This is with the Bose System.

Let me clarify.
It is possible to tap the audio signal both before and after the OEM Amplifier.

If you tap the signal before the OEM Amplifier, the definite advantage is that you can get rid of the OEM amplifier and save space. In addition, you will not have to deal with the crazy inborne equalization and crossover protocols that the OEM amplifier is invoking on the sound. However, depending on your setup, you may encounter a significant amount of unwanted noise/hiss if your aftermarket amplifier gain is set too high. The reason for this is that you will need to use an active LOC to boost the signal for appropriate levels for your aftermarket amplifier to handle. An active LOC will boost the entire signal it receives, and you cannot boost sound in the manner without also boosting noise.

If you tap the signal after the OEM amplifier, you can use a passive LOC to cut the amplified signal down to line level for your aftermarket amp. Doing this assures practically no unwanted noise/hiss from the OEM headunit. However, if you choose this method, you will have to deal with the in-borne equalization and crossover protocols programmed into the OEM amplifier. Many users on the boards have consistently complained about these protocols messing up the quality of their music. However, I am told that there is a way to minimize the unwanted effect of the OEM amp's crossover protocols by recombining the post-LOC signal with Y-cables.

Personally, I have not yet tried the second method, but may do so soon. I have implemented the first method in my vehicle, currently using the OEM headunit with an Alpine MRV-F340 Amp for my cabin speakers and an Alpine MRD-M301 Amp for my sub. The gain on the amps are currently turned way down to almost minimum to avoid unwanted noise/hiss. I am going to add a Pioneer AVH-P7500 headunit soon that has 5v pre-outs. Hopefully this will get rid of thr unwanted noise/hiss when i turn up the amp gain with the new headunit. If not, I will have to go with the second method.

Most of this info was formulated from correspondence I've had from David of Navone.

 

I've attached the LOC before and after the bose amp...AND in my car the bass is much cleaner and louder when I tap into BEFORE the amp. I spoke with D. Navone and he insisted I tap in AFTER, however I trust my ears and there is a substanial improvement tapping before the Bose amp.

 

Almost forgot to add, I have no noise or hiss. But my friend has the hiss problem, when he taps before the amp.

 

I am using a Peripheral products Venn 4 before the amp (anybody want to buy a Bose amp?). I would not be surprised if it sounded the best with just putting RCA connected on the on the wires from the head unit. Still waiting for the clean sweep by Jl.

There is a massive thread about it I thought at Sound Domain but can't find it now. They talk about how a few different Bose systems work. The one in th eG does not have the pure signal but the fancier GM products do. It was expressed that the HU may actually have a flat frequency response but I m not sold on it.

need to find that thread,it is book marked at home....

Mark

 

If you're using the JL 500/1 Slash series... there's no need for the LOC. I tapped the signal before the Bose Amp, and it sounds great! I have the gains barely 1/3 of the way up.

If your 500/1 is not the slash series, then you'll need a LOC. Check the specs of the amp or just refer to the JL website.

 

I experienced similar noise/hiss problems when tapping before the amp, which were removed when switching tap after the amp. Did not use a LOC so cannot comment on the effect on the LOC.

 

You can try the PAC AOEM-NIS2, plugs in-line with the Bose stereo and presents 4 balanced RCA outputs... no cutting or splicing... so you can keep your stock amp powering your door speakers and put in a new one for a subwoofer install. I bought mine for ~$50 on eBay.

 

anyone else use one of these? I'm thinking about trying it out

 

I got it, and it did not match the connectors on my 2005 G35 coupe Bose system. Not sure why not, but it wasn't what I was looking for

Dave

 

Can the PAC AOEM-NIS2, install after the bose amp or does it connect to the HU ? since I already got the PAC-AUX install for my IPod, can I still use these two together ?

 

You can run an aftermarket amp without using a JL cleansweep. The cleansweep is not necessary for our car unless you desperately want an aux. input in your trunk. Many many posts about it on this forum. If you really want to run a cleansweep, more power to you. But if you're simply looking for a stealth install, it's not necessary. Do a search for "balanced inputs"