Powering a BeachTek audio adapter with an external battery source

I run my rig off an Anton-Bauer Dionic 90 battery (through a 3rd-party battery adapter), a 3-hour-rated lithium-ion setup which has more stored power than I know what to do with. Given this convenient power source (with 5v, 7.2v, 12v and 15v connections on the adapter), I prefer that all the accessories on the rig run off the same power source to avoid last-minute confusion as to what on the camera has fresh batteries and what doesn't.

That, and it sure saves on batteries.

Amongst the accessories on my rig is a BeachTek DXA-5Da audio adapter, which - unlike my monitor - does not have any source for power other than a 9V battery box. Granted, the 9V power source is used only for the VU meter and headphone amp - audio devices hooked up to the unit will pass the signal to the camera with or without a battery - but it's nice to have these features at hand without worrying about battery life.

Granted, in the time that I've run it, I've used alkaline 9V batteries, not lithium - which probably account for my assessment of 9V battery life in any electronic equipment. You mileage may vary.

The unmodified BeachTek DXA-5Da

With that said, I contacted BeachTek about the voltage requirements of the unit, wherein I found out it will run equally as well on 12 volts as 9, with no issue.

EDIT: The 12V source caused an unreasonable amount of static and electronic noises when shooting. I later installed a 12-to-9V step-down adapter in the box, which I have added to the list below.

As my Anton-Bauer adapter has a 12v power source, I figured I'd take advantage of it - in a home-spun method.

Anton-Bauer adapter plate w/12v output

I located a power plug and wire off a useless Chinese doo-dad that would mate with the cable provided with the adapter and stripped the wires for soldering to the BeachTek:

Donor 12v wire

So, out came the screwdriver, and apart came the BeachTek.

WARNING: 
These photos are for example purposes only. Opening up any electronic device as shown will void its warranty and most certainly cause possible injury or death to your person and/or others. Doing so will also ruin your sex life forever. Do not try this at home or on the moon. Your stupidity will never be my responsibility in a court of law, because you free me and everybody else in the world of liability by opening your electronic stuff.

Now that that's over with, let me continue.

The DXA-5Da comes apart via the four screws at the base (hidden by four adhesive caps). Not much room to work with, particularly as the battery leads limit your ability to move the bottom half of the box aside to work in.

One drill bit later:

After a bit of debate, I decided that this location near the battery door would be the most ideal location to place the wire. Nothing would be in the way inside, and it'd be equally free of the controls at the front.

Adapter wires soldered - note tie wrap to keep the wire from pulling through

Soldering the wires into the existing 9V leads couldn't have taken more than 30 seconds.

EDIT: These procedures show the 9V unit being connected directly to the 12V source. Due to the issues relating to this combination, I purchased a 12V-to-9V step-down converter on eBay and wired it in-line with the 12V power input. The step-down unit would not fit in the BeachTek without modification, so I cut a hole in the 9V battery box, and glued the unit in from the back as shown:

 
It's a convenient and quick way about it, but given that there is no switch to re-direct the source power from the battery leads or the wire, I'd be hesitant about allowing someone other than myself to use it - combining a 9V battery and the 12V power source on the same circuit could be a nice invitation to fry something (probably the most expensive thing on your rig, as Murphy would have it).

EDIT: Now that the step-down unit takes up the area where the 9V battery would otherwise be, there is no risk of someone running the unit off of the 12V lead and a 9V battery at the same time. I did not solder the new leads to the 9V contacts either, so it wouldn't work even if one jumped it with alligator clips.

From the outside, neat and clean.

At any rate, it works perfectly off the 12V from the Chinese A-B adapter, with the step-down unit installed in the BeachTek. Excuse the funky look of the VU meter; it looks normal in person. Must have had the polarizing filter set wrong.

Success!

During my discussions, BeachTek informed me that they are working on a new adapter for release in the future that may interest me. No word of what it is.

I'm already going nuts in anticipation.

-Kurt - "Man with the 5D"