Balanced mic to unbalanced input

[HueyNRolf]

Mods, This is a very common question. Please sticky.

There are quite a few balanced mics out there; NTG-2, SGM-1X etc. So why go balanced?

Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.

http://en.wikipedia.org/wiki/Balanced_XLR

If you're recording to a camera (XH-A1) or recorder (Zoom H4/n) which has a balanced input, you're good to go. Just connect your mic up with an XLR cable and you're balanced.

If, however, you want to record to an unbalanced device, HVx0, zoom H1, H2. You'll need to terminate the balanced signal to maintain protection from signal interference.

You can use an XLR audio adaptor like the Juicedlink:



http://www.juicedlink.com/audio-preamps-mixers-etc-c-66

You'll find a lot of useful information (see learn stuff), about getting better sound, here as well as product info.

These adaptors will keep your cable run balanced and provide other pluses (pre-amp, independent gain control between channels). But there is a lower cost option which will terminate the balanced signal:



http://www.bhphotovideo.com/c/produc...00_Low_to.html

Such transformers use a simple balun:



A type of electrical transformer that can convert electrical signals that are balanced about ground (differential) to signals that are unbalanced (single-ended).

http://en.wikipedia.org/wiki/Balun

What about mating the XLR cable to a 3.5mm jack with a simple converter, that works too, right?



http://www.bhphotovideo.com/c/produc..._3_5mm_to.html

Yes, it does work but, because the adaptor grounds out a phase, the signal won't be terminated properly. So your whole cable run will be unbalanced and, therefore, susceptible to signal interference.

[drapeama]

Thanks for the time you invested to solve the question Huey. All the info is now in a single post. Glad you took the time to put all that together.
This would definitively be in the stickies.

[HueyNRolf]

Thanks for the time you invested to solve the question Huey. All the info is now in a single post. Glad you took the time to put all that together.
This would definitively be in the stickies.

I'll save a lot of time in long run. I, and others, can just link this up in future.

[drapeama]

I'll save a lot of time in long run. I, and others, can just link this up in future.

Yeah, you won't have to explain it again and again...! Might be nice to link some comparisons too.

[basicbill]

Very informative. My question is... what is the minimum length of a "long cable"? At what cable length does noise become a problem?

Bill

[Almohada]

Hey Bill, I'm not an expert on that stuff but let me add that whatever the length, I'm sure quality plays a huge factor. Maybe that should be taken into consideration. I think a long run is 20-25 ft but wait for Huey to confirm that

[HueyNRolf]

Very informative. My question is... what is the minimum length of a "long cable"? At what cable length does noise become a problem?

Bill

That's a bit like asking how many drinks can I consume without getting busted for drinking and driving?

I'd say that if you're booming into a recorder worn in a sound bag ( by the boom op), the risk of signal interference is minimal, so you might get away with it. If you're booming back to a camera, then you should definitely make sure the signal is balanced.

When I boom, I'm usually recording to a balanced device; either a balanced sound recorder in a sound bag, or back to camera with balanced inputs.

Many years ago, when I was a young man. I'd carry condoms with me on nights out on the town, just in case I got lucky. If you can protect yourself (for a reasonable price), you might as well.

[Janke]

what is the minimum length of a "long cable"?

Depends on the environment. I've used 20-ft unbalanced cables with no problem, but that was outside, in a rural setting, with no electric interference nearby, and all mobile phones switched off...

But, I actually prefer to have the "talent" carry a digital recorder (got two of them) in a pocket, and a lav mic clipped to the lapel or hidden inside the clothes (beware of rustle, though!)

[HueyNRolf]

Depends on the environment. I've used 20-ft unbalanced cables with no problem, but that was outside, in a rural setting, with no electric interference nearby, and all mobile phones switched off...

Reasonable point. But even in the Finnish hinterlands you could get zapped by a satellite coming through your space. Stay balanced, stay safe and keep watching those skies!

[basicbill]

Alrighty. Then how does one determine whether inputs to a device are "balanced"? The specs for my Canon HF S200 say only "Microphone Terminal - 3.5 mm stereo mini-jack." Not much help there.

Bill

[HueyNRolf]

Alrighty. Then how does one determine whether inputs to a device are "balanced"? The specs for my Canon HF S200 say only "Microphone Terminal - 3.5 mm stereo mini-jack." Not much help there.

Bill

It's unbalanced. A balanced input will use an XLR connector, in 99.9% of cases.

[Almohada]

Now 1/4" connector are a different story. They could be balanced and unbalanced. Could go from quarter inch to XLR or eight or whatever.

Huey, what about cable quality. I know there is a lot of cheap stuff out there. I have a 50ft 12 ch. snake, imagine using that on a film shoot!

[Janke]

This means that users of HVXX and TXi cameras, and simple recorders like the Zoom H1, will always have unbalanced inputs.

You can either take the risk of interference, and just use a cable that grounds the - signal, and use the + signal for "hot" (the tip on a 3.5mm plug) OR you can use a balanced cable and a balun transformer at the camera end of the cable - this will convert the signal to unbalanced, while still keeping the cable balanced.

Beware of connecting the + and - signals as L and R stereo inputs, that may cause problems (or maybe not, if you invert one channel and add them - a way of recording a balanced signal with unbalanced equipment... )

[basicbill]

Great discussion guys. I've already learned a lot this morning before my second cup of coffee. Thanks.

Bill

[cgbier]

Great discussion! That really should be a sticky!

Aaaaadmiiiiiiin!

[Erik Bien]

Done. BTW, there's also a lot of useful info on this topic in the XLR Lingo thread.

[Randy Malone]

This will probably help a lot of people. Very nice to have such a concise post with all the necessary info if even just as a reference.

[askclifford]

I want to buy this adapter for my Azden SGM-1x to go into a Tascam DR-07 MkII.
http://www.bhphotovideo.com/c/produc...-header-589872

One review said this adapter either was not compatible or was noisy when working with this mic. Is this true?

[HueyNRolf]

One review said this adapter either was not compatible or was noisy when working with this mic. Is this true?

It's one of two bad reviews, who knows? Maybe the adaptor was defective? The thing to do is buy well ahead of when you need it, test it and return if it's not right.

[cgbier]

2 out of 58 (with one of them apparently clueless).
I have that thing and it works great.

[MrMicah]

I might have missed it in here or in my other searches, but I'm curious about how to deal with the situation of an 'unbalanced' to 'unbalanced', with a balun or something in the line to reduce noise.

If there was a Mic with a 3.5mm (unbalanced) MALE plug it could travel down a boom pole or whatever on a long (unshielded) cable to a recording device with a 3.5mm input, this is unbalanced all the way and so there is a risk of a noisy recording?

The Pearlstone Balun mentioned above does not help (without adjustment) as it has a XLR FEMALE to 3.5mm MALE connection. (Its assuming an XLR output from the mic)

Would you need a short 3.5mm FEMALE to XLR MALE connector at the Mic end, then the Balun, then use a long 3.5mm cable to the recorder? Doesn't the long (unshielded, non XLR) cable pick up noise after the balun is introduced?

Or do you only need to kill noise just prior to recording, so you could run a long (unshielded) cable out of the mic, to a short 3.5mm FEMALE to XLR MALE connector, then the Balun just before the recorder?

Or do you need to run a shielded (XLR cable) along the length of the boom - hence some other adaptor cables in the mix?

(Yes, a XLR mic, phantom power etc might be easier, but for the moment I've got unbalanced at each end)

[Janke]

do you need to run a shielded (XLR cable) along the length of the boom

Basically, yes.

OTOH, it all depends on the location. Outside, with no electrics or cellphones nearby, I have managed with a 20 ft unbalanced (3.5mm) cable all the way...

[drapeama]

Outside, with no electrics or cellphones nearby, I have managed with a 20 ft unbalanced (3.5mm) cable all the way...

I've been able to record clean audio with myEX-503 Lav, inside and using an extension cable...in the living room. No prob.

[MrMicah]

Basically, yes.

Thanks. Sorry for the multi questions in one.

However, with this balun, if you wanted to run XLR cable the length of a boom, you would need a setup like:

Mic (3.5mm MALE) => 3.5mm (F) to XLR (M) => XLR cable along boom (F/M) => Balun => Recorder

While this gives XLR cable over the length of the boom, the signal does not become 'balanced' until just before recording and still might have noise picked up along the length of the boom? Or the cable shielding is what protects this part?

I guess I should check to see there are baluns with other end connectors.

OTOH, it all depends on the location. Outside, with no electrics or cellphones nearby, I have managed with a 20 ft unbalanced (3.5mm) cable all the way...

I do understand that not having balanced lines does not mean you WILL get poor audio, you just increase the liklihood, so you may as well protect yourselg if its affordable. <Insert previous condom reference here. :-)>

Thanks for your help.

[cgbier]

Uhm, hold on a second here. You have a microphone with a standard 3.5mm plug? Then you don't need that whole XLR/Balun setup. In 99.9999% of all cases, a mic like yours doesn't provide a balanced signal. All you can do is to plug that mic directly into the cam and pray.