Non-Bose, Bose, Metra, and You.

[DaveRulz]

There have been a lot of questions regarding wiring the Metra kit lately for both Bose and non-Bose, so I figured I'd try to consolidate some information to help people with their installations.

I put together what I feel is a great resource if you are wiring up any system in a Mazda6. I've attached the PDF that I've created.

Non-Bose
-Uses 4 ohm speakers
-Does not have an external amplifier
-The Metra harness "Speaker" wires will lead directly to the speakers.

If you have the Non-Bose system, wiring up your new stereo to the stock speakers and wiring is very easy, just follow the instructions that come with the Metra kit. The 4 ohm impedance of the speakers will not cause any problems with an aftermarket deck and you don't have to worry about a factory amplifier mucking things up.

Bose
-Uses 2 ohm speakers
-Has an amplifier under the passenger seat
-The Metra harness "speaker" wires actually lead to the preamp input of the amplifier. Examine the wiring harness diagrams I have attached and you'll see what I'm saying.

Given this information, it's important to note: If you have the Bose system, and you hook up the speaker wires of your new head unit to the "speaker" wires in the Bose harness, you will be sending an amplified signal to the Bose amplifier's preamp input and the result will be less than stellar, actually quite crappy, sound.

On the other hand, this also allows you to easily integrate an aftermarket deck using it's preamp (rather than speaker) outputs. So you can run the Bose system off of a different head unit. Research shows that the signal processing for the Bose system is actually performed in the amplifier. So the system should perform identically even if you replace the head unit.

To do this, it's as easy as soldering on 4 male RCA plugs to the "speaker" wires in the Metra harness. The negative "speaker" wire should be soldered to the pole on the plug that connects to the ring. The positive "speaker" wire should be soldered to the pole on the plug that connects to the post. Once you've done this for the FR, FL, RR and LR "speaker" wires, all you have to do is plug in your front and rear RCA jacks from your head unit and all should work well.

One thing to note on this sort of set up. You will want to be very judicious with the volume control until you figure out how the system is going to perform. Some aftermarket head units have very strong preamp signals that could easily overdrive the Bose amp if care is not taken. If it turns out that your system is reaching full volume at low settings on the volume control, the preamp output will probably have to be padded.

Another note on the Bose system is that there is no way to run the stock Bose speakers off of an aftermarket head unit without using the Bose amp. Firstly you'd have to bypass the Bose amp all together and I'm pretty sure there is no harness made to do this like there is for other cars. Secondly, the low impedance (2 ohms) of the speakers would either have your head unit going into protection, or fry the amplifier section all together. Both of which are not good situations.

You can use an aftermarket amplifier to drive the Bose speakers since every amp I can think of is 2 ohm stable. However, given the signal processing built into the Bose amp, you probably won't be very satisfied with the sound.

If you want to use the aftermarket Deck to run some aftermarket door speakers, you're going to have to either make up an amplifier bypass harness using the diagrams I made, or run new wiring into the doors. Kinda a pain in the ass, but until there is an amplifier bypass harness made, it is your only choice.

I think that covers the basics of using the Metra kit with both systems. Let me know if anyone has questions or corrections.

[lapis_blue_beast]

Makes me happier and happier every day that I didn't waste money on bose.

Would be a good topic to pin.

[bamaboy23]

Glad I didnt get the Bose also, i wanted to change all speakers and everything anyway. But this is what a forum is suppose to be about. People helping each other out with useful information instead of useless attacks. Great write up, and I know alot of people are going to enjoy it.

[EvilEvilPanda]

Very intuitive. I just have one question. You mentioned that the signal processing is built into the amp. If I were to replace the amp and speakers without replacing the deck, the sound wouln't be very satisfactory?

[DaveRulz]

Originally posted by EvilEvilPanda@Oct 28 2005, 11:07 AM
Very intuitive. I just have one question. You mentioned that the signal processing is built into the amp. If I were to replace the amp and speakers without replacing the deck, the sound wouln't be very satisfactory?

[snapback]544898[/snapback]

Nope, the exact opposite. The bose amp and speakers are made to work together. They compensate for using crappy speakers by EQing the hell out of them to make them sound "good". Keeping the stock head unit and replacing the amp and speakers with aftermarket goods is a great way to upgrade the system.

[ChoppaBoy]

answered all my questions, thanks dave

[Arizona6]

awesome, thank you ;D

[Bfrere]

Good information and since you seem to know a lot about the 6 audio, would it be possible to put a 6 cd changer into a normal non-bose 6 radio?

[DaveRulz]

Originally posted by Bfrere@Oct 28 2005, 07:10 PM
Good information and since you seem to know a lot about the 6 audio, would it be possible to put a 6 cd changer into a normal non-bose 6 radio?

[snapback]545356[/snapback]

I don't know the answer of that for fact, but from what I've read, no.

[UCLeadGuitar]

Great write up Dave and thanks for all your help when I was installing my HU. I am actually going to be trying to install a 6 disc in my friends non bose...will let you guyz no how that turns out.