# Help, how to wire a remote turn on lead for two amps



## Stewart (Jul 14, 2006)

I have two amps going into my trunk and I need to wire a remote turn on lead for both of them. Can I just connect the cable from the head unit and two remote turn on wires comig from each individual amp, so there will be 3 wires connected in one twist, or is there a better way?


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## crash813 (Aug 23, 2005)

Use a bosch relay with power coming from the battery and the radio turn-on wire for the switch. Protects your radio and amps much better than tying them all together. Its not necassary but is better.


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## tdgesq (Apr 16, 2006)

I've used the same remote power lead going into the headunit for the rest of my components on quite a few occasions and never had a problem.


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## Chaos (Oct 27, 2005)

A relay is only really necessary if you are running several amps and the current from the deck turn-on lead is too low to turn them all on. Two amps shouldn't give you any trouble, but you could still use a relay for good measure.


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## crash813 (Aug 23, 2005)

Its very easy for a piece of equipment to fry your hu with that small turn-on wire and vice-versa, since most have no type of surge protection on that line. The more pieces of equipment, the more chance for that to happen. With avg hu $300-$500, $500+ DSP units, and $500 amps, I just assume use a $5 relay for added insurance. Its just lazy not to. Also makes it easy to add more equipment later like XO's, eq's, fans, etc.


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## tdgesq (Apr 16, 2006)

What does the relay do exactly? I've never used one, so I don't know. I guess I always assumed that the draw on the remote lead was too small to damage anything and that the fuse on it in the automobile would burn before you had a problem.


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## solacedagony (May 18, 2006)

Hey crash, can you post a link to where you get your relays?


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## minitruck_freq (Mar 27, 2005)

http://www.partsexpress.com/webpage.cfm?webpage_id=3&SO=2&&DID=7&CATID=47&ObjectGroup_ID=31

parts express had a sale on relays a few months ago and i bet i have about 25-30 of them now. any auto parts store will have them as well.


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## MarkZ (Dec 5, 2005)

crash813 said:


> Use a bosch relay with power coming from the battery and the radio turn-on wire for the switch. Protects your radio and amps much better than tying them all together. Its not necassary but is better.


This is actually sort of a myth. Most Bosch relays (except for some of them specifically designed for things like alarms) are rather large. By large, I mean have low coil resistances. As a result, the relay will draw far more current from the HU than the amps would have alone.

If you're going to use a relay, use one of the small 12v Radio Shack ones (1A or 5A). Look for coil resistance -- the higher it is, the less current it will draw. But personally, you shouldn't need a relay at all until you start approaching 4 or more pieces of equipment.

Edit: as an example, the ones that mini posted from parts express may not be good ones to use (I don't see specs on it). The coil resistance could be less than 50 ohms, meaning the relay will draw over a quarter of an amp. By comparison, a typical amplifier will only draw about 50-100mA, and a small Radio Shack relay like this one will draw only 40mA or so altogether:

http://www.radioshack.com/product/i...1&cp=&origkw=relay&kw=relay&parentPage=search


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## FoxPro5 (Feb 14, 2006)

How many of the Bosch relays would I need if I have 3 amps, my Kicker SXRC, and my Eclipse BLA to turn on when my HU powers up (5 total)?? Or would I need something else? Thanks!!


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## zfactor (Oct 19, 2005)

use the relay.....pin 86 in from radio, 85 solid ground, 30 12volts fused, 87 out to amps

b-squad 1 should be fine for 4-5 amps...


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## MarkZ (Dec 5, 2005)

B-Squad said:


> How many of the Bosch relays would I need if I have 3 amps, my Kicker SXRC, and my Eclipse BLA to turn on when my HU powers up (5 total)?? Or would I need something else? Thanks!!


No, the point of using the relay is to be able to feed the remote wires of ALL the devices you use with a single remote turn on. So just one relay will do the job. Run all your devices off it.


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## gabe8501 (Jan 24, 2006)

Ok, cuz I'm silly like that.... somebody tell if this would work before I blow up my junk.

I run pin 86 from my h/u's remote wire, use 85 as a ground (any ground? one of the grounds from one of my amps?), 30 12 volts fused (can I use the 12 v constant on the h/u's wiring harness? how's about the power wire from one of the amps?), and then 87 out the amps I want turned on.

Forgive me for my elementary questions, I'm a noob.


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## FoxPro5 (Feb 14, 2006)

Understood, thanks Greg and Mark!!


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## zfactor (Oct 19, 2005)

gabe8501 said:


> Ok, cuz I'm silly like that.... somebody tell if this would work before I blow up my junk.
> 
> I run pin 86 from my h/u's remote wire, use 85 as a ground (any ground? one of the grounds from one of my amps?), 30 12 volts fused (can I use the 12 v constant on the h/u's wiring harness? how's about the power wire from one of the amps?), and then 87 out the amps I want turned on.
> 
> Forgive me for my elementary questions, I'm a noob.


pin 86 correct... 85 GOOD GROUND i recc a 10-12 awg personally, 30 = 12 volts fused no do not use the hu 12 v power wire for amps is fine...87 correct


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## Pseudonym (Apr 17, 2006)

i have a relay and will use it if my current method is a bad one. here we go...remote wire is run from HU to amp, then a 2nd remote wire is run from the 1st amp to the 2nd. bad?


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## joey_kev (Mar 12, 2006)

daisy chain
I have 3 amps and I used daisy chain to wire the remote turn on cable for each amp


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## tdgesq (Apr 16, 2006)

Pseudonym said:


> i have a relay and will use it if my current method is a bad one. here we go...remote wire is run from HU to amp, then a 2nd remote wire is run from the 1st amp to the 2nd. bad?


IME, not bad.


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## zfactor (Oct 19, 2005)

for 2 amps that should be fine the realay is required though when many amps or pieces are used


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## Vestax (Aug 16, 2005)

Uh, I don't know why people do this, but 30 should be out to the amps, 87 should be your fused constant. It's an extra safety caution when you don't want 87a to be live when the HU's off.

And to answer somebody's question on what's a relay, it's just an electromagnetic switch and in layman's terms, the simplest function is to drive something with more power using little power or to reverse a polarity on output.


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## chuyler1 (Apr 10, 2006)

I'm running 2 amps and a crossover off my head unit. The HU also powers a disc changer and DSP. No problems.


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## FoxPro5 (Feb 14, 2006)

Question 1. In using the relay to switch on my 3 amps, BLA and SXRC I should do the following:
30 to B+
85 to G
86 from HU remote turn on
87 out to amps, BLA and SXRC

But then I find this while seaching just now and it says that pin 85 should be in from the HU and pin 86 to ground. Which one is correct?

_Now let's talk about applications. One common use of a relay is for multiple amplifiers. Normally, if you run any more than three audio components off your decks remote output, it is recommended that you use a relay to provide higher currents. Also, if you wanted to power something like a fan, or neon lighting, you need a relay to keep up with the higher demands these devices place on your remote. Take a minute and guess if you can see how it is done. All you have to do is *connect 85 to your decks remote output wire, and 86 to ground*. Then, connect 30 to a fused 12 volts source, and 87 to your outgoing remote line. Remember that the relay can carry up to 30 amps, but if your wire can only handle 10 amps, you should use a 10 amp fuse. 87a is not used, but I recommend taping up that pin, or pulling the wire out of the base, so that it does not short out._ http://www.teamrocs.com/technical/pages/relay_basics.htm


Question 2: What about powering the BLA and SXRC. Should I run seperate leads off the battery for each of those?? Or use another relay for that too??


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## zfactor (Oct 19, 2005)

doesnt matter either way will work depends on who you ask


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## minitruck_freq (Mar 27, 2005)

ive ran 2 amps, eq and xover from the HU remote with no trouble. i just use a barrier strip as a "distrubution block" and ive used relays. ive had good luck with both.


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## FoxPro5 (Feb 14, 2006)

Well I got it wired up and it works like a champ. I went back and checked it and the relay was pretty hot to the touch...given it was 98 stinkin degrees out but still...does that mean anything? Sorry for all the questions.

BTW I found the best surpluss store where I got the realy from today for only $1.50. Got 30' of 16 gauge cheapo wire for $3. :woot:


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## alphakenny1 (Dec 21, 2005)

B-Squad said:


> BTW I found the best surpluss store where I got the realy from today for only $1.50. Got 30' of 16 gauge cheapo wire for $3. :woot:


that means your system won't sound good. speakers wires makes a difference  .


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## FoxPro5 (Feb 14, 2006)

alphakenny1 said:


> that means your system won't sound good. speakers wires makes a difference  .


Well I noticed a pretty significant increase in SQ once I crossed out Road Gear and wrote in Monster!


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## solacedagony (May 18, 2006)

B-Squad said:


> Well I noticed a pretty significant increase in SQ once I crossed out Road Gear and wrote in Monster!


Not to mention that significant increase in horsepower. Hehe.


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## BodegaBay (Dec 16, 2005)

I never thought about this type of potential problem until I needed to wire up three amps. 

I then read up on the topic at #23, Amplifer section of the Basic Car Audio Electronics (BCAE) website, to which the administrator specifically states:

"*The remote input current for amplifiers varies with the amplifier and the model. Some draw minimal current. Others draw a little more. The upper limit of a properly functioning amplifier is approximately 50ma (0.05 amps). If you're using/controlling more than 2 amplifiers, it is (in my opinion) much better to use a relay to control the amplifiers. Actually I really prefer having a relay in the remote circuit (no matter how many amplifiers I'm using) because it protects the head unit's remote output circuit in case of a short circuit."* 

He even gives you a primer on how to set up such a relay circuit.


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## FoxPro5 (Feb 14, 2006)

I forgot how much I love that site. Thanks for the links Bodega


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## oldschoolsq (Nov 29, 2006)

I have the PG TiDD10 & TDD5 for my system & LOVE it  

ftp://208.187.38.55/Phoenix_Gold/Manuals/Accessories/TiDD10_TDD5_Manual.PDF


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## andrei (Oct 25, 2006)

as i haven't seen a relay before... aside from being able to power up devices with little current, it also acts like a power distro block? please correct my impression, if im wrong.

also how many devices can a single relay power? im going to use 3 amps and a 701 at the least. will one relay suffice? thanks


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## illnastyimpreza (Oct 25, 2006)

quite pointless if u ask me. I run 4 amps and have never had ANY problems for 5 years now.


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## DonutHands (Jan 27, 2006)

the relay does not power the amps. the relay is only used for the small remote turn on wire.


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## cvjoint (Mar 10, 2006)

I run 6 amps off of the eclipse remote turn on w/o any problems.


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## seankurz (Feb 10, 2013)

What if I'm just running 2 amps, 1 for front and rear and the other for sub? I read this thread and can't really make heads or tails on what to do... Using a clarion cz702 to an alpine mrx f65 and alpine mrx m110. Daisy chain the remote turn on, relay, or just crimp both to the (blue/white wire) remote lead on the hu? Where would you put a relay? 
Somewhat new, so thanks ahead of time


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## seankurz (Feb 10, 2013)

minitruck_freq said:


> ive ran 2 amps, eq and xover from the HU remote with no trouble. i just use a barrier strip as a "distrubution block" and ive used relays. ive had good luck with both.


im only running 2 amps, how would you wire up with a barrier strip?


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## Maylar (Dec 6, 2012)

For 2 amps there's no problem at all just jumpering the remotes together. The days when amp remotes took a lot of current are loong gone.


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