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You should ALWAYS bypass the Bose amp....here's why

327K views 721 replies 251 participants last post by  Cstout 
#1 · (Edited by Moderator)
A while ago, I posted that I was getting some serious static/noise from my JVC KDSH909. The problem was the Bose amp.

I had just hooked it up with the wiring harness and although the sound quality was better, there was noise. I bypassed the amp this weekend by just putting a jumper wire between the correct wires down at the amp's connector. The noise problem has completely gone away. I highly recommend bypassing the Bose amp. :thumbs up:
 
#152 ·
ok i did the bypass and now i am trying to figure out how to get the stock sub to work. I remember seeing a picture of how the sub rca from the headunit connects into the trunk wiring, but I can't find it. So I will explain what i did. I cut the wires under the seat for the BOSE amp and soldered those so its bypassed. Then I plugged that harness back into the amp. Shouldn't this give power to the Bose Sub? I then ran the RCA outs from the sub output on the headunit to the trunk and cut the other ends off. Then cut the green and wht/grn wires next to the bose xover in the trunk and connected the rca wire into those. Turned on my HU and turned on the SUB in the menu and nothing. Is there something that I am doing wrong here?
 
#153 ·
uh no.......

is the amp for the bose sub even getting power? if so, how did u tie the rca's in with the wires going into the sub?

also, if you did follow my method, the only wires that should have been cut should have been the ones going to the 4 speakers. Left front, right front, left rear, right rear. and then should have been tapped into the input wires of the amp, or the output wires of the headunit. No other wires should have been cut. Then the harness should be plugged back into the amp, then everything should work. what you are doing is still giving the amp full signal so it can do whatever it wants to send sound to the sub. but since the speakers arent connected to the amp anymore and are connected directly to the stereo, you get to enjoy the better sound.
 
#154 ·
the amp should be getting power. I only cut the 4 speaker wires and soldered them together and plugged the bose amp back in under the seat. nothing else was touched.

then the rca's I connected to the sub out on the headunit and took that and ran it to my trunk. I cut those ends off the rca and connected that into the sub amp in the trunk. the green and wht/grn wires.
 
#155 ·
so u cut open the rca cable... the center of one channel of the rca cable is positive, and the outer wiring is negative. so im assuming you connected both centers of left and right, to positive, and both outsides of the rca to negative.


perhaps theres a crossover somewhere thats set, or something isnt turned on.
 
#156 · (Edited)
thank you that has to be the problem. I just cut off the middle part in the middle of the strand of copper. I didnt know negative runs in there. Its late but I might go try this right now. So let me go do that. No one mentioned anything about how the rcas looked inside when doing this. Now only if I could see that pic of how this was done. Thanks again!!!
 
#157 ·
no no no...........

if you take one side of the RCA pair... so you have (o) looking from the top. the ( ) is the negative. and the o is the positive. so what you would do is combine both centers from Right and Left. then combine both outsides from the Right and Left (without having the center touch the outside strands of wire). then connect them to the sub.
 
#158 ·
just did it, plus ran the rca under all the carpet and stuff. thank you!! it worked. so in case anyone else had the same problem as me, you just do what he said with connecting the middle parts of the RCA to the light green wire and the outer part of the rca to the grn/wht wire. and magic it works. Of course I wasnt expecting much from this sub, but its nice to have it doing something while it sits in the trunk. Thanks again!!
 
#160 ·
Does anyone if this piece works from crutchfield to bypass the amp? (I'm about to install a new HU and want the HU powering the speakers, but still want the stock bose sub to work).

Crutchfield custom wiring harnesses are lifesavers! You'll save many steps when installing an aftermarket receiver in your car. Simply splice the color-coded wires on your Crutchfield harness to the wires from your aftermarket radio — and do it in the comfort of your home without having to struggle with splicing wires behind your dash. (Most of the wire splices can be made on your work bench or kitchen table. Soldering is best, crimping is also very popular — see "Recommended Accessories").

Next, plug the Crutchfield harness into the harness that you removed from your factory radio.

Since you didn't have to cut off your car's original radio connector, it's easier to put the factory radio back in when you sell your vehicle or return it at the end of the lease. Just plug the factory radio back in and keep the aftermarket radio! Best of all, the harness is free with most of the receivers Crutchfield offers! 30-day warranty.

Connections:

Note: This harness uses your factory amp. The aftermarket radio you use with it needs to have 2 sets (front and rear) of preamp outputs.
» 12V constant power
» 12V switched power
» chassis ground
» illumination
» dimmer
» left and right front RCA connectors
» left and right rear RCA connectors
» 30-day warranty

 
#161 ·
No that is not what you want. all that does as explained before, is allow use of the Preouts on the aftermarket stereo to interface with the bose amp. it does not bypass the amp, as there is NOT a harness that does this yet. the only way to do it is by modifying the wires at the bose amp. so you will be still using the bose amp to power everything...
 
#162 ·
Ok, cool. I'm still trying to wrap my head around how to bypass the amp and use the stock sub. I'll probably have more questions, but from what I can gather, I'm basically taking the speaker wires from the HU and connecting them directly to the speaker wires going out of the amp (that lead to the speakers) -- does that sound right?

That seems a bit simplistic, since throughout the previous posts there's talk of splicing and tapping and all that. Not too knowledgeable of wiring, but hope I can do this ;)
 
#164 ·
Yeh, I need to read it a bunch of times over, since nothing really sticks when I start hearing splicing, tapping, etc. etc.
 
#165 ·
I don't suppose anyone has some pics of the input & output side of the bose amp? I'm finally addressing this topic since I have my deck coming in, and I think I understand the bypass process (of jumping the HU and speaker wires). Not exactly clear on how to keep the stock sub in tact, by "cutting off the output wires and plugging the harness back in." Any guidance before I get down in there would be great (and apologies for the question, since this is quite a long thread already)
 
#167 ·
i will take some pics tonight or tomorrow of how i did my bose amp for the stock sub. i basically ran the RCA plugs from the subout on the new headunit, then connected those to the amp in the trunk. Then you cut the color coded wires on the bose amp under the seat and connect them to each other. So pretty much the wires that come from the stock headunit to go into the amp, from there they go to the speakers.

Now you are bypassing the amp and direct connecting the speaker wires. Anbd that all takes place under the seat. I just cut the wires and soldered them together. The original poster suggests tapping and spliucing wires. But that method doesn't allow the amp in the trunk to power on when your stereo turns on. Will post pics though, probably will help some out in here.
 
#168 ·
Hey travanx! Thanks for posting all that you have on this topic so far, but I have a question. My HU has an RCA sub output like yours and a ran a cable to the trunk for future use. I already cut the speaker output wires in the back of my aftermarket HU. If I leave the stock amp under the seat plugged in, would I be able to connect the stock sub by just doing what you did with the RCA cables? Do I have to bypass anything since the speaker wires have already been cut from the back of the HU (I ran my own wiring from an aftermarket amp)? Or did I already bypass the amp by running my own wires (sorry, Im new to this stuff)? Thanks for the help!

phon
 
#169 ·
i dont think you need to bypass anything if you are just connecting the sub to the HU. but I dont understand when you mention the aftermarket amp. whats that powering? i am going to assume you mean you ran your own wires for the speakers to a new amp? that is bypassing the amp then.
 
#170 ·
Yeah, my after market amp is powering my aftermarket front and rear speakers. But, since the rewire, the sub is no longer connected. What I wanted to know is... If I leave the stock amp under the seat plugged in, would I be able to connect the stock sub/amp by just doing what you did with the RCA cables? I assuming the stock amp under the seat powers the stock subwoofer..? Or are there two amps? I just want to know if I can hook the stock sub up to my HU by doing what you did. Thanks for replying!

phon
 
#171 ·
just run the sub rca's and you splice those into the sub in the trunk. i took a pic but its hard to see. i will post it later. the bypass yuo want to keep plugged in because it makes the amp for the sub turn on with the car. the amp for the sub is in the trunk next to the sub. but the remote turn on is on the bypass part.
 
#173 ·
I tried hooking up the sub in the back and it didn't work. I am using a 'Y' adapter, but that should work, shouldn't it? Light green to the ( ), striped to the 0. Right? Also, like a dumbass, I pulled out the green/striped wires out of the harness instead of cutting them. Will it still connect if I just stick the new wire(the one Im using to connect the rca's) in the proper holes? Or did I really screw up? Please help!

phon
 
#174 ·
i am gonna post a picture, but of course i forgot that the tape is in the way to show whats going on. i think i explained it pretty clearly in one of my posts on here though.

 
#175 ·
I attempted the bypass where instead of splicing wires, I made jumper wires and plugged them into the female harness. However, when I turned the radio on, I get nothing, no sounds, no noise, nothing. When I pull the jump wires out and plug it back into the Bose amp, I get sound again...

Can anyone provide some insight on what I could be doing wrong? Apparently, the method I tried has worked for some...
 
#176 ·
Is it possible to take an aftermarket HU, plug in the 98+ harness, disconnect the Bose amp completely, and use the preamp output on the HU to go to an aftermarket amp (4 channel) that will power the speakers? Just checking to make sure before I go out and spend like $200 on an amp, thanks.
 
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