Ok, I've been doing alot of research for this problem. this past
weekend i added a 4 channel amp to my existing system, consisting of an
Alpine headunit, Alpind MRD-M300 mono amp for my 12' Kenwood, 6.5 Boson
components (installed professionally) and my stock rear speakers. I
have a 97 Blazer (if that matters).

I added an Alpine MRV-F340 4 channel bridged to just my components. I
have both amps powered through a distribution block with all 8 awg
cable. i have both amps grounded to a common bolt about 6 -12 inches
from both amps. The weird thing is when i installed all the equipment
the first time i had no problems but when i did a little moving of
things around (when i wasnt in a rush to finish) and some clean up
work, when i turn the engine on i have that awful whine that increases
with the RPMs. when the truck is off..no problems!

I have done some research on here and kind of narrowed it down to a
ground loop. when i disconnect the rca's the whine is gone. the only
thing i can think of is adding another distribution block for my ground
and either running one cable to a good ground or directly to the
negative battery terminal. i dont know if that will work.

I'm kicking myself soo much because there was no problem for about 5
hours runnning around, but then i had to be anal and make the instal
look professional and look what happens. If you guys have any ideas, im
all hears. imm very particular on my sound system and this is causing
me chaos.

HELP Please!!!! Thanks to all!

-Chris

ok forgot to mention that the whine is comming only from the components
and not the rear factory speakers. so im not too sure if the noise is
coming from the amp or the head unit but leaning towards the amp since
the whine is only coming from the speakers connected to the it.

I take it that you moved your grounding location when you moved things
around? If so, it should be a simple matter of trying a different grounding
location for your amp(s). Contrary to popular opinion, grounding the amps
to one, central locatoin is NOT necessary. You might also want to make sure
that the ground wire(s) are bolted to bare metal, not a painted surface.
You can just scrape the paint away if needed.

Tony


--
2001 Nissan Maxima SE Anniversary Edition
Clarion DRZ9255 Head Unit, Phoenix Gold ZX475ti, ZX450 and Xenon X1200.1
Amplifiers, Dynaudio System 360 Tri-Amped In Front and Focal 130HCs For Rear
Fill, Image Dynamics IDMAX10 D4 v.3 Sub

2001 Chevy S10 ZR2
Pioneer DEH-P9600MP Head Unit, Phoenix Gold Ti500.4 Amp, Focal 165HC
Speakers & Image Dynamics ID8 D4 v.3 Sub

2006 Mustang GT Coupe

Contrary to popular opinion, grounding the amps
to one, central locatoin is NOT necessary.

Tony's right on all points. But I would add one thing. You may want to try
grounding your head-unit to the same place you ground your amps (just run a
12 gauge wire from your HU ground, or HU chassis, to the spot where you
ground your amps). This is my stock advice I always give, and I'll tell you
why. I had a car years a go with TERRIBLE alternator whine. I tried ALL
the standard remedies (moving the grounding points, beefing-up my ground
cables, running my RCA's far from my power cables, etc.), and nothing
worked. Then I tried running a wire between the chassis of my HU to the
grounding point of my amps and, like magic, no more alternator whine (well,
in truth, there was still a little, but it was barely noticeable).

Anyway, that seemed to work for me, and now I do this WHENEVER I build a
system, just for insurance, because it is so easy to do when one is in the
process of installation.

MOSFET

so should i wire the ground coming from the HU to my amp ground point
or the actual chassis of the HU?

It shouldn't matter (they're all connected), but try the grounding wire that
comes our of your HU (or you can use both).

MOSFET

"Chris" wrote in message
oups.com...
so should i wire the ground coming from the HU to my amp ground point
or the actual chassis of the HU?

Oh, and if you try this, let me know if it works! OK?

MOSFET


"Chris" wrote in message
oups.com...
so should i wire the ground coming from the HU to my amp ground point
or the actual chassis of the HU?

Yes, those Radio Shack things work quite well. But, IMHO, I just don't like
the idea of something that may be degrading the quality of my sound. But
they really do work.

MOSFET

"Chris" wrote in message
ps.com...
will do. i also went to Radio Shack and bought their ground loop
isolator. Has that worked for anyone?

ok. i wired the ground from the HU to my common ground in the
trunk....thing is that when i did i dry run without going throught the
dash it worked but as soon as i ran the wire behind the dash and along
the floor...buzzzzzz and on goes the whinning...and as for the ground
loop isolator from RS both ends are male, and im using both my HU
preouts, so im not sure how that should work. Also should my amp being
using all 4 RCA jacks for two channels...i bridged the two so i dont
know if thats why i only get sound out of one speaker when using on the
front preouts. let me know if you understood that!

yea thats what i thought but when i only used one set of preouts i was
only getting sounds out of one speaker then when i hooked up the other
one it was coming from both...i'll double check the manual but it wasnt
all that informative on the setup of different types of installs...but
i will def see if that will work.

i found a pretty good page for noise suppression.

http://www.crutchfieldadvisor.com/le...ers_noise.html

It has nothing to do with opinion. Grounding everything at the same spot
reduces noise because there can be no ground potential difference in one
spot. If it is necessary or not to do it depends on your car and cabling and
equipment.

"Tony F" wrote in message
...
I take it that you moved your grounding location when you moved things
around? If so, it should be a simple matter of trying a different
grounding location for your amp(s). Contrary to popular opinion, grounding
the amps to one, central locatoin is NOT necessary. You might also want to
make sure that the ground wire(s) are bolted to bare metal, not a painted
surface. You can just scrape the paint away if needed.

Tony


--
2001 Nissan Maxima SE Anniversary Edition
Clarion DRZ9255 Head Unit, Phoenix Gold ZX475ti, ZX450 and Xenon X1200.1
Amplifiers, Dynaudio System 360 Tri-Amped In Front and Focal 130HCs For
Rear Fill, Image Dynamics IDMAX10 D4 v.3 Sub

2001 Chevy S10 ZR2
Pioneer DEH-P9600MP Head Unit, Phoenix Gold Ti500.4 Amp, Focal 165HC
Speakers & Image Dynamics ID8 D4 v.3 Sub

2006 Mustang GT Coupe

It has nothing to do with opinion. Grounding everything at the same spot
reduces noise because there can be no ground potential difference in one
spot.

You're EXACTLY right. I don't think Tony was trying to imply that this was
an opinion, just that it is not always necessary.

MOSFET

ok i added aistributiob block for my ground cables...didnt fix it. i
switched the rca setup on my amp for just one pair..didnt fix it. now
it makes a weird noise when the truck/radio is off kind of like when a
cell phone is close to speakers and is about to ring it picks up the
signal, but my phone wasnt even on...so now im leaning to the problem
being in my dash, either the HU or the antenna...anyone ever come
across this?

~Chris

Have you tried the Radio shack ground-loop blocker yet? Look, I have used
those before and they work great. What I said before about effecting sound
quality was just what I IMAGINED MIGHT BE HAPPENING, but in actual practice,
I DID NOT notice any degradation in SQ.

I have seen cars where EVERYTHING is tried, but alternator whine still
exists. It sounds like you may be getting to that stage. The problem is
that even when you try running a ground wire from your HU ground to your amp
ground, you are still going to get different negative potentials because
your HU is ATTACHED to your car in the dash (this is why you seem to have
problems ONLY when it is in the dash). If you want to try one more desperate
approach, you could try grounding your amps to the dash-grounds OR figuring
out a way of electrically isolating the chassis of your HU from the dash.

But, at this point, I think I would go with the Radio Shack thing.

MOSFET


"Chris" wrote in message
ups.com...
ok i added aistributiob block for my ground cables...didnt fix it. i
switched the rca setup on my amp for just one pair..didnt fix it. now
it makes a weird noise when the truck/radio is off kind of like when a
cell phone is close to speakers and is about to ring it picks up the
signal, but my phone wasnt even on...so now im leaning to the problem
being in my dash, either the HU or the antenna...anyone ever come
across this?

~Chris

where is you headunit tied into the power????

my HU is wired up right through the factory harness...nothing special
with that setup...i havent tried the RadioShack ground loop isolator
yet, but it has a weird setup to me, why does it have sets of male
ends...im thinkin it should have 1 male 1 female, right?