Power and Ground wires for an amplifier, where do they connect?

Skuza

Skuza

Well-Known Member
Nov 1, 2006
1,459
Lake St Clair, MI
Boat Info
400 Sundancer
Engines
7.4L Horizons
I am going to install a new amp on the boat and am familiar with cars and how its done but on a boat its different. No ground to start. I am wondering where I should connect the power because I know its not done on the battery terminal itself. Same goes for the ground. I seen two large distribution terminals on the fwd bulkhead in the bilge where the pos and neg connect and then tie into accessory items. I'm thinking this would be a good place to tie in at. On the positive side there is a thing that resembles a solenoid thats kinda throwing me. Some of the wires appear to be labeled as to their use but I havn't opened up the grey tracking that they are held in to analyze it further. Anyone who's done this tell me how you did yours.
 
First thought,, "Is this a trick question?"

There are a few bus bars through out the boat. The buses are usually near switch panels, breakers and helm. If it's a high powered amplifier, run heavy gauge wire to a main ground point or the engine blocks. Otherwise, use the closest bus bar. Same with B+. Low power can be sourced from the DC distribution panel. Otherwise, you have to go to the engine room and pick off power from something there. The solenoid with the two heavy cables is the cross over for the emergency start switch. You can tap there, or at the starter, or on the switched side of the battery switch. Don't forget a fuse or circuit breaker within 6" of where you tie in.

Best regards,
Frank
 
Thanks FC. Not a trick question. I am aware of the smaller bus' throught the boat for small load stuff but for a high power amp (720w max) I want to get to a "main" power source. Just didn't want to run all the way to the engine room at $2-3 per foot if I didn't have to. I will check behind the main panel but I doubt there is a large enough supply wire there to tap into.
Also I am thinking of re-running larger guage wire for the sub as the factory supplied stuff seams a little small for a 300w rms sub.
 
Most high power amp wires go to the battery.
 
You must go straight to the battery both ground and power. Make sure you use heavy 4-8 gauge wire with a inline fuse on the power. Always connect the power line first then the ground. A key note also is to make sure the amp is connected by remote turn on to the stereo (blue). If not you will have to toggle the power.
 
What is a MBSS? I was at the boat last night and looked behind the main breaker in the cabin. There is a large DC supply cable (positive and negative) probably 1 guage coming into a bus with about 5 leads off of that for cabin lighting. Could I tap in there or would I be taxing the 1 guage wire that supplies the cabin? I would like to avoid the 35ft of wire I need to make it to the batteries.
Is 4 guage that much more worth it than 8 for a ~700w amp? I know bigger is better especially for a long run like I will have.
 
Skuza said:
What is a MBSS? I was at the boat last night and looked behind the main breaker in the cabin. There is a large DC supply cable (positive and negative) probably 1 guage coming into a bus with about 5 leads off of that for cabin lighting. Could I tap in there or would I be taxing the 1 guage wire that supplies the cabin? I would like to avoid the 35ft of wire I need to make it to the batteries.
Is 4 guage that much more worth it than 8 for a ~700w amp? I know bigger is better especially for a long run like I will have.
Click to expand...


MBSS(Main Battery Selector Switch).
I think your bus in the cabin with the larger guage wire leading to it should be fine but definitely fuse it.
 
Check our these guys: www.darvex.com for your wiring needs. I've used them a couple of times their pricing is great and shipping is fast. Make sure to go with the HPM series of speaker and power wire. The wiring is tinned making it marine grade.
 
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At what point/wattage/size does one decide to go directly to the battery? I added a 2nd amp to our boat, not a monster one, and just spliced positive/negative off the existing amp to it. It lights up but the sub does not thump like I thought it would so perhaps I need to wire it directly to the battery?
 
Mrsrobinson, I would think about wiring it to the battery or a main bus. When I first started messin with car audio years ago I powered my amp with 18 guage speaker wire not knowing any better. Finally a buddy looked at it and couldn't believe I didn't fry the amp. I bought 8 guage and when I turned it on I couldn't believe the difference. I was like I installed a whole new system! The bass difference alone was unreal. I wouldn't expect this dramatic of a difference in your setup as the factory supplied wire is probably 10guage but running two amps might be pushing it. It definately wouldn't hurt to run a seperate wire for the new amp. Its just a pita to run this stuff on boats!
 
You need heavy enough wire to avoid significant voltage drop under conditions of high current draw. Funky wires, superfine conductors, surface conductors, litz wire, etc. are all blue smoke and mirrors. Just use heavy enough marine grade conductors so that you get 13 volts at the amp. Tapping the feeder at the cabin main probably is a bad idea since the voltage can drop below 12 with all of the 12VDC accessories running. Connecting directly to the battery is unsafe. You should not connect before the battery switches and the fuse must be within 6 inches of the connection. There's hardly any difference between connecting to the battery and connecting though the switch, which is wired with 0/4 or 0/2 cable.

Best regards,
Frank C.
 
Well friday night I hooked up the new amp. It sounds great but still have to dial in the frequency and gain settings. I used the factory wiring and methods also, just basically unplugged one and plugged in the other.
Now I have encountered another problem! The wall that the sub is mounted in is now fluttering to the point I'm concerned about it cracking the gelcoat! The fiberglass is only about a quarter inch thick there. The sub is mounted near the floor right next to the captains chair. I turned down the gain to the sub for now but am gonna have to think about reinforcing the area now. Im thinking about epoxying some treated wood to the backside of the wall. Also I would like to make a ring out of wood that the subwoofer mounting screws would bite into giving the cutout some more strenth. Starboard might be a great idea but probably pricey. I wonder how well 5200 would stick to starboard for my intended purpose?
 
Your sub is in the same spot as ours. We have some vibes now, but not enough where I would consider reinforcements. I even feel slight vibes in the cabin. Sounds like you have too much bass.

Maybe seal the with some kind of thick foam/rubber? I know they make a sound dampening backing you can line the trunk/doors of a car with. Perhaps you can add this?
 
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