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Old February 24th, 2008, 11:33 AM   #1
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Line/Mic level

I have an Azden FMX-20 portable mixer that I would like to use with the ouput of a soundboard. The problem I see with this is that the soundboard only has a line level output and the FMX-20 dosen't have a mic/line switch, so I'm guessing that a line level signal will be to hot for this little mixer. Is there a way to reduce the line level to mic level? If I do this would I lose the balanced signal?

Thanks for any help

Ben
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Old February 24th, 2008, 12:17 PM   #2
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Just surf over to Markertek or any of the other broadcast supply houses and search for "attenuator."

You'd need the barrel type that accept XLR female on one end and XLR male on the other.

Ideally, you want about 50db attenuation, but the switchable types that offer 10-15-25db pads work just fine at the highest setting.

They all pass balanced signals properly.

The Hosa unit (ATT448) is significantly cheaper and probably works as well as the units from Audio Technica, Shure and others - but these are "buy once and use forever" gadgets - so I don't know anything about quality differences.

Actually, these are useful early in your career - but after you grow into better cameras with switchable inputs and/or mixers that are switchable, they tend to live in your overall kit but hardly ever get used.

Good luck.
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Old February 24th, 2008, 12:37 PM   #3
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Thanks Bill!

Would I need 2 per channel to get all the way down to -50db?
The Hosa model goes to -40db, could I get away with just one or do you think 2 would be better.

Thanks again for the quick answer

Ben
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Old February 24th, 2008, 02:56 PM   #4
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Quote:
Originally Posted by Ben Moore View Post
Thanks Bill!

Would I need 2 per channel to get all the way down to -50db?
The Hosa model goes to -40db, could I get away with just one or do you think 2 would be better.

Thanks again for the quick answer

Ben
Rather than just a pair of pads (yes, you'll need one for each channel) I'd suggest you get one or two Direct Injection (DI) boxes. DI's are purpose built for exactly this application. The economy models from Whirlwind, Hosa, Rolls, etc will be in the same general ballpark pricewise as good quality pads plus they also serve to properly transform the impedances and isolate the soundboard and mixer from each other to prevent ground loops. You need either two single channel units or a dual channel unit for stereo. A quick search on B&H for "Direct Audio Box" will turn up a lot of choices in a variety of price ranges.
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Old February 24th, 2008, 10:36 PM   #5
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My Whirlwind EDB1 direct boxes, which I believe are typical for this type of animal, take two parallel unbalanced TS plugs at the input and provide one balanced XLR at the output. I can use one box to mix unbalanced L and R down to balanced mono, or two for balanced L and R.

But if the sound board only has balanced XLR outs you'll need just the right adapters to go into the unbalanced phono inputs of the boxes. In that case you'd probably be better off with the simple in line pads.
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Old February 25th, 2008, 02:44 AM   #6
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Originally Posted by Ben Moore View Post
Thanks Bill!

Would I need 2 per channel to get all the way down to -50db?
The Hosa model goes to -40db, could I get away with just one or do you think 2 would be better.

Thanks again for the quick answer

Ben
Ben,

No. As long as you get the signal down into the right GENERAL range there's no need to be at precisely 50db.

Most mic inputs can handle a line level padded down to 40, 30, or even 25db perfectly well. You just have to turn the mic input down commensurately.

With 50db attenuation, you'd expect the channel strip volume slider or pot to be set in the normal range - 3/4 of the way to the top of it's travel - just as if a mic were feeding it rather than a line level.

With half that attenuation, you can expect to run the slider or pot open half that far.

If you're recording something REALLY hot, like a drag race - you'll probably miss the difference between the 25 and 50db pads.

But for normal level recording, it won't be a problem.

Good luck.
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Old February 26th, 2008, 02:15 PM   #7
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Thanks Guys for all of your input!
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