[kaigoss69]

OP did not make it clear whether he had noise with NO RCAs connected. In any case, the problem seems to be the RCA plugs picking up noise, and NOT the HU putting out noise through the speaker cables.

[digitaldav]

Originally Posted by kmarei

he was talking about the HIFI headunit, not the amp
is your setup HIFI headunit->technic harness-> XD600/6?

Yes to all 3 questions...

[digitaldav]

Originally Posted by kaigoss69

OP did not make it clear whether he had noise with NO RCAs connected. In any case, the problem seems to be the RCA plugs picking up noise, and NOT the HU putting out noise through the speaker cables.

From what I have read testing amp by using shorted rca or muting plugs, some call them, connected to the input of the amp can determin if noise is generated from the amp. I have done this and again there is no noise when mute plugs are connected to the input of amp. Even with the gain turn way up there is no noise when input is shorted.

OP did not make it clear whether he had noise with NO RCAs connected? Quote
No noise even with no rca cables connected, that is without the mute plugs connected...

[VP Electricity]

Originally Posted by digitaldav

From what I have read testing amp by using shorted rca or muting plugs, some call them, connected to the input of the amp can determin if noise is generated from the amp. I have done this and again there is no noise when mute plugs are connected to the input of amp. Even with the gain turn way up there is no noise when input is shorted.

Are ALL the RCA cables disconnected from the amp when you do this test?

Is there any chance that your RCA cables have the L and R shield common, or have any metal barrels touching each other or touching ground? ASre they coaxials rather than twisted-pair?

The (-) on the shield out of the BMW HU is NOT a common-ground signal like RCAs are supposed to carry. You want to make sure you don't have metal barrel RCAs touching each other or ground, and you don't want a coaxial, foil-shield RCA, you want a twisted-pair RCA.

[kmarei]

Originally Posted by digitaldav

From what I have read testing amp by using shorted rca or muting plugs, some call them, connected to the input of the amp can determin if noise is generated from the amp. I have done this and again there is no noise when mute plugs are connected to the input of amp. Even with the gain turn way up there is no noise when input is shorted.

OP did not make it clear whether he had noise with NO RCAs connected? Quote
No noise even with no rca cables connected, that is without the mute plugs connected...

so basically if you remove all RCAs from the amp = no noise
if you short all the RCA input jacks on the amp = no noise?

and did you try hooking up an ipod/iphone to the inputs of the amp?
did you get noise?

[sunpole]

Over the long weekend, I got finally got my Jehnerts set and XD600/6 installed. There is a very annoying hissing static noise coming out of the front speakers.

Here is my setup on my HiFi system,

HU -> Technic's Harness -> XD600/6

RCA inputs:
Front L/R for Ch 1/2
Y split Rear L for Ch 3/4
Y split rear R for Ch 5/6

Ouputs:
Ch 1,2 Fronts
Bridged 3/4 L underseat
Bridge 5/6 R Underseat

Diagnosis performce thus far,

- I tried both battery ground and left rear ground post, results the same.

- Noise is audible even when gain set to minimal and volume all the way down to zero

- Noise goes away when unplug the front RCA inputs

Any idea? It seems to be a common problem, is there a standard solution?

[kaigoss69]

Originally Posted by sunpole

Over the long weekend, I got finally got my Jehnerts set and XD600/6 installed. There is a very annoying hissing static noise coming out of the front speakers.

Here is my setup on my HiFi system,

HU -> Technic's Harness -> XD600/6

RCA inputs:
Front L/R for Ch 1/2
Y split Rear L for Ch 3/4
Y split rear R for Ch 5/6

Ouputs:
Ch 1,2 Fronts
Bridged 3/4 L underseat
Bridge 5/6 R Underseat

Diagnosis performce thus far,

- I tried both battery ground and left rear ground post, results the same.

- Noise is audible even when gain set to minimal and volume all the way down to zero

- Noise goes away when unplug the front RCA inputs

Any idea? It seems to be a common problem, is there a standard solution?

I would try using different RCA cables. Also, why are you splitting the inputs? The amp is designed to work with 2, 4 or 6 channel inputs. Get rid of the y-splitters and set the input switch to 4-channel.

[dmatre]

Originally Posted by sunpole

Over the long weekend, I got finally got my Jehnerts set and XD600/6 installed. There is a very annoying hissing static noise coming out of the front speakers.

Here is my setup on my HiFi system,

HU -> Technic's Harness -> XD600/6

RCA inputs:
Front L/R for Ch 1/2
Y split Rear L for Ch 3/4
Y split rear R for Ch 5/6

Ouputs:
Ch 1,2 Fronts
Bridged 3/4 L underseat
Bridge 5/6 R Underseat

Diagnosis performce thus far,

- I tried both battery ground and left rear ground post, results the same.

- Noise is audible even when gain set to minimal and volume all the way down to zero

- Noise goes away when unplug the front RCA inputs

Any idea? It seems to be a common problem, is there a standard solution?

Interesting. Over the weekend I installed my Jehnert underseat subs, XD600/6, and Morel door speakers. No hiss or noise whatsoever. I ran Power and Ground cables together from the battery, to the amp. Gains are set low, but not at minimum. (Maybe 10%-15% up from minimum)

My system is not bridged, but rather is using 1/2 for fronts, 3/4 for rears, 5/6 for underseats.

Digitaldav didn't mention whether his system was bridged or not. Maybe this is an item common to both of you?

One other question: (maybe important, maybe not) Is your amp chassis grounded? Mine is actually attached using adhesive-backed velcro, so I guess technically the amp chassis is not grounded (unless grounded internally)

[sunpole]

Originally Posted by kaigoss69

I would try using different RCA cables. Also, why are you splitting the inputs? The amp is designed to work with 2, 4 or 6 channel inputs. Get rid of the y-splitters and set the input switch to 4-channel.

Tried using a few sets of RCAs, and changed the channel selection from 2, 4, 6 with different input methods. No luck, still noisy..

[sunpole]

Originally Posted by dmatre

Interesting. Over the weekend I installed my Jehnert underseat subs, XD600/6, and Morel door speakers. No hiss or noise whatsoever. I ran Power and Ground cables together from the battery, to the amp. Gains are set low, but not at minimum. (Maybe 10%-15% up from minimum)

I am happy it worked out for you. Talking about 2 days of hard labor on labor day weekend!

Do you start hearing noise when turn up more?

One other question: (maybe important, maybe not) Is your amp chassis grounded? Mine is actually attached using adhesive-backed velcro, so I guess technically the amp chassis is not grounded (unless grounded internally)

Put a towel underneath the chasis, no luck!

[kaigoss69]

Originally Posted by sunpole

Tried using a few sets of RCAs, and changed the channel selection from 2, 4, 6 with different input methods. No luck, still noisy..

If you have the possibility, hook up an external audio source to the amp, such as portable DVD player, iPod or a home CD/DVD player. If the noise is still there, try moving it to a different location. If that still doesn't work, then my guess would be you either have a grounding problem, or the amp is defective.

[dmatre]

Originally Posted by sunpole

I am happy it worked out for you. Talking about 2 days of hard labor on labor day weekend!

Do you start hearing noise when turn up more?

Put a towel underneath the chasis, no luck!

Sorry, it was worth a try.

I've had my system turned up to where it was starting to distort without any type of hiss at all.

From they symptoms reported (hiss goes away when RCA plugs disconnected) it sounds related to the head unit in some way. I wonder if you could jump 12VDC to the 'remote on' input on the amp (after removing the wire that's there now - so you don't feed power back toward the head unit), and see if there is any hiss when the car is off, but all of the cables are connected? This might tell you if the problem is in the cabling, or in the actual powered section of the head unit itself.

This might help to isolate the problem... working step-by-step until you find it.

Good luck!!!

[balu4k]

Hi, Any solutions to this hissing problem. I have the same exact problem after the JL xd600/6 install, i hear the noticeably hiss from my mids even when the HU is off ( ignition on ) or even when HU is playing CD at volume zero. I don't hear the Hiss if i disconnect the RCA's. Mine is HIFI system on E92 2009 model. I even hear the hiss even after lowering the input gain, but the hiss sound is little less but still noticeable.

[balu4k]

Hissing is very low or almost gone if my gain is set to zero for channel 1 to 4. does the amp / whole set up expect to sound good with the gain set to zero? the JL user manual says to raise the gain until i get a 17.4 volts per channel for a 4 ohm speaker connection.. just wondering if some one can help posting their setting for the above combination

[ctuna]

All the stock Hi Fi speakers are 2 ohm
So if that's what you have they are now getting 100 watts RMS instead
of the 12 watts RMS for the doors that the stock High Fi puts out.

[black335isport]

I have exactly the same situation: I installed JL XD 600/6 with Technic's harness. There is a hissing noise all the time (radio turned on at 0 volume or turned off altogether).

What I have tried:
- I unplugged all the RCA cables and the hissing noise is still there. Also when I plug them in one by one the hissing noise is audible on all speakers.
- the gains on the amp are set at minimum on all channels - the hissing noise is still there
- I sanded the tip of the ground cable and connected it back to its location ( above the amplifier on the left side) - the hissing noise is still there
- I changed the High-pass to Low-pass to None and still the hissing noise is there, but with a slight different tonality (it sounds just a little bit different)
- the only time when the hissing noise disappears is when the amplifier is turned off.


Could this be caused by a bad amp because I am running out of options?

Notes:
- I have a 2009 335i with HIFI stereo - for now I still have the original speakers, the only change is the JL amp.
- for the installation I followed exactly the steps from this link: http://www.the9thyard.com/2012/03/e9...o-upgrade.html

Any advice is highly appreciated!

[Technic]

Originally Posted by black335isport

I have exactly the same situation: I installed JL XD 600/6 with Technic's harness. There is a hissing noise all the time (radio turned on at 0 volume or turned off altogether).

What I have tried:
- I unplugged all the RCA cables and the hissing noise is still there. Also when I plug them in one by one the hissing noise is audible on all speakers.
- the gains on the amp are set at minimum on all channels - the hissing noise is still there
- I sanded the tip of the ground cable and connected it back to its location ( above the amplifier on the left side) - the hissing noise is still there
- I changed the High-pass to Low-pass to None and still the hissing noise is there, but with a slight different tonality (it sounds just a little bit different)
- the only time when the hissing noise disappears is when the amplifier is turned off.


Could this be caused by a bad amp because I am running out of options?

Notes:
- I have a 2009 335i with HIFI stereo - for now I still have the original speakers, the only change is the JL amp.
- for the installation I followed exactly the steps from this link: http://www.the9thyard.com/2012/03/e9...o-upgrade.html

Any advice is highly appreciated!

My bet is a bad amp... any hiss when you plug the OEM amp back?

[black335isport]

OEM amp does not produce any hiss. I will start the return/exchange for a new amp process tomorrow.

[black335isport]

I replaced the amplifier and the hissing sound is still there. Any ideas on what to do next?

[Technic]

Originally Posted by black335isport

I replaced the amplifier and the hissing sound is still there. Any ideas on what to do next?

Try a different 12V point, or even a different route for the 12V cable as the last resort.

[Sirrus]

My E92 produced a lot of noise near the middle of the trunk area. I never completely got rid of the hiss, but made it quiet enough to ignore. Definitely check cable routing options.

If the harness gives you a 12v output, I'd be curious to know what happens when you use that. Obviously you shouldn't play any music like that though, for risk of overloading the wires.

[black335isport]

Originally Posted by Technic

Try a different 12V point, or even a different route for the 12V cable as the last resort.

I tried a different route for the 12V cable and no changes in the hissing noise. I did not change the 12V point though as I did not have another slot available for this - just out of my curiosity why would this make any difference?

As a side note I noticed that the hissing sound does not increase in a linear way with the volume of the sound. Actually at the level I listen to it does not increase almost at all or at least I cannot hear any noticeable difference. When I switch the Head Unit to CD or Aux while no CD or Aux is there and I turn the volume all the way up at some point (closed to the max level) the hissing sound level increases a little bit.
After I changed the front door speakers to Morel Hybrid Ovation and the under seat woofers to Jehnert the hissing sound is there.