Wiring an amp

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

I have wired an amp for a vehicle plenty of times. But I just bought an amp for my boat and im wondering...where do i run the ground wire? there isnt a frame that I can attach it to. So do I just run it to the negative terminal on the battery? with the positive and negative terminals hooked up to the amp will that cause a drain on the battery? halP!

pet575 · Posted: May 19, 2008 11:31 am Post subject:

Should be a ground up near the dash connections that the ignition and/or gauges are all hooked into.

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

yeah...good idea. is there a specific gauge ground wire needed? because running that fat wire to that would be unsightly.

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

600 watt amp btw

ttuclint · Addict Joined: 12 Aug 2003 Posts: 984 City: Lubbock, TX

ground to the battery.

gx205 · Outlaw Joined: 23 May 2007 Posts: 118

I just went thru the same situation on my boat.

I added an amp for my subwoofer, and couldn't find a good ground. My local stereo place told me that on all of the boats he has installed amps on, the best bet was to run directly from the battery.

I asked him the same question, as whether or not it would cause a constant drain, and he assured me it wouldn't.

You should have a blue wire coming out of the back of your radio. This is your "remote" turn on lead. That will hookup to your amp, and only when your radio comes on, will it turn on your amp. So when your radio is off, the current from your battery is just making a loop, to the amp, and then back to the battery with no drain.

I added a second amp to my stereo to run the speakers, and jumped the power from one amp to the other, BUT again my stereo guru advised me to run the ground back to the battery. he told me the ground is very important in whether an amp works right or not.

You might want to think about adding a second battery. I did just incase i listen to the music too long while I'm relaxing in a cove, and then take a chance of the boat not starting. I might not have needed it, but I'd rather ne safe than soory. I installed a duel battery switch, so i'll simply turn one of the batteries off while I'm listening to music without the boat motor running, and then if it does get too low on juice, I'll simply turn the switch to the other battery, start up and drive away.

Hope this helps

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

gx205, thanks for the great response. I have a rule on my boat that when the boat ignition is off the stereo is off too. So i wont be adding another battery for a bit. Thanks for the help.

but will I need the 8 gauge wire to run the ground too? I dont have enough 8 gauge wire to run back and fourth. would a regular 16 gauge wire work ok for the ground? the amp is a sony xplod 600 max power. but only 55 rms to each channel.

Brit Rider · Posted: May 20, 2008 12:32 am Post subject:

brichter14, I install marine audio, here's my opinion: You must use 8ga wire (minimum) and run it all the way back to the battery. You also need to ensure that you are fusing the power cable within 18" of the battery.

Do not be tempted to use any grounding blocks you find in the boat - they won't take the power of your amp and at the very least you risk damaging the boats wiring and having a poor sounding stereo, and the very worst you'll toast your boat.

gx205 · Outlaw Joined: 23 May 2007 Posts: 118

brichter14, Yes I agree with Brit Rider 100%, as what he says about using an 8ga minimum is exactly what my stereo guru advised me also.

As I stated before, and now Brit Rider, has too, is that it is really important that your amp/amps be grounded solid. So that just basically leaves you to have to go back to the battery to get a good ground, as we all are missing the metal frame that cars have.

This is a great board for information, and I'm glad i could help yo

RUSSIAN · Posted: May 20, 2008 6:08 pm Post subject:

I'm not disagreeing with brit rider, BUT my stereo, amps, tower lights etc have been run to the "grounding block" on my boat for 10 years, no issues. But I believe that block has a wire that runs to the same spot that the alternator is grounded. With that said, I will be running a new negative wire back to the main ground when I put in the new battery setup. The cost of copper these days will definitely make you question your wiring decisions.
Just an FYI, the negative terminal on a battery is not ground. In fact the current leaves the negative terminal and returns to the positive terminal

wakeskateordie · Newbie Joined: 17 Feb 2008 Posts: 17

Running a wire to the negative post of the battery is the same thing as running the ground on the amp to a cars body or frame. In a car the negative terminal of the battery is wired to the frame, and the frame is working as the wire.

Obviously in a boat there is no metal frame to use as the battery's ground hookup so you have to be wired to the battery.

Locate your amp as close to the battery as possible. A car's frame makes a way better conductor than 8ga wire. With 600 watts I think 4 ga might be better if you have to go more than 10 feet or so.

RUSSIAN · Posted: May 20, 2008 8:04 pm Post subject:

IF(thats a BIG if) you are getting 600 watts out of that amp you could be using 50 amps at full load. Most #8 wire is rated at 50-55 amps. #4 would be overkill for this application. Voltage drop can be determined if all factors are available to me(wire type, size and length of conductors). But at these small distances, it is usually negligible. Like I said, the cost of copper these days makes you question your wire decisions.

RUSSIAN · Posted: May 20, 2008 8:20 pm Post subject:

According to this page, a 600 watt amp draws 96 amps. Not sure where they came up with that figure, but this might be a good source to figure things out. My figures are based off ohm's law.
http://www.the12volt.com/info/recwirsz.asp

Edit, those numbers seem way off for the current capacity of the conductors Rolling Eyes

Brit Rider · Posted: May 21, 2008 12:19 am Post subject:

RUSSIAN, yeah thats a 600 watt Peak amp, you need to work your figures off it being 300 watts.

No disrespect but just because running off a common ground post in your boat has worked doesn't mean it will work for others - especially others with very limited audio/wiring knowledge. You may just have a higher calibre boat that uses better wire, or not have all the options boxes ticked where some high current draw options could have been added at the factory, or you could be overloading the wiring and just not know about it (I'm sure you don't have ALL your switches on at the same time, but what if you did..). I know that in all the sports boats I've ever worked on the wiring is the smallest it can be.

jonyb · Addict Joined: 06 Oct 2007 Posts: 844 City: Paducah

Ground wire size should be the same size wire as the power wire. You guys are saying a minimum 8 ga., but that's too vague. If the amp has a 4 gauge power terminal, then you need 4 gauge ground wire straight to the battery.

going to a terminal in the boat is okay if there's an amp there now, and you're replacing it. Hooking the ground to a terminal could make that dist. block draw more current than it can handle.

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

the amp is installed and working great. thanks for your help everybody. my tower speakers can now be heard while boarding...amazing!

i ran the ground to the battery btw.

pet575 · Posted: May 21, 2008 7:17 am Post subject:

I agree with the other opinions on here that, if possible, you should ground directly to the battery. I was merely answering your question as to where you *could* ground to. While grounding the ignition block CAN work, the best place is the to battery. A poor ground just complicates you getting the best sound you can from your system-which is what you are looking for here.

Brit Rider · Posted: May 21, 2008 12:29 pm Post subject:

jonyb, We know the specs of the amp, its a 300RMS/600Peak amp, drawing no more than 40amps... 8ga is fine for that amp; that's not being vague, its fact based on experience and knowledge.

You would also have to put hundreds of amps through a distribution block to over load it - I think you meant "to overload the common ground running to the dist block".

brichter14, Great to hear - care to share any pics of the install?

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

ill take some. heres a pic i took yesterday w/ my camera phone. The amp makes a huge difference. my tower speakers used to crackle out at around 35 volume but at 46 its still crisp!

http://www.imagedump.com/index.cgi?pick=get&tp=532875

some fisherman said the water was at 68 degrees. felt better in the water than it did in the boat....

Brit Rider · Posted: May 21, 2008 1:02 pm Post subject:

Good looking tower set up... Cool

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

thanks, other board rack comes tomorrow...now just need a mirror.

RUSSIAN · Posted: May 21, 2008 5:18 pm Post subject:

Brit Rider, I know what your saying, and that is why I am redoing alot of the wiring in my boat, one phase at a time.
There numbers are still off, 300 watts would be drawing 25 amps. Also, as an example #10 thhn is rated at 55 amps, for a single conductor in free air, at 90C. We rate our conductors at the 75C temp(electrical trade), putting it at 50 amps for a single conductor in free air. Putting that wire in a raceway completely changes things,dropping it to 35 amps at 75C. My boat has raceway's and I bet alot do, And I imagine most installers are not aware of derating. Although car/boat audio does not fall under the NEC(that I can find) it should be a reference point when installing any electrical system.
I believe my boat has #6 from the fuse block back, and to the ground block.

If anyone is interested, here is a link to an NEC reference site.
http://www.nfpa.org/freecodes/free_access_document.asp?id=7005SB
Article 310.60

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

too complicated.

RUSSIAN · Posted: May 21, 2008 8:33 pm Post subject:

Sorry for that brichter14, but electricity is complicated Very Happy

Brit Rider · Posted: May 22, 2008 1:04 am Post subject:

RUSSIAN, good info for sure and thanks for posting that up. But I think we can all agree that 8Ga for that install would be sufficient and a safe choice, as would fusing it to 40amps. Its not over fused,but it allows leeway. Very Happy

wakeskateordie · Newbie Joined: 17 Feb 2008 Posts: 17

In my post earlier I was thinking 600 RMS watts. Didnt realize it was a smaller amp. Sounds like 8ga would be just fine for this setup.

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

So i talked my friends into going on the lake today even though it wasnt sunny. But at around 530 the clouds were thin enough to let some rays in and there wasnt anybody on the lake. It was butter the whole lake.

Earlier I decided that i wasnt going to put subs in the boat so i bridged the connections of the amp to all four tower speakers. wow. Now these arent anything special. Insignia's from best buy. got them on clearance for 60 bucks....for all four. and the amp is a sony xplod from wal mart for 80 bucks(friends discount).

You can hear the music while riding so clearly now with the amp. I didnt think it would be possible w/ so cheap of a setup. But we were riding today listening to tunes and carving on the fresh butter. great day.

Brit Rider · Posted: May 23, 2008 7:01 am Post subject:

brichter14, Awesome, sounds good to me! Very Happy

jonyb · Addict Joined: 06 Oct 2007 Posts: 844 City: Paducah

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

its a sony xplod, my speakers are very loud. problem solved. bai!

Brit Rider · Posted: May 25, 2008 5:12 am Post subject:

jonyb, As stated, we already knew it was a Sony Xlpod Amp, we knew it's power draw, we knew all the variables we needed to know, apart from the quality of the Common Grounding post in the boat.... Please quit picking hairs. The problems solved, brichter14 is stoked at his new setup (rightly so!).. we don't need to go over and over offering advice that isn't needed again and again Laughing

eric-holmes · Outlaw Joined: 19 Jun 2009 Posts: 150 City: Searcy

Im reviving this old thread (so that way no one can tell me to search Cool

). I just want to make sure I have this straight. I can run my ground wire back to the neg terminal on the battery and that will act as the ground? I have never done this before and I just want to make sure it will work ok. And as long as I have a remote wire there will be no constant draw on the amp.

LS1_SE7EN · Criminal Joined: 17 Jul 2009 Posts: 92 City: Chattanooga

eric-holmes, Correct.

eric-holmes · Outlaw Joined: 19 Jun 2009 Posts: 150 City: Searcy

Awesome. Thanks.