Line vs Mic XLR input

[Paul Elertson]

When using the XLR inputs on my XH-A1 I normally have it set to mic and use the manual setting to get the sound I want.

I was recently filming at a conference and getting my feed from a sound board in the room. During testing, I was picking up a lot of static and background noise. The sound guy said I should be using it in line and not mic since it was a line feed from the sound board. However, when I tried using the line mode I would get no sound at all. I ending up using mic mode on my camcorder and had the feed from the sound board turned down really low. Ended up working fine for what I needed, but...

Is something potentially wrong with my camcorder? Or am I missing something that needs to be done to use the line feed?

Thanks in advance,
-Paul

[Paul R Johnson]

It's unlikely your camera is dodgy - when you had too much signal and switched to line, you lost all signal? It could simply have been too much for mic level, but not enough for line? Other than that - I'm stumped.

[Paul Elertson]

Thanks for the reply Paul.
We did try turning up the feed into the camcorder on Line mode and we still got nothing. ( I also turned the attenuate on and off)

Is there any way to test the line mode? has anyone here used line on their XH-A1?

edit: Sorry if these are dumb questions, I will admit I am not the most experience in the audio areas.

[Peter Manojlovic]

Hey Paul...I'm in the same boat as you...
The XHA1 is funny...


I use an XLR Mic that's mic level in Ch.1.
I use a Sennheiser wireless for Ch.2. Since the [line.mic] switch is set to [mic], this forces the Sennheiser to get attenuated at the [xlr mic att.] switch.

I believe if both XLR sources are coming off the board as Line level, then the [line.mic] switch can safely be set to [line]..

[Eugene J. Kulak]

I had the same problem some years ago with my Sony gear. Problem went away when I came out of the sound board with this first. A3F XLR Jack-to-1/4" Plug Adapter/Transformer - RadioShack.com

[Les Wilson]

Professional sound boards output are usually from the mixer's auxillary output which is usually 1/4" line level. When I had an A1, I used both line and mic level inputs. The A1 audio block design restricts you to having both inputs be either line or mic. You can't have one or the other. I think that was fixed in the A1s.

Anyway, something is odd here. The sound person said the signal was line level and you setup your A1 XLR audio block to be line level and got distorted audio. Yet setting the audio block to mic level gave you clean audio albeit loud. Is that right? What kind of cabling was used to go from the mixer to the camera?

The way this is handled properly is to use a "direct box". I prefer Whirlwind. You run a 1/4" cable from the mixer to the direct box and then an XLR cable from the direct box to your camera. The direct box transforms the line level signal to mic level. Is it possible the sound person had a direct box in the signal flow?

You get what you pay for with direct boxes BTW. YMMV

[Don Palomaki]

Sounds like an issue with the conenction. Sound board auduio output could be balanced or unbalanced, and depending on where it was pulled and how it was conencted/cabled to the XH-A1 you just might see what you saw.

For example, if a 1/4 TRS conenctor is conncted to an unbalancd stereo output at one end, and connected to a balanced input at the other you can get significant signal cancellation of the momo component of the audio.

What was the exact methog of conenction. Which sound board outputs, wht sorts and kinds ot cables and conenctors were used to the XH-A1?

[Roger Van Duyn]

Hey Don, not to hijack the thread, but do you have any links explaining the noise cancellation you described? I think that's what I experienced on a major gig a few months ago. Had one microphone that volume dropped to next to nothing and had to boost nearly 45 db in post (that's right, thought there was no audio at all until I noticed a faint bouncing up & down in the meters within Avid).

The few other times I'd used line level, no problems.

[Paul Elertson]

Thanks for all the reply's everyone.

Originally Posted by Les Wilson

Anyway, something is odd here. The sound person said the signal was line level and you setup your A1 XLR audio block to be line level and got distorted audio. Yet setting the audio block to mic level gave you clean audio albeit loud. Is that right?

Whenever my camcorder was set to line, I could not hear anything.

Originally Posted by Les Wilson

The way this is handled properly is to use a "direct box". I prefer Whirlwind. You run a 1/4" cable from the mixer to the direct box and then an XLR cable from the direct box to your camera. The direct box transforms the line level signal to mic level. Is it possible the sound person had a direct box in the signal flow?

You get what you pay for with direct boxes BTW. YMMV

Thanks for the info, I will look into this.

Originally Posted by Don Palomaki

What was the exact methog of conenction. Which sound board outputs, wht sorts and kinds ot cables and conenctors were used to the XH-A1?

I believe it was 1/4 to XLR adapter(like Eugene mentioned above) sent through the headphones out on the sound board. I could be mistaken on this, was not my job to set up sound in the room and the board was not mine. The sound crew set up the board and ran an XLR cable to my camcorder (channel 1).

[Jay Massengill]

If the sound person truly did send the HEADPHONE OUTPUT of the mixer using a regular 1/4-inch TRS male to XLR male cable, then that would result in no sound for any signals that were pan centered on the mixer. This is due to using a regular mono balanced cable to send a stereo unbalanced signal. The Left and Right from the headphone output are in-phase with each other until the balanced XLR input of the camera inverts the polarity of one side. However this should have occurred when your camera was set to either Line or Mic input.
If the sound person used the adapter from Radio Shack referenced above hooked to the headphone out, cancellation would occur due to the right signal being connected to ground before the transformer. The cable would be carrying a balanced signal of nothing. Plus the Radio Shack adapter is the wrong XLR gender and would have needed a male to male XLR gender changer.
Perhaps when the camera was set to Mic input, only one signal pin (either pin 2 or pin 3) of the XLR was actually making it into the input. This would result in -6db attenuation, but it would still be too hot for a Mic Level input.
As mentioned, a passive direct box is the normal way an unbalanced aux output from a mixer can be sent at balanced mic level to a camera. You should also engage the Ground Lift switch on the direct box to avoid ground loop hum if you are plugged into AC power from an outlet any distance from the AC outlet the audio equipment is plugged into.

Also for any camera that can supply phantom power to its mic input, make sure it is set to OFF when receiving a signal from a source other than a mic that requires phantom power!

[Roger Van Duyn]

The OP said the audio guy sent a line level out the headphone jack of the mixer. I didn't think it was possible to send line level out the headphone jack of a mixer. Of course, I don't know all that much about audio ( but I've run into "audio guys" who knew even less than me).

The only times I've used headphone outs from a mixer into an XHA1 has been into the 1/8" stereo mini jack on the handle.

[Jay Massengill]

Depending on the headphone volume control (and discounting for the sake of simplicity impedence issues), the headphone out of most house mixers is capable of being equal to the line level output.

The key is knowing that the balanced input of the camera will be inverting the phase of one of the signal pins of the XLR cable. As you say, sound people's knowledge can run the gamut from very experienced to very inexperienced.

On the sound forum here, the issue of sending stereo unbalanced to a mono balanced connector and getting total phase cancellation comes up every few months, usually when someone has purchased a regular balanced adapter cable and tried to use it when a specialized cable is needed.

[Paul Elertson]

Originally Posted by Jay Massengill

Also for any camera that can supply phantom power to its mic input, make sure it is set to OFF when receiving a signal from a source other than a mic that requires phantom power!

I made sure phantom power was off.


It appears I most likely wasn't missing anything about the x-a1 set-up, and I need to learn more about the sound board and audio side of things.

[Don Palomaki]

Sound board headphone jack output is typically 1/4" TRS stereo and could well be line level. (Mackie mixer for example provide something like up to +20 dbV from a 60 ohm output.)

If conncted to the XLR input on the XH-A1 via a simple TRS-to-XLR patch cord (tip (left) -2, ring (right)-3, sleeve (ground) -1) it is recording the "difference" signal between the left and right headphone signals. For mono program material this amounts to the degree of imbalance in the channels, and could very easily end up a mic level signal thanks to the cancellation. (This also demonstrats the noise cancelling properties of balanced connections [aka common mode rejection].)

Consumer and some prosumer stereo microphones have an unbalanced stereo output on a 1/8" TRS output. This could easily be connected to a balanced XLR mic input (e.g., tip to pin 2, ring to pin 3) resulting in only the difference signal being recorded.

People setting up sound boards at places such as hotel conferences are not always professional sound folks. It is a good idea to arrive early, carry a complete kit of cables, adapters, isolators, and gender benders, and do functional and level checks before the program starts.

As an aside, this also was a not an uncommon issue when folks played stereo video that was recorded with out of phase audio channels on a mono VHS VCR - cancellation of audio on the linear track.