Fellas,

Just have one question. I am considering an Alpine setup with two 2-channel 80x2 amps. I might need to connect a relay on the power antenna lead....wondering where the connections need to be made. I have never connected a relay before, and I want to do it correctly. Thanks in advance everybody.

BTW, I did a search of old threads, and that did not really help me. Hope you guys can!

 

On the power antenna lead???

I hope you mean on the remote amp output lead.

On my HU, I accidentally hooked up to the antenna lead (blue wire) instead of the remote lead (blue/white wire) and my amp wouldn't run while I was playing a CD.

So, you might want to make sure it stays on if you want it to.

My bet is you don't need a relay, just run the wire direct. If you want, you can measure the coil impedence on the amp remote input to see what current you'll be drawing. Then add up all 3 amps and make sure you're not exceeding the current capacity of the wire.

 

Thanks raider, yeah I meant the remote amp output lead. I am glad you corrected that. I did not catch it when I typed that!

Anyway, I may be running two amps....do I need a relay if I only run two? I may take up your advice and test the wire. Thanks again.

 

So, here's what you need to look at:
R=V/I
Maximum current (I) on an 18 ga. wire is .54 A
So, you're resistance cannot exceed 22.2 ohms. I'd say 20 just to be on the safe side.

Now, this just makes sure you don't exceed the current capacity of the wire, but it's not saying your stereo can pump out that much juice. However, I'm pretty sure that if you're not on that number, you'll be safe.

 

Don't worry about running two amps. Typical deck output is up to 500mA. The most I've ever seen on an amp turn on draw is 200ish mA. You'll be okay as long as you stick with a reputable mfr. 18 guage wire will handle it too!

 

IEEE... Coil resistance on the amps? I thought these things were solid state units!



97xltV8

Also, if you feel the need to run numbers for something like this, don't forget you'll be running 14+ volts most of the time!

 

well, whether it's a coil or solid state, there is still an impedence on the contact.

 

You'll be fine, I have 2 amps with a total of 600 watts running with one turn on wire jumped from one amp to the other. This with the stock HU.

 

I have 3 amps running off of the remote turn on with absolutely 0 probs.

 

Thanks for all the info guys. Very helpful. I am not too worried, but I just wanted to make sure.

Right now, I am running one 2-channel MTX for rear Kappas. I will soon be upgrading to a 4-channel Alpine (I hope) for the four mains, and use the MTX to drive a sub. That is all I would like. I will likely use some Monster Cable speaker wire to carry the current from the H.U. to both amps. Should be fine.

 

I would just like to point out that every single amp manufacturer out there will provide max current draw on the remote lead if you only look at the spec sheet that comes with the amp. If you don't have it then you could of course measure impedance but that does not accurately depict current draw in all cases since voltage in your truck will constantly change as you drive and music plays. The relay is cheap enough and easy enough to wire. Therefore, there really is no excuse not to be using one just to air on the safe side. In most cases I agree that a relay is not needed (usually up to about 4-6 amps can run direct from the remote wire itself). Look on the bright side, even if you did have a ton of amps all connected directly to the remote lead the worst that would happen is your amps wouldn't get enough current to turn on. Most HU's these days have protection built in to them on the remote turn on leads anyway.

If you want to use a relay just wire 87 to constant + 30 to your remote wire going to amps leave 87a unhooked and the last two are your coil and one will connect to the remote turn on of the HU and the other to ground (does not matter which direction).