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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: JimmieC on April 16, 2014, 04:00:57 PM

Title: Naiant Littlebox v1.5 - turn off phatom power
Post by: JimmieC on April 16, 2014, 04:00:57 PM
The Littlebox (v1.5) I picked up has a 3-way switch to turn the power from low voltage (P20V), off (turns off unit), and high voltage (P48V).  Can the this preamp be operated as an amp without supplying phatom power?  If I use the low voltage (P20V) power would it damage the playback / source system if it doesn't need or take phantom power?
Title: Re: Naiant Littlebox v1.5
Post by: obaaron on April 16, 2014, 05:07:11 PM
Mine has the same switch but also has another switch to turn mic power on/off.  Im guessing that you need this switch to still pass a signal minus phantom
Title: Re: Naiant Littlebox v1.5
Post by: JimmieC on April 16, 2014, 05:27:28 PM
The Littlebox I have is http://taperssection.com/index.php?topic=167591.0
Title: Re: Naiant Littlebox v1.5
Post by: jibooer on April 16, 2014, 05:50:03 PM
Paging Jon...
Title: Re: Naiant Littlebox v1.5
Post by: Phil Zone on April 16, 2014, 08:20:42 PM
Like obaaron said, that can't be the case you must have a mic power switch. It's a special option that a few littleboxes have floating around. So the one you have cannot do it. Below is a picture of mine so you can see
Title: Re: Naiant Littlebox v1.5
Post by: JimmieC on April 16, 2014, 09:02:18 PM
Not a big deal especially if major surgery.  I was just going to put some music through it from playback system with the output tranformers on/off and different gains to see a difference or saturation.

Is it true a xlr cable could be built with resistors that could remove the dc power and just pass the signal?
Title: Re: Naiant Littlebox v1.5
Post by: JimmieC on April 16, 2014, 09:35:28 PM
Thanks for all the responds and info.
Title: Re: Naiant Littlebox v1.5
Post by: TSNéa on April 18, 2014, 09:34:08 PM
Quote from: Jon Stoppable on April 16, 2014, 09:21:57 PM
Capacitors, not resistors.

Hello Jon,

I have a somewhat similar question. I hope I'm not off topic.

I own a "naked" Littlebox (two 3-positions switches, on the right side of each knob) and I was considering using it sometimes with a dynamic microphone, but those are said to dislike P48, unless it is strictly balanced, which I can assume as you built it but not check... :-[  And anyway I cannot imagine how any voltage could reach the coil / the ribbon as those are isolated from the shield in a balanced cable  ???
So in order to get rid of any hazard, what would be the best solution?

Thanks in advance for your answer.
Title: Re: Naiant Littlebox v1.5 - turn off phatom power
Post by: TSNéa on April 19, 2014, 02:49:43 AM
Thanks Jon for this very helpful answer. I suppose the item you refer to is the ITP Inline transformer-coupled microphone amplifier?

The two mics I have in mind are a ribbon Beyerdynamic M160 (most of people know, I guess) and a LEM DO21B, a moving-coil one (French made, pretty rugged and used by French TV channels for decades in ENG and variety shows (even for singing but no longer!):
http://www.dcaudiovisuel.com/product_info.php/products_id/240/language/en

(http://www.dcaudiovisuel.com/images/lem/lem_do21b_1.jpg)

I bought mine used from a magician, more than thirty years ago. Still working.

If I read correctly the ITP specs, I can use any of those mics (in mono interviews), either through my Littlebox to my Olympus LS-5, or directly into the LS-5 (in a light configuration) with "a variable gain range of +22dB to +42dB"? It sounds nice... I'll PM you.

End of the off topic. Sorry for that and thanks you all.  :)