Weird stereo noise issue

Ok so after wiring up a neighbors boat a 2003 Xseries 205v hull we have a perplexing stereo noise issue .
I
First off little background on what's in it. He has a Syn 2 powering a pair of pro 80's. A Syn 4 powering 4 Polk UM 650 on the rear 2 channels and a kicker I think L10 or 12 on the front bridged. He has distribution blocks coming off a stereo battery strictly dedicated to stereo. 0 gauge from Bart to the block and 4 gauge from the blocks to the amps. The head unit and amps are all grounded to the blocks. Te Syn 2 is running directly off the head unit a Clarion M475 from the rear RCA. The front RCA goes to a PAC LC1 controller and then back to the Syn 4 rear channels for the 4 inboats. And the third set of non fade RCA from the head unit run to another PAC LC1 and then back to te Syn 4 for the sub. We originally used JL audio clear twisted cables 18ft to run from the head unit to the 2 LC1 located at the drivers helm and got a noise. He then ordered up some xScorpion quad shielded RCA cables and still got the same noise. It has to do with the RCA runs to the PAC LC1 we think because when eliminated the noise is gone.

The noise is Only in the inboats . Whether we switch outputs from the head unit front or rear we thought maybe blown channel, or swap lc1 controllers. When the lc1 is at full open volume there is no noise, when the lc1 is a full close no volume there is no noise, but when the lc1 is around half volume we get interference when the boat is running that is like crackling and crackles casters with the Rpms going up. The weird thing is is again at full wide open on the lc1 no noise at all and at full close meaning no volume to the speakers no crackling?


Any thoughts?

He first thought maybe interference from under the dash with all the electronics but before I upgraded to a 420 I ran mine the same exact way with zero issues although with kicker amps.

Sounds like the lc1?? Didn't you say you eliminated that and the noise was gone?

Yes but we also had a brand new out of the box lc1 as well for a total of 2 and both do the exact same thing. So really not sure.

have you swapped the LC-1s to make sure it's not a bad LC-1? Sounds like you did.

And then also swapped RCAs so it's not a bad RCA (even though they are new)?

If the RCAs and LC-1s sound fine on a different amp, regardless of the HU's RCA input, then I'd start to think it's the amp.

Wimpy HU preouts, plus double run could also be exacerbating any other probs if you are cranking the gains to compensate. Did you try that planetaudio EQ yet? This might be a good test case.

Yea that ppi eq was installed on the club boat we were outfitting. I was just going update that thread. That precision power eq worked ok. It is more designed for a car audio environment as the eq adjustments were tailored for a cars small in door speakers with no mid bass and some nice meaty 6x9 on the rear channels as the frequency adjustments are set up that way. It's not really a "dual zone" per say as the adjustments are not the same frequency levels on each front n rear zones. The adjustments are cumbersome as well in the moving marine environment. Using the fade and getting to sub dial is a bit clumsy.

We took a chance as it was priced right, it works and sound clean, we can't return it, but I wouldn't recommend it again. I would choose the clarion eqs 746 if I had to do it over. The adjustments for fade, sub and volume are all much better laid out in my opinion.



To answer yup we swapped RCA cables from the Jl to the x scorpion and the from the front to rear channels of the pre amp outs on head unit. No matter the combo same noise. Also with 2 different lc1. So beginning to think its the amp I guess. Which I wouldn't have guessed. 4 month old Syn 4

I guess what we haven't tried yet is running the Syn 2 of the lc1's to see if we get tfe same noise as well to isolate the Syn 4.

If you eliminated the lc1 and went direct to amp, then you didn't hear the noise. It wouldn't be the amp... That's if I read your first post correctly.. Now if both lc1's do it, I still think its the lc1 Unless your gains on your amp are up to high?

Swatguy - I just skimmed this over while at an outside birthday party for a kido.... so I might have missed something. But I'd suggest a quick check and bypass EVERYTHING and plug a 3.5mm jack into an iPod, and the RCA's right into your cabin amp. This effectively drives a stake right into the middle signal path of your setup. If the noise goes away, the problem is upstream in either an EQ or deck ground loop.

You'll receive a lot of good information here on WW, but the key to all of this is, isolate isolate isolate. When you do -- only then can you remedy the situation. Don't change to many things at one time or you might create other problems and really derail yourself in the quest for no noise.

If its only happening in the cabin amp, your half way home in isolation.

-Brian
Exile Audio

Thanks Bri, Never thought about going directly from iPod to the amp like that Perfect way to see if it's head unit related besides RCA swaps. The head unit is grounded to a d block but it's power sources are still factory.

True.

The gains on the amp are at about 3/4 for the cabins and were set with the volume maxed at 3/4 of the head units max until distortion. the sub gain is at about between half n 3/4. Again just tuned and set off distortion by ear. No tools or fant scopes

Ok swat, 3/4 gain seems Kinda high for 4- 6.5 on Half a syn4 running 2 ohm.... Im NOT "mister know it all" but usually on a syn4 I've never breached the 1 o'clock point on tuning, I have found the sweet spot to be just a hair higher than 11 o'clock... But this is my experiences with tools...
Anyways, have you had time to bypass the lc1 and go directly to amp and see if it's still the same noise? I read your post wrong because I did think you already did that and the noise was gone...

3/4 gain does seem high on a Syn4 that is run at 2-ohms stereo or 4-ohms bridged. If you where running at a higher impedance with anemic preamp voltage then maybe I could see setting the amplifier input gain that high.

David
Earmark Marine

I will check the exact gain amounts when we get to the boat tomorrow. Maybe I am off a bit . It's def more than the 12 o clock tho. The clarion is only a 2 v output on the pre amps if that matters and the iPod source has to be run off the 3.5 mm aux input cable.

Having tuned it with the cd feature we would have def backed off the gains as with the cd it is def distorted at the same gain levels with the cd source vs the aux source. I thought this was the proper way to dial it In as the iPod is really the only source used. The aux in level is also set to medium on the head unit. The gain to the sub I believe is around 12 tho as mentioned

I am going to head down tomorrow and get in the boat again with my neighbor and test it. I will go with a direct source to the amp via the rcas direct from the iPod. Oh yea and the iPod source volume isn't maxed either it's couple clicks down from full tilt as well to help distortion.

So got to mess around with it today. It' looks like its the Syn 4. While when we originally bypassed the LC1 we must have had te RCA cables in just the right position to not get the interference that try when we eliminated te LC1's.

However after today running a source directly to the amp bypassing the head unit and the LC1 we picked up the noise. It was weird. Basically when you move the RCA cables while attached to the inputs whether it was the directly from the iPod, from head unit ,or through the lc1 the noise would change and get louder or softer. We tried all 4 diff RCA cables and same issue. Still the engine whine/ crackle noise. It's only on the rear input for sure so there has to be a bad rca input on that line or something. When you twist the cables or orient the cables a different way at the input site , it's hard to explain , the noise changes and adjusts. We also threw a kicker 450.2 just to te inboats and no noise.

Guess the amp will have to go to Wetsounds unless anyone has an idea that's above my minimal knowledge. Amp is def under warranty. Apparently I am kryponite around the ws gear this season. Had my 3 mos old 420 go down and had to send that back twice out of pocket To get it resolved, was on a demo boat and one of the pro 80's gave way, and now a basically brand new Syn 4 has got issues it seems. My 420 after playing for apprx 5-10 min would all of a sudden just distort like crazy on the tower channel. No doubt Wetsounds stepped up and took care of it, still a bummer as i had to foot the bill for freight twice and most likely will again here for the amp. Hopefully we'll get it solved and up and running here soon.

Whoops also one thing we did forget to try is grounding the rcas to the amp chassi. I left the extra wire his house. Think that's worth a shot?

Don't go shorting the RCA shield ground to the amplifier chassis. First check the topology of the particular amplifier. If the RCA ground shield reads full continuity with the speaker output ground (remember that one output channel is inverted to facilitate bridging) then you are creating new problems. Usually the RCA shield is intentionally 'above ground' and must stay that way.
If movement of a particular RCA creates noise it should be easy to determine whether it is related to movement of the RCA cable or movement of the RCA chassis connector and it should be easy to determine whether the noise is boat operation related or with the boat completely inoperative.
If it is the amplifier connector then it can be a simple matter of a cold solder joint from the RCA ground to the circuit board. The amplifier in question has the connector strain relieved directly to the chassis which usually prevents this but it is still possible. There are many with cheap equalizers having non-relieved RCA connectors that are frequently going to experience this exact noise over the next couple of seasons.

David
Earmark Marine

So after spending some time on this we were able to arrow down the culprits.

There were actually 3 issues we able to isolate. I blown tweeter on his speakers it was in the bow so we really couldnt notice at first as we were so concentrated on tge noise from coming thru the cockpit speaker right next to our ear, one bad aux cable that I really have no clue how could go bad it was ever kinked or anything but it's fried, and the main culprit was a voltage guage before the distribution block. His system had this digital voltage guage in line right before the distribution block that came with his install kit a while back when he did his first install. Well the negative ground wire actually had worn thru inside the unit and was making contact with metal inside the digital guage. It seemed to have been giving off some interference that was magnified more through the longer cable runs, but only when that clicked on when the boat was running. So eliminated the above 3 and viola.......


I am wondering if the kicker amp didn't pick it up due to the fact if was only 150watts per channel whereas the syn 4 is pushing way more wattage.

Good deal! Atleast you found your culprit and the noise is gone!! Kudos bro!