I don't see any Y splitters in any of the photos. My assumption is they had a set of RCA cables coming from the LOC and used Y splitters to feed the signal to all four speaker inputs on the amp, but with channel 1 and 2 having wires just lying there unused I can't help but think they daisy chained the speaker together

    Again, without being there in person it's hard to tell as I can't track wires too well in photos.

  • In the audio setting of the head menu, make sure the RCA output is set on 'sub'. It can be set to full range or sub.

    Can you post more pics of the other side of the amp where the inputs are, please ?

    Do yourself and favor and run new 18-16 gauge speaker wire from the speaker outputs of the head to the high level inputs of the amp. Run new 16 gauge speaker wire from the amp speaker outputs to the speakers. You might can use some or all of what is there already, only correctly this time.

    Go to the local 'shop' and demand your money back for the labor part of the install.. They do not know what they are doing. I hope they didn't charge you much for the amp.

    GLH Geeked

All Replies
  • The boss amp has high level inputs, so no need for the LOC. You connect the 8 regular full range speaker wire outputs from your head to the amp high level harness. Connect the RCA output from the head to RCA sub input (ch5) on the amp.

    Lots more settings and amp gain adjustments if you need help with those.

    GLH Geeked

  • May I ask for the model numbers of the speakers and the HU you have? As GLH stated, you can use the High level speaker inputs on your amp, if you haven't disposed of the plugs for them. It'll require you running the speaker wires from the HU to the speaker level inputs on the amp and then new speaker wires directly to the speakers. As for the single preamp output your HU has, I'd like to look up specs on the hU and find if it's for rear, sub, or rear/sub selectable.

  • The speakers are kicker ks65s and the head unit is a pioneer DEH-3300ub. I just connected the two outputs on my HU to the sub input on the amp and had RCA cables run from the LOC to two Y cables. The black cable connected to the Y is plugged into channels 3/4 and is somehow making all 4 speakers play, however the distortion is still there. The white cable is making no sound at all, no matter where i plug it into. I'm really confused. GLH, what exactly do you mean the speaker wire outputs to the high level harness?

  • Quite honestly, I'm not sure why an audio shop would "professionally" install a system using Y splitters in such a fashion. I mean that's more of what a novice would do. Really, they should have used a 4-channel LOC or just wired the HU to the amp via the speaker level inputs.

    While I'm not GLH, the speaker wire outputs are the wires coming out from the Pioneer HU to feed the power to the speakers, they should be white and gray for the front speakers and purple and green for the rear speakers. The wires with the black line are the negative while the solid colored wires are the positive.

    The High level inputs are the inputs on the amp that will allow you to feed the signal to the amp by means of the speaker wire outputs of the Pioneer HU. They are located next to the RCA inputs on the amp (to the left of channel 1 and 2 to be exact). You need the plugs that came with the amp to go that route however, which the shop may have discarded. 

    As for all your speakers playing with the channels 3 and 4 RCA cables attach, are your speakers wired to the amp in parallel on channels 3 and 4 with no speakers wired to channels 1 and 2?

    Would you please take a few photos and post them to help clarify how they wired things up?

  • I'm with Weigel21 on this, I think whoever installed/wired up your system did you no favors at all and it's a mess. We should be able to get it all straightened out, it you bear with us, answer the questions we have, and do what it needs on your end.

    GLH Geeked

  • I found out that lots of things weren't wired, which explains a lot. 

     

     

    Image and video hosting by TinyPic

    Those are channels 1 and 2.

    Image and video hosting by TinyPic

     

    I'm not completely sure what this is. It's coming from the back of the head unit.

     

    Image and video hosting by TinyPic

    Two wires coming from the PAC LOC.

    Image and video hosting by TinyPic

     

    And thankfully I found these. So how exactly would I run the speaker inputs to these things?

    Also, they're pretty tough getting in the amp. Should I just shove these into the amp until it fits? Or is there a certain way to do it?

  • Wow, that looks like a mess indeed.

    I have no idea why they wouldn't have capped of loose unused wires like they did, not very professional I must say.

    Truth be told, without actually being there to see everything first hand I'm not entirely sure how much help I'll be, but...

    In your first photo you say those wires you're holding are wired to channels 1 and 2 on the amp? Why the **** would thay have wires coming from an amp's speaker outputs just loosely lying about in the trunk?! Sorry, that's just a little frustration towards whomever wired up your system.

    Now you said all speakers play, but I only see two sets of wires coming off the amp from channels 3 and 4 that would be used to power your full-range speakers. This has me wondering if they have all four of the speakers wired to the amp in parallel to the two channels being used somehow.

    In your second photo I believe I see three wires being held, a white, white/black, and purple/black. The White and white/black would be front left speaker outputs from the HU and I have no idea why they wouldn't have capped them off as that could lead to shorting out he internal amp if they were to make contact to something. The Purple and black wire is the ground to the rear right speaker, again, not sue why they just left it hanging.

    Are there any more unused wires behind the HU?

    As for the wires on the LOC, without knowing the model of the LOC I couldn't begin to tell what they are for sure.

    Lastly, in your last photo I see you do have the plugs for the high level inputs on the amp (glad they didn't toss those, at least they did one thing for you), but I see you have one set of RCA cables lying next to the amp. Are those the only two you have to plug into the amp coming from the LOC? I don't see any Y splitters in any of the photos. My assumption is they had a set of RCA cables coming from the LOC and used Y splitters to feed the signal to all four speaker inputs on the amp, but with channel 1 and 2 having wires just lying there unused I can't help but think they daisy chained the speaker together

    Again, without being there in person it's hard to tell as I can't track wires too well in photos.

  • In the audio setting of the head menu, make sure the RCA output is set on 'sub'. It can be set to full range or sub.

    Can you post more pics of the other side of the amp where the inputs are, please ?

    Do yourself and favor and run new 18-16 gauge speaker wire from the speaker outputs of the head to the high level inputs of the amp. Run new 16 gauge speaker wire from the amp speaker outputs to the speakers. You might can use some or all of what is there already, only correctly this time.

    Go to the local 'shop' and demand your money back for the labor part of the install.. They do not know what they are doing. I hope they didn't charge you much for the amp.

    GLH Geeked

  • BTW, I'm thinking the amp MIGHT output 75-100 watts x 4 and 300 watts x 1.

    GLH Geeked

  • GLH

    They do not know what they are doing.

    I believe I can agree with that statement, but I'll hold off until we get this system fixed and find the issue to truly announce such.

    The LOC they used is a 2-channel I believe and I don't know why they used it, but it should have been connected to the matching wiring on the HU, with the exception of the two brown wires. Those are to be grounded to the car if the amp doesn't produce output with the other wires properly connected. I can't say that it wouldn't help to ground those brown wires, but I can't say it will either. Personally, the route they took makes little sense IMO.

    As for the actual output of that amp, I don't think GLH is too far off and those output ratings would be at 2 ohms. With your 4 ohm speakers I'd say the amp pumps out closer to 50RMS per channel. On the sub channel it might do something like 300RMS@2 ohms, but with brands like Boss it's hard to tell without having the amp tested, which quite honestly I feel the money spent to do so would be better spent towards the purchase of a new amp.



    [edited by: Weigel21 at 8:24 AM (GMT -5) on Mon, Feb 13 2012]
  • Weigel21
    I feel the money spent to do so would be better spent towards the purchase of a new amp.

    Concurrence once again !

    GLH Geeked

  • Okay, so I need to clip off the wires going to the PAC LOC and instead have individual 16 gauge speaker wires connected to all those individual wires, then run them to the speaker level inputs on my amp?

    And also from my first picture, I'm guessing those are amp outputs and are run straight to the speakers. Would I need to rewire that so all four channels are being used? How should I do that?

  • Yes to the first paragraph and 18 gauge is big enough from the head to the amp. Remember left-right, front-rear, pos-neg.

    1st sentence, 2nd paragraph - not sure. 2nd sentence - yes and be sure to keep up with what I wrote in my 2nd sentence, above. With 18-16 gauge speaker wire, from amp speaker outputs to each speaker. I wouldn't trust anything that shop did to be correctly wired already.

    GLH Geeked

  • Okay, thanks. So how exactly do you run the amp outputs to the speakers? Like, what route should i take to go to the door panels? And should I run them parallel or in a series or anything like that? I have 2002 GMC Envoy if that tells you guys anything. 

  • You will need to move trim and door panels and drill thru wiring molex to get into the doors with the wiring. Call Crutchfield and order the tech sheets or go to an auto parts store and get a Chilton or Haynes manual or go to the GM dealership and see if they will let you print out of a shop manual. Can you tell where the 'audio shop' ran the wiring into the doors ?

    GLH Geeked