After upgrading the speakers and amplifier in my 06 TSX I have been getting a loud hissing noise when the volume is turned to zero or the HFL is activated. My amp is a JL A6450 and I am using Infinity components and coaxials. I have tapped into the HU balanced outputs using a fabricated harness. The hiss is present with the engine on or off and the amplifiers gains are slightly less than half. Help!!!!!!!!!!

 

i have everything aftermarket in my CL-S and i get a hiss from my rear speakers... not loud.. it's always there even wen i turn on the music (most of the time its so loud it "covers" the hissing sound)

 

ground loop isolator???


might fix the problem

 

researched on a car audio forum. should be what g22 said....

check your grounds first.

 

Checked grounds yesterday and everything checks out. I will try a GLI this evening.

 

The TSX audio system is completely different then any previous Acura or aftermarket audio system. Most of the “tricks of the trade” will not work with the TSX. A GLI is not needed.

The check the following.
The amp gain is set up with a DVM and a test tone disk, the JL manual has the details. If you gain is too high you will get hiss a zero volume.

Check that the ring of RCA connectors measure the same resistance to the amp ground as the pins of the RCA connectors.

Make sure that the shield wire of each line is open “not connected” to ground. You do not need any shielding or signal ground connection between the HU and amp. Balanced signals do not reference ground so you can never have a ground loop and you will never need a GLI. If you ground the shield wires you could introduce a ground loop or create an antenna for noise. The shields only connect at the HU side.

I got your PM, I just got back from holiday and will make some more Harnesses this week.

jeff

 

Thanks Jeff, I will await purchase instructions. In the mean time I ran an 8 gauge wire from the amp directly to the battery and the hiss disapeared leaving me with a slight whine. I currently have the amp grounded beneath the deck. Is there a better location to ground the amp? The shield wires are only connected at the HU and are open at the RCA end. I will break out the DVM and start measuring resistance between the RCA connectors and my current ground and will post my results.

 

You might be onto something. The ground location you chose to connect the amp to may have a large noise level. Direct gnd wire to the battery is best, but maybe not practical. The closer you get the source, the battery the cleaner the power.

If the DVM test leads are long enough, measure your amp gnd terminal relative to the bottom of the battery. I'm guessing you'll see an ac voltage present. If so, that's your noise, whine, buzz or hums you hear.

Otherwise, merman has already mentioned the most likely causes.

 

You must pick a ground location that is heavy gauge metal and spot welded to the chassis. The thin metal that the XM receiver is mounted to is not good enough. The braces behind the rear seat are bolted in so they are also no good. I grounded to the brace that runs along the trunk floor behind the rear seat. Clean off all the paint and primer.

jeff

 

OK, I moved the ground to the frame near the spare tire. The hiss is minimized but the low whine is still present. I have measured the resistance between ground and the RCA ring and then the RCA tip and read approximately 100K across all four as the numbers were not steady. Is this good or bad? I also noticed if I set the amp to high power input there is no noise present. However the sound quality seems affected as the gains must be turned up to almost maximum.

 

Did you grind/scrape the paint and primer off of your ground point? It is imperrative that you be grounded to bare metal.

 

Yes , down to the shiny metal.

 

Update....noise ppears to be coming from the rear channels. Resistance readings match the front and all solder connections appear OK from visual inspection. Will re-solder the connections on my 14 pin plug to see if this helps. Also, I know this isn't necessary but I tried a GLI on the rear channels and no noise, however sound quality took a hit.

 

Sounds to me like you have the rear channels pined wrong or perhaps your pins are not making a good connection. Since the GLI cleaned it up I would guess that one or both rear channels have a connection to a shield wire. Good troubleshooting so far.

I have a harness ready to ship, PM me if you want it.
jeff

 

I sent you a PM.
Thanks Jeff.

 

mercman, i have tried to PM you as well but i cant seem to do PMs yet. How can i get hold of one of your harness's? As soon as you get another one done, i am ready to buy.

Thanks

 

Do you have the rear channels bridged? Did you plug the rear channels into the front section of the amp and check for the hiss?

Your harness is ready.
jeff

 

No, the rears are not bridged. I am utilizing all six channels with channels 1 and 2 connected to the front and 3 and 4 connected to the rear. The amp input mode is set to sum powering two 6" bazooka tubes on channels 5 and 6. I will try the rear channels into the front section and post my findings.

 

I swapped the front and rear RCA connections on the amp and the noise remained. Unplugged the front section, still noise with the rears still connected to the front input. Reconnected fronts to the rear inputs and disconnected the rears currently in the front no noise.

 

now that the problem seems to be isolated to the rear Rca plugs, do both left and right channels cause noise? Perhaps it can be traced down to just a single channel that needs to be rewired/soldered/repositioned etc.

probably not anything, but other experiments
1-I assume the bazooka tubes are completely passive (no additional power supplied). If there was power applied to those, i'd try disconnecting them (another potentially bad gnd connection). a quick test ...

2-another quick test, what if you take you amp out of sum mode?

 

The bazookas are passive. I have narrowed it down to the rear left and have ordered the bypass harness from Mercman. The scosche connector I modified for my harness appears to have a bad connection in that area, so I will swap out with the Mercman harness when it arrives.

Thanks everyone for the assist. I will post an update once everything is reinstalled with some pictures.