E46 Fanatics Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 14 of 14 Posts

·
Registered
Joined
·
100 Posts
Discussion Starter · #1 ·
does anyone know where the factory h/u is grounded to?

I am using the factory h/u to Audiocontrol EQX to Alpine amps and I have noise that I can not get rid of, even with the EQX input & output turned all the way down.

I have the EQX and amplifiers grounded directly to the chassis ground connection just in front of the factory amplifier, as well as a small ground loop between the three components. Ground wires to the amplifiers is 4 gauge. I have tried different ground locations with no change. At this time, the factory amp is disconnected, I tried it connected too, just in case it closed a ground loop with the factory h/u, but no luck.

Any suggestions would be greatly appreciated.

Shawn
 

·
mod-er-at-or-er
Joined
·
1,186 Posts
The factory HU is not the issue. Ground all of your amps and EQX to one point, one on top of the other. Try to ground it next to the passenger seat and sand some of the paint down. I used to have noise, but now it is gone.
Some places in the chasis have more current, so you get noise. I'll post a pic of where to ground soon as I find it.
 

·
Registered
Joined
·
346 Posts
Would you say this is a better mounting spot than the factory battery ground? Thats where I have my amps grounded too and I have road noise as well.
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #5 ·
I talked with one of the techno weenies (I can say that, I am a techno weenie wanna be) at my local a/v store. He has used Audiocontrol on several occasions, and done a number of installs on BMW's. He said it is the s/n ratio on the head unit that I am hearing, which isn't an issue with the factory amp. He said the only way to deal with it is turn the input gain all the way down on the EQX, and then use the output gain to adjust volume. I did this, and can still hear a little noise, but only with the key on and my ear near the speaker. I really can't hear it driving down the road. The frustrating part is I know the turn down on the gain is robbing me of more dynamic sound. I must admit though, the difference with and with out the EQX is incredible.

None the less, the amps and EQX are grounded to the same location as you suggested, but I am using an existing grounding lug. I will try a new location as you suggested, but what about the h/u, is there no need to include the h/u in the ground loop?
 

·
Registered
Joined
·
10,387 Posts
Are you getting alternator whine? When you say noise, pls be more specific so we can help.

First, did you play with the ground selector switch on the inside of the EQX? That can reduce or eliminate noise issues.

Second, if you still have noise, go to this link:

Audiocontrol Tech

Download tech papers 103 and 1002. They will help you in troubleshooting the noise.

Audiocontrol products seem to be sensitive to ground loops. This is good because it prevents problems down the road.
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #7 · (Edited)
No alternator whine, noise is consistent with or with out the engine running and regardless of the volume setting of the h/u. It is more of a hissing/huming noise.

Get in the car, turn key to accessory volume on h/u all the way down, I hear the noise. Crank the volume way up, during the silence between tracks on a CD I hear the same noise at the same level as I did with the volume all of the way down. I just went out to the car to double check, I heard a "pop" when the unit came on, I turned the key off, then back on, no pop, almost like there was a little stored energy while the car sat.

I tried the three different setting on the EQX's internal ground switch, no change.

I just read the two articles you suggested, I'll have to read them again to get everything to sink in, but I know I need to grind off the paint and double check the ground.

I wonder if it is an issue with the EMI from the amps. Right know both amps are on one board, I have each amp ground directly via 4 ga to a terminal lug, as well as a 10 ga wire that is daisy chained between the two amps and EQX terminated to the same ground lug.

I take it you do not buy the s/n ratio of the head unit that the guy at the stereo shop noted. If I can find a walkman or something and plug it into the EQX RCA inputs that should confirm or rule out the h/u correct?

Thanks for the input.
 

·
Registered
Joined
·
10,387 Posts
I just can't imagine any CD player being that noisy that it would bother anyone.

Likely, your input setting on your EQX will be all the way down or close to it. Which is fine. You are trying to do is step down the high voltage of the speaker inputs to a lower preamp level so that amp won't clip.

What kind of amp are you using? Some amps clip at a 2V input. Your goal is to minimize the gain on the amp and maximize the output gain on the EQX without making the overload light flicker at full volume with no bass or treble boost.
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #9 ·
Oh, okay.

The input gains on the EQX are turned all the way down. I am using Alpine T-320's, but I have the gains turned up pretty high, and the output gains on the EQX turned up about 50%. One is bridged for the sub, the other drives Boston Accoustic Pro's up front. Nothing for rears. I got the Alpines because they supposedly accept high level inputs (the system is much noisier w/o the EQX.) I had tried a VEN4 too without much success. I have pretty good hearing and out of place noises drive me absolutely nuts. Might not bother some, but definatlye an issue for me.

I'll try the ground and gain adjustments tomorrow.

Thanks.
 

·
Registered
Joined
·
10,387 Posts
Yes, now you are on the right track. Amp gains are usually noisy since amps aren't really built for that purpose. The reason why amps have a gain is to ensure compatibility with a wide range of head units.

That is where the EQX comes in...it can cleanly increase the gain if needed. The end result when you install the EQX, you should start with the amp gains all the way down. Only turn them up if you have all the gains on the EQX all the way up...but that will likely not happen.

Turn your amp gains all the way down unless it mutes the amp...then increase the gain slightly and make the adjustments on your EQX.
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #11 · (Edited)
I thought keeping the gains fairly high on the amp would be the best with noise from the gains coming when you used them to turn down. I tried your suggestion and ended up with:
EQX inputs turned up about 15%
EQX outputs turned up about 95%
Amp gains turned up about 40%
With this setup I can still hear a very faint noise with my ear right next to the tweeter, but it can't be heard during normal driving with low volume.
I found that if the EQX input was turned all the way down, I had to turn the h/u volume up a lot and got clipping.
I still need to double check the grounds and clean up the install, but the EQX is definately worth the money.

I'll let you know how I make out with the ground location.

Know it is time to start working with the EQ.

Thanks for the help.
 

·
Registered
Joined
·
10,387 Posts
Depends on the quality, but head units will usually clip at full volume. That is where the quality factor comes in...and that is where the OEM HU lacks.

Higher quality HU's have a high preamp voltage and low resistance (100 milliohms or less). Also, the preamp section won't clip...usually due to high resistance and/or poor quality. That's why Kenwoods suck...the Excelons have an output resistance in excess of 500 milliohms on some models.

Yes, audiocontrol makes great products that are reasonably prices. IMO, the only other equalizers that rival audiocontrol is ID and those cost an arm and a leg.

I can see that my (and djabaley's) audiocontrol sales pitches have propagated increased use! :thumbup:
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #13 ·
Yep, definately an Audiocontrol fan, keep pitchin'

Now I just need to spend some time tweeking the EQ.

Looking at Audiocontrol as an add on for my home theater too.
 

·
mod-er-at-or-er
Joined
·
1,186 Posts
Guess it wasn't a ground issue then. Constant noise is usually caused by gains, equipment or cables.
 
1 - 14 of 14 Posts
Top