presonus blue tube power supply polarity

[pellikkan]

Hi everyone, thanks in advance if you can share any info here.

I've got a presonus blue tube two channel mic preamp that
I got off an auction site, but it came without a power supply.
The rear side power input said 18 V, so i ordered an 18V
power supply on ebay. The power supply has polarity of
positive + on the inner pin. The preamp doesn't seem to function,
in that if I plug a mic in the front, none of the led lights light up.
So before I go and cut the 18V part of the cord and reverse the
polarity I wanted to check with anyone to see if they might know
the correct polarity, or enough about these units to help out.

There seems to be no help doing a google search, although
there does seem to be an issue with the units being sold with
16V power supplies from presonus, even when it says 18V on the rear.
Maybe the 18V one is actually too much? After all, I tried plugging
some power supplies with a bit higher voltage into some guitar
effects pedals and the thing wouldn't work.

These external power supplies are really starting to aggravate
me big time. Last night I went to a gig and grabbed my cell phone's
power supply thinking it was my keyboard's, and got to the gig across
town and my keyboard woulnd't work,....for cryin out loud, why don't
they come up with some kind of standard or something

Thanks for any elucidation on the problem!

 

[moresound]

You should have gone to radio shack and gotten one of those universal power supplys the kind that you can take the end off and 180 it so as the polarity is reversed.

 

[MOFO Pro]

Often the polarity is listed in fine print right next to the power jack... It's not really a good idea to be randomly plugging in dc plugs when the polarity is not known, but most equipment has blocking diodes to protect from just such an occurrence. Maybe it's the other way, and maybe it still works...

 

[mshilarious]

The current BlueTube needs 16VAC, that is probably your issue.

 

[MOFO Pro]

that's actually good news...