Antenna lead voltage question - Sean? Doug? Anyone?

I'm putting some tower speakers on a buddy's boat. The antenna lead out of the HU already is taken (For what, I have no idea). Anyway, I'm working with a JBL 80.4 on this. I've already wired the RCAs. Now I need the signal to turn it on (which usually comes from the power antenna lead). He wanted a kill switch anyway, so that he could choose to turn the tower speakers off (I've got one on my boat and it works great). My question is this: Since the antenna lead already is taken, can I run a hot wire through the "Kill" swith to the "antenna lead" slot on the amp to tell it when to turn on? Are there any voltage issues I need to worry about?

I'm thinking that this would work fine. This wire is solely used to tell the amp when to turn on, so I'm thinking (and hoping) that any ol' 12 volt signal will do the trick. It's the RCAs that will actually be carrying the stereo signal. He'll be able to turn the tower speakers on with the switch as he wishes. Anything I'm missing here???

Just tap the remote lead and run it to the amp. You can get taps at radio shack

Check the amp to see what it will take power wise for the signal on imput. If it will take that many volts then no prob your good to go. If not just tap into the pwr ant. lead and put a switch on the new wire before the amp. You don't touch pwr wires that way(switches cut down on amps to the "amps")and you don't have another higher voltage line to fuse and worry about shorting out. That's how i would do it.

There should be a blue wire coming out the back of the head unit. This is the amp remote wire. It is low current and can handle quite a few amps.

Yep, usually a blue wire like Peter mentions.

The power antenna lead might only work when the radio on the head unit is on. If so, that amp will only turn on for the radio...

I know the stock Waterproof Clarion power ant leed (blue) is quite week. It can't/will not turn on to many Amps'. I had to install another relay to fire my system up. Thas a good question How manny amps is to much for a Deck to turn On?

I'm running 3 amps off of my Pioneer deck. The relay is a good idea if you have a lot off of the remote (amps, eq, crosser...)

ive seen some remote turn on leads that were only rated to 300 milliamps (.3amps) so if your running multiple amps add a cheap radio shack relay and it doesnt even have to be one of the heavy duty head light relays from an auto parts store since youll only likely be using about an amp or so to turn on everything. If you overload this remote turn on lead you may damage your head unit.

i use a relay on my remote turn on just to be safe.

I REALLY appreciate everyone's input!!

I thought I was sure, but now I'm wondering: Am I worried about amps, volts or both? I assumed that the remote lead would be carrying very few amps and 12 volts. Is this an incorrect assumption? If this is correct than shouldn't any 12 volt ignition-enabled wire be good to turn on the amp?

Also, I'm confused by Bob's comment that this may harm my HU because it won't be connected to the HU in any way. That's the heart of my question: Can I use something other than the HU to turn on my amp. Now I can certainly see how if I get this wrong it could screw up the AMP, but unfortnately my amp literature doesn't say what the appropriate range for the REM in is. I've written to JBL so we can see if they respond.

Thanks again for your help. It's awesome that I've got a stereo question and the first place I come is WAKEWORLD. Y'all are the best.

The amp remote lead needs 12 Volts input and a very small current to turn on. The head unit power antena output puts out 12 Volts and (depending on mfg) a small amount of current.

You can use any 12 volt source to remotly turn on the amp. You could even jumper it to the 12 volt lead of the amp going straight to the battery, BUT: It would be on all the time! You can hook it up to the ignition switch so it comes on/off with the boat, you could hook it up to a switch on the dash that switches 12 volts. As long as you get 12 volts to the amp remote turn on lead it will come on. You can also put a switch in there anywhere inbetween the power source and the amp. But just remember if you do not connect the amp remote to some sort of switched supply that is on/off with the radio/boat, it will get left on and it will drain the battery.

The smartest way to do it this:

take the power antenna lead from the HU, hook it directly to a relay. Then the output of the realy should go to 1) whatever it was hooked to previously, 2) a switch that then goes to your amp that will drive the tower speakers. This will let your friend be able to turn on/off the tower speakers whenever the radio is on and their is no chance of leaving the amp on when the boat is not in use.

FYI...
Relays are electromagnetic switches that take a small current source (same voltage system) and use that to switch contacts that can handle larger currents (typically same voltage). They are commenly available at radio shack or autoparts stores.

Good luck.

Tony, if you use the antenna lead from the HU it may only be hot when the HU is in the Radio mode. Some Sonys do this for example. I'd just use the remote on (blue wire) or any other switched 12v source.

Tony,
I have my amp wired like you are asking. I ran a wire from the hot terminal of my amp, to a switch, then back to the remote terminal of the amp and it works great. I can turn it off and on at the drivers seat (unit on other side of boat) so I can hear the rider or driver when I am riding.

Sean, You are correct that some models do use an amp turn on lead and a power ant lead. One will typically be blue and the other blue/white. In that case if you use the power ant wire then the amp won't work with cd's, etc... only radio.

I assumed that our boys (matt) radio did not have this two wire setup, since he did not mention the remote amp turn on lead, and also stated that the power ant lead was already in use and he didn't know why, which I assumed he didn't have a power ant, but probably already had an amp in their running the factory speakers that he was unaware of, or it was just connected to a factory harness that was not in use/would be in use if the optional amp was installed. That lead me to believe his stereo probably didn't have the two wire system. Just my assumptions, but good point to make for some that are unaware of that setup.

Chris, yep any of those things will work fine, only drawback with that is if you forget to turn it off after a day of riding, it will leave the amp on and drain the battery over time. Not a huge deal, just a pain when you are at the boat ramp ready to go!

One other thought just to CMA (cover my a$$) if you connect the wire to the battery, or the battery connection of the amp it is a good idea to put a fuse in line at that point. If the small turn on wire (typically 18ga) were to short to a ground somewhere you could potentially have a serious problem or fire. Installer rule is to fuse all lines at any "power source". And a power source is any point where you are taking power from. If it is fused up stream, make sure the wire can handle the current of the rated fuse or place another one with appropriate size fuse at that point. Amp turn on fuse would only have to be a 3 amp fuse, but you could use a 5 or 10, you are just trying to protect the wire comming off the battery or amp terminal. A shorted 18 Ga could eaisly carry 10+ amps long enough to blow a 10 amp fuse. Sorry for the long and drawn out post, hope it makes sense.

Tony, good point but the lighted switch helps with that. I have gotten into the habbit of running a quick light check before I leave the boat. I left my master switch on one time and it killed my battery. I have an onboard charger that I plug in when I get the boat home, so the amp wouldn't really do much harm, but the lighted switch is a plus.

You got a backup plan... that works!