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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: flatbroker on March 16, 2014, 10:33:40 PM

Title: Balanced Output from Three Wire Battery Box?
Post by: flatbroker on March 16, 2014, 10:33:40 PM

Long time lurker and first time poster here.  Great place.

Thanks to Hyperplane's excellent knowledge base sticky on 3 wire battery boxes on this site I have made a couple.  I would like to know if there would be a way to implement the pseudo balanced output circuit described in the attached pdf to feed a couple xlr inputs on a preamp?

I have phantom power supplies and adaptors, but a battery box with balanced outputs would be a lot more portable, not to mention concealable.

I have searched the site and see that pin 1 can be connected to pin 3 to make the connection unbalanced.  If there is no sonic penalty doing this versus the Jensen circuit then I'll go that route.  Hopefully one of the resident electronics experts will chime in.

Thanks

Title: Re: Balanced Output from Three Wire Battery Box?
Post by: DSatz on March 17, 2014, 09:01:47 PM

You can always* feed unbalanced signals into balanced inputs; there's no need for conversion. All you need is a simple adapter.

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* OK, probably there is an exception somewhere in the universe, but I can't think of one at the moment.

Title: Re: Balanced Output from Three Wire Battery Box?
Post by: flatbroker on March 17, 2014, 10:24:50 PM

Does the simple adaptor just ground pin 1 to pin 3?  If that's all there is to it I'll replace the two xlr inputs with a 3.5mm female jack (tying all the pin 1 and 3 wires to the barrel and each pin 2 wire to the ring and tip) and re-house the preamp into a project box half its current size.  The preamp has switchable phantom power so I'll have to hardwire that switch in its off setting.

If I'm on the right track I can make things even more compact by putting the three wire circuit inside the project box and use the preamp's 9v battery to power the mics.  That way I would have two TA3F's in and a 3.5mm cable out of the preamp. 

The guinea pig preamp would be a Beachtek DXA-SLR if it matters.  It only has 15dB of gain to start with.  Will I lose most of it doing this?  If so I can hack up a couple old Shure FP11's.

Thanks for your help.

Title: Re: Balanced Output from Three Wire Battery Box?
Post by: lsd2525 on April 08, 2014, 11:22:39 AM

Where is the sticky on building a box? Can't seem to find it.

Thanks, Dan

Title: Re: Balanced Output from Three Wire Battery Box?
Post by: 2manyrocks on April 10, 2014, 10:49:32 PM

http://taperssection.com/index.php?topic=72994.msg976869#msg976869