Too much "hiss" after new speaker/amp install -- help!

[h4ldol]

Hi folks,

I just installed (myself) a set of new components (JL C5-650) and a new amp (Clarion XC1410) in my 2014 Toyota Sienna. Here's the background:

- I am using the stock navi HU along with a Rockford Fosgate 4-channel line out converter to take the high stock audio outs to low RCA outs.

- The line out converter is grounded (2 wires for front and rear) to a metal bolt in the metal frame that the HU bracket is attached to.

- The remote turn on is connected to a fuse tap in the fuse box (for a power outlet so switched on with ACC/ignition only).

- The amp is grounded (probably about 1' long cable) to a metal bold that attaches to the front passenger seat (amp is under the seat). And paint had been scratched off pretty well prior to the ground wire attaching to the bolt firmly.

- The power cables run on the opposite side (probably over 2 feet away) from the RCA/speaker wires.

I turned it on for the first time yesterday and was disappointed by the very prominent "hiss" in the background. It's constant and isn't affected by turning the enginge on/off. It gets louder with HU volume increase but doesn't seem to be affected by anything else.

** Any thoughts? **

- Most of my online research suggests that improper/inadequate grounding could be the main reason.

- I may try to change where the amp grounding cable attaches to by taking it off the seat attachment bolt and drill it straight into some unpainted sheet metal with those "grippy/spikey" washers.

- The line converter seems to be grounded okay to the metal bolt but maybe it should be grounded to the HU ground wire instead? I guess that will need to be spliced into the cable since the cable presumably goes on to get grounded on the chassis after it leaves the HU harness.

- I will be changing the RF line out converter to a PAC line out converter that has a remote turn on wire but not sure if that's likely to help anything.

- The amp does not have any gain control (besides switching from low for RCA or high for stereo inputs).

Thanks in advance!

Click to read more...

 

[gstokes]

The line-out converter could very well be the problem and then again it could be ground loop or something else, but you mention a switch for RCA or speaker level inputs, this would indicate you have speaker level inputs so why not eliminate the line-out converter and just go line-out straight to the amplifier, bypass the preamp and head straight for the mains ..

Another thing you might consider is mounting the amplifier chassis to a piece of wood instead of the car floor, then ground appropriately..

 

[DARKHART 10+ year member]

Sounds like the gains on either the amp, converter or both are turned up too high, try backing the gains down.

 

[BoomTaco64]

i would change the ground from the factory bolts. sure they are solid grounds but are not the best for electrical connections. then i would check the gains and LOC gains as well.

 

[TheFiverMan 10+ year member]

I had the same problem. it was my LOC. You may need to ground it to stop noise.

 

[fasfocus00 5,000+ posts]

you should have used the Alpine Power Pack instead since it has Line Level inputs. You should get the female and male OEM plugs to connect all the wires and put the amp behind the head unit. so many problems could have been eliminated by doing it this way.

 

[h4ldol]

Thanks to everyone for the replies/input, it's greatly appreciated!

Sounds like the gains on either the amp, converter or both are turned up too high, try backing the gains down.

I was thinking that too, but the amp (XC1410) is a compact amp and actually has no gain controls, aside from low setting for RCA input and high for speaker level input. The Rockford line converter also has no gain controls, but the PAC one that will replace it does, so maybe that will help.

i would change the ground from the factory bolts. sure they are solid grounds but are not the best for electrical connections. then i would check the gains and LOC gains as well.

Yep, that's one thing I plan to try today when I get home from work. I guess I'll try a different grounding spot by drilling into some sheet metal with a star/spiked washer, ring connector, and some self-tapping screws. I never felt great about the amp's ground connection.

I had the same problem. it was my LOC. You may need to ground it to stop noise.

Good to hear, I was hoping that the LOC was the issue and that the grounding was not done properly or adequately.

The line-out converter could very well be the problem and then again it could be ground loop or something else, but you mention a switch for RCA or speaker level inputs, this would indicate you have speaker level inputs so why not eliminate the line-out converter and just go line-out straight to the amplifier, bypass the preamp and head straight for the mains ..Another thing you might consider is mounting the amplifier chassis to a piece of wood instead of the car floor, then ground appropriately..

I was wondering about the line out converter since the ground wires were hard to attach to the bolt (I didn't have the right size right connector so I just stripped a length of it and wrapped that wire around a screw and tightened it, and did both grounds to the same screw). I used the RCAs for ease of routing the cable and to "future-proof" it in case I later want to install an aftermarket HU with RCA outs. The amp is under the front seat just lying on top of the carpet... no metal contact. Do you think it still needs a non-metallic pedestal to sit on?

The new PAC line out converter actually has a gain control so hopefully that will help too.

*** Question though: ***

The old line out converter had 2 brown ground wires (one for front and one for rear RCAs). The new one has one brown "chassis ground" wire and one black "audio ground input" wire. It also has a 12V yellow wire. I did some research and please let me know if this is what I should do, or something else:

1. Connect 12V yellow wire on line converter by "splicing into" the yellow wire that goes into my stock stereo wiring harness. That is, don't cut the stock wire and connect, but rather connect (like a "T" intersection) the yellow line converter wire to the middle of the stock 12V wire.

2. Connect the black "audio ground input" wire similarly to the stock ground wire that goes into my stock stereo wiring harness, also by "adding" it to the stock wire rather than cutting the stock wire to make a connection.

3. Connect the brown "chassis ground" wire to some metal on the receiver bracket (via screw). Or should this also connect to the stock ground wire that the "audio ground input" wire connects to?

Thanks for the input again, it's been invaluable.

 

[h4ldol]

So I got the PAC LOC today and swapped it for the Rockford LOC that I had installed previously. I made a better ground attachment for the LOC, but still just to a metal screw (between the screw head and a washer, although not ideal as the screw goes into a metal thread but lies on top of plastic trim). This LOC needed 12V so I tapped into the stock 12V power wire leading into the original wire harness. I did not connect the remote turn on wire (left it connected to the fuse wire tap).

Anyway, the hiss is gone and not really any noticeable noise so I'm pretty happy. I didn't do anything to the amp or the amp's ground cable so I guess the prominent hiss was from the LOC, probably the poor ground cable connection and/or the LOC itself. The PAC LOC seems better and does have gain controls for front/rear channels, which is nice.

Thanks for all the help everyone! What an ordeal the speaker/amp installation was... I must have spent a good 30 hours on it all together, if not more, but it was a good and mostly fun experience. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[TheFiverMan 10+ year member]

Glad everything worked out for you!

 

[h4ldol]

you should have used the Alpine Power Pack instead since it has Line Level inputs. You should get the female and male OEM plugs to connect all the wires and put the amp behind the head unit. so many problems could have been eliminated by doing it this way.

Thanks for the input/suggestion. The Clarion amp I have also has speaker level inputs but I used a LOC because I wanted to run RCAs (for future upgrade to aftermarket receiver that will have RCA outs). That Alpine (KTP-445U) is pretty compact like my Clarion (XC1410) but even so, there's no way either will fit behind the dash as originally I had hoped due to almost no extra space behind the dash, unless I put it way behind the dash (as in next to the firewall). It fits nicely under the passenger seat though.

Glad everything worked out for you!

Thanks!