Device flashes on and off on long USB cable- how to splice it?

[prehensile]

I've just bought two USB cables for a MIDI keyboard that demands lots of power, it runs fine with the 6 foot cable but with both the 9' and a 12' cable the device just flashes on and off and can't switch on.
normal devices are all right with these cables, just not those that demand more power. So the data is all right, it's just the resistance of the cable .

I am thinking of either replacing the whole length of the cable with some more quality cable just keeping the ends, or of searching the 3V line in the cable and patchig it with a quality wire. what wire should I use? How would you go about it? Cheers!
Should I fiddle with the BIOS?

[Agent]

You need a repeater on it. I dont think re-wiring it will make much of a difference to be honest for various reasons.
somthing like http://www.meroncourt.co.uk/prodview/291 will work.
Just google it and you'll find a few

[prehensile]

I only want less than 5 m and I have some spare belkin pro series wire (from a 15 meter PS2 cable which was a defective cheap buy from ebuyer) and some phone wire I could use to splice the voltage line.

[5lab]

why not stick a powered hub on the far end of the cable, then plug the keyboard into that?

[prehensile]

Because I would have to buy one, I've already just bought 2 USB cables- I know that buying is fun, but learning how to make all cables yourself is really useful, because you can tailor any cable you like, monitor cables, audio cables etc. also it's faster than getting something through the post-it only takes 10 minutes.

in studios you can get audio cables that are so good they are practically super conductors (lol) . My bet is that one of those would be able to carry a USB signal for 50 m just like a normal cable would carry it over 2 m.
Truth is, I have just linked a strand of the belkin cable on the 5V line and the device almost stays on all right , I will patch the whole cable with something quality. It's only to reach one meter further than normal.

The oddest thing is that the volt meter measures the USB cable at 6V which is 20% higher than normal-does that sound dangerous to anyone else?
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UPDATE

Just for fun, I patched the cable with 8 m of belkin , with double wires for the neutral and 5 V lines, and it goes along 8 m line, it doesn't seem to restart at all. it is probably the most power demanding device you can get as well, too much for some laptops.

I can't believe I spent a fiver on two dodgy USB cables when I could have made a better 1-I even contemplated it carefully.

yummy I want
http://www.sonicstate.com/news/shownews.cfm?newsid=2390

[prehensile]

Just as reference , and cable with 10 times less resistance will have exactly the same properties with a 10 times longer cable-so it is possible to use long cables.