Hey guys,

I tore my TSX apart today and installed an amp and sub. I tapped into the low level outs and RTO wire in the factory amp's wiring harness... Took some pictures of the installation process...will post soon.

It went really smoothly, but as I was driving later today I noticed a little alternator whine coming through the main front/rear speakers (still run off the little factory amp). I imagine the whine is coming through the sub as well, but I can't hear it because of the frequency range.

I have run into this with other vehicles and usually ended up tying the low level input negative leads to body ground near the head unit. I was just wondering who else ran into this with this vehicle and how they fixed....wanna make sure I am thinking of the right fix...

lata,
mark

 

A quality line driver helped the noise I was getting.

 

Is there really only one person that had this problem? No one else got alternator whine after tapping into the low level outs on the head unit?

If anyone else has suggestions for fix, let me know... For now, the sub is disconnected, cause the whine was too annoying...

 

You should try posting this in our Audio & Video section: https://acurazine.com/forums/forumdi...aysprune=&f=22

 

I gave you a suggestion to fix it...What else did you want?

 

Dan is right... I don't come over here much.

First off, find out if the noise remains with the car running and the system OFF. Yes, off.

If it does still occur with the system off, then your passive speaker xovers are picking up noise, probably from the airbag ECU (where are they located?)

If it goes away with the HU turned off, then take your amp's input gain and turn it all the way down (yes, ALL the way down) and see if the noise goes away.

If it does, then either leave it all the way down (like I did when I had the JL amp) or see joe's suggestion.

BTW< it helps if you tell us what your gear in on this kind of T-shooting thread. Good luck and keep us posted.

 

Wait a minute... these are still off of the FACTORY amp? OEM speakers and OEM amp?

If you unplug your interface for the RCA's does the noise go away? If so there is a new ground loop for the OEM amp/OEM HU. Not sure how that would work...

Sounds like a GLI inline is what I would do... not my favorite, but with a hybrid system like that it's not a bad choice (and hopefully temporary)

 

Did you make sure to run the signal line and the power line down opposite sides of the car? Dont run those side by side. If you do, the lines will pick up noise from one another.

 

That probably wouldn't cause noise to come out the OEM amplifier.

However, if you want to check it, pull your fuse at the sub amp and see if you stil have noise out your tweets.

 

This is exactly what's happening. I can hear the noise (changes pitch with engine rpms) coming from the rear factory speakers, and the sub. It doesn't change volume when I turn the vol up/down on the HU, so I know its on the input side of the OEM amp (not a HU problem). If I turn off the stereo, or unplug the RCAs from the sub amp, sound goes away.

So its definitely a ground loop somewhere in the system. As for equipment, I am using a Rockford Fosgate Power 400 amp (about 4 years old). Its a great amp, but it seems to be prone to ground loop problems, as I saw this in my last car too. There I fixed it by grounding the RCA negative leads to the HU casing. Not sure if that is the right fix here or not.

Can you recommend a good GLI...where to get one? I see line drivers and GLIs all over the place, but I don't know which are junk and which are good... Thanks for your help guys.

P.S. the only reason I posted over here, is cause I didn't get any hits on some of the stuff I posted to the A/V section

-mark

 

The ISO2LITE works fine for me...

http://www.soundgate.com//index.php?...ca755be66277f7

I bet you can find them cheaper than that though.

This one works OK:

http://www.hifisoundconnection.com/S...d/0/rid/118099

If you were running a full range system you could try this:

http://www.jensen-transformers.com/ci2rr.html

But it probably costs too much for a bass amp issue.

BTW, mp, when I click on your handle and click on "threads started" or on "posts made" I can't find ANY posts you've made in the AV section??

 

Thanks, el dude. I will check those out.

One other question... What's the closest, solid grounding point in the trunk? I had trouble finding one, other than the seat belt bolt under the back seat, but the bolt there is too big for the connector I have.

I swear i posted to the a/v section, but you are right. I just searched as well. That must have been on AW or some other acura site.

-mark

 

If you want to use an OEM bolt, what about the tiedowns? I think they're bolted in pretty good.

I'll look in a bit...

 

You are probably right. I will take a look at the tiedowns. Thanks, el dude.

-mark

 

I wanted to post the correct fix for the alternator whine (at least in my case). I ran a ground line from the negative leads of one of the preamp outs (at the HU) to OEM amp mounting bolts. It seems the OEM amp doesn't have a strong ground source and it doesn't have good separation of the signal ground from power ground. Supplementing it in this fashion discourages ground signal travelling over the signal lines.

-mark

 

Glad you fixed it. Not sure I agree with your explanation's phrasing, since it seems to have nothing to do with your mod, which caused the onset of your problem, yah?

From what I can tell, the makers of this gear went to a LOT of trouble to isolate the signal (-) from chassis ground in their wiring. Taking the signal (-) to ground is a useful experiment but seems like a last-ditch kludge from a permanent wiring standpoint (to me, anyway, who has done it in cars before but not usually permanently).

The fact that it worked fine until you added an amp indicates that their design was not flawed. My suspicion is that the HU "seeing" two signal grounds of different potentialities was the primary cause of a problem. The ground was plenty good enough when the OEM amp was the only amp, right?

You seem to be deducing the ground was "bad". Did you meter it?

 

Hmmmm....I gotta try this now. You say the negative side of the RCA/pre-amp output to the OEM Amp ground? I gotta try this. I tried connecting the shielding to ground, maybe this will work for me as well.

 

You are probably right that this is kind of like taking a sludge hammer to fix the problem, but it did fix it...not partially, but completely.

Not sure what about my amp installation caused the problem in the first place...Could be the rockford amp I am using (since I had this problem in my last car too, with the same amp). I wonder if the rockford amp has poor isolation of power ground and signal -, causing the power signal to bleed into the signal lines.

In any case, I don't know any downside to the fix. El dude, please fill me in if you can think any risk to this fix.

-mark

 

Yep preamp out neg (of either channel you tapped on the input side of the OEM amp) to mounting bolt on the OEM amp worked for me.

-mark

 

Do yo remember which preamp out it was? Fr Drvr? Pssgr? I am gonna try it.

 

I tapped into the two REAR low level inputs on the input side of the OEM amp, when I ran the signal lines. I believe I used the RL- as the one I took to ground last night (but either should work)...

This would be pin B10 or B13 on the pinout diagram of the OEM amp.

Let us know if this also works for you...

-mark

 

Ok so I have a similar problem, I just got some Monster Cable 401 cables and that eliminated about 60% of the whine, but there is still alittle left. The one intresting item is that it remains after I turn the car off, for about 5 seconds, than I hear what must be a solinoid closing and it stops. If this was the ABS ECU, how do I work around this? Is there an additional ground I can add?
Or should I get a line supressor?

Current setup:
Alpine HU with dedicated power/ground to the battery.
MC 401xln cables to an amp in the spare tire well.
MC 12awg wires to speakers?
Power wires run down the drivers side.
Speaker and RCA's are down the center.

 

If it happens after the system turns off then where are the speaker level xovers? They are probably picking up that ECU - move them 6" farther away and see if the noise vanishes.

As far as the chassis grounding of the signal, here's a good article on the topic:

http://www.prosoundweb.com/studyhall...ng/ground2.php

And a good quote from it:

Connecting signal ground to the chassis in each unit can only be done in one place in each unit. If done twice, one leaves the possibility open that the noise currents will flow through a path shared by audio.

So that's essentially what you did - provide a second signal ground to chassis ground (through the amp).

You *might* have eliminated the noise by lifting the signal ground at the amp end.

So I'm glad it worked... I was just being picky about your phrasing. You created the ground loop in the first place, not the Honda engineers : )

 

Thanks for the article. And yes you sir are correct, I created the ground loop, not Honda. This stuff is so tricky in cars, and so easy when you are in a house, using A/C current, and your ground is really headed to ... the ground.

-mark

 

It didn't work for me! It acted the same as when I connected all 4 shield to ground. The signal level went down and the humm went away when the car was off, but when I turned the car on it became a very loud whine that reacted with the engine.

 

I went to radio shack on the way home and picked up 2 sets of these:
Catalog #: 270-054 Ground Loop Isolator


And like magic everything sounds wonderful.

My problem is solved!

 

I finally had some time to work on the car again today... put in a ground loop isolator and removed the negative to ground link I had added. Have to admit, the ground loop isolator worked better than my solution...probably a better fix, for anyone else who has this problem. Thanks, guys!

-mark