loaked

I am willing to try anything to get this fixed, I cant let it beat me! With that in mind once I finally figure out the solution I will post all the details, and hopefully anyone reading this will benifit from it.

jbondox

I am willing to help... but ya have to bare with me... You need to mute all the input channels with a muting plug or a shorted RCA, turn the gains down to 0, crossovers off, and add a speaker to every output channel of the amp.

if you need to see if it is the car power supply, just hook the amp up outside of the car using another vehicle or a benchtop power supply

I doubt it has anything to do with the vehicles electrical system


take some pictures and post them

loaked

I did try the mute plugs, I had some old RCA's laying round and unscrewed and soldered(sp) the positive to the negative and screwed it back together, and the noise was still the same. Its a 2 channel amp, with pre-outs, I didnt mute the pre-outs though, I wouldnt think that would make a difference. And yes I did turn the gain on the Hi-Low converter all the way down, and the gain on the amp all the way down, and tried all 3 settings on the crossover. There is no bass boost or other knobs on the amp. One thing I didnt try is to bridge the amp, I should try that for the hell of it...

If I hook one channel up at a time I get noise, if I hook up both channels at the same time, noise just comes out of 1 channel. Again I didnt try to bridge it though. I will do that thursday just to see what happens, but the amp wont be running bridged, as it powers a set of components.

Thats one thing I still have gotten a chance to do is hook the amp up to a different power supply. I just dont have one. I only have thursdays to mess with this thing. Only thing I can think of is to pull the battery out of my other car and try that, and ground it to the Mercedes chassis.

I tried to use the battery in the trunk without all the other cables comming from the positive battery terminal, but then the car wouldnt start(duh). So that didnt work.

jbondox

just hook the amp up to the other battery and try not grounding it to the car, disconnect the turn on wire and jump it over from the power on the other battery.

loaked

Well I was going to mess with this yesterday but ended up going to the shooting range all day with some friends. So I didnt get a chance to mess with it.

But even if I do hook the amp up to a different power source and the noise goes away... then what?

jbondox

look at the power

vherok

Wondering if any of this was resolved?
I have some noise in my new system now.
I am taking it to a Pro shop tomorrow, they are going to help chase down the noise issues and build the cabinet for the sub woofer's and amps.

I have a low lvl white noise that is on at all times when the system is powered.
I also have alternator noise that rises in pitch with engine RPM.

Have stock cd player speaker lvl outputs-> Audison bit one-> 8 channel amp. Will be adding single monoblock amp to power the sub's.

I will let you know what we do to fix it.

jbondox

check if the noise goes away when the USB is connected to the laptop/bit1

also sounds like the input gain needs to be lowered to lower the noise floor...as for alternator noise, ensure the bit1 and amps are grounded at the same place, turn the input gain down on the amp and raise the output of the bit1. using shorting plugs on the amp will help huge to locate the alt whine...

with the hi lvl signal going to the bit1 I doubt it is generated before.

also try by doing track 1 again with the amps turned off

loaked

Well tomarow is another day off, no plans, so I will connect the amp to an outside source for power, and go from there. Please, vherok, let me know what fixes your issue(s) once you get it done.

vherok

Hi all.
After a few hours of trouble shooting there ended up being 2 issues.

First there was a ground loop problem, we nailed this down by measuring the impedance from the ground wire connections on the units connectors to a known good ground point.
Two of the grounds were fine and measured 0.2 ohms, one although attached at the same point and soldered (appearing to look good) was measuring 4.8 ohms!
I have no idea why the wire or the connectors were bad, we simply threw it away and replaced it. That fix got rid of the alternator whine, the way it was explained to me is that the amp was pulling a ground through the RCA cable shield because it was the path of least resistance.

The second issue, a constant buzzing noise was still present after the ground issue was fixed. This sound was there with the car running and not. Probably being induced into the system by the onboard mercedes computer or some other electronics in the car that function when the key is on.
We isolated this by hooking the Audison unit up to a power source outside the car, the buzzing was completely gone.
The fix for this was simple enough, we installed a noise filter on the positive power wire. It was a cheep unit and tomorrow I plan to make two of my own filters that will be rated at a much higher amperage.

I found a nice guide here.
http://home.comcast.net/~jbperkins/a..._whine_filter/
It was made to remove alternator noise but it should work well at removing other anomalies.

Hope this helps.

loaked

Well I spent the day yestdery messing with this again. I pulled the battery out of my Ford Expidition and hooked the amp up to it and what a shocker, there was no noise with the engine on lol. Amp sounded great, I even sat there for a while just listening to it for a while as I still have yet to really get the chance to hear it in action.

This helps a lot! This is what I was looking for. I knew there was some kind of filter for the power line that could possibly fix this. Good find! I had looked some up online before but wasnt sure which one would work. And no one else really knows anything about them.

I will attempt to construct one, what would need to be done differently that would make it handle more amps, like 40 amp is what I would need.

Thanks for comming back and letting me know your solution you used.

loaked

I wonder if it would be easier to just buy one of these:

http://www.parts-express.com/pe/show...&vReviewShow=1

But its only 35amp. My amp is 20x2 fusing.

jbondox

just to let you know you can add a capacitor inline (half or a whole farad) to your power wire and it will filter, also the battery is a filter...

hiss is a noise floor issue and is caused by improper gain matching, alternator noise is different ground potential

rob13572468

If you are running mids/highs off of the amp then you are likely not using full power on the amplifier... you could certainly try the 35amp filter.