When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I'm trying to plan out my my sound system build that is hopefully going to happen next week.
So my question is if any one knows what kind of signal is transferred from the head unit to the amp? Obviously they aren't high voltage outputs or more people would use them. Does anyone know if they are low voltage outputs or data or optical or something else? I'm pretty sure it's not an optical signal but you never know. If it's low voltage that would be really really REALLY cool.
The reason I'm asking is so I can bypass the factory amp with it's factory EQ entirely. I'm hoping to use a raw, untouched signal from the factory head unit to get the best signal possible to put into my DSP.
Worst case scenario I can pull the head unit and meter the lines to figure it out but if you guys can save me the time that would be great.
Here is a post I wrote for another member asking similar questions. Short answer: there is a differential bus between the HU and amp. The amp has the DACs that convert the data to analog signals you can use. You have to go after the amp unless you are an audio engineer.
EDIT: I had to regenerate the image because the link used before was deleted. Now that I am looking at the full wiring harness breakdown, I see there are 6 signals running from the HU to the amp on connector A that correspond to 4 corner speakers, the front center and sub woofer. It seems plausible that you can capture these signals to run to your EQ and amp. I can only speculate what the Bose Bus is for.
Originally Posted by oo7spy
In general, an after market system with an amp is achieved by catching the signal somewhere between the HU and speakers, supplying that to the new amp, and driving your new speakers from the amp.
The RL head unit goes to a factory Bose amp. This is a low power line that is only used to transfer the audio signals. The amp takes this low power signal and amplifies it to a high power signal that can drive the speakers. Here is the wiring diagram for the amp. (The amp is on the passenger quarter panel of the trunk.)
From the signals here, I have high confidence Bose uses a differential bus to transfer the audio data from the head unit to the amp, Bose Bus +/- (A10 & A11). The amp decodes the data and converts it to analog signals that go to the speakers. Because of this, you cannot do anything with the wires from the HU to the Bose amp.
You will need to capture the signal on the speaker side of the amp. (This is what the PAC AOEM-HON20 is doing, but PAC-Audio doesn't have a system for the 2G RL that I can see on their site.) Take the signals from the Bose amp that are going to the speakers you want to replace, connect them to your amp, and run your amp signals to your speakers. You can capture the Bose amp signals either by a line-out converter or by plugging the wires going to the speakers directly into the amp if it has signal level inputs. I would suggest the signal level inputs because that will keep the surround sound capabilities unmodified. EDIT: Your amp does have them. They are called speaker-level inputs as described at the very bottom of the page here: http://www.crutchfield.com/S-c2hBfl6...r-IX500-4.html Be sure to take note of this. I also suggest unplugging all of the other speakers at the speaker so that they can be plugged back in if you every revert to stock. However, I would leave the sub-woofer plugged in (unless you have another option for a sub-woofer). I say this because otherwise you will have two sets of speakers driven by two different amps, and the levels probably won't match. By doing this, you will have a stand alone system that can use any speakers that will match your amp.
By going this route, you will only need to cut the wires for the 4 speakers you are replacing. Everything else can be disconnected at the speaker.
If you really wanted to go all out, you could put a DSP between the Bose amp and your amp to clean up the quality and adjust levels, but it is not necessary to achieve what you are asking for.
Looks to me like I may be able to use those wires going from the H/U to the amp as you've speculated. I'll have to meter them to make sure the signal won't damage anything but that image will help me out immensely.
I'm curious as to why the bose bus lines are there too. I'm almost wondering if it's for volume control and the signal wires are just straight signal with no level adjusting going into the amp. If that's the case I may have to use the speaker outs on the factory amp.
Inputs compared to outputs confirms that the crossovers are all built into the bose amp, which is something else I want to bypass so I can get a full unfiltered signal going into my DSP.
I'll measure them this weekend and report back with my findings.
going to happen next week.
