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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:
 
#444 ·
I still can't get bass from my stock bose sub in the trunk with my aftermarket HU. I did the bypass and left the sub wired in and have the plug connected to run through that amp, but no dice. Therefore, is it possible to wire the stock sub via RCA cables much like normal subs?
 
#445 ·
Ok, so would not bypassing the bose amp give me static and interference that is associated with the engine starting (i.e. when I turn the lights or blinker on the noise reacts)....I'm driving myself nuts, I tried grounding the actual unit to different spots...but nothing. What do I do, lol? When just the electricity is on, its golden (perfect sound).
 
#453 · (Edited)
i have a sorta static noise coming from my speakers. its basicly a ticking noise that goes with the engine. ie at idle it's a slow tick....tick......tick, like maybe 5 beats per second and then it increases as I accelerate.

is it likely that this could be fixed with this bypass?

edit: nevermind, its most likely due to the ground i used for my avic bypass.
 
#454 ·
alright i just got done bypassing the amp....i just cut the harness and and put the wires together...same thing as you did except different....i turn my stereo on and i get no noise at all....i turn it up and i can barely hear anything...all the speakers are working there's just no volume at all....what is the deal here? is my headunit just that weak? it shouldn't be
 
#460 ·
Ok, sorry to post this as the thread is already a bit long to read and I hate to add another question, but I've read as much as I can do for now, and I'm hoping someone will know what I should do. I'm a complete newb to this..

My situation is this: Type-S, so I've got all the Bose stuff.

I just picked up a Pioneer Z110BT head unit, a 400w amp, and a 12" sub. Looking to hook it all up in the next few days with my buddy, and hoping to get some direction for my specific install.

I bought the metra amp integration harness from the CRSX store... did I do the right thing, or did I want the "regular" one? Am I able to achieve the best audio quality while still using the harness I bought?

And, what should the general process be for me - like what should I be wiring together, and should I be bypassing the bose amp?

Thx a lot for the help and patience everyone!
 
#461 ·
I also have a Type-S witht he Bose system, I'm also putting in a new head unit. I got that amp integration harness, but you have to keep in mind it's only good if your head unit has enough pre-amp RCA outputs for it. My head unit has only one pair of pre-amp outs, which I'll be using for a sub that I got. So I'm gonna have to do a bunch of splicing and stuff to connect this harness to the correct wires, PLUS bypass the amp. If your HU doesnt have enough pre-amp outs, get the regular harness.
 
#464 ·
I have a question relating to this, I tried to install a aftermarket HU without bypassing my bose amp and for some reason something burned up and all the lights for my radio and my a/c lights are all off now. my cluster gauge lights still work. does the bose amp have anything to do with this burning?
 
#466 ·
I just want to say, I always thought about bypassing the bose amp, but now I don't have any static or alt. whine and I am still using the amp! Secret? 2 monster noise filters. They will cost you though, 40$ each. Best 80$ I have ever spent though since I hate messing/cutting into factory wiring.
 
#468 ·
Hi Millerh

I'm really slow about these whole connection things. I try to read your whole post so many time but I really dont get it at all. Sorry for being slow but is anyway you can explain to me how to do this whole by pass thing in a easier way please or another wy that mor clear? If you would attack more pictures it would be helpful. Sorry to bother...Please help..I'm new to this club
 
#469 ·
Sorry, I don't think I can be mcuh more help. I've had a TL for about 5 years now, so haven't really even thought of this. Most of what I did has faded into a deep memory...the best I can do is what I documented here. If it's not clear enough, maybe think about taking the car into a custom car audio place and have them work on it. Working on your car does require some technical/mechanical aptitude and if you're not comfortable with it even after reading some instructions there is some risk of messing some things up which I'm sure you don't want. My recommendation is don't start a piece of work on your car unless you are confident you can do it. There are plenty of other people out there who do this sort of thing as their job.

Regarding bypassing the amp. The important thing to keep in mind is that you are simply just bridging the wires across the amp connector. So all you really need to do is splice into one wire on the aftermarket head unit side, look at the wiring diagram, and splice into the appropriate wire on the speaker side. There are a million ways to do it. I chose splicing contacts and pluggable wires. But you could just as easily cut all of them and solder them together for an even better connection. The only thing that matters is that pin out diagram on page 1 of the thread.

And remember, this is only needed if you are using an aftermarket head unit and experiencing a horrible static noise. If you're not, don't worry about it. It will work just fine with the Bose Amp and have better connections that aren't jerry rigged.
 
#471 ·
As far as I know, here is the theory of why this is happening...I'm no audio engineer, so this is mostly speculation.

Any output from an amplified signal is going to have some amount of noise in it. When your amp is only amplifying a line out (like a CD or iPod), that noise isn't really audible. BUT, when you are feeding an already amplified signal into another amp (Bose amp in this case), the Bose amp will amplify the entire signal including noise from the first amp. Now you get an irritating hum. Either that, or there is some sort of interference since an amp is not designed to accept already amplified signals. My guess is that if the head unit you are using can do a line-out you won't get this. Also if the head unit you are using is better than the one I had, you also might not get this.

The point is that as a general rule, you don't want to double amplify your signal. If you are going to use a new amp to power your speakers, you will want to wire those independently as well.

The instructions I put here in this thread are unique to the situation where you bought a new head unit and want to use its internal amplifier.
 
#472 ·
So the aftermarket headunit is amplifying the signal already then sending it to the Bose amp which then amplifies the noise from the first amplified signal? lol did I understand that right?...

And the headunit Im going to pick up is the kenwood x494 excelon, but no idea on the line out. As far as wiring the amps independently, Ill be wiring them like most lol from the headunit straight to the amp using rcas...is that what you mean by independently?
 
#473 ·
So under the seat, there will be two plugs connect to the bose's stock amp. One of the plug is the audio units and one of of them is the speaker units. So basically you just connect the audio unit wire to the speaker unit wires like the diagram above and it will bypass the amps right?
 
#474 ·
Yes, that's right.

And to the other poster above, that "amplified noise" is how I always thought of it. Not sure if that is 100% right, but it seems to make sense to me. I mean think about it, the stock system uses the amp under the seat to amplify the sound. But an aftermarket head unit has an amp already built into it. So if you are using the aftermarket head unit to power your speakers AND going into the Bose amp which also powers your speakers...something ain't right there. I think you are amplifying an already amplified signal.
 
#475 ·
Where did you guys ground the headunit at? I have not bypassed the amp yet but have a slight whine when the radio is turned low. I was going to try another grounding location before trying this bypass.

If I did bypass the amp would it be best to keep the sub wired throught he amp like stated above>
 
#478 ·
Iam thinking about doing this bypass but just want to see if there was a better way to delete the stock amp since this thread has been around since 02. Was there ever a harness made to do this amp bypass? Or is there a better way to bypass the bose amp? Thanks
 
#479 ·
there is no bypass harness but the metra 70-1725 allows you to integrate the bose with an aftermarket HU
 
#481 ·
For those of you who like soldering...

I decided to solder in a set of connectors so I could make whatever cut/splice wiring changes I wanted to but still retain the option to quickly go back to stock. There are 26 pins in the amp connector, but only 22 are used, so I grabbed a pair of 24-pin ATX motherboard main cable extensions. I cut the connector off the wire harness and soldered the male/female ends of one extension cable onto the amp wire harness/connector ends.

Attached pics show ATX extension cable (just removed from packaging) and soldering the ATX connector to the Bose amp connector.

Be very careful when soldering to the wire harness, as some wire colors are repeated and once you cut the wires free from the connector, you won't be able to sort out which one actually went to which pin. I chose to cut/solder gradually to guarantee I wouldn't mix up any same-colored wire pairs.

Lots of solder and heat-shrink later, I now have the ATX connector between the wire harness and Bose amp. I can now make whatever wiring changes I want to in between my other ATX extension cable and plug it in, so my wiring will be: wiring harness w/ ATX connector -> ATX extension cable -> ATX connector attached to Bose amp connector -> Bose amp. If I want to go back to stock, I can simply remove the ATX extension cable.

Question for the audio experts in the house: I only have a mono (single RCA cable) sub output on my HU. What would work better, using the stereo outputs to drive the sub only, as per inmylrg, or bridging all 4 channels and driving it with the sub output, as in NSR_dc5's post?
 

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#482 ·
I'm about to install an aftermarket HU,

I have the metra 70-1725 amp integration harness.

Would it sound alot BETTER to use the regular harness (without the RCAs) and bypass the amp?

Or should I only do the bypass if I end up getting hissing/static with the metra 70-1725 harness?
 
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