# Adding a second amp. Remote wire question.



## sinister mob (Jan 11, 2010)

Currently I have a Pioneer HU and one amp supporting fronts and sub. I will be adding a second amp just to power the sub and then using the current amp to power rears. Pretty basic set-up.

However I have a relay also in the system to be able to play DVD while moving. The relay also uses the HU remote as "power". So the remote out of the HU goes to the relay and to the amp as my awesome diagram represents:










The question is remote wiring of the second amp. Here are possible choices that I could do (please add more if you think of any):

1. Add in a second remote wire and attach where the relay/amp1 split is. Thereby having one remote from the HU to 3 different wires (amp1, amp2 and relay). The relay remote wire is about 10 inches and is under the dash. The amp1 remote runs to the rear of the vehicle.

2. "Jump" from amp1 to amp2 with a short remote wire. (basically a loop).

3. Split the amp1 remote in the rear of the vehicle and run seperate wires to each amp - off of the current remote line to the rear.

I am also concerned with 3 different items connected to 1 remote out from the HU and concerned if I should go to a bigger guage wire anywhere, fuse anything, etc.

Not worried about power/ground for the second amp as I have that down.


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## gbryant (Jul 18, 2008)

jump amp to amp... very little load on relays...shouldn't be problem


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## cbrei1023 (Dec 2, 2008)

No problem jumping it from amp to amp.


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## nineball (Jan 17, 2008)

whenever you have more than 2 items that need power from the remote line you should use 12v relay. they (headunits) don't like it when you try to power too many things on that line. if the relay that you speak of is what i have described then i would connect all 3 items to the output on it. if not, buy one and power everything from that.


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## sqshoestring (Jun 19, 2007)

9ball has it. I like the awesome diagram btw 
You can run 2 maybe 3 amps off a HU, but they are getting to the limit. Old HU could run much more like small fans and 4-5 amps, whatever....not newer ones.


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## sinister mob (Jan 11, 2010)

nineball said:


> whenever you have more than 2 items that need power from the remote line you should use 12v relay. they (headunits) don't like it when you try to power too many things on that line. if the relay that you speak of is what i have described then i would connect all 3 items to the output on it. if not, buy one and power everything from that.


Unfortunately the relay is used to operate the "fake" ground for my HU to be able to play DVD while driving. So the remote goes in as power to the relay, then there is a double ground and a ground going out back to the green wire on the HU. So the remote ends at the relay.


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## nineball (Jan 17, 2008)

then buy another 12v relay


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## sinister mob (Jan 11, 2010)

nineball said:


> then buy another 12v relay



Sounds good. Would I then run all 3 items off of the new relay? See my updated awesome drawing below:










Or add the relay to just the 2 amps and leave the current relay tied directly to the HU?










Also just to reiterate, the current relay for the DVD turn on is not connected to +12v. Just the HU remote in and double ground. Set-up to throw the ground signal back to the green wire to simulate a pulled e-brake. Same as the video for the AVH-P4200DVD relay bypass.


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## sqshoestring (Jun 19, 2007)

I'd run one relay on the HU and everything else after that, though I'm sure the HU could run both relays it is better minimize current draw on the remote if you can.


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## slade1274 (Mar 25, 2008)

In before quenching diodes come up......


Relays


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## ca90ss (Jul 2, 2005)

sqshoestring said:


> I'm sure the HU could run both relays


I wouldn't risk it, I've tested several bosch relays and found they require anywhere from 125ma-200ma to energize the coil and with most hu's these days having a maximum current on the remote output of around 300ma it's not worth taking the chance imo. If it were me I'd get out the dmm and see how much current the remote terminal on each amp draws before deciding whether or not a relay was even needed. I've tested amps that require as little as 1ma for the remote terminal so the relay may not even be necessary.


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## sqshoestring (Jun 19, 2007)

There is also a radio shack relay some use that draws less. If you ask me its bs they can't run hardly anything on the remote.

Here
Relays
Note most amps take way less than a relay.

Relay
RadioShack.com


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## sinister mob (Jan 11, 2010)

slade1274 said:


> In before quenching diodes come up......
> 
> 
> Relays


That was the first place I looked. I also wondered about the Radio Hack relay listed.

Pioneer lists 300 mA max for the remote line.

I will see if I can find the amp mA usage. If the by-pass relay is consuming ~ 200mA and each amp is less than lets say 10 mA, I will be fine just adding in the second amp with no additional relay. I can jump a remote line from amp 1 to amp 2.

This is why I love sites like this. I can find out ahead of time if I will set my car on fire...


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## sqshoestring (Jun 19, 2007)

Lol, the same link, the best one I found on relays.


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## sinister mob (Jan 11, 2010)

Called Fosgate support. Explained the layout. They said I will be fine jumping from one amp to the other. The remote out on the Pioneer will support the relay and 2 amp loads.


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## PorkCereal (Nov 24, 2009)

If you piggy back remote wires and get subwoofer pop when turn on/off what do you do now?


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## Candisa (Sep 15, 2007)

Always use a relay if you use more than 1 load on the remote.

headunit --> relay --> anything else

Isabelle


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## sinister mob (Jan 11, 2010)

Right now I don't get any pop with 1 amp and the remote out split to the by-pass relay and the amp. I assume there won't be a pop if 2 amps are connected to the same remote? 

However it may make sense to just add in an additional relay before the by-pass relay and let the +12v power from the new relay run the 2nd relay and 2 amps. Then the +12v draw of relay # 2 will pull from battery power as opposed to HU remote power. That way the HU remote is only powering 1 relay and there will be no possible damage to the HU internals. It is worth the $3.99 to add it in during the install.


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## gbryant (Jul 18, 2008)

Please... I had three PDX amps on an Alpine HU... no prob..


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## Knobby Digital (Aug 17, 2008)

Candisa said:


> Always use a relay if you use more than 1 load on the remote.
> 
> headunit --> relay --> anything else
> 
> Isabelle


As many above are saying, a relay can easily draw more than a few devices chained on the HU. Depends on your amps and whatever else you want to turn on.



sinister mob said:


> That was the first place I looked. I also wondered about the Radio Hack relay listed.


I'm using the RadioShack PC relay referenced on BCAE. Works just fine.


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## sinister mob (Jan 11, 2010)

I may look into the Radio Shack one.....

AVH-P3200BT - powers Bosch relay for DVD bypass and Punch P400-4 currently. Adding a Punch P200-2 to the system. Best info I could find was on BCAE referencing ~ 45 mA per amp. Add that to the relay of ~ 200mA and still under the 300 mA. But better safe than sorry for less than $5.


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## nineball (Jan 17, 2008)

sinister mob said:


> Called Fosgate support. Explained the layout. They said I will be fine jumping from one amp to the other. The remote out on the Pioneer will support the relay and 2 amp loads.


is fosgate going to fix your pioneer hu for free if it gets damaged as a result? 




sinister mob said:


> But better safe than sorry for less than $5.


exactly. for such a little cost and a few mins of wiring you would be silly not to.


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## sinister mob (Jan 11, 2010)

nineball said:


> is fosgate going to fix your pioneer hu for free if it gets damaged as a result?
> 
> exactly. for such a little cost and a few mins of wiring you would be silly not to.


Agreed. I have to remove the HU again anyway to add the RCA so 2 more wires won't make a difference. Good stuff.....


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## sqshoestring (Jun 19, 2007)

On the other hand you can find a DMM for $10 that shows draw, though I don't know if its ma I'd have to look.


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