Amp Turn On Relay
July-8th-2002, 05:25 PM
#1
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Join Date: May 2002
Posts: 74
Amp Turn On Relay
I have one 12" Kicker Comp sub in the trunk of my '02 Pro ES. The sub amp is in the trunk also and gets it's signal by tapping into the rear speaker leads. I am using the factory head unit as a source.
The installers wired the amp turn on wire to a switched fuse at the fuse box. This worked well, except that the amp was on whenever the car was. I found that when I turned off the radio, the amp did it's job and amplified any noise the head unit put out when it powered down. The noise ranged from nothing to a loud hum, depending on how high I had the gains set on the amp.
I found a workable gain setting on the amp, but wanted just a tad more bass than this setting provided. Increasing either the gain on the amp or the level on the line level converter generated noise.
I could get more bass by using the head unit's tone controls, but that made the bass sound bloated, losing the tightness I previously had with the lower tone settings.
I figured that if the amp turned off with the head unit, I could eliminate the noise I was getting when the head unit powered down. A friend showed me how to do this with a cheap relay from radio shack, a couple of minutes with a soldering iron, and some spare wire.
I'm here to tell you the relay works great. Here is how I ended up including it in my system.
First I bought the relay. It is Radio Shack Catalog # 275-232 and is called a 5VDC Reed Relay. Costs about $2.
When the stock radio is on, it generates about 6 volts at the speaker leads. I checked this with a volt meter, using the positive terminal of the speaker and ground. The relay activates at 5 volts, so this is enough power to trip the relay.
I tapped into the + signal to one of the rear speakers and soldered the other end of this wire to one end of the coil on the relay. I soldered another wire to the other end of the coil and attached that to a ground. I used one of the metal parts of the rear speaker basket.
This basically passed the current through the relay gates when the radio was operating, closing the circuit. When the radio is turned off, the current opens the relay.
I attached the existing turn on lead to the relay's "normally open" pin. Again, a bit of solder connected the wire and the relay.
The last connecter on the relay is the "common" pin. The wire from this pin goes to the amp's turn on connector.
A bit of electrical tape covered up the connetions on the relay and I tested the system out. I found I was able to turn the adjustments on the line level converter up all the way from about 1/2. I turned down the gain on the amp to dial in the bass I wanted. I can get as much bass as I want, with absolutely no noise when the head unit turns off.
As I already had the wire, solder, soldering iron and electrical tape, I have a total investment of less than $3. I had never used relays before and thought it would be complicated. It wasn't.
I had found various signal sensing devices that would do the same thing. They ranged in price from about $11 to $35, and probably work well too.
If you are looking for something to turn your amp off with the factory radio, any of these signal sensing devices will do the job. The 6 volts generated by the factory head unit at the speaker connector leads is sufficient to power all the units I looked at. Most require a minimum of 4.5 volts to activate.
I just wanted to share my positive - alright cheap - DYI solution.
Happy listening!!
The installers wired the amp turn on wire to a switched fuse at the fuse box. This worked well, except that the amp was on whenever the car was. I found that when I turned off the radio, the amp did it's job and amplified any noise the head unit put out when it powered down. The noise ranged from nothing to a loud hum, depending on how high I had the gains set on the amp.
I found a workable gain setting on the amp, but wanted just a tad more bass than this setting provided. Increasing either the gain on the amp or the level on the line level converter generated noise.
I could get more bass by using the head unit's tone controls, but that made the bass sound bloated, losing the tightness I previously had with the lower tone settings.
I figured that if the amp turned off with the head unit, I could eliminate the noise I was getting when the head unit powered down. A friend showed me how to do this with a cheap relay from radio shack, a couple of minutes with a soldering iron, and some spare wire.
I'm here to tell you the relay works great. Here is how I ended up including it in my system.
First I bought the relay. It is Radio Shack Catalog # 275-232 and is called a 5VDC Reed Relay. Costs about $2.
When the stock radio is on, it generates about 6 volts at the speaker leads. I checked this with a volt meter, using the positive terminal of the speaker and ground. The relay activates at 5 volts, so this is enough power to trip the relay.
I tapped into the + signal to one of the rear speakers and soldered the other end of this wire to one end of the coil on the relay. I soldered another wire to the other end of the coil and attached that to a ground. I used one of the metal parts of the rear speaker basket.
This basically passed the current through the relay gates when the radio was operating, closing the circuit. When the radio is turned off, the current opens the relay.
I attached the existing turn on lead to the relay's "normally open" pin. Again, a bit of solder connected the wire and the relay.
The last connecter on the relay is the "common" pin. The wire from this pin goes to the amp's turn on connector.
A bit of electrical tape covered up the connetions on the relay and I tested the system out. I found I was able to turn the adjustments on the line level converter up all the way from about 1/2. I turned down the gain on the amp to dial in the bass I wanted. I can get as much bass as I want, with absolutely no noise when the head unit turns off.
As I already had the wire, solder, soldering iron and electrical tape, I have a total investment of less than $3. I had never used relays before and thought it would be complicated. It wasn't.
I had found various signal sensing devices that would do the same thing. They ranged in price from about $11 to $35, and probably work well too.
If you are looking for something to turn your amp off with the factory radio, any of these signal sensing devices will do the job. The 6 volts generated by the factory head unit at the speaker connector leads is sufficient to power all the units I looked at. Most require a minimum of 4.5 volts to activate.
I just wanted to share my positive - alright cheap - DYI solution.
Happy listening!!
Last edited by Aydu; July-8th-2002 at 05:55 PM.
July-9th-2002, 09:58 PM
#5
Protege Owner
Join Date: Dec 2001
Location: Oklahoma City OK- where it is flat
Posts: 487
www.davidnavone.com also sells an outstanding unit that performs the same function with a little tighter tolerences, I have used them in my protege, and other stock headunit installs. It is a neat solution to the problem! Thanks for sharing your solution!
July-10th-2002, 04:27 PM
#6
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Join Date: May 2002
Posts: 74
I saw Dave's unit on his website. I've heard his equiipment is excellent and does the job well. He's also got a good selection of various devices that will work well with stock head units.
The remote turn on from Dave was about $35 plus shipping. When my friend suggested trying the relay for less than $3, I had to give it a try.
If I was doing a professional install at a shop, I'd definately go with one of these aftermarket prefab units. For my purposes, I'm not sure close tolerance of the electrical switch is a factor. I was just looking for the amp to turn on and off with the head unit, which it does.
Sites like Dave's are a great asset to those of us who want to get better than stock sound, while maintaining stock appearance.
With the performance I'm seeing from my system - stock except for the additon of a sub and sub amp, I'm not inclined to think about upgrading the head unit anytime soon. The stock speakers will probably be the next thing to go, followed by an amp to power the new speakers.
I've been thinking about the JBL 80.4 amp to power replacement speakers. I'd probably use a reverse wiring harness to connect from the stock radio to the amp and a standard wiring harness to connect the amplified signal through the factory wiring to the speakers. Keeps from messing with the stock wiring in any way.
Probably going to look at mounting the amp under one of the front seats. The JBL amps have speaker inputs that automatically turn on the amp. This is probably what I'll try to get this amp turned on and off automatically and avoid having to use a separate hi/lo converter.
The remote turn on from Dave was about $35 plus shipping. When my friend suggested trying the relay for less than $3, I had to give it a try.
If I was doing a professional install at a shop, I'd definately go with one of these aftermarket prefab units. For my purposes, I'm not sure close tolerance of the electrical switch is a factor. I was just looking for the amp to turn on and off with the head unit, which it does.
Sites like Dave's are a great asset to those of us who want to get better than stock sound, while maintaining stock appearance.
With the performance I'm seeing from my system - stock except for the additon of a sub and sub amp, I'm not inclined to think about upgrading the head unit anytime soon. The stock speakers will probably be the next thing to go, followed by an amp to power the new speakers.
I've been thinking about the JBL 80.4 amp to power replacement speakers. I'd probably use a reverse wiring harness to connect from the stock radio to the amp and a standard wiring harness to connect the amplified signal through the factory wiring to the speakers. Keeps from messing with the stock wiring in any way.
Probably going to look at mounting the amp under one of the front seats. The JBL amps have speaker inputs that automatically turn on the amp. This is probably what I'll try to get this amp turned on and off automatically and avoid having to use a separate hi/lo converter.
July-10th-2002, 08:04 PM
#7
Protege Owner
Join Date: Dec 2001
Location: Oklahoma City OK- where it is flat
Posts: 487
No question your solution is outstanding. I like you think Dave has a good site. Dave is a friend of mine, so I have to say that
I wish more shops knew of using a relay to turn on amps from the stock headunit. It adds more possibilities for systems and would be doing customers a true service. I have a volt meter, and even at idle, turned on amps draw power.
I had the exact same problem in the past with system noise of a fuse block switched amp.
While I changed to a aftermarket head unit head unit recently it had nothing to do with short comings of the stock Mazda CD. Indeed, I thought the stock unit to be a great signal source. I move only because car audio is a passion and hobby of mine, and my daughters. I install, and she helps, and gets to listen.
JBL makes great hardware for the money, some of the best mid fi on the market, I would recommend their amps and thier speakers to anyone looking for aftermarket with the best performance for the dollar.
The install you are describing would be great for the posting going on about a aftermarket system in a leased car, superior sound that is stealth and reversable.
I wish more shops knew of using a relay to turn on amps from the stock headunit. It adds more possibilities for systems and would be doing customers a true service. I have a volt meter, and even at idle, turned on amps draw power.
I had the exact same problem in the past with system noise of a fuse block switched amp.
While I changed to a aftermarket head unit head unit recently it had nothing to do with short comings of the stock Mazda CD. Indeed, I thought the stock unit to be a great signal source. I move only because car audio is a passion and hobby of mine, and my daughters. I install, and she helps, and gets to listen.
JBL makes great hardware for the money, some of the best mid fi on the market, I would recommend their amps and thier speakers to anyone looking for aftermarket with the best performance for the dollar.
The install you are describing would be great for the posting going on about a aftermarket system in a leased car, superior sound that is stealth and reversable.
August-8th-2002, 03:45 PM
#8
Protege Newbie
Join Date: Jul 2002
Location: Toronto, Canada
Posts: 11
If you want to control your amp using any IR button check this site:
http://www.mitedu.freeserve.co.uk/Ci.../ir_switch.htm
Manado_P5
http://www.mitedu.freeserve.co.uk/Ci.../ir_switch.htm
Manado_P5
August-26th-2002, 02:59 PM
#9
Registered User
Join Date: Jun 2002
Location: New York City
Posts: 265
I tried the method kindly shared by Aydu.
I will vouch that it works beautifully as he said.
It's perfect. I didn't even need to solder. Instead, I used crimping butts and some electrical tape.
Such an elegant solution!
I will vouch that it works beautifully as he said.
It's perfect. I didn't even need to solder. Instead, I used crimping butts and some electrical tape.
Such an elegant solution!
August-30th-2002, 09:47 AM
#11
Do you ZooM?
Join Date: Nov 2001
Location: Edmonton, AB (That's in Canada, by the way)
Posts: 845
fuzzy...
Originally posted by Aydu
I attached the existing turn on lead to the relay's "normally open" pin. Again, a bit of solder connected the wire and the relay.
The last connecter on the relay is the "common" pin. The wire from this pin goes to the amp's turn on connector.
I attached the existing turn on lead to the relay's "normally open" pin. Again, a bit of solder connected the wire and the relay.
The last connecter on the relay is the "common" pin. The wire from this pin goes to the amp's turn on connector.
I know the wire you used for the common pin, but not the normally open pin?? Where does that one go? Into the HU?
August-30th-2002, 03:09 PM
#12
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Join Date: May 2002
Posts: 74
The normal turn on lead is just a wire run from a switched fuse in the fuse box. It provides the 12 volt signal.
When the head unit turns on, it sends a 6 volt signal through the speaker leads. You route this signal through the relay. When the signal is present, the relay passes the current from the fuse box wire through the relay and into the common pin.
The wire going from the common pin goes to the amp's turn on switch. This provides the amp with a turn on signal when the head unit is on, no signal when the head unit turns off.
The relay basically uses a low voltage signal generated by the factory head unit's speaker leads to tell the amp when to turn on and off. The current needed to power up the amp needs to be 12 volts, so it has to come from the fuse box.
Hope this makes things a bit clearer. It's really easier than it sounds as the relay just has 2 ins and 2 outs. Different currents and paths for the 6 and 12 volt signals.
When the head unit turns on, it sends a 6 volt signal through the speaker leads. You route this signal through the relay. When the signal is present, the relay passes the current from the fuse box wire through the relay and into the common pin.
The wire going from the common pin goes to the amp's turn on switch. This provides the amp with a turn on signal when the head unit is on, no signal when the head unit turns off.
The relay basically uses a low voltage signal generated by the factory head unit's speaker leads to tell the amp when to turn on and off. The current needed to power up the amp needs to be 12 volts, so it has to come from the fuse box.
Hope this makes things a bit clearer. It's really easier than it sounds as the relay just has 2 ins and 2 outs. Different currents and paths for the 6 and 12 volt signals.
August-30th-2002, 03:18 PM
#13
Do you ZooM?
Join Date: Nov 2001
Location: Edmonton, AB (That's in Canada, by the way)
Posts: 845
Originally posted by Aydu
The normal turn on lead is just a wire run from a switched fuse in the fuse box. It provides the 12 volt signal.
When the head unit turns on, it sends a 6 volt signal through the speaker leads. You route this signal through the relay. When the signal is present, the relay passes the current from the fuse box wire through the relay and into the common pin.
The wire going from the common pin goes to the amp's turn on switch. This provides the amp with a turn on signal when the head unit is on, no signal when the head unit turns off.
The relay basically uses a low voltage signal generated by the factory head unit's speaker leads to tell the amp when to turn on and off. The current needed to power up the amp needs to be 12 volts, so it has to come from the fuse box.
Hope this makes things a bit clearer. It's really easier than it sounds as the relay just has 2 ins and 2 outs. Different currents and paths for the 6 and 12 volt signals.
The normal turn on lead is just a wire run from a switched fuse in the fuse box. It provides the 12 volt signal.
When the head unit turns on, it sends a 6 volt signal through the speaker leads. You route this signal through the relay. When the signal is present, the relay passes the current from the fuse box wire through the relay and into the common pin.
The wire going from the common pin goes to the amp's turn on switch. This provides the amp with a turn on signal when the head unit is on, no signal when the head unit turns off.
The relay basically uses a low voltage signal generated by the factory head unit's speaker leads to tell the amp when to turn on and off. The current needed to power up the amp needs to be 12 volts, so it has to come from the fuse box.
Hope this makes things a bit clearer. It's really easier than it sounds as the relay just has 2 ins and 2 outs. Different currents and paths for the 6 and 12 volt signals.
SO - where do I attach my line in the fuse box? This is the box under the dash right? Not the one in my engine bay?
I'm a total noob at doing amp installs!!!
Last - there's two power lines going into the stock HU, a pink/black wire that's described as batt. accessory. and the blue/red one that's always on.
What does the batt. accessory line do? Could a guy use this instead of the line to the fuse box?
August-30th-2002, 10:20 PM
#15
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Join Date: May 2002
Posts: 74
Any 12 volt signal that turns on and off with the ignition switch will work. I just used the switched line that my installer ran from the fuse box located below the dash on the driver's side. I've also heard of people using the power to the lighter, as it switches off an on with the ignition on the Protege. Some cars have power going to the lighter all the time, so it would not be a good choice in those vehicles.
The wires you mentioned on the radio harness would probably work too. The fuse box method was already wired for me, so I went with that. I just wanted to control the amp with the factory head unit, rather than the ignition switch.
You don't need a high power signal for the amp turn on lead. For power to the amp itself, you should run a separate power line directly from the battery, with a fuse to prevent a fire if anything goes haywire.
The wires you mentioned on the radio harness would probably work too. The fuse box method was already wired for me, so I went with that. I just wanted to control the amp with the factory head unit, rather than the ignition switch.
You don't need a high power signal for the amp turn on lead. For power to the amp itself, you should run a separate power line directly from the battery, with a fuse to prevent a fire if anything goes haywire.