lookAblack98TA

iTrader: (4)

ok so i have an aftermarket headunit and i am running an amp for my speakers and an amp for my sub ... with that being said, when i turn my car on, both amps power but only one plays (usually the bass amp). so i unhooked both of the remote wires and hooked one up at a time (stereo still sitting in passenger seat). well each amp works fine as long as i hook one remote wire up at a time, so i ran remote wire from one amp to the other then from the other amp to the radio... same problem (only one plays). any ideas on what could fix this?
thanks

Richiec77

iTrader: (3)

What head unit are you using? Do you also have it powering on a powered antenna too? Anything else hooked up or is it just the 2 amps? What 2 amps are you using?

It sounds like the HU isn't supplying enough current to turn on the 2 amps which is a little wierd. If you just run a jumper between the 2 amps it's the same as running 2 wires from the HU back to each amp. You are still running in Parrallel and splitting/dividing the current.

The HU at this point sounds like the problem. It could be the amps, but it's hard to diagnose the problem thru the internet and with no other information.

lookAblack98TA

iTrader: (4)

yeah i havent hooked up the power antenna yet i wanted to try and figure out the situation wiht the amps first.. they are small amps one being a fosgate and the other an even smaller JL. i guess the next step would be to triple check connections and maybe pull out the voltage meter. thanks for the help

dragonrage

Try unhooking the remote wire. Then on each amp, put like a 560 ohm resistor (doesn't matter exactly the value, 680 should work, 1k should work, and just a short should work but I don't like recommending people short things out) from power to remote. See if they come on then (at once). If so, you'll probably need to rig up a transistor as a buffer.

If anyone says anything about a relay, ignore them, as a relay would draw more current than the amps would anyway.

dave70

iTrader: (2)

Did you check for voltage drop from the H- U If you want to drive to Thibodaux i'll look at it 4 you. (504)430-6212 Like i said at the Lakefront I need a meter to figure it out . Give me a call . Or if i have to head that way i could meet you somwhere.

fredmr39

Amps are 120-200 mA in current draw to turn on, I thought, and an automotive relay needs ~160 mA to turn on. Two amps need likely around 250 mA at least to turn on.

How would the current draw from the HU be greater?

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I say give a relay a shot if any readings you take seem normal. Can't hurt to try, and it's cheap - and simpler than messing around with other things.

pentavolvo

or try hookin the remote to switched ignition instead of the headunit remote and see if they both come on with the ignition and play

with that said ive ran 3 amps off of a remote wire on multiple occasions and never a problem

dragonrage

A relay is the wrong component to use. I have said it before and I will say it again: car guys think a relay is the answer for anything and they are rarely correct. You want a transistor here. It can draw less than 10% the amount of power of a relay if you use it with the right resistor values (actually, you could probably get it to use under 1mA) and it's not mechanical so it will not die.

fredmr39

but a relay still draws less current from the HU than 2 amps would... His HU would most likely be able to activate the relay since it seems to be turning on at least one amp...

WhiteBird00

iTrader: (4)

Plus...relays are readily available and easy to install for less experienced installers.

I find the opposite problem - too many people don't use relays when they should so they end up running way too much current through switches and small gauge wire.

However, I seriously doubt that a relay is the right solution here because there should be no problem using the remote turn-on wire to activate two amps. The total current draw to activate those amps should be well within the capabilities of the head unit turn-on circuit. It would appear that there is some other problem - perhaps a faulty head unit or an amp drawing too much current.

fredmr39

Agreed 100% - though your HU should be able to handle the load, it might not be able to for whatever reason. A relay could bring the amps needed to something within the HUs reduced (if that's the case, and for whatever reason) capabilities. So though you aren't really correcting the HU problem, but avoiding it.

First, you might be best off trying pentavolvo's suggesting above. It is simple to do, and free (assuming you have spare wire) and will help eliminate the HU as the problem, or your wiring, etc.

transambandit

iTrader: (6)

okay dont know if this has been asked yet but does your hu have seperate hook ups for your sub and front end? Or are you daisy chaining the 2 amps, meaning you are running 1 set of RCA cables off the headunit and connecting an rca cable from the first amp to the second amp or are you running 2 seperate rca cables to the amps. Seems to me that if both amps are powering on but you dont get sound out of 1 i would check the rca cables first before the relay.

WhiteBird00

iTrader: (4)

We've all been assuming that only one of the two amps was powering up. transambandit has a good point - the OP only says that he's not getting sound from the second amp. He didn't actually say that it wasn't powering up.

Question to lookAblack98TA...are both amps powering up but one not providing sound? Or is the second amp not powering up?

fredmr39

Post #1 said that USUALLY only the bass amp turns on... So I assumed there were other times the other amp was only on, and that both played. Otherwise, that would imply that both amps when on potentially have problems playing.

Do they share a common ground?