rca routing opinions needed

For a while my 04 STi was full of audio equipment that I do not sell / offer... yet is supposed to be my demo car (had all the equipment from before I started the business). I am in the process of slowly changing it all out as I sell off my current stuff. Last week I sold off my Polk components and replaced them with a set of Alpine Type R components. I wanted to make sure I was getting the most out of the speakers so instead of connecting them to my current Kicker 700.5 5 channel, I decided to take an Alpine MRV-F300 that has been sitting in my inventory for a while (was ordered to replace what was believed to be a blown amp in a customers car... but I found out that it was simply a poor installation and a bad ground connection... so the amp has been sitting ever since). I opted to bridge the Alpine 4 channel amp to maximize the output to my fronts and then also bridged the 4 channels of the Kicker to my rears. I was hesitant with bridging the Kicker because I heard mixed reviews on whether it could be bridged stereo or only mono... but it seems to be working great. Anyways, from what I could find, the Alpine and the Kicker still required all 4 RCA inputs to be connected so I had to use a few splitters to complete the task.

The problem is that I now have very slight backfeed (alt. whine) coming through the speakers. It exists regardless of whether the engine is running or not. Since the only thing that I changed was adding a power wire from my cap to the Alpine, a ground from a ground distribution block to the Alpine, and the RCA splitters, I would have to assume that the splitters are the culprit.

My over-all plan is to eventually run 2 of the same Alpine MRV-F300 amps (both bridged for now until I have the time / money to do a 4 speaker rear deck lid). So when the time comes, am I better to split the rca's behind the head unit and run 2 sets of 4 channel rca's back to the amps or keep it split at the amps and try to move them around so they are furter from the power wires at the amps??? Moving them will be tough because they only really come together when they get near the amp (maybe the last 12" or so). As far as money goes, I can get decent RCA cables for a good price so if I will get better sound by running 2 separate 4 channel rca's then I'd rather do that. I really don't want a demo vehicle with alternator whine... lol.

Before anyone asks, I have a true 1/0 awg ground from a solid point (sanded down seat belt bolt) to the dist. blow then 4 awg to each amp. The cap is there simply because I had it, and it works well as a dist. block for the power. I will probably end up removing it when I re-do the setup. The car also has all new 'Big 3' wiring and even a couple extra grounds to make it perfect. Up until adding the new amp, I never had any hint of back-feeding.

On a final note, yes I know this is probably a dumb post to be coming from a shop owner, but ever since my C.City days, I've always been more into the remote start / convenience / etc. aspect of installations and never really did much with audio other than the standard everyday installations. But now that I am a shop owner, I am starting to get more into the audio aspect and want to make sure that I am doing everything in my power to get my customers set up correctly the first time... but training is a long work in progress.

Sorry for the long post, but to those who read through it, I applaud and thank you!!

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

For normal listening, how loud is the radio? ## out of ##?

If you dim and brighten your dashlights, does the pitch of the noise change?

It is currently an AVIC Z2 w/ Z3 HDD. I typically listen to it between 10 and 20 out of 60 or 80 I think (never really went up that high... lol).

The noise is there even with the engine off but does not seem to change with much at all. Even at varying RPM, it is very minimal change. I am about 95% certain it is because of the added RCA interference. I only had a few 'cheaper' splitters laying around and I honestly couldn't tell you for sure if they were twisted or not... I believe they were.

I guess my main question out of that whole ramble is whether it is better to put the splitters behind the head unit or back at the amps. I'm thinking behind the head unit would be better because the amount of current flowing is minimal compared to the amps and so I would think the 'disturbance field' (no idea what you would really call it) would be a lot less.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

Turn the gains all the way down on the amplifier. Does the noise go away? Your deck goes to 40. If you turn the gains down, you will have to listen to it at 25 or 30, but you should still be able to max your amp out if you needed to.

yea definitely adjust your gains down a little. noise problems are probably the worst because it can be so many things causing it. only rarely is it only because of the rca or where they are ran, as long as its a decent rca then you should have no problems. my guess is the alpine might have a higher sensitivity than the kicker so it will pick up noises that were always there and make them audible more so than that kicker.

also i will note that kicker amps are super picky and easy to mess up for the same reason that pioneer radios are prone to noise problems. as someone who also worked at circuit city, you should know this. i can feel you though when you say that you are more into alarms than sound, i was too, but i was forced into being a more well rounded installer by the people who trained me and the fact that after they decided to fire half of everybody i was the only one left who knew anything...

anyway back to kicker amps, did you at any point unhook the power and ground for that kicker amp with the rca still plugged in? the inputs on those amps like to blow because it will try to ground itself through the rca plugs.

i think you might be ok though because you said its only a light noise, if the inputs were blown it would be very noticable. if you can adjust your gains a little and make the noise go away then you'll be fine with that. set it to where your loudest listening volume is about 3/4 of the max on your radio.

have you upgraded the big 3? that could also help you with a noise problem

I have updated the big 3. The gains are already turned down to match the amp. After all that, I decided after getting home from work to pull everything out and get started on my new amp rack setup so at the moment i only have that Alpine 4 channel connected (need at least some sound... lol) and there is zero noise again. I will probably leave it this way until I get all of the new equipment... so sorry for wasting your guys' time... me and my damn last minute plan changes. lol.

When I was at C.City, I was the go to guy for almost all remote start / alarms so I really didn't do a whole lot with audio... but I do know what you are saying about the Pioneer and Kicker equipment.. lol.

Luckily my final system will consist of the Kenwood DNN770 and all Alpine equipment, so I won't have to worry about that at all.

Thanks again guys!

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

it was probably the kicker making the noise then, you probably made a ground loop with the two amps. sometimes grounding blocks can cause problems too. i think your new system will be a better one although i am not a fan of kenwood either.