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View Full Version : urgent car audio help - aftermarket headunit with bose



Silver98A4
12-13-2006, 06:23 PM
I know i have posted a lot of threads about head units and whatever but i'm so close to having everything working.


I have:

Alpine CDA 9856
Metra-70-1787

http://enfigcarstereo.com/shopsite_sc/store/html/media/METRA_70_1787.jpg


The 4 RCAs are correctly placed into the back of my head unit. The other part of it connects with wires from the wires coming out of the back of the alpine. Those wires deal with power, the RCAs deal with the speakers. One of the regular speaker wires coming out of the metra harness is blue with a white stripe, it says that it is the amp turn on wire.

At first i did not have that wire connected to anything, the radio would power on but i got absolutely no sound out of my speakers. I realized that the metra harness must need some power, so i connected that blue (amp turn on) wire coming from the metra to every single wire possible that dealt with power. I tried the blue remote wire coming out of the alpine, the yellow power wire coming from the alpine, the red power ignition wire coming from the alpine....everything.

As soon as the blue amp turn on from the metra gets connected with power, i get wonderful sound from my speakers and all is working well EXCEPT:

at this point whenever i hit a button on the head unit that switches something or requires power (hitting the source button to change from Tuner to CD for example), there is a large "pop" heard through the speakers. This happens when I hit a majority of the buttons on the head unit. Also, when i go back to tuner it will say Tuner, then it takes a half second to get the station signal, then it pops, then music starts playing, it pops once more...then it plays fine until I hit another button on the head unit.

Basically, i think that there is interference between the bose amp and the alpine head unit. That is the whole reason i reasearched and bought the Metra 1787..it is supposed to allow you to connect aftermarket head units to amplified systems.


PLEASE, SOMEONE WHO HAS AN AFTERMARKET HEADUNIT AND HAS USED THE METRA AMPLIFIED HARNESS, PLEASE HELP ME AND TELL ME WHERE YOU CONNECTED YOUR WIRES, ESPECIALLY THE BLUE "AMP TURN ON" WIRE.

i'm really frusterated right now and desperate for help. i have been waiting to install this thing for a week, i finally got the time and it POPs...

burner799
12-13-2006, 06:56 PM
except your head unit puts out power at 4 ohms and bose is at 2 ohms...........

Silver98A4
12-13-2006, 07:10 PM
you make a good point, but many people have added aftermarket head units to their bose systems with the metra kit...


i read somewhere a ground loop isolator might solve this problem....i saw a picture of one though, im not sure how i would hook it up.

burner799
12-13-2006, 07:34 PM
if nobody answers i can ask some of the guys at work tomorow.

ny02s4
12-14-2006, 09:30 AM
I had the exact setup in my Audi about 6months ago. My "pop" wasnt that noticable at all. Just make sure you DIDNT connect the speaker leads (grey and white) to the Alpine. You dont need those cause only one of them work and its for the hands free/gps speaker on the drivers door about the main woofer. The only way you can eliminate that pop is to install a resistor on the amp turn on lead. Im not sure of excatly what OHM to use, but i do know it will definitly solve your problem.

johnnybravoa4
12-14-2006, 09:35 AM
I had a similar set up as well i never had any problems.. i didnt get any pop..

Silver98A4
12-14-2006, 11:41 AM
I had the exact setup in my Audi about 6months ago. My "pop" wasnt that noticable at all. Just make sure you DIDNT connect the speaker leads (grey and white) to the Alpine. You dont need those cause only one of them work and its for the hands free/gps speaker on the drivers door about the main woofer. The only way you can eliminate that pop is to install a resistor on the amp turn on lead. Im not sure of excatly what OHM to use, but i do know it will definitly solve your problem.


all of the power wires out of the alpine wires are connected into a plug that plugs into audi power wires. even if i had connected the speaker wires coming out of the alpine, they wouldn't connect to anything because the harness that i have would end them there.

my speakers are being run through the preamp RCAs on the alpine...i'm going to look into a resistor..

i didnt think that there would be any problems with this. my whole understanding of buying the metra 1787 would be so that it would be plug and play and would integrate everything with the bose amp.

ny02s4
12-14-2006, 02:22 PM
yea, that metra harness is pricey but it works. Try a 1500 ohm resistor.

Silver98A4
12-14-2006, 02:23 PM
thats the problem, i bought it and it doesn't work


i mean it works, but i have a "pop" everytime i hit a button on my head unit...i think a ground loop isolator might fix it but i might need 2 of them

ny02s4
12-16-2006, 09:51 AM
sounds like you have the loudness turned up all the way and or something is wrong with your Alpine.

sandnessmj
12-16-2006, 12:39 PM
i think a ground loop isolator might fix it but i might need 2 of them

Try a turn-on delay. Should wire inline with the turn-on lead for the the factory bose amp. It delays the signal by a short time, that way any 'pop' from the head unit being turned on doesn't get amplified by the amp.

Ground loop isolators are usually for whining and humming that you hear from the speakers...

rarak69
04-08-2008, 02:13 PM
Darn i just ran into the EXACT problem today in my car as well with an alpine 9884...no solution yet, i ran a ground from rca shared ground to the amp. no deifference.

any news on a resistor?

bigdyll
04-08-2008, 02:26 PM
that's odd.... I bought Alpine 9884 from crutchfield and have it installed 2 weeks ago (with provided harness and all) everything worked fine, except there's some constant static when in tuner mode (radio). But I always use my ipod in the car anywayz. CD player works fine too. I just connected all the wires according to the diagram. And there is some weird wiring going on with Bose setups, but the RCA jacks are the ones that really matters anywayz.

and yes, the blue wire is for amp power (remote pwr or amp pwr whichever it was labled)

JaVa
04-08-2008, 02:48 PM
the pop is a gound loop.

Vreihenmotor6
04-08-2008, 02:56 PM
you have all the parts you need, possibly your radio isn't providing enough current to drive the amp and the mode selection causes a voltage drop enough to have the amp turn off, or maybe you connected the amp wire on the harness to the antenna out from the radio

a properly used relay will most likely cure your problem

Stampy
04-08-2008, 04:07 PM
upgrade the ground, don't use the harness ground.

fred2ka4
04-08-2008, 04:08 PM
The best thing to do is eliminate the Bose amp and go with an aftermarket amp instead. It will work better with your head unit and you won't have these problems.

The blue wire should go to the blue wire (remote turn-on) on your Alpine head unit.

Stampy
04-08-2008, 04:09 PM
^^ yep

rarak69
04-09-2008, 08:28 PM
hmmm its a hit or miss it seems, i talked to my boy at the local circuit city who is a car audio guru....he said its hit or miss on audi's. hmmm. odd that its like that. a ground loop isolator would work. but like others have said, screw the bose amp.

i was trying to save money, the pop doesnt bother me that much right now. but i will save up for components for the front and 2-ways for the rear and run those off the headunit. then a new amp for my old JL's for the trunk. gotta find another PPI a600.2 and ill be happy, mine has water damage from storage :(

JaVa
04-10-2008, 10:38 AM
just regound the headunit, take some small guage wire stirp it and wrap it around the rca connections and groun this to the case of the radio. i know it sounds like a hack job but i have seen it done many tims with good results.

newtonc2001A4V6
04-10-2008, 07:26 PM
You need to get a Hi-Low adapter, that will solve the problem. I can call the master installer at Ultimate Electronics (South Denver, CO) to get a part number if necessary. He said he has fixed multiple Audi's that have had this issue.