Wire an amp with no ground location

Thread Starter

evilduks

Joined Apr 17, 2014
2
I am building a boombox into a customized backpack. In this setup would be two 6.5 in speakers, 2 horn mounted tweeters, and hopefully a subwoofer. To power the sub, I need an amp. I am planning to use a 400W amp designed for car use, but everything I've seen says that the amp won't function without the ground. Any advice as to how I could make this work?
 

Alec_t

Joined Sep 17, 2013
14,280
Agreed. The battery weight alone would be considerable.
And I, personally, wouldn't want to be within earshot when the boombox is working :)
 

alfacliff

Joined Dec 13, 2013
2,458
fortunatly, a "400 watt" car stereo amp is actually a lot less power, a real 400 watt amp would have to have a lot of current to feed it. the only possible problem I can see is that the speaker outputs going to the amp would have to be isolated through a transformer so that the ground problem would be eliminated. car stereo shops should have the transformers.
 

crutschow

Joined Mar 14, 2008
34,285
fortunatly, a "400 watt" car stereo amp is actually a lot less power, a real 400 watt amp would have to have a lot of current to feed it. the only possible problem I can see is that the speaker outputs going to the amp would have to be isolated through a transformer so that the ground problem would be eliminated. car stereo shops should have the transformers.
Speaker terminals are normally isolated from ground. You only need a transformer if one of the speaker wires is connected to ground in an automobile.
 

alfacliff

Joined Dec 13, 2013
2,458
and how are they connected in the boom box? isolation would solve many potential problems. auto stereos sometimes "bridge" amplifiers to get more power, then there are no "ground" connections on any speakers.
 
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