Aftermarket Headunit w/ stock Bose

[dminter]

I just had my 2005 g35 coupe stock Bose headunit replaced with a Eclipse AVN726E

My main issue is static on the whole system, most noticeably on the rear speakers even when the volume is at 0.

It is going back to the radio shop this week but they tell me it may be a problem with the aftermarket headunit and the Bose amp.

They said if they can't fix it they would just run speaker wire from the headunit. I find this to be unacceptable.

Any thoughts or suggestions on things I can do or make them do to correct my static issue?

thanks!

[Deezflip]

it's just the way it is....it's hard to get the bose amp to cooperate with any aftermarket headunits. Using the aftermarket headunit's internal amp and directly connecting them to the speakers wouldn't be such a bad idea(as long as the internal amp can handle 2ohm speakers). Although the headunit might run a little hotter even if it's capable of running 2ohm. However, this will completely bypass the bose amp.

Another option would be to swap out the bose amp with a nice 4 channel amp, but i would also recommended running some better RCAs instead of using the stock signal cables originally intended for the bose amp.

[dminter]

Is there a proper way or adapters to hook up the amp? maybe they used the wrongs one/method?

I don't really have the $ for the amp lol

[Deezflip]

I don't think it's necessarily any of the adpaters used. If i'm not mistaken, the bose system consists of a balanced signals for noise reduction.

Replacing any of the bose components seem to disrupt those balanced signals, I'm not really familiar with balanced signals but my best guess is that the bose has it's own way of suppressing noise in other ways of a simply grounded it the chassis.

I swapped out my bose amp for some cheap 4 channel rockford amp on craigslist for $50 and it sounds great. I had some noise when I used the stock signal wires originally intended for the bose amp. So i replaced those with some shielded RCA and all the noise dissappeared. You can give some new RCAs a try but the bose amp will still induce noise probably.

[mattyjman]

i think deezflip hit it on the head...you have an amp that is designed to run differential balanced, and with the new headunit it is sending just a regular unbalanced signal. This can cause the noise you are hearing. In my experience working at a shop, we would NEVER do a deck with a bose amp, without bypassing that amp with a rewire. Then you run into impedence issues, which led us to the most common solution...not do it unless they are buying speakers too. It costs more, sure...but in car audio you have to fix the weakest link first. Now that you have the HU done first, best option would be new speaks and a rewire...just my .02 though.

[Gilley]

The Bose amp is the worst part of the Bose system. It's low powered and has funky sound shaping built in.

[pfarmer]

Originally Posted by dminter

I just had my 2005 g35 coupe stock Bose headunit replaced with a Eclipse AVN726E

My main issue is static on the whole system, most noticeably on the rear speakers even when the volume is at 0.

It is going back to the radio shop this week but they tell me it may be a problem with the aftermarket headunit and the Bose amp.

They said if they can't fix it they would just run speaker wire from the headunit. I find this to be unacceptable.

Any thoughts or suggestions on things I can do or make them do to correct my static issue?

thanks!

You most likely have an unbalance set of rca outputs connected into the balance inputs of the Bose. This is bad for several reasons including grounding the negative half of the balance input. If a shop did this you may want to go to another shop. If you are staying with the Bose amp (which I would replace) then what you need is what is called 'balance transmitters'. These will convert rca to balance and should be installed as close as possible to the head unit. You may get away with a balance converter which cost about 20 bucks but these are typically inductor based and will degrade the sound and will not impedance match.

There are many 2 ohm amps so probably the best way if one is on a budget is to find a reasonably priced amp, keep the speakers, and then upgrade from there. I would get a 5 channel amp so you can connect all door speakers and a sub in the back. Many have 2 ohm options which can be changed later if you change your speakers. However aftermarket speakers such as Infinity are also 2 ohm. You'll probably have to set the levels down low until you upgrade the speakers and then you may want to look at the speaker wire gauge on the stock speakers as that may need to be fixed as well.

Optionally check the output impedance capability of the head unit which is probably close to equal that of the stock Bose in other ways. Most do not have a dc-dc converter and therefore will output about 22 1/2 watts per channel with standard single sets of push pull outputs. This is pretty much standard with the built in head unit amp as your rail voltage is your battery/alternator voltage. You will however probably lose the use of your sub.

If the budget was not a concern I would do the following:

One -

Connect the rca outputs of the new head unit to balance transmitters with a high output voltage (up to 50 volts). This increases the signal to noise ratio.

Two -

Run new balance lines to the back.

Three -

Connect the balance lines to balance receivers capable of the higher voltage balance transmitters. These receivers can now either convert the balance signal to rca or if the amp supports it to a lower level balance signal.

Four -

Run new speaker wires to the doors, etc. Install quality speakers with heavy isolation damping mats everywhere.

Five -

Enjoy.

If noise is low you can eliminate number one and number three. I would however go with number two and run this down a separate path than your speaker wire or power (and anything else) by at least 18 inches (or as far as practical).