Amp Remote Wire - Audiophile System
- Thread starter skizot722
- Start date
skizot722
Well-Known LVC Member
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)?
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)?
skizot722
Well-Known LVC Member
That's what I am saying. The stock amp remote wire (turn on) is only about 6.9 volts. The amp requires more voltage than that for the remote lead. So, it will not work.
skizot722
Well-Known LVC Member
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.
joegr
Dedicated LVC Member
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.)
skizot722
Well-Known LVC Member
Thanks for the idea on the 5V relay. It sounds like a pretty good way to fix this.
joegr
Dedicated LVC Member
You may be able to find one of these at your local Radio Shack.
http://www.radioshack.com/product/index.jsp?productId=2062478
http://www.radioshack.com/product/index.jsp?productId=2062480
http://www.radioshack.com/product/index.jsp?productId=2062478
http://www.radioshack.com/product/index.jsp?productId=2062480
skizot722
Well-Known LVC Member
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
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
skizot722
Well-Known LVC Member
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?
joegr
Dedicated LVC Member
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.
skizot722
Well-Known LVC Member
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.
joegr
Dedicated LVC Member
You can use 2N3904 instead of 2N4401, and 2N3906 (their anything PNP pack) instead of 2N4403.
skizot722
Well-Known LVC Member
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:
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:
joegr
Dedicated LVC Member
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:
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.
skizot722
Well-Known LVC Member
Yeah, I'm guessing there isn't a mechanical power relay in the amp.