slo007

Here's the Setup:

- Alpine Type R 6.5 components in front
- JL 12W3v2 sub
- JL e4300 4 channel amp

OEM amp powers rear door speakers. Rear deck (6x9s) is OFF.

The Install by the Local Audio Shop:

RCA audio wires take signal from head unit, bypassing OEM amp. It arrives to JL amp in trunk, but first goes through an isolator (GLI). From the trunk, it goes back up front where it connects to the Alpine components.

The amp takes the same input from the HU and puts out a bridged connection to the sub.

The Problem:

I'm getting very high pitched noise coming from the components when the engine is either ON or OFF.

Oddly enough, this noise is not present when the engine is OFF and there is no GLI in the RCAs. Of course, when I turn the engine ON, I get all sorts of engine noises (i.e. RPM), so I need a GLI.

The Attempts to Fix it:

The shop tried two GLI in sequence and it didn't help. They claim this GLI works well in every other car they work on.
They tried different GLI brands and it didn't help.
They hooked up a high-end RCA cable around the outside of the car from the HU to the amp and it didn't help.
And they hooked up the amp ground to the OEM amp ground and it didn't help.

We also tried disconnecting the Soundgate AUX input to no effect.

I moved the amp ground earlier last week from the fuel pump ground to the chassis left of the rear seats and it also didn't help.

The Result:

A very sad TSX owner. :'(

Anyone have any suggestions? The store guys are sure it's not the amp. And they told me connecting to the high-level inputs on the amp would have no effect.

Their solution is to downgrade to a 1 channel amp for just the sub. But the components sound so sweet when the engine is OFF and there's no GLI in the RCA... I really want this to work.

jiggaman

why don't you just run the components off of the original amp. and then run the amp for the subwoofers off of the rear 6x9s?

slo007

The volume with the OEM amp is lower with these high-end speakers (and stock speakers was already poor). I get a much better stage with more power, and the quality of the sound is noticeably improved, too.

Plus it was expensive and it should work!!

The sound from the sub is excellent no matter what (different frequencies?). So that connection is fine.

jiggaman

ask either bass mechanic or electro. they seem to know what they are talking about.

callmetsx

It has alot to do with where the car's power lines and your speaker wires intersect. They should not be anywhere near each other otherwise you will get disatortion. Shops frequently dont even consider this and the result is poor sound.

If the speaker wire is near the power lead for the amp, for instance under the carpet, you will definately know it.

slo007

I mentioned that to the store and they told me no way. This bites!

Would an LOC help anything?

How about increasing the voltage of the audio signal from the HU?

Thanks for your input.

Bass Mechanic

sounds like the shop didnt tap the preamp signal from the HU correctly. maybe they have the ground and signal wires crossed. i dont know if the stock HUI has a floating or common ground on the HU or not.
it's really hard to tell what is causing the problem witout myself being able to trouble shoot it in person

slo007

Thank you for your input.

Bass Mechanic

you know reading your post again it sounds like you got a couple of nitwit installers. the solution is to tap the signal using an LOC after the factory amp.

if it were me i would have told you to leave it stock, or just amp the speakers after the stock amp.
reason is that the stock HU attenuates the bass as you turn up the volume. you will find you have too much bass when the volume is low and not enough when its up loud.
youll constantly be adjusting the bass.

jiggaman

Bass mechanic,

let me get this straight. so what you are saying is that we could run an aftermarket amp off of the stock amp to power the door speakers/tweeters/rear6X9s ?

Dan Martin

That can't be good for sound quality. You would be amplifying the noise generated by the first amp and the line level converter.

vsokolov

the way I test it is, I get a brand new radio and hook it up to the amps thru rca (of course aftermarket one) if everything works than you need a new head unit which they messup if no than problem is somwhere else. And never in my life I have used a ground loop isolator the just kill sound, whoever can't solve a problem without one they don't worth a penny

Bass Mechanic

actually amping the signal from the amp is not as bad as you might think, because if there are no speakers connected to the amp ther is little to no distortion because there is no load on the amp,
and im pretty certain there is no switching power supply in the stock amp because there usually isnt enough power there to justify it.

you wont need a GLI im sure of it and as for signal you will have more than you need so you can keep the new amp gains set to the minimum setting. this will help reduce the noise if any.

i agree with vsokolov if they cant solve it then you should not be paying them to mess with your car. any good installer knows how to solve these types of problems. i know i could

slo007

Well, I'm driving by the store tomorrow and making another appointment for service next week. I'll print this thread and another couple I found, and take them with me. Obviously, if they can't fix it, I'll be asking for a refund. Anything less and the local BBB will be receiving a couple letters from me, as well as JL Audio; which just picked them up as a dealer this year.

Hopefully the posts where you guys call them idiots will motivate them...

Altersys

Did your installer utilize the factory line-level shield leads? They need to do this to keep the facotry shield and your aftermarket RCA shields shorted to each other, or you will get EMI variances that cannot be referenced to ground at your amplifier. This will result in whine, noise, etc.

-Alt

Altersys

In case you dont have the wiring diagram, the shield terminals on the SMALLER connector that goes into the factory amp are:

driver: brown
front pass: brown/yellow
left rear: gray/blue
right rear: gray

Your installer needs to short these leads to the shield of the respective RCA's for each channel individually. This will require cannibalization of one end of your RCAs to gain access to the shielding. This is where competency and good soldering skills come in handy. Hopefully they know what they hell I'm talking about and can do the right thing by you.

best of luck,
-Alt

slo007

Thank you, I'll pass this info to them. My appt is on Wednesday morning.

Altersys

No worries... best of luck man.

And keep in mind that it's usually a combination of things that causes noise. You may find that one fix simply reduces the problem but doesn't eliminate it entirely. Follow all the guidelines already mentioned about running RCA's along proper paths, only allowing power and ground wires to cross interconnects at 90 degree angles, etc. The average installer won't give a crap and won't follow these basic requirements.

slo007

Alright! The store fixed the noise, finally.

They had the car from 9am-3pm and installed a P.I.E. LOC just before the JL amp that virtually eliminated all the noise. Listening to music now is a fun endeavour.

At the same time, they did one nice thing and two really bad ones.

First, they changed the crossover settings to -6db for the tweeters. They were two bright (sounded metallic) and the sound is much improved. I'm happy with this.

Now the bad:

They put a humonguous gash on the plastic liner just by the center drawer (to reach the amp), while pulling it out. I specificaly showed them how to remove this on my first visit! Stupid people. The mark is over 1/2" long and 1/16" wide and the plastic turned white/gray a bit where it happened. Most people won't notice it, but it was the first thing I saw when I got in the car. It's so visible that it bugs me a bit. When I open the lid, there's another one on both sides that is visible... :'(

Then they adjusted the fader controls where I cannot set the sound front and back anymore. They told me the set the sound more up front since the Alpines are better than the rear OEM's, but why in the hell do this in permanently? I don't understand what they were thinking. Fortunately, it's not something that I play with all the time so it's a-okay. (But it pisses me off.)

Finally, I noticed a gash on the bottom of my steering wheel. This must have come from some tool they were carrying... and it actually bugs me the most because every time I turn, my hands feels the leather/vinyl is damaged.

Moral of the story: find a really good friend to help you with the speaker and amp install. I was concerned about the NAV and possible problems I might have with the electronics of the car... these are way overrated, as stores have no idea what they are doing. With the information I gathered here online and some other audio forums, I could have done a better job and saved over $200 in labor. And I could have purchased everything online and saved another $100 or so.

Live and learn, I guess.

Dan Martin

Sorry to hear that Slo. I've always done any audio work on my cars myself for exactly the reasons you mentioned. Most of the stuff is so modular these days that it's like playing with lego. Anyhow, keep your eye open on ebay because I've seen OEM TSX steering wheels for cheap in the past.

jiggaman

that's rediculous that you should have to pay ANY labor if they did all that damage to your car. if i were you i'd make them eliminate the labor cost of your bill.

ortiz

Agreed, if you payed $200 to get a professional install, you should have gotten a profesional install. It is just wrong for them to damage your ride and not fix it.

slo007

Yeah, you guys are right; but now it's too late to go back and yell at them. They'll claim it wasn't them.

It sucks... :'(

cbb

So, if the HU drops the bass w/ increased volume, how did all you guys get around this w/o installing a new HU? I'm putting in new components, new rears, a 10" JL sub, a 4-channel, a single channel, and an Audio Control EQ. Its all crap though if the HU doesn't put out a quality, solid signal.

jiggaman

you'd have to ask my stereo installer what they did. all i know is that my system kicks ass and i kept the stock HU, door speakers and tweeters

callmetsx

It depends on what speakers you choose to put in. I put in Alpine's with a sensitivity of 92 db and there is absolutely no change in volume. The same spot on the dial is just as loud now as it was before. Along with the sub, it sounds great - nice and clear.

cbb

I guess I wasn't really referring to "volume changes" that come w/ new speakers. Bass Mechanic, in his post on this topic, says that the HU has some variable EQ that cuts bass as you turn up the volume. You can't overcome this dynamic EQing with any EQ unit that I know of. So, if this true, why isn't anyone complaining about this?

jiggaman

probably cuz it's not that big of a deal. in fact i don't even notice that, so there you go. i don't feel that my installer took any special precautions to overcome this. i do know that my installer set the crossovers for my door speakers so that they don't have to deal with low bass frequencies which cleaned up there sound quite a bit.

slo007

With a 12" sub pushing 150 watts (RMS), I don't notice any drop in bass. Especially at higher volumes.

As JiggaMan explained for his setup, the components in mine are also not getting the lower frequencies (cut off in the amp), so I don't even have to deal with this.

jiggaman

hey Slo007,
i've notice since my install that my treble seems to be higher for the same treble setting on my HU than it was previoiusly. isn't there an adjustment on the amplifier that makes it possible to lower high level frequences?

slo007

Check the explanation under Filter Controls (2) and Precise Frequency Selection Chart, pages 7 and 15 respectively (printed in document).

http://www.jlaudio.com/amps/pdfs/e4300_MAN.pdf

I noticed the same in my car, and will try to play around with this setting and see if it makes a difference.

Altersys

Is this variable EQ definitely occuring in the head unit, or is it occuring in the OEM amplifier? My bet is that it's at the amplifier because then the variable EQ could be tuned for each driver and excluded for others.

slo007

I think it's in the OEM amp, but it's hard to tell since we don't have the specs for it.

Altersys

I hope you're right... but I'm with you on this one. It just makes the most sense.

I should be taking some measurements somewhat soon (in the next couple of months... yeah i know that's a while but I'll document everything I find for you guys ok?)

I have a scope, pink noise generator, sine wave generator, etc etc... this will allow me to plot the frequency response of the preouts relative to head unit volume setting.

slo007

I have a ruler. Will that help?

Altersys

Actually yes, for time delay measurements