Choosing an XLR adapter for your camcorder

So, if you want to use a high-end microphone with your camcorder and you don’t have an XLR jack, you’ll have to find a way to convert from the XLR cable to the 3.5mm connector on your camera. We explored two alternatives.

The first was a “line matching transformer” from RadioShack, specifically the A3F XLR Jack-to-1/4″ Plug Adapter/ Transformer. Since this product output to a 1/4″ plug, I added a 1/4″-to-3.5mm converter, officially the 274-875A connector, to connect to my camcorder. Total cost was under $20, besides the XLR cable. This rig is shown in Figure 4. 

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Figure 4.The Radio Shack line matching transformer.This right angle setup looks almost painful.

In my lab setting, this setup generally worked well, though it converts the stereo signal from the microphone to monaural, and doesn’t supply the plug-in power required for many microphones. Ergonomically, however, it’s clearly not a field solution, since one inadvertent bump would probably rip my camera into multiple pieces.

If I used the line matching transformer route in the future, I would choose the Shure A96F transformer, which inputs XLR and outputs 3.5mm, with a flexible cable that avoids the right angle attachment shown in Figure 3. Mail order price for the A96F is around $40.

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Figure 5. The business ends of BeachTek’s excellent DXA-8.Click the figure to view the full sized image in a separate browser window.

The other alternative we explored is the BeachTek DXA-8 Ultimate Adapter, which lists at $399 but can be found for a few dollars less via mail order. Figure 5 shows the two faces of the product, back and front, which screws into the tripod mount beneath your camcorder, with a similar mount on its bottom so you can continue to use a tripod.

On top, the unit has three connectors, two for XLR cables and one for an unbalanced 3.5mm connector. The output is a 3.5mm connector with microphone power, so you can plug it into any camcorder with a microphone jack.

The twin XLR connectors mean you can use the DXA-8 to mix together two microphone signals, controlling respective volume with the two volume dials shown on the bottom of Figure 5. In contrast with the line matching transformer approach, the DXA-8 captures stereo, not monaural output.

The 48V switch to the right of both volume controls means that the DXA-8, which is powered by a 9-volt battery, can supply phantom power to condenser microphones. In addition, the LMT buttons engage a “limiter” function that prevents distortion from hot inputs, a critical feature when accepting LINE-level input from a sound system. The unit also has preamplifiers that boost the low signal from microphones, which can eliminate hiss.

After using the different approaches to converting XLR input, I liked the BeachTek under-the-camera approach much better. If you don’t need all the functionality of the DXA-8, consider the DXA-2, which sells for around $125 and provides one XLR port and one unbalanced 3.5mm input, with volume control but no phantom power or limiters. I would definitely buy this over the RadioShack or even Shure A96F approach.

About Jan Ozer

I help companies train new technical hires in streaming media-related positions; I also help companies optimize their codec selections and encoding stacks, and evaluate new encoders and codecs.

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