audio problems using mini mike jack
 

Help!

We recorded a number of interviews using a lav which we ran through an xlr-mini cable into the mini mike jack next to the onboard mike on our XL1S. We noted there is another little jack there but ignored it and now we are worried.

After a number of experiences where we heard the sound fine through headphones on the tape and in our computer through headphones, but did NOT hear it on a standard VHS or mono speaker on our G4, we realize we have a problem.

(Now we use the MA 100 but have a new problem - static or distortion on the R channel. We are going to send it and the camera to NJ...)

What is it?

Is sound only on hi fi tracks of the tape? Is it not on hi fi but somewhere else?

We have a very moving short documentary where the main interview was done this way. Advice?

Jane, can you identify the lav microphone used? Manufacturer, model number, etc.

The way you describe it, I think the audio is actually there, but you're not getting it to VHS properly.

Chris, it has happened with a nice Audiotecnica shotgut mike, also. So, I don't think it is the mike.

What is strange is that when I digitize the interview into Final Cut and play it back using the G4 standard speaker, no sound. But with stereo headphones or throught an external speaker system, sound is there. The tracks in FCP (and in Premiere in a PC) show sound.

PS I was also wondering about the export settings from Premiere (on a PC) to our Canon XL1S... since this has happened with a number of interviews before we started using the MA-100 box. But I have tried and tried and can't figure out what is going on. The audio meter on Premiere show sound as normal...

I figured out a messy workaround for a screening recently, but have no idea what is going on:

I exported to the Canon camera onto mini-DV. Then, I played out from the camera, but rather than play out sound L to L and R to R, I ran L to both L and R and it seemed to do the trick. But this means that the R channel is not being used, and that I need a second DV deck or camera to get a DV tape that has all tracks on it...

What did we do wrong?

Hello Jane,
I'm not sure of all of the various convolutions of your trials but here, at base, is what I believe is going on.

The mini "Mic" port that you are using is capable of bringing-in 2 channels (stereo) of sound. The XLR-to-mini cable (or adapter) you are using is probably designed to handle only 1 channel, which is fine since your mic is only 1 channel. As such, it's only making contact with 1 channel inside the Mic port and only 1 channel (Left) is being recorded to tape...which is correct. (BTW, the "2nd hole" is used to provide power to the standard mic. It's not usable for other applications and has nothing to do with the sound signal.)

The reason you're not hearing anything through the computer's speaker after capturing the footage into FCP is probably due to a combination of your FCP Preferences and main System Preferences (Sound) settings. Check those.

So I basically think that everything is working fine. Excuse me if I've misinterpreted your dilemma.

The mini-phone mic input jack on the XL1 is stereo unbalanced.

The likely cause of the "no mono sound" is the the XLR-Mini phone adapter cable. The mini-phone plug probably looks like a stereo plug. Actually, as copnnected to the mic, the mini-phone adapter is probably balanced with the tip being the (+) and the ring corresponding to the (-) of the XLR connector on the mic. The sleeve is ground (and electrical center or midpoint of the mic output).

This results in the left and right channel recording close to equal but out of phase sound. When combined into a mono signal for the VHS linear track, or mono output of the computer, you get phase cancellation and near silence. Yet you will hear sound in both ear phones and from stereo speakers. (The sound is out of phase and may even have a "floating" stereo image rather than a solid centered image.)

Proof of the pudding - If you invert the right channel in your NLE you will probably find the sound you are missing. Alternatively, in Premiere you should be able to silence the right channel sound and mix the left sound into both channels.

Dear Friends:

I think you have helped me solve this. I panned sound to the left on the interview segments and it appears to have resolved our problem.

This community is a great resource and I am sure I will be writing again soon.

Jane Regan