Constant Speaker Hiss troubleshooting/ advice??

[David Analog]

It is possible that a difference in either the supply or ground potential could add noise, although rarely this type of noise as described. But you have to deal with and eliminate this possible cause first. ALL audio equipment grounds should reference the same point. ALL audio equipment positive supplies should reference the same point. This should be taken in the strictest sense. No exceptions.

Usually a constant hiss, like white noise, or like the sound of a distant waterfall, is a product of extra signal processing like an EQ or an inequity in gain between audio electronics.
Every signal processor will add hiss as a byproduct to some degree. Some more than others. It's a matter of how much you can reduce it and whether you can still tolerate it.
A tower HLCD speaker doesn't create hiss but will ruthlessly reproduce hiss just like it does music content. And for an HLCD to be effective and intelligible at wake range it must be voiced a bit aggressive in the treble region, where you are most sensitive, and where hiss is most audible.
You'll never completely eliminate hiss when the volume is all the way down and you are at rest. You can only minimize it. The hiss shouldn't be a distraction when underway and with the volume raised as both the wind & engine noise plus music content will mask the hiss.
So if you complete the first phase and you still have hiss you can move on and assume it's an equipment or gain issue. It can either be an inherent quality in equipment or an inequity in the gain structure between equipment. To narrow the cause of noise, disconnect the RCA input of the last electronics component (amplifier). Ideally you would short the RCA input rather than leave it open. Turn the input gain of that component to no higher than 35%. The noise remaining is owned by that component. Reconnect and move backwards through the signal path to the next upstream component (EQ). Disconnect it's input, reduce the input gain to a reasonably low level and repeat the test. Next, move to the source unit and test differences between various sources whether iphone or CD. For example, a low voltage iphone source or a Bluetooth module can reduce gain placing an inordinate responsibility on a following gain stage to elevate the gain....thus a multiplication of the noise floor. An introduction of an upstream component resulting in a sudden and substantial increase in noise will narrow your focus. Some causes are more fixable than others.
Also, keep in mind that amplifier and equipment input gain controls are by no means a volume control and a reduction in the input gain does not necessarily constitute a reduction in the final output power. With some consistency people tend to set gains too high, especially amplifier gains, and this directly creates noise. Ideally you want to begin the signal path with high gain/voltage and keep the gain level consistent from beginning to end. Or, begin with a high gain/voltage and slighty reduce gain from beginning to end. Never so much gain as to saturate an input of the following component, which is unlikely. And never having to correct a gain loss by significant multiplication in one stage/component. A gain roller coaster is a certain path to noise.

[core-rider]

Just to jump in, where is the best place to ground if you have a perko dual battery switch.

Sent from my ASUS Transformer Pad TF700T using Tapatalk

Negative battery post is the best place if you are talking stereo equipment. You don't have to take all wires to the battery. I run a 1/0 gauge cable from the B- to a distribution block that splits to each amp and a small distribution block that handles lighting, HU, and EQ. In effect this makes all wiring go back to B-.

[core-rider]

Core,
I agree with you on the ground being the likely cause. Just so I understand are you saying to start by running all the grounds to the same B- on the one battery where the 600.2 amp is grounded and leaving the B+ power sources as is for now? Or do both B+ and B- need to originate from the same source/ battery?

Personally I would do both B+ and B- incase you ever ran into a situation where you needed to kill power to all stereo equipment. I guess for testing purposes you could temporary just the B- to see if it fixes your issue though.

[ffmedic74]

Just to jump in, where is the best place to ground if you have a perko dual battery switch.

Sent from my ASUS Transformer Pad TF700T using Tapatalk

[Paxdad]

Core,
I agree with you on the ground being the likely cause. Just so I understand are you saying to start by running all the grounds to the same B- on the one battery where the 600.2 amp is grounded and leaving the B+ power sources as is for now? Or do both B+ and B- need to originate from the same source/ battery?

[core-rider]

Number 1 thing to do is make sure ALL stereo components are powered from the same source... HU, EQ, amps... everything! It sounds like your grounds are coming from different sources which most likely is the problem. It creats different resistance values for each component and that is transfered to the speakers in the form of noise.

Move all the gounds to a common source B- and see if that doesn't help.

[Paxdad]

I have aconstant “hiss” sound through my speakers when the volume is turned down fairlylow to no volume at all. With the volume turned up the “hiss” goes undetectedthat I can tell. Please note this is a “hiss”not a “whine” that is commonly producedfrom an alternator noise. The hiss is constant and does not get louder with anincrease in engine RPM etc or increase in volume. The hiss is there when theengine is off and system on as well.
Here is abit of information that I hope helps:
Boat: 2008 SANTE210

• Clarion CMD 5 head unit with remote (I do notuse the head unit other than to power on the system) Remote is set to AUX.
  
• WS 420 EQ- It is the model before the presentmodel out now
  
• Arc Audio XDi805 amp for in boat speakers and WS10 subwoofer
  
• Arc Audio 600.2 amp for WS Pro 485 towerspeakers

As far as I can track down the ground for the 600.2 isrunning directly to the port battery post and the ground for the XDi805 isrunning to the existing ground wire that is in the stock wiring harness for thefactory (old) Polk amp. I assume it is running to the battery selector switch.I have not been able to determine where the ground for the head unit is runningto specifically however, it appears to be tied into some other ground wiresrunning to ???.
12v positive power to both amps is being supplied by one ofthe original wires from the circuit breaker and the other positive wire isgoing to the positive battery selector switch on the starboard side of the boat. Any assistance in how to proceed fromhere to eliminate the hiss will be greatly appreciated. I had a local marinestereo service due the amp upgrades last year and have been really disappointedin the install details to say the least, and don’t care to take it back norrecommend them to others in my area.