SA stereo ground

[Broke Pilot]

Anyone know where the headunit (screen) is grounded on the SA?
Been playing with the amps since I’m getting a pretty good hiss at nominal gain settings and I’d be willing to bet that screen isn’t grounded to the batteries like the rest of the system.
I’m trying to avoid putting in a line driver.

On a side note, does that screen have any normal speaker wires on the backside? Or is it RCA out only?

[MLA]

What Screen? IIRC, that boat uses the Murphy ICE black box. I believe the screen on the helm acts more like a remote display.

The ICE has neither high level speaker leads as theres no internal amplifier, not does it have RCA plugs. What it does have is 8 chnl low level pre-amp output terminals.

Yes, id avoid a line driver as it will amplify any noises, rather then eliminate them.

[Broke Pilot]

Oh good I get to break into that rats nest of wires to find the ground. After crawling around in there taking measurements and playing a bit, that wiring job is just about unacceptable.
I’ll look up an ICE box. Dunno what that is really. Can’t we just have a normal sound system?!? Lol

[Broke Pilot]

So this is what I found, and even the pictures look like a supra display screen lol.
From what I can see in their wiring they want the ICE grounded either to the amp (weird and doesn’t seem like a good idea) and/or the display. I’d bet SC grounds it to the display which is probably where the noise is coming from.
Guess I’m gonna go play electrician. Thanks MLA! Dunno what we’d do without you sometimes!

[MLA]

From what I can see in their wiring they want the ICE grounded either to the amp (weird and doesn’t seem like a good idea)

Its absolutely the most ideal spot for the source unit ground. Just note, the ground is not the only circuit that effects unwanted noise.

[russellsmojo]

I think you will want a line driver unless you bypass the black box and do eq with Bluetooth.

The line driver will make those jl amps and speakers come to life. I heard about a new line driver out that is better at regulating voltage. I will try and find the model.


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[MLA]

Sorry, but I have to caution again, a line driver will not fix existing noise, but likely amplify it.

As to a line driver, the ICE is capable of 4 zone volume control. So your line driver would have to be capable of as many zones as your current system is configured. Say you have 3 zones: in-boats, woofer and tower. You would need a 6 chnl line driver.

[russellsmojo]

Sorry, but I have to caution again, a line driver will not fix existing noise, but likely amplify it.

As to a line driver, the ICE is capable of 4 zone volume control. So your line driver would have to be capable of as many zones as your current system is configured. Say you have 3 zones: in-boats, woofer and tower. You would need a 6 chnl line driver.

I bet existing noise is from amp gains being so high because there is little to no voltage out of ice. I doubt this boat is wired any different than the other supras coming off the line. Stick a volt meter on the out puts and it is shocking how little ice puts out.

On the zones it’s an easy fix. Remove 4th zone which is bow and tie them in with cabin.

Having had two supras I found no way to get system sounding right without a line driver. Never tried external eq but I suspect it would have worked.


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[Broke Pilot]

Oh I know this is one of a thousand places noise could come in, but this seems the most logical place to start. And with my obvious limited knowledge of the system this will be interesting

[Broke Pilot]

I bet existing noise is from amp gains being so high because there is little to no voltage out of ice. I doubt this boat is wired any different than the other supras coming off the line. Stick a volt meter on the out puts and it is shocking how little ice puts out.

On the zones it’s an easy fix. Remove 4th zone which is bow and tie them in with cabin.

Having had two supras I found no way to get system sounding right without a line driver. Never tried external eq but I suspect it would have worked.


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When I first got the boat the gains were cranked. It would blow your ears off by 25 on the volume lol.
I tuned it by pairs on the amp. It sounds great, but there’s still some hiss, even with the gains all the way down and the motor off. It’s nothing anyone would ever notice at this point, but it still bugs me. I know it’s there and that’s all that matters!

In my experience, JL amps always tend to be a little noisy from the start anyway. They’re super sensitive. I could almost bet if I threw a 6 channel Kicker KXA or iQ in there the hiss would be gone.
I love JL, just not the amps.