HU constant or acc supplies running power

ive been wondering for ages, does the constant wire from most HU's supply all the current AND the memory and the ACC wire is to switch it with the ignition, therefore only needs a small current, or the constant is
to hold memory and ALL power is supplied by the ACC wire, therefore constant only needs a small wire.

which head units work one way and which head units work the other way, like most pioneer work like this, or most kenwood work like that, depending on what you know
thanks for the help, this has been bugging the doodie outta me

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-Ben

From what I've gathered, since my Alpine HU has the fuse on the constant wire, it's probably the one delivering the real power for the HU. I think the ACC wire has about the same function as the remote wire on an amp. Just there to tell it when to turn on. But I'm just basing this off of what makes sense to me, I'm not sure.

It depends on the manufacturer... I have seen them go both ways. Cheaper units USUALLY power through the accessory, with the constant just being there for memory functions.

Higher end units, or units with higher output power specs will be powered through the +12 lead, with the accessory lead being a "remote" lead.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

factory head units usually are powered through the constant....so it makes sense for the aftermarket headunits to draw their current from where it is most plentiful. It is true though that really cheap units power through the accessory.

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Seth Alvo     NY
Mobile Electronics Installer