Hi,
I need to find a box to convert mic level to line level, Balanced XLR inputs to Unbalanced Phono/RCA outputs, all to run off battery power, anyone got any suggestions? (p.s. some control over mic levels may be handy too...)

There's a wide range of options for you, depends on just what you need it for. Behringer has a battery operated mixer under about $100. At a more professional level something like the Sound Devices MixPre is a good choice - 2 XLR mic level inputs with phantom and faders. XLR +4dBU line level outputs plus -10dBV stereo line output on a 3.5mm TRS jack (a stereo TRS plug to dual RCA Y-cable is just a couple of bucks at Radio Shack and a jillion other places). Headphone monitor. Internal battery or external 6-18VDC power.

Might just be worth while getting a Direct box - You can get some with level controls, but most "Active" boxes will provide a 20db pad switch. The behringer costs around $30 from Guitar Center.

To change mic level to line level you need a preamp.

To convert "Balanced XLR inputs to Unbalanced Phono/RCA outputs" you need an adaptor. I have one by TecNec (model OTL-2S) that has XLR inputs and RCA outputs and is passive; it doesn't need a power source and works fine. A good source for this kind of device is Markertek.com. Have them send you one of their catalogs; it is full of this type of gizmo.

Best wishes,
Peter
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http://www.parkfilms.com

Thank you all for your suggestions

The passive ones have a transformer inside of them. They match impedances, but you need enough gain in the next stage for it to work. Also, they work best with microphones that have good sensitivity.

One tip: keep the wire short after you've converted to unbalanced. If it's long and finds its way near a power cord, you'll get hum.

Also note that the passive ones don't have phantom power. It's no problem with dynamic mics, or mics that take batteries, but if the mic needs phantom power, then you need a preamp.