Use of balanced audio is of value mainly with long mic cables, say more than 20', or if you are shooting in electrically noisy environments. Electically noisy means lots of stray electrical and changing magnetic fields - like a place filled with complex active wiring; e.g., a TV studio.

For most home video where the mic is fairly close to the camcorder the benefit is likely negligible and a simple adapter (such as Radio Shack mentiond above) that just grounds one side of the balanced line making it unbalanced will work OK.

Note that connecting one side of the balanced line to the right channel input and the other to the left channel input, as will happen with the B&H link adapter, will result in audio in the channels that is 180 degrees out of phase. If combined (as in the linear track of a mono VCR), the audio cancels and you get near silence. If played ona good stereo system you get a strange sound image.

By the way there are alternatives to the MA300 in about the same price range, including XLR adapteers from Sign Video, Studio 1, and Beachtek. Each has its advantages and disadvantages, as are discussed in other threads here.

noisy XLR inputs on GL2
 

I'm a relatively new owner of a GL2.

I bought the XLR accessory shoe (the MA-300), so I could connect the output of a mixer board to the audio XLR inputs hoping to get good quaility audio.

As soon as I connect a standard XLR cable from the output of this mixer board to the input of the MA-300, I get a pretty annoying hum. (The mixer board has all it's outputs turned all the way down, and no inputs are connected to the mixer board.) I tried another mixer board and the hum is less, but I have the feeling that neither mixer board would have any hum if hooked up to other equipment.

I'm wondering if my MA-300 is defective or if the GL2 in general just has very noisy audio input. Is there is some trick to fix this? (Or do I need to find another mixer board?)

Does anyone know a good way to get the output of a mixer board into the audio input of the camera without any extra noise?!

Are you using AC power to the camera when this happens? Using battery power lessens the chances of a "ground loop." Unfortunately the MA300 doesn't has a ground lift switch like it's aftermarket competitors (beachtek, sign video, studio 1), which can also help.

The MA300 (line the MA100 and MA200) uses electronics to do the balanced-to-unbalanced conversion, not transformers, so yo do not get the same degree of isolation from the source. If using battery does not help, you may find it helpful to use a direct box to isolate the camcorder from the mixer board.

I use a Mackie 1202 mixer and and use an RCA (out of the Mackie) to 3.5 (into the GL2) cable to run directly into the camera. I really get excellent sound with this arrangement and no noise. I would be inclined to use the MA-300 only with an XLR microphone plugged directly into it.

Thanks!!!

Using battery power instead of AC power, solved the problem of noise XLR inputs. Does sure sound like it was a "ground loop."

However using battery power in practice isn't practical.

I tried again with a borrowed and much more expensive mixer board -- one I'm suspecting isolates it's output from AC power much better, and the noise is gone. I guess I'll use this one until my friend wants his expensive mixer board back.

Cheap mixer board: Shure SCM268 (about $300)
Expensive mixer board: Shure FP32 (I think over $1,000)

Try an audio isolation transformers with ground lift; e.g.,

http://www.bhphotovideo.com/c/produc..._Splitter.html