Amplifier Help!

[Mikewire]

Aeron will chime in, but I'll throw my 2 cents. You have a ground loop, and it's an easy fix. Either move your ground for your new amp to somewhere else on the chassis or get a ground loop isolator over at Radio Shack.

Oh and BTW, this thread is worthless without pics

[Johnny Chopsticks]

Okay, so after a few hours of sleep and class, I got the chance to re-assess the whole stereo problem.

When the car is running, I can hear the alternator through the speakers but not subs. I know it's the alternator because the pulsing gets faster and starts to whine when I give the engine gas. I also thought I had a ground loop, so I tried using a 15 foot piece of 4ga high strand wire I had leftover to attach the negative battery post to the spot where all the amps are grounded on the chassis. No change. So then I disconnected the amp grounds from the chassis and used the 4ga wire to run the negative directly to the negative post. This actually made the feedback WORSE . Not only was the noise in the speakers louder with more whining, but also the subwoofers were giving feedback (low beat pulsing).

So I reattached the amp grounds back to the original chassis location, and disconnected the power wire from the amps. I then used the 4ga wire to attach the positive battery terminal to the amps to see if the feedback was from the power wire. Nothing changed from the original issue. I'm not sure if a ground loop isolator will help, because I tried so many grounding configs in hopes of eliminating a ground loop, with no good outcome.

As for when the car is on "Accessory," I realize that I do in fact hear noises, whether it be listening to the radio, using the multi-cd changer, or playing a cd in the deck itself. When I listen to cd's in either the multi or deck, I can hear the laser moving around and occasional digital "beeps." When listening to the radio, I only hear very quiet "static" with the volume set to zero.

And when I have my touchscreen out, I hear humming in the speakers.

I'll take some pics tomorrow and post them asap (my gf has the camera right now).

[Mikewire]

So it's not the amp ground then, but probably your HU. How did you ground your HU? Sometime the ground in the harness isn't solid enough, so you may try bypass the harness and route a new ground to the chassis.

[Johnny Chopsticks]

Mike, thanks for the advice. I went to Radio Shack and picked up two ground loop isolators (need one for channel A and B) and installed them. It cut out about 90% of the alternator noise; no more ticking, but there is a little bit of whining that can still be heard when the volume is at zero (also changes pitch when I give the engine gas).

As for the noise when the car is in "Accessory": It is GONE! Thanks again for the advice, I admit I was skeptic of how well gli's work. There is no more "laser" noise, and my speakers don't whine when I have my touch screen out. I still need to find out how to completely get rid of the whine when the car runs though...

As for my HU, I used the original ground wire from the old stereo. I'm not sure where it leads exactly; I'll trace it and find out.

So for awhile there, I thought that me doing two of the "Big 3" install could have screwed it up, but that just doesn't make sense. I mean, I'm reducing the resistance to ground for the battery to both the chassis and engine block. All that's left is to go from +terminal to alternator, but that looks way too difficult on my car without a lift.

Also, does anyone know if any music quality is lost by using gli's?

[Mikewire]

Sweet man, glad that helped.

When Aeron get on here I'm sure he'll throw some info at you too...

[Rennwagen1]

TURN YOUR GAINS DOWN!!!

Keep in mind that you are only using very small speakers, so you do not have to have your gain up very high, probably not even half way. You need to turn the gains down(possibly on your sub amps also) and then just run higher volume on your deck. You probably have at least a 4V output, so use it. Just because an amp says it put out xxx watts and your speakers will handle xxx watts does not mean that you get 100 watt speakers and then need a 100 watt amp. You will get better sound(and more longevitiy out of your equipment) if you turn the gain down halfway on that 100w amp and turn you stereo up more. I could go into this more, but with the GLI and the gain adjustment you should be okay. Also with grounds, you want the SHORTEST ground length possible, so make it as short as you can. This may mean that it doesn't look so good or flow with the other wiring, but it will sound better. And I am sure you are already doing this, but make sure that your ground and power wires are the same awg.

Not always a good idea:

[Johnny Chopsticks]

Thanks Aeron, I'll try that out and get back to you. However, I already know that all my gains are set to "1", which is the halfway point on the amps. I never turn the amps past 3/4 power on any install (only 1/2 on mine) because it starts to sound like ass. I'll turn down my gains and test my system both with and without the gli's. Do gli's reduce sound quality? I read on some other forums that people have had issues with how music sounds after installing gli's.

My ground wires are pretty much as short as possible, except maybe 1 foot longer than absolute tautness. Running from the +battery terminal is 1/0ga wire through the passenger side of the car to the back, then splices out to two 4ga wires; one goes to the speaker amp, the other goes to another splicer into two 4ga for both the sub amps (picture in my Garage thread). The sub amp grounds are 4ga and go into the return splicer back to one 4ga, then ground to chassis. Speaker ground is 4ga and goes to same sub amp ground location.

What should I set my cross-overs at? The HU and amps all have built-in cross-overs. I know the speakers have a freq range of 75-25000Hz, but have the HP CO's set too 100Hz. I have no idea idea of the subwoofer range, but have the LP CO's set to 200Hz.

[Johnny Chopsticks]

Aeron and Mike, whenever I meet you, I want to buy you both a drink. I can finally sleep in peace tonight.

I adjusted down my gain on both sub amps and the speaker amp, and now my stereo system is living in harmony. I never thought it was possible after last night. I tried both reducing the gain with and without the gli's, and I decided to keep them installed; I didn't notice any difference in audio quality.

My HU has 5V pre-outs, so that definitely helped. However, when I lowered all gains to 5V, the music was very clear but never got that loud (even with the HU volume maxed). So I had to come to an even balance between gain level and VERY small noise; I doubt many people would even be able to hear it if I told them it was there. So now I'm content with life.

Again, a HUGE thanks to both Aeron and Mike for your knowledgeable input. You've saved me hours of work and taught me some new stuff on car audio.

[kompressorgolf]

car audio is fun, used to be HUGE into it.it can be a bastard tho. i plan on building a custom setup in my street sweeper, (future 68 beetle project) nothing crazy, two amps, one for the hi's and mid's, and a 500 or something to a JL 8W7. custom enclosure in the back. i heard a 12W3 in a beetle, and it was enough to upset the stomach at times. im not about the crazy bass anymore, but some nice lows make everything nice.

[Johnny Chopsticks]

Okay, I just took some pics of the amp and the install in the spare tire space. Everything is still working great, and music sounds better than I could ever have imagined (even from just using 4x6 plates). Adding an amp is TOTALLY worth all the money/hours spent (and headaches suffered) to install .




The X600F without front cover.


The bracket I had to make to mount the amp, using the original bolt locations for the spare tire. Made of spare 3/4" MDF board, then carpeted.


It is amazingly sturdy. No movement at all.




The wires are a mess in this pic, but cleaned up nicely. I just hope I never get rear-ended...