Looper's Delight Archive Top (Search)
Date Index
Thread Index
Author Index
Looper's Delight Home
Mailing List Info

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Date Index][Thread Index][Author Index]

RE: Midi phantom power



Title: RE: Midi phantom power

>>>my amp tech could easily hook up 9 volt through one of the wires of the midi cable that is unused. My new Midi control device, a Kenton Spin Doctor, sais it needs 9V d.c. @ 250 mA.in the manual. Can the EDP supply this without getting into trouble? Can I simply try this out without coursing breakdowns? Matthias? Kim?<<<

andreas, I wouldn't recommend putting the extra load on any power supply like this, as you're straightaway inviting reliability problems & voided warranties & so on.

 
what I do with my midi rig (& I've written this up to the list at greater length before) is use the "spare" connections of the midi cabling to distribute + & - 12V from a /laptop/ power supply. this approach has the benefits that the power pack can be replaced easily, works anywhere in the world & has an absolutely flat output that won't put hum onto the midi data signal.

at very least, the 9V needs to be regulated. if it doesn't say "regulated" on the power supply, it isn't.

there are some more caveats for even the most experienced techs: quite a lot of midi devices, especially those from japan, don't have the midi din socket fully populated. that is to say, the outer pair of contacts are physically absent. many commercially available midi cables also lack these connections; though the pins are there in the plugs, there's no electrical connection to them.

I made my own midi cables with all the pins connected, & for certain bits of gear there's a second, shorter cable coming out the back of the din plug alongside the midi cable, to go to the power jack on the boss/roland/korg/whatever.

 
also, it's common practice to have the ground lifted at one end of a midi connection; this is usually achieved at the receiving end &, while it doesn't preclude use of the ground wiring for the power supply, one should take care not to create an unwanted midi grounding.

most small midi devices, like the kenton & doepfer controllers, carry the same spec on their cases- "must have 9V at 200mA" or whatever, & then you open them up & find a 7805 there every time. I can't remember the last time I saw a bit of gear that didn't have it's own internal voltage regulation, except for stomp-boxes.

but I have done this & made it work & now there isn't a single "wall-wart" in my live-rig.

duncan/r.m.i.



***************************************************************************
CONFIDENTIALITY NOTICE

The contents of this e-mail are confidential to the ordinary user
of the e-mail address to which it was addressed, and may also
be privileged. If you are not the addressee of this e-mail you may
not copy, forward, disclose or otherwise use it or any part of it
in any form whatsoever.If you have received this e-mail in error,
please e-mail the sender by replying to this message.

It is your responsibility to carry out appropriate virus and other
checks to ensure that this message and any attachments do not
affect your systems / data. Any views or opinions expressed in this
e-mail are solely those of the author and do not necessarily
represent those of MTV Networks Europe unless specifically stated,
nor does this message form any part of any contract unless so stated.

MTV reserves the right to monitor e-mail communications from
external/internal sources for the purposes of ensuring correct
and appropriate use of MTV communication equipment.

MTV Networks Europe
***************************************************************************