Amp Remote Wire - Audiophile System

FYI for anyone wanting to use the rear Audiophile harness for an aftermarket amp and subs. The remote wire (bolded below) will not work for the remote turn on lead for an aftermarket amp. That wire only carries about 6.9 Volts, and the amps are looking for at least 10.5 - 14 volts.

What I ended up doing is tapping into the fuel pump motor relay, which gives me enough voltage. However, doing it this way prevents the amp from being powered when on accessory; the key must be in the "On" position. Does anyone know of a better solution to get power when the key is in the accessory position (without running a wire all the way to the head unit)?

The trunk connector (on the drivers side) is number C465 and the sub audio uses these pins:
1 = yellow/red: switched hot
3 = shield for low level audio signal
5 = red: constant power from battery junction box fuse F418 (20 amps)
7 = white/red: low level LEFT audio signal
8 = grey/red: low level RIGHT audio signal
 
Are you sure?

It takes almost no voltage for a remote turn on lead to turn on an amp. What amp is this?

If you have NAV, you can try that.
 
Are you sure?

It takes almost no voltage for a remote turn on lead to turn on an amp. What amp is this?

If you have NAV, you can try that.

Positive. I think it depends on the amp. This is a Rockford Fosgate Punch 300 watt monoblock. The manual even says it requires 9 - 16 volts for the remote lead. I don't have the NAV unfortunately.
 
Positive. I think it depends on the amp. This is a Rockford Fosgate Punch 300 watt monoblock. The manual even says it requires 9 - 16 volts for the remote lead. I don't have the NAV unfortunately.

Well, the neat way to do this is to use a couple of transistors and resistors to translate the 5/6V voltage to 12V.

A less neat, but easier way, would be to use a 5V relay. (Wire the stock turn-on signal to the coil, and the aftermarket input & +12V to the contacts.)
 
Well, the neat way to do this is to use a couple of transistors and resistors to translate the 5/6V voltage to 12V.

A less neat, but easier way, would be to use a 5V relay. (Wire the stock turn-on signal to the coil, and the aftermarket input & +12V to the contacts.)

Thanks for the idea on the 5V relay. It sounds like a pretty good way to fix this.
 
Awesome!

Does the following look about right then?

Pin 30 = constant [positive (+12 volt)] power
Pin 85 = ground
Pin 86 = 6 Volt remote wire from the stock harness (yellow/red wire)
Pin 87 = amp's remote input terminal
 
The actual pin numbers will vary according to the particular relay used.
Of the two that I posted, the reed relay would probably be the best as it should draw the least current.

See diagram
 

Attachments

  • relay.pdf
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Just for fun, here's a possible transistor circuit.
 

Attachments

  • transistor.pdf
    6.3 KB · Views: 181
Just for fun, here's a possible transistor circuit.

I may have to try the transistor circuit. The 5VDC relays state a max coil
voltage of 6.5 volts. I'm reading 6.9 on my meter.

Btw, what transistors are those in the diagram?
 
I may have to try the transistor circuit. The 5VDC relays state a max coil
voltage of 6.5 volts. I'm reading 6.9 on my meter.

Btw, what transistors are those in the diagram?

They're labeled. Go to somewhere like www.digikey.com and search for 2N4401 and 2N4403. There's nothing special about those two, dozens of other transistors would work.


You could put a 1N4001 or similar diode in series with the relay coil and reduce the 6.9V at the turn-on output to 6.2V at the coil.
 
Just for fun, here's a possible transistor circuit.

I couldn't find the 2N4403 at radio shack. Is there a similar transistor that could be used?

Edit: I bought the 2N3906, as it looks like it should work as a substitute for 2N4403.
 
I couldn't find the 2N4403 at radio shack. Is there a similar transistor that could be used?

Edit: I bought the 2N3906, as it looks like it should work as a substitute for 2N4403.

You can use 2N3904 instead of 2N4401, and 2N3906 (their anything PNP pack) instead of 2N4403.
 
Thanks for the help, joegr. I got the switching circuit using transistors/resistors done today, and it works great. One thing I did notice though is that in the circuit "off" state, there is about 1.04 Volts going out the collector pin of the 2N4403. Should R1 be more like 30.0K instead of 3.0K? Because the aftermarket amp will not turn on with 1.04 Volts, it's not a huge deal to me, I was just curious.

Also, do you think it's necessary to put a reverse-biased diode in parallel with the aftermarket turn-on +12 Volt lead to prevent kickback voltage from harming the transistors?

Here's a picture of the board:

trans_switch.jpg
 
Thanks for the help, joegr. I got the switching circuit using transistors/resistors done today, and it works great. One thing I did notice though is that in the circuit "off" state, there is about 1.04 Volts going out the collector pin of the 2N4403. Should R1 be more like 30.0K instead of 3.0K? Because the aftermarket amp will not turn on with 1.04 Volts, it's not a huge deal to me, I was just curious.

Also, do you think it's necessary to put a reverse-biased diode in parallel with the aftermarket turn-on +12 Volt lead to prevent kickback voltage from harming the transistors?

Here's a picture of the board:

trans_switch.jpg


I don't think that the 1V is an issue. I wouldn't increase the base resistor too much. You could add a resistor (say 1 to 3 K) between the emitter and ground of the last transistor.

If there is a mechanical power relay in the amp, then yes a diode between the aftermarket amp turn-on and ground would be a very good idea.
 
I don't think that the 1V is an issue. I wouldn't increase the base resistor too much. You could add a resistor (say 1 to 3 K) between the emitter and ground of the last transistor.

If there is a mechanical power relay in the amp, then yes a diode between the aftermarket amp turn-on and ground would be a very good idea.

Yeah, I'm guessing there isn't a mechanical power relay in the amp.
 

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