White noise through speakers??

[McTafur]

So I just did an audio upgrade where I installed (4) jl 7.7s, 10 in sub and (2) 6.5s all powered by jl 6 channel amp/ head unit. Sounds great but I noticed distinct noise between songs or if the volume is up with no music. Any ideas?

 

[txav8r]

You may find that the noise is there even if the volume is down. It is the HU hiss, not the amp. But the amp is amplifying the HU noise. I had the same issue. I only noticed it in the barn, out in the open, it was barely identifiable.

 

[Murf'n'surf]

What are you using to play the music? Bluetooth? CD? iPod?

 

[McTafur]

Mostly blue tooth. I pod does it as well via fusion ip600

 

[redthumper9]

It is a possibility that your gain levels on your amp are to high. For reference, you should be able to turn your head unit up to around 3/4 volume before you start to hear distortion/clipping. If not, back your gains down some. This is not the real way to set your levels, but it may give you an idea if they are to high.

 

[McTafur]

Ok, great. Thanks for the tips

 

[scokill]

It is a possibility that your gain levels on your amp are to high. For reference, you should be able to turn your head unit up to around 3/4 volume before you start to hear distortion/clipping. If not, back your gains down some. This is not the real way to set your levels, but it may give you an idea if they are to high.

x2 on the money.

 

[txav8r]

This is happening on a fusion ip600? I question the background hiss. I have had it explained to me in less than laymen's terms, looked for ground loops, considered additional troubleshooting, but the bottom line for me was that it was simply background noise from the HU. In tuning your system, you get the max out of the HU without clipping. Then you get the max out of each of the zones of your amp without clipping, then the sub channel without clipping. After that, you turn down the volume all the way and you have a hiss in the background...what can be set too high? If it hisses at zero volume? That is what I had. It was kind of like the needle on the turntable (if you guys remember what real vinyl and a stylus was like) in the groove on the album transmitting the sound of the needle riding in the groove before the track started. I don't know if this is normal or something isn't right, but mine did it too on the stock HU with it amplified. And it was definitely the HU creating the noise, not the amp.

 

[redthumper9]

This is happening on a fusion ip600? I question the background hiss. I have had it explained to me in less than laymen's terms, looked for ground loops, considered additional troubleshooting, but the bottom line for me was that it was simply background noise from the HU. In tuning your system, you get the max out of the HU without clipping. Then you get the max out of each of the zones of your amp without clipping, then the sub channel without clipping. After that, you turn down the volume all the way and you have a hiss in the background...what can be set too high? If it hisses at zero volume? That is what I had. It was kind of like the needle on the turntable (if you guys remember what real vinyl and a stylus was like) in the groove on the album transmitting the sound of the needle riding in the groove before the track started. I don't know if this is normal or something isn't right, but mine did it too on the stock HU with it amplified. And it was definitely the HU creating the noise, not the amp.

You sort of reiterated my point. The way you just described to set up his system is pretty much what I do, but it sounds as if that may have not been done yet. He said between songs, etc......not at zero volume. I used to see it all the time in our shop, people coming in with noise as he described only to find their amp gains were maxed out. The gain adjustment is there to match the head unit output with the amp input. If they are not close, you will introduce noise. Id suggest taking the steps Mel and I described first. If that doesn't help, more troubleshooting may be necessary.

 

[woodard1983]

do you have a multiple battery setup? If the batteries are isolated then you need to make sure and have the head until and amp on the same battery....

also check to make sure that your RCA cables aren't running right next to your power wires...you have a ground loop somewhere in the system

 

[txav8r]

That may be a poor assumption on my part @redthumper9 , that he had noise at zero volume. I did and that was more what I was pointing out, that even when set correctly, it still produced a background noise that was modulated as you increased the amp gain levels. And I did have both amp and HU on the same ACC bus along with isolation of power/rca cables...but they are going to parallel at some point, they all go to the same amp. I will be very curious to know if the ip600 has the same background noise as the stock JBL head unit. Or if this is a condition being introduced by somehow setting it up wrong. I went through this for weeks and it never went away and the consensus was that the HU caused it. But it didn't matter what source you played, if it passed through the HU, you had the noise. From FM, to iPod, to AM...I don't think I ever tried a CD in it. If @McTafur does have it set up good and does have the hiss at zero volume, and a fix is found, I hope to pass that along to @DawgDaze as he has that boat now. But to my knowledge, it is the HU. Did I even say anything in that paragraph? lol

 

[scokill]

I have zero noise in my IP600, I have isolated amp only battery. Here is what I'd do. Unplug the RCAs from amp. Assuming you have appropriate cables, plug ipod, ipod, etc. directly to amp. Play some music at high and low volume, move to zero volume. If there is no noise then it's head unit, RCA cables coming from head unit, HU ground, interference, etc. If there is still white noise then to me it's the amp...either it's just the noise floor, gain too high, appropriate level input on amp not selected (if the inputs are manually switchable (line/speaker high/low level, etc.), potential ground issue.

 

[txav8r]

Just to reinterate...my noise was NOT apparent on the water or even in the yard. It was only when I was inside barn with pretty much total quietness without surrounding noise or other influence. I don't know if that makes a difference, but in the lab, you can hear things you can't hear other places.

 

[redthumper9]

Just to reinterate...my noise was NOT apparent on the water or even in the yard. It was only when I was inside barn with pretty much total quietness without surrounding noise or other influence. I don't know if that makes a difference, but in the lab, you can hear things you can't hear other places.

Yeah.....I have a very slight bit in mine as well, but not apparent outdoors or on the water.

 

[David Analog]

When you run into noise there is no better assistance than the qualified dealer, like Odin from Earmark Marine.
Proper system tuning can resolve noise but also make a gigantic difference in the performance level of your investment. From boat to boat the same equipment can perform differently.
Here is the place to start with white noise. White noise would sound like a constant distant waterfall and independent of the boat running. The noise amplitude will not change with a change of volume although it will certainly be more obvious at a low volume because there is nothing to mask the noise. For noise diagnosis, always take the signal path in reverse.
Remove the RCAs from the amplifier input. Short the amplifier inputs so an open input is not another source of noise. Run the amplifier input gain at 40% which is the norm when you have adequate preamp voltage. Then turn the amplifier on. All noise heard at that point is totally owned by the amplifier.
Now move upstream in the signal path. Do the same test on the input that is used for the BT with the input shorted. All additional noise that is heard at that point is totally owned by the HU.
Then add in the BT with it's input shorted and the iphone disconnected.
Once you introduce a pocket of noise, then your focus will narrow to that link in the audio path.

 

[txav8r]

@David Analog , can you describe how to "short" the amplifier, BT, inputs? You have explained this to me differently before, or I understood it differently...or possibly misunderstood it!

 

[Ryan Vogels]

Making it short and sweet... but basically the same as above.

If you have dual batteries, make sure the amp and HU are not grounded to separate batteries. (ground loop)

After that I would disconnect the RCAs to see if the noise goes away. That should quickly help determine whether or not is coming from the amp, or upstream. If it is not the amp, you may want to try a different set of RCA cables to be safe. If the RCA's are fine then you know it is most likely from the head unit or something attached to it.

I would argue the 40% gain piece. Most amps have the volt listed under the gain control. The idea is to match that with the preout voltage of your deck. 40% is not a universal number! Gains are made to match the preout voltage, not adjusting the volume!!!

 

[David Analog]

@David Analog , can you describe how to "short" the amplifier, BT, inputs? You have explained this to me differently before, or I understood it differently...or possibly misunderstood it!

Take one half of an RCA cable as a jumper and plug the Left RCA input into the Right RCA input. If you have the amplifier input configured in the 2-channel mode then you only have to short those inputs. If not then short all live inputs. Otherwise you leave that input open, like an antenna, for induced noise. It's just a good idea to be thorough when going through these diagnostic steps.

 

[David Analog]

"I would argue the 40% gain piece. Most amps have the volt listed under the gain control. The idea is to match that with the preout voltage of your deck. 40% is not a universal number! Gains are made to match the preout voltage, not adjusting the volume!!!

"

Let's get it back in context. We are simply diagnosing noise here and NOT tuning the system. The HU voltage isn't particularly relevant when the HU isn't connected. If an anemic HU voltage or particularly weak BT output voltage causes an inordinately sensitive amplifier input in order to get the amplifier at full power (via a test tone, DCM measurement, etc.) then we can isolate and possibly repair that condition along the way. But that's placing the cart before the horse.

 

[PaulyB]

I have this happening in my 4 REV8 tower speakers! GRRRRRR.... it seems to amplify a bit more when I switch my RGB LEDs on....