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The Something Awful Forums > Discussion > Automotive Insanity > Ask Us About Car Audio, Part 4: Gasp Harder
 
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The Wonder Weapon
Dec 16, 2006



 I'm looking at a head unit (http://www.crutchfield.com/p_070XML8150/Dual-XML8150.html) for my 2002 Audi TT. I've installed a few head units back when I was in highschool, but that was a decade ago, so I want to make sure I know what I'm doing before I do so now. I saw three things that gave me pause:

"You'll need to fabricate a trim plate in order to install your new receiver. Professional installation may be required."
and
"You may not be able to close the factory radio cover if you install a stereo with a fold-down faceplate or a protruding faceplate."
and
"The Crutchfield harness does not have an accessory power connection, so you will need to connect your new receiver's accessory power wire to a source of accessory power in your vehicle."

What's all this about fabricating a trim plate? Does that mean the thing will just have a small gap without a trim plate, or will it affect the unit's stability/usability?

My car does in fact have a face plate that flips over the stereo. Is there any way to know if it will fit, or am I stuck guessing?

I don't really understand that bit about the power connection. What does it mean?

* # ¿ Apr 26, 2013 21:32
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# ¿ Apr 27, 2024 14:38
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The Wonder Weapon
Dec 16, 2006

LloydDobler posted:

This channel might help: http://www.youtube.com/user/Enfig/videos?query=audi+tt

In one of the install videos he shows that there are some side blocks you can buy to adapt an aftermarket radio into the slot, I'm surprised that crutchfield doesn't carry them. I think the note about accessory power means it won't work with the key in position 1, but I'm not 100% on that. Also he shows that pretty much any stereo with a protruding knob or button of any kind will prevent the cover from coming down, but detaching the face (if it's detachable) will allow it to come down.

Also note that Crutchfield does carry the wiring adapter and removal tools but because it's such a cheapass stereo it doesn't include them for free. They're $15, worth every penny. Make sure you add them on regardless.

Hey I haven't decided exactly what I'm going to do yet but I just want to say thank you for all the info. SA is so worth the $10.

* # ¿ Apr 29, 2013 14:46
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The Wonder Weapon
Dec 16, 2006



 A few weeks ago I was asking about putting a new stereo into my car. Well, I did, and it mostly went fine. I put this unit (http://www.crutchfield.com/p_105KDX250B/JVC-KD-X250BT.html?tp=5684) into my 2002 Audi TT ALMS with Bose speakers. The music is playing fine, but the all of the speakers make a loud pop every time I turn the car on, off, mute, or change sources. It's not deal breaking, but it is rather irritating. They never made this sound before I changed the unit, and once the music is playing, it sounds absolutely fine, so I don't think the speakers blew. What could be causing this?

* # ¿ Jun 29, 2013 21:52
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The Wonder Weapon
Dec 16, 2006

Aflicted posted:

The Bose system in my MB had a separate amplifier. It was using line level inputs and amplifying them. The speakers were also a non-standard impedance. If there is a separate amp it could be causing the pop when it is powered on/off. If there is not an amp and the speakers are very low impedance like mine were, it is really not good for the internal amp in the HU.

I'm not entirely sure what this means, nor what to do about it

* # ¿ Jul 1, 2013 19:58
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The Wonder Weapon
Dec 16, 2006

Aflicted posted:

In most Bose systems, and from what I have read about yours, the HU that you replaced actually feeds a separate amplifier that drives the speakers. I think yours is somewhere behind the passenger seat in a compartment. Usually systems like this are full of proprietary components that don't always play nice with aftermarket stuff. The amp is probably looking for a turn on command that is not from a standard 12v turn on lead. The speakers themselves could be a non-standard impedance. Usually an amp in a HU is rated to power speakers with 4 Ohm impedance. This is pretty standard, but the Bose systems can run anything, and running something outside of the impedance rating can be detrimental over time to the amplifier in the HU.

In my Mercedes, I had a Bose factory system. The HU had individual leads for each speaker that ran to the trunk where the Bose amplifier was. This then amplified the signal and drove the speakers in the car. The speakers in the front were an effective 2.34Ohm or something crazy. The rear doors were 2Ohm, and the rear decklid speakers were another impedance. I removed the Bose amplifier, but did not want to use the amp in the Pioneer HU I had, because of the wonky impedance levels it would see from the speakers and the potential to end its life early. I picked up a 4 channel amp to drive everything because it was better equipped to handle down to 2Ohm. This is purely anecdotal on my one car, but everything I have read points to it being similar in other factory Bose systems in Audis, Nissans, etc... Most of this info, I found on Club202.com which was specific to the 202 chassis C class cars. The site is all but extinct now, but you should be able to find a good bit on the Audi Bose systems with a bit of searching.

Some quick on-lunch googling found me this post: http://forums.audiworld.com/showthread.php?t=2849942&highlight=bose

The poster mentions exactly my problem (popping when changing sources) and says I would need "Floating ground adapter(s)." Is this what he is referring to? http://www.sonicelectronix.com/item_34321_Scosche-FGAB.html Does his suggestion sound like total crap, or is it reasonable?

* # ¿ Jul 2, 2013 18:50
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The Wonder Weapon
Dec 16, 2006

The Wonder Weapon posted:


Aflicted posted:

Aflicted posted:

[quote="The Wonder Weapon" post="416991799"]
A few weeks ago I was asking about putting a new stereo into my car. Well, I did, and it mostly went fine. I put this unit (http://www.crutchfield.com/p_105KDX250B/JVC-KD-X250BT.html?tp=5684) into my 2002 Audi TT ALMS with Bose speakers. The music is playing fine, but the all of the speakers make a loud pop every time I turn the car on, off, mute, or change sources. It's not deal breaking, but it is rather irritating. They never made this sound before I changed the unit, and once the music is playing, it sounds absolutely fine, so I don't think the speakers blew. What could be causing this?

The Bose system in my MB had a separate amplifier. It was using line level inputs and amplifying them. The speakers were also a non-standard impedance. If there is a separate amp it could be causing the pop when it is powered on/off. If there is not an amp and the speakers are very low impedance like mine were, it is really not good for the internal amp in the HU.

In most Bose systems, and from what I have read about yours, the HU that you replaced actually feeds a separate amplifier that drives the speakers. I think yours is somewhere behind the passenger seat in a compartment. Usually systems like this are full of proprietary components that don't always play nice with aftermarket stuff. The amp is probably looking for a turn on command that is not from a standard 12v turn on lead. The speakers themselves could be a non-standard impedance. Usually an amp in a HU is rated to power speakers with 4 Ohm impedance. This is pretty standard, but the Bose systems can run anything, and running something outside of the impedance rating can be detrimental over time to the amplifier in the HU.

In my Mercedes, I had a Bose factory system. The HU had individual leads for each speaker that ran to the trunk where the Bose amplifier was. This then amplified the signal and drove the speakers in the car. The speakers in the front were an effective 2.34Ohm or something crazy. The rear doors were 2Ohm, and the rear decklid speakers were another impedance. I removed the Bose amplifier, but did not want to use the amp in the Pioneer HU I had, because of the wonky impedance levels it would see from the speakers and the potential to end its life early. I picked up a 4 channel amp to drive everything because it was better equipped to handle down to 2Ohm. This is purely anecdotal on my one car, but everything I have read points to it being similar in other factory Bose systems in Audis, Nissans, etc... Most of this info, I found on Club202.com which was specific to the 202 chassis C class cars. The site is all but extinct now, but you should be able to find a good bit on the Audi Bose systems with a bit of searching.
Some quick on-lunch googling found me this post: http://forums.audiworld.com/showthread.php?t=2849942&highlight=bose

The poster mentions exactly my problem (popping when changing sources) and says I would need "Floating ground adapter(s)." Is this what he is referring to? http://www.sonicelectronix.com/item_34321_Scosche-FGAB.html Does his suggestion sound like total crap, or is it reasonable?
[/quote]

Several weeks later, and I am continuing to battle with this. I just today installed that linked Floating Ground Adapter, which apparently did nothing to solve my popping problem. (And also for some reason instructed me to connect White to White/Black, and White/Black to White, Gray to Gray/Black, etc etc. Odd.) It did add so much additional wiring bulk that my HU can't fit completely into the bay, though.

My HU has normal speaker wires as output, but it also uses 2 RCA plugs to power "Rear/subwoofer." I've got the front speakers and all the additional wires (power, ground, etc) coming out of the normal HU wiring, and then the two RCA jacks also running into one of the wire harnesses. In my re-wiring and double checking, I noticed that I have no sound at all when I unplug the two rear/subwoofer RCAs, so apparently the front speaker wiring does nothing? I put my hand over the front speakers in the door when the music is actually on, and it feels like sound is coming out of them, so I'm slightly confused.

My primary goal here is to make sure I'm not going to blow up my HU, and my secondary goal is to get this drat pop to stop.

I'm also 99% that my car has the Bose amplifier inside, for what that's worth.

HU wiring guide in question:

* # ¿ Jul 27, 2013 21:47
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# ¿ Apr 27, 2024 14:38
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The Wonder Weapon
Dec 16, 2006

MikeyTsi posted:

Did you get polarity reversed on your speakers or something?

I...don't think so? I checked the wiring 3-4 times, and I'm pretty sure I've got it correct as far as the diagrams go.

* # ¿ Aug 3, 2013 05:58
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The Something Awful Forums > Discussion > Automotive Insanity > Ask Us About Car Audio, Part 4: Gasp Harder