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Stereo experts chime in... cable run length

Old 11-21-2016, 12:42 PM
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Default Stereo experts chime in... cable run length

Making some adjustments in my AV system by taking advantage of the 110v for the salon DVD, TV, audio system. With that I am free to move my 8 channel amp and head unit which are currently nice and dry in the salon closer to the 12v system on the bridge if I want.

I have two choices -

Leave the amp inside and run 4 sets of 25' RCA cables to the bridge where the head unit will be

Move the amp upstairs, use short RCAs, and run 25'+ speak wires back down to the 5 speakers in the cockpit

I'm literally talking myself in circles on this and the only sort of speaker, AV, cable-geek info I can find online are home audio stuff. Clearly on a boat we have all sorts of external influences and interference so not sure if one cable is better suited for a long run. Long speaker cables are easier to run and cheaper but last thing I want is a hum in a 7 speaker system.

For what its worth I'm dealing with M800 amp, 4 7" speakers, 2 8" speakers, and 1 8" sub.
Old 11-21-2016, 01:18 PM
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I would opt for the second option. The AV cables carry low voltage signal and prone to picking up and feeding the amp low level interference. The shorter the better. Long speaker cables on the other hand run higher audio voltages to the speakers and any low level noise is swamped by the signal. Just make sure the DC supply to the amps new location is heavy enough to carry required current.
Old 11-21-2016, 01:32 PM
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2nd vote for shorter RCA cables... they are more sensitive and pickup noise more so than speaker cabling, the RCA cable itself is also more delicate. High quality braided speaker wire will cover the distance without issues. I also second the supply cable to the amp, make sure it is adequate.
Old 11-21-2016, 01:42 PM
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Braided speaker cable... I was going to use plain Ancor 14ga tinned speaker wire. Is that not up to par?
Old 11-21-2016, 01:53 PM
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Originally Posted by Lead Change View Post
Braided speaker cable... I was going to use plain Ancor 14ga tinned speaker wire. Is that not up to par?
Sorry what I meant was "Stranded" wire... just like the Ancor marine stuff. If you can keep the speaker wire runs somewhat separated from other power wires it will also go a long way to avoiding interference.
Old 11-21-2016, 04:56 PM
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The best way to keep noise to nothing is to keep your ground short. So long rcas are far better. Especially if no noise exsists now.
Modern rca's that are of good quality like jl or WS wetwire can withstand a lot of rf.
Old 11-21-2016, 05:46 PM
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The JL Audio M and MHD amplifiers have always been differential input and this makes induced noise through the RCA cable unlikely. And recently Wetsounds has adopted the same approach. A feature you do not find on cheaper amplifiers. Still you should run a high quality 100% shielded RCA cable. Even with a differential input, twisted pair makes me nervous in a boat. And when possible avoid parallel runs in close proximity over long distances to supply cables. A long cable between a source component and the HU is more of a concern to me.
If you are interfacing AC audio/video components, such as an AC DVD or LCD, with DC audio equipment, be prepared to add isolators to those RCA interconnects.
Old 11-21-2016, 06:43 PM
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Originally Posted by Dockholiday74 View Post
The best way to keep noise to nothing is to keep your ground short. So long rcas are far better. Especially if no noise exsists now.
Modern rca's that are of good quality like jl or WS wetwire can withstand a lot of rf.
Are you seriously advocating that long RCA cables carrying millivolt signals installed on a boat suffocated with rf interference and being fed to an amplifier, are better than long speaker wires running 24 volt AC audio to speakers?
Old 11-21-2016, 07:08 PM
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Originally Posted by isitstuffed View Post
Are you seriously advocating that long RCA cables carrying millivolt signals installed on a boat suffocated with rf interference and being fed to an amplifier, are better than long speaker wires running 24 volt AC audio to speakers?
I don't advocate running 25 plus feet of ground wire through any of that either. He said there was two choices. Leaving amp in cushy dry place with and I imagine shorter distance to batt. Or putting amp outside on fly bridge and re installing. Lot easier to try quality rcas and see if anything is picked up then re wire an amp. Worst case is put in a line driver eq up there that can isolate rcas and input like a ws420.
Old 11-21-2016, 07:09 PM
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Originally Posted by David Analog View Post
The JL Audio M and MHD amplifiers have always been differential input and this makes induced noise through the RCA cable unlikely. And recently Wetsounds has adopted the same approach. A feature you do not find on cheaper amplifiers. Still you should run a high quality 100% shielded RCA cable. Even with a differential input, twisted pair makes me nervous in a boat. And when possible avoid parallel runs in close proximity over long distances to supply cables. A long cable between a source component and the HU is more of a concern to me.
If you are interfacing AC audio/video components, such as an AC DVD or LCD, with DC audio equipment, be prepared to add isolators to those RCA interconnects.
So you suggest a solid core rca? Any suggestions on brand? Was checking out Amazon and the options are limitless.

Awesome conversation so thanks for the dialogue
Old 11-21-2016, 07:48 PM
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Originally Posted by Dockholiday74 View Post
I don't advocate running 25 plus feet of ground wire through any of that either. He said there was two choices. Leaving amp in cushy dry place with and I imagine shorter distance to batt. Or putting amp outside on fly bridge and re installing. Lot easier to try quality rcas and see if anything is picked up then re wire an amp. Worst case is put in a line driver eq up there that can isolate rcas and input like a ws420.
I understand your thinking, I see the OPs post may have been misunderstood.
He advised moving the head unit and Amplifier "closer to the 12v system on the bridge". Then running maybe 4 or more 25 foot long speaker cables back down to the Salon speakers.
I take that to mean a capable power supply is already on the bridge. Besides if you have no interference to start with (by not using long RCAs) you don't need to dissipate it through a ground wire which is separate from the battery negative. There should already be a common bonding point on the bridge for grounding electronics up there anyway so relocating the Amp next to the head unit seems straight forward assuming the head unit has a remote downstairs.
Old 11-21-2016, 08:03 PM
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Originally Posted by isitstuffed View Post
I understand your thinking, I see the OPs post may have been misunderstood.
He advised moving the head unit and Amplifier "closer to the 12v system on the bridge". Then running maybe 4 or more 25 foot long speaker cables back down to the Salon speakers.
I take that to mean a capable power supply is already on the bridge. Besides if you have no interference to start with (by not using long RCAs) you don't need to dissipate it through a ground wire which is separate from the battery negative. There should already be a common bonding point on the bridge for grounding electronics up there anyway so relocating the Amp next to the head unit seems straight forward assuming the head unit has a remote downstairs.
I think it comes down to how it's all re installed that concerns me. Since he doesn't mention it havin to go through metal tubing it shouldn't be to hard to avoid rf. Also since there is no noise now it's grounded well. Hate to see him move it and then get noise through the 12v set up that is up there. Hell split the rcas and run them all isolated using an audio control matrix in the cabin and a media master up top. That will take care of any noise and give him 7 volts.
Old 11-21-2016, 08:11 PM
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Well 12v is relative. The boat is 24v so the Vanner in the engine room sends the 12v to the bridge. Nothing up there is close to the batteries but the only 12v distribution panel I have is on the bridge. Currently amp is the salon is wired upstairs to that panel, as is the HU.

Benefit would be much shorter run to that 12v panel, not nessisarily the main batteries.

Literally no chases to run through. She's a a 30 year old Carolina boat... all wood. Problem is that power and audio do in fact run next to one another. Just part of having allot of "stuff" crammed in a small package.
Old 11-21-2016, 09:32 PM
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Originally Posted by Lead Change View Post
Well 12v is relative. The boat is 24v so the Vanner in the engine room sends the 12v to the bridge. Nothing up there is close to the batteries but the only 12v distribution panel I have is on the bridge. Currently amp is the salon is wired upstairs to that panel, as is the HU.

Benefit would be much shorter run to that 12v panel, not nessisarily the main batteries.

Literally no chases to run through. She's a a 30 year old Carolina boat... all wood. Problem is that power and audio do in fact run next to one another. Just part of having allot of "stuff" crammed in a small package.
Not all audible interference is derived from the power supply wiring of equipment. Power supplies with heavy currents induces magnetically AC noises, like a transformer does, whereas others radiate noise through the air as RF interference. I have, in the last few years, found that the most P in the A culprits of noise are high intensity LED lighting and HID Floodlight retrofits including new installations because they both use switching driver technologies in the audio range of frequencies and beyond between 100 Hz and 50kHz. Although 50 kHz is too high, after mixing in radio circiuts can also be heard in speakers as white noise. I only mention this as Dock correctly identifies no noise is present now, but could be for an old boat that undergoes said lighting retrofits.
Old 11-22-2016, 04:25 AM
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man guys, getting a crash course via this thread, much appreciated. I actually did do an LED refit so I'll pay extra attention to that. I only have maybe a dozen or so since shes just a small 41' thats definitely something I can work around.

So you guys lost me a few posts ago... is the consensus longer RCAs or speaker now that you have a few more details.
Old 11-22-2016, 06:36 AM
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Originally Posted by Lead Change View Post
man guys, getting a crash course via this thread, much appreciated. I actually did do an LED refit so I'll pay extra attention to that. I only have maybe a dozen or so since shes just a small 41' thats definitely something I can work around.

So you guys lost me a few posts ago... is the consensus longer RCAs or speaker now that you have a few more details.
I think now that we have a clear picture I would have installed the amp up in bridge the first time. If I would have gotten noise then I would have addressed it. The thing is now you have no noise. I seriously doubt using good RCA cables will introduce noise unless you purposely try and make them.
Order some jl marine rcas and call it a day.
Old 11-22-2016, 07:06 AM
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I think what you're seeing is that there are a lot of factors that play into audio quality. Quality cabling, isolation from other wires, proper grounding, good power source, noise filters.... Any one of these can cause noise.

Reality is that you need to take everything into consideration. I do agree seeing you have everything already wired, try to run a quality long RCA cable to the amp and see how it sounds. You may not even notice an issue and it would save you from having to relocate the amp etc...
Old 11-22-2016, 07:23 AM
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I hope this helps....http://morrowaudio.com/about-us/ssi-technology
Old 11-22-2016, 12:57 PM
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Originally Posted by David Analog View Post
I don't think any of that is anything other than opinion and advertising. If anyone was seriously hearing the difference in audio by using their brand of cables, they would be 10 years old with ears to match. My ears frequency response rolls off at 10 kHz due to my age. The sound quality in a boat is rubbish compared to your lounge room anyway. If anyone was serious about hearing music to that level of accuracy, they have a condition called 'audiophilitis' because they first have to have the best possible speakers and the same for their amp and source unit and use Litz wire for all cabling. The waffle about skin effect is true for various frequencies from a scientific point of view but I doubt if its audibly detected in music which spans only 25kHz at best. The concern here is not the perceived quality of the sound which is an individuals perception anyway, but the content, that being having clicks, crackles and pops everytime someone flushes the toilet or squeeling, hissing and whines when the engine runs or pumps turn on.
I suppose an analogy would be buying Bugatti Veyron driving it at the Nurburgring fitted with cross ply tyres.
Old 11-22-2016, 01:07 PM
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When I was working with Phoenix gold back in the late 80's early 90's we had the same literature. I know you can "hear" the difference in cheap crap rcas vs quality. To what extent nowadays due to compressed music etc I don't know. Set of those cables probably cost more then some systems.

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