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Ok this my be a crazy question but I figured this would be the best place ask it.  I have a Kenwood Excelon x700x5 amp and I want a quick way to cut off the subwoofer, " is case of law enforcement or what not".  I know the double din I have has a subwoofer off setting but it would take to long to shut off quickly.  I have done it many times before by putting a toggle switch on the remote wire before the amp.  The problem is I have a 5ch amp and if I put a toggle switch on the remote wire it will shut off all the sound, not just my subwoofer, and I don't want to do it that way.

So the question I have is can I put a 2 way toggle switch on one of the speaker wires for the sub (pos or neg), that way when I run the neg straight to the speaker and run the pos through the toggle switch and back to speaker.  Would there be any problems or power loss by doing this?  Also if I have a toggle switch with an led light on it can it still be used?  Or do I just need a 2 prong switch, either on/off.  Thx for your help!,

Verified Answer
  • Can't effectively put a toggle switch inline on the sub's wiring. I'm unable to locate the amp you say you have, but either way, you have way too much power going through the wiring for the sub than a typical toggle switch could handle.

    I'd recommend buying a universal RCA gain control knob and wire it into the RCA's to the amp's sub section. This would give you much easier access to sub volume control and turning the gain knob all the way down, while it may not shut the sub off, would lower it to a MUCH lower level.

    Something like the PAC LC1 would do the job.

  • Cool question:

    Scott F.
    Also if I have a toggle switch with an led light on it can it still be used?

    First off, switches can light up different ways.  Some switches have separate terminals for the LED - these will work fine.  Most switches have a GND wire and when connected, the switch lights up when the switch has power and is closed.  I don't think this would work with the switch directly (not sure what AC current will do to the LED), but it should work with a relay - I will cover that below.)

    @Weigel21 - I think it's probably a Kenwood X700-5 amp.

    There are two ways to do it:

    http://www.the12volt.com/ohm/ohmslawcalculators.asp#voltage

    A capable switch inline with the Pos (or Neg) wire like you said would probably work.

    Assuming 500W @ 2-ohms, you are going to see 31.62278 VAC and 15.8 Amperes through the switch.  I actually think most switches will handle that - I seem to remember most of them rated for 250 VAC, and this is a basic one and supports 20 A.

    Problems:

    • You are (SHOULD BE) already running 12-gauge wiring to the sub.  Running the wire from the amp (trunk?) to the dash and back to the sub (trunk) is going to increase the wire length, which means you need thicker wiring even than 12-gauge.
    • It might be hard getting 10 or 8-guage wiring terminals to attach to that switch.
    • It will be a pain running two lengths of 8-guage wiring through the car from the subs to the dash and back.

    There is a simpler solution, though, it's called a RELAY!!!

    Standard wiring (Normally Open Contacts):

    • Wire the speaker POS (or NEG) wire across the NO load terminals of the relay (30 and 87).
    • Mount the relay in the trunk (probably near the amp).
    • Ground terminal 86 of the relay - you can use the amps GND terminal or GND location for this.
    • Splice into the remote wire from the head unit and run an additional wire to the toggle switch.  Run thin (18-gauge or so), wire from the other terminal of the switch to Terminal 85 of the relay.
    • When the radio is on and the switch is in the closed position, the relay is energized and the light is on and the sub plays.  When the radio is on and the switch is in the open position the light is off, the relay is de-energized and the sub shuts off.   When the radio is off, the switch is not illuminated.
    • Advantage here is the switch is illuminated normally, so if you need to find it quickly you can, disadvantage is the light is usually on.

    Alternate wiring (Normally Closed Contacts) (slightly preferred):

    • Wire the speaker POS (or NEG) wire across the NO load terminals of the relay (30 and 87a).
    • Mount the relay in the trunk (probably near the amp).
    • Ground terminal 86 of the relay - you can use the amps GND terminal or GND location for this.
    • Splice into the remote wire from the head unit and run an additional wire to the toggle switch.  Run thin (18-gauge or so), wire from the other terminal of the switch to Terminal 85 of the relay.
    • When the radio is on and the switch is in the open position, the relay is de-energized and the light is off and the sub plays.  When the radio is on and the switch is in the closed position the light is on, the relay is energized and the sub shuts off.   When the radio is off, the switch is not illuminated.
    • Advantage here is that if the relay fails (unlikely), the sub will continue to work, you just won't be able to shut it off with the switch.
    • The switch is only illuminated when the sub is turned off - personally, I would prefer that, but you might not - there isn't a huge drawback to wiring it the other way if you want it to light up when the sub is ON.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

All Replies
  • Can't effectively put a toggle switch inline on the sub's wiring. I'm unable to locate the amp you say you have, but either way, you have way too much power going through the wiring for the sub than a typical toggle switch could handle.

    I'd recommend buying a universal RCA gain control knob and wire it into the RCA's to the amp's sub section. This would give you much easier access to sub volume control and turning the gain knob all the way down, while it may not shut the sub off, would lower it to a MUCH lower level.

    Something like the PAC LC1 would do the job.

  • Cool question:

    Scott F.
    Also if I have a toggle switch with an led light on it can it still be used?

    First off, switches can light up different ways.  Some switches have separate terminals for the LED - these will work fine.  Most switches have a GND wire and when connected, the switch lights up when the switch has power and is closed.  I don't think this would work with the switch directly (not sure what AC current will do to the LED), but it should work with a relay - I will cover that below.)

    @Weigel21 - I think it's probably a Kenwood X700-5 amp.

    There are two ways to do it:

    http://www.the12volt.com/ohm/ohmslawcalculators.asp#voltage

    A capable switch inline with the Pos (or Neg) wire like you said would probably work.

    Assuming 500W @ 2-ohms, you are going to see 31.62278 VAC and 15.8 Amperes through the switch.  I actually think most switches will handle that - I seem to remember most of them rated for 250 VAC, and this is a basic one and supports 20 A.

    Problems:

    • You are (SHOULD BE) already running 12-gauge wiring to the sub.  Running the wire from the amp (trunk?) to the dash and back to the sub (trunk) is going to increase the wire length, which means you need thicker wiring even than 12-gauge.
    • It might be hard getting 10 or 8-guage wiring terminals to attach to that switch.
    • It will be a pain running two lengths of 8-guage wiring through the car from the subs to the dash and back.

    There is a simpler solution, though, it's called a RELAY!!!

    Standard wiring (Normally Open Contacts):

    • Wire the speaker POS (or NEG) wire across the NO load terminals of the relay (30 and 87).
    • Mount the relay in the trunk (probably near the amp).
    • Ground terminal 86 of the relay - you can use the amps GND terminal or GND location for this.
    • Splice into the remote wire from the head unit and run an additional wire to the toggle switch.  Run thin (18-gauge or so), wire from the other terminal of the switch to Terminal 85 of the relay.
    • When the radio is on and the switch is in the closed position, the relay is energized and the light is on and the sub plays.  When the radio is on and the switch is in the open position the light is off, the relay is de-energized and the sub shuts off.   When the radio is off, the switch is not illuminated.
    • Advantage here is the switch is illuminated normally, so if you need to find it quickly you can, disadvantage is the light is usually on.

    Alternate wiring (Normally Closed Contacts) (slightly preferred):

    • Wire the speaker POS (or NEG) wire across the NO load terminals of the relay (30 and 87a).
    • Mount the relay in the trunk (probably near the amp).
    • Ground terminal 86 of the relay - you can use the amps GND terminal or GND location for this.
    • Splice into the remote wire from the head unit and run an additional wire to the toggle switch.  Run thin (18-gauge or so), wire from the other terminal of the switch to Terminal 85 of the relay.
    • When the radio is on and the switch is in the open position, the relay is de-energized and the light is off and the sub plays.  When the radio is on and the switch is in the closed position the light is on, the relay is energized and the sub shuts off.   When the radio is off, the switch is not illuminated.
    • Advantage here is that if the relay fails (unlikely), the sub will continue to work, you just won't be able to shut it off with the switch.
    • The switch is only illuminated when the sub is turned off - personally, I would prefer that, but you might not - there isn't a huge drawback to wiring it the other way if you want it to light up when the sub is ON.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • The amp I have is a Kenwood Excelon X700-5 50W x 4 + 500W x 1 @ 2 Ohms car Amp.  The question I have is with running the Universal RCA gain will i run into any power problems?  Will it take any power away from my amp/sub?  If not I would have to say this looks to be the best option.  They are pretty cheap on Amazon also.

  • @TigerHeli

    You are (SHOULD BE) already running 12-gauge wiring to the sub.  Running the wire from the amp (trunk?) to the dash and back to the sub (trunk) is going to increase the wire length, which means you need thicker wiring even than 12-gauge.

    I was told by crutchfield that 14g wire should be plenty to power the sub.  I actually ended up getting enough 14g to rerun my entire system (dash/soundbar speakers) with it.  

    All the other info in your comment seems a little complex.  I am no audiophile so some of it seemed "greek" to me.  But I may of just read it to fast.

  • The universal gain won't cause any power problems.  Things I don't like:

    • Requires one more RCA - Possible noise issue - but with an aftermaket HU, it's not THAT bad - one RCA from dash to level control, and one from level control to amp.
    • Usually DOES NOT have an on/off switch, so you have to turn the volume down and back up.  Slightly less convenient to remember what volume you had it at than a simple toggle switch.

    14g is probably okay.  BCAE1 is pretty conservative in the ratings, but you don't want to run large wiring thru the car (for a power circuit).

    Scott F.
    All the other info in your comment seems a little complex

    Rats, I tried to make it simple.

    Let me try to break it down a little more and then see if you re-read it and it makes sense.

    You wanted to use a simple toggle switch to turn off the power from the amp to the sub.  That could work, but you are running a lot of power through the switch - generally not a good idea.  The solution is to use a relay.  This is like a remote switch.  When the relay see power from a small current switched, it closes and let's the high power (amp wires) go to the sub.

    A similar example if your headlights - rather than running thick wiring behind the dash to your headlight switch, the small wires at the switch activate a relay which sends battery power to the headlights.

    Essentially, there are two ways to wire the relay up.

    The most common way, the relay contacts between the amp and the sub would be open.  A toggle switch is wired between the remote wire of the radio and the relay.  When the radio is on, power flows to one leg of the switch.  When the switch is close, it activates the relay and turns the sub on.  Open the switch and the relay opens and the sub turns off.

    The other wiring is slightly different.  The relay contacts between the sub and the amp are normally closed.  And the toggle switch is normally open.  When you close the toggle switch, power flows to the relay and OPENS it so the sub stops playing.

    There are really only two functional differences in the wiring:

    • First method, if the relay fails, your sub will not work until you replace the relay.  Second method, if the relay fails, you sub keeps working - it just goes back to how it works now and the switch will not shut it off.
    • Lighting:  First method, the light on the switch will be ON whenever the sub is powered.  It will turn off when the sub is off.  Second method, this is reversed, the light is OFF when the sub is powered and comes ON when you shut the switch off.  (If you don't connect the GND terminal of the switch, the light never comes on in either case).

    You actually had the concept correct originally, it's just a different way of accomplishing it.

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs