I'm sorry to be making my first post a question, but I was searching for answers and found this great forum.
I want to use a Sony Camcorder (HDR-XR160) to video some seminars we produce. For our big events we have a professional videographer come in, but we do loads of smaller events that I would like to DIY record as well.
These events might have 40-50 people, a PA set up, with mixer at the back of the room. The speaker uses a wireless mic (Shure with a headset)
From the mixer/camera at the back of the room, to the speaker on the stage, might be 10-12 metres.
I bought the Sony for this purpose, but have never been able to get good sound recording. I bought it, because it has an external mic input.
So, what I am trying to do is take a stereo sound output (twin RCA) from our PA mixing deck, and take it into the camera (3.5 mm jack). This way we pick up a clear sound from the speaker on the stage. Me. As you can tell, I'm not a techie!
But whenever we try this, we get buzz.
It was suggested that we don't use external power, as the earth might be causing the buzz. But even on battery, the buzz is still there.
Another 'expert' suggested we use a Beachtek device along with the camera. Still getting background hiss.
Another suggested it might be the auto gain control. But that did not fix it.
My plan B is to use a Shotgun mic on the camera, but we'll still pick up a lot of ambient sound, and whoever is using the camera will probably have to track back and forth as I 'pace' the stage. Otherwise I'll be coming in and out of the mic 'pickup zone'.
I just thought maybe someone out there might have solved this problem. I have asked our videographer, sound guys. No one can work out what the issue is........
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Is the problem that I am taking a line output to a mic input? But no one I have asked has mentioned that as a problem, and all the seminars I go to, people are taking a sound feed direct from the mixer to their camcorder. I think......
The HDR-XR160 has a microphone input. That means it accepts mic, NOT line level audio. Ideally there are 1/8" terminated mics, shotgun or otherwise that can be used for this, but I take it you'd rather use the mixing deck line outs. But even if you were to find a way of attenuating the audio to match the mic input level requirements, that would necessarily mean the camcorder has to be in a fixed spot (on a tripod somewhere).
I have been in this exact same fix before and tried several methods. In one, I made a passive attenuator to attempt to bring down the line level by -40dB. I was successful, but, as you noted, no matter that the camcorder was battery powered and the cables were shielded and ground-terminated at either or both ends, it still resulted in hum. If I'm not mistaken, that Sony has two audio control choices: normal and low-level. Normal is the one that wretchedly applies AGC. The low level choice would have been good, but probably to ensure that no clipping will occur on any external mic that may be used, Sony has elected to make the gain so low that while devices like Beachtek will work, they also introduce copious hiss. This is why pros use XLR-input camcorders, but that is another topic.
In the end, two methods worked for me.
In one, I used a Shure UHF wireless system (PG1 transmitter, PG4 receiver). The PG4 has two outputs: one balanced XLR, the other single-ended 1/4" phone jack. It's a simple matter of plugging the XLR out to FoH mixer (for the audience), and the 1/4" out direct to the camcorder mic in (for AV recording). With this approach I can use up to two wireless systems so up to two people onstage can have mics on them and get cleanly recorded. The PG4 output is hiss- and hum-free, and I have shot video on several camcorders like the Sony SR12 and CX550, and Canon HG10 successfully. You have to have the appropriate 1/8" stereo phone plug to two 1/4" mono phone plug cable, for one.
The method above is OK is the camcorder is in a fixed spot and no more than two wireless mics are used. If there are more mics, and they feed into the FoH mixer, and/or the camcorder has to wander around, I just ignore the camcorder audio. Instead, I get a dedicated recorder like the Zoom H2, H2n, H4, R16, etc. These devices have line-in, and accept the mixer outputs. The mixer output is effectively recorded onto an SD card. In post NLE, I sync this clean audio on the video using whatever the camcorder mic picked up as cue.
I currently use the second method almost exclusively, even that I often use pro camcorders with XLR inputs and can use shotgun mics with them. Not having to worry about deliberately recording audio with the camcorder is very liberating. There is even a side benefit: the omnidirectional mics on (one of) the camcorders pick up audience reactions and applause, which I can still use later to mix in with the recorded mixer output in the way I want.
Other issues will crop up, like syncing the separately recorded audio with video in NLE, but on the whole, this is trivial compared to other problems concerned with using the camcorder mic input. I have discussed tips in separate posts here on videohelp.com how I sync'd the audio with video in NLE and more.Tablet? No, I don't have a tablet. I have a life.
1. It is NOT the fault of the grounding, as you have found out.
2. Did you buy the Beachtek device? And if so, which one? (Model# please). This could make a difference.
3. Regardless of using external or internal mikes, it is often (though not ALWAYS) unprofessional and counter-productive to use the Auto-Gain. So it should be turned off! But this would not introduce buzz anyway (just possibly enhance existing buzz).
4. A shotgun mike will quite improve your wanted/targeted signal vs. unwanted/ambient signal ratio, but still doesn't give you the CLOSE PERSPECTIVE you should be getting from a properly positioned boom or lav or desk/stand/podium mike. Sounds like you've figured this out also.
Couple of things I noticed in your cam's manual:
It is expecting a STEREO mini plug. And it also mentions "plug & power". Are you using an appropriate Mono-to-Stereo adapter from you mike cable/beachtek? Because, if the supplied power is leaking into the audio channel through mismatched pinouts, this could result in exactly the kind of thing you describe.
Also, everybody's idea of what is considered "buzz" might be different. Could it be you are actually experiencing overload distortion? This would be a DIRECT RESULT of piping a line level output into a mike input. You are right in questioning the practice of doing so without modification in-between. It would NEVER sound correct. However, that is likely the exact reason your aforementioned "expert" recommended the beachtek device: one of it's prime jobs is often to convert line level to mike level (in addition to giving options on jack type, pinout, phase and/or level adjustment).
You don't mention what mixer (model #) you have been using either - maybe it is not set correctly. Has anyone checked it's line out with a compatible device to monitor and see if it is sending a clean signal. One of the prime strategies of troubleshooting is to test EACH LINK in the chain to rule out problems occuring during that link. Swapping out with a "known good" is usually how best to go about this.
Have you tried getting a "Sony-branded Stereo Plug-n-powered" external mike to test? That would be the ultimate way to see if the final link (the external input gain stage) was not faulty.