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#334787 - 06/07/2010 13:53 Okay to power a small device off the amp remote line?
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7057
Loc: Pittsburgh, PA
I'm going to be adding an XM receiver to my empeg install. Right now, my amp is hooked up to the amp remote line, but it gets its power from another circuit, and just uses the amp remote line to switch on/off. The XM receiver I'm adding draws 500 mA max, so I thought I could just connect it to the amp remote line and ground that are going into my empeg wiring harness. Is that the best way to go for a small device like this?
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- Tony C
my empeg stuff

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#334793 - 06/07/2010 17:37 Re: Okay to power a small device off the amp remote line? [Re: tonyc]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 30578
Loc: Seattle, WA
I'm used to seeing labels on amp remote lines that indicate the maximum amount of current that you can draw off of it. I'll bet 500ma is well within the limits. Someone more qualified will surely respond here, but that's my guess.
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#334797 - 06/07/2010 18:07 Re: Okay to power a small device off the amp remote line? [Re: tfabris]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13498
Loc: Canada
The Amp Remote line appears to be fused at 1.25A, fed from a DC-DC convertor that is rated somewhat above that.

Still.. I'd try and keep things below 0.5A, rather than risk burning out the empeg's onboard PSU circuitry. Nasty to repair, that stuff.

Cheers

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#334800 - 06/07/2010 18:20 Re: Okay to power a small device off the amp remote line? [Re: mlord]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7057
Loc: Pittsburgh, PA
Yeah, I definitely don't want to risk blowing out my empeg's PSU. Do the amplifiers themselves typically draw any appreciable amount of power on the remote line? I know very little of this stuff, but it seems to me if it's just signaling the amp to turn on, and the amp itself is getting its power from another circuit, the draw should be minimal, right?
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- Tony C
my empeg stuff

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#334801 - 06/07/2010 18:28 Re: Okay to power a small device off the amp remote line? [Re: tonyc]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13498
Loc: Canada
I expect that amps with a "remote line" would be using it to power a relay.

A mechanical 12V relay coil is usually in the 300-400ohm range, so the current draw would be less than 1/20th of an ampere.

If they use a solid-state relay or (MOS)FET device instead, then the draw is no more than a tiny few milliamperes.

Cheers

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#334803 - 06/07/2010 18:37 Re: Okay to power a small device off the amp remote line? [Re: mlord]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7057
Loc: Pittsburgh, PA
My amp is a JL e4300 series. It says "MOSFET Power Supply" in the manual, but I can't find anything that specifically mentions the remote line's draw. I guess I'll dig out my multimeter tonight and test it out. If it's just a few milliamps, I should be fine, since the XM unit says "max 500 mA", and evidence on the internet suggests it's generally around 200 mA.


Edited by tonyc (06/07/2010 18:38)
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my empeg stuff

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#334826 - 07/07/2010 13:03 Re: Okay to power a small device off the amp remote line? [Re: tonyc]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7057
Loc: Pittsburgh, PA
Well, I did the install last night, and everything is good. Hooked up the XM receiver, ran the antenna, and started writing the user app that will be controlling the receiver and displaying station/track info. I haven't actually subscribed to XM yet, but will do so as soon as I have enough control over the receiver to go through the activation process.

FWIW, the amp remote line draws 4 mA, so I didn't bother measuring what the XM box draws. I'm fine as long as it obeys the 500 mA specification. Thanks for your help, guys.
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- Tony C
my empeg stuff

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