Re: VHS sound


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Posted by Rick Denney on October 23, 2002 at 10:47:42:

In Reply to: VHS sound posted by Alex on October 22, 2002 at 20:21:52:

Joe is right, but it goes even beyond what he says. Here are the likely culprits:

1. Camcorder microphones are optimized for voice, and have very poor frequency response in the low register, and poor sound pressure level capabilities. Thus, they don't record low, loud sounds very well.

2. Automatic volume control. This is probably your worst culprit. The camcorder diligently levels out all your efforts at dynamic control. When you play loudly, the loudness is masked, but any edge in your sound during loud playing comes through. Thus, all you get is the difference in tone color, without the corresponding difference in volume. This is also called gain-riding, and it's good for making radio and TV stations that do voice and pop music sound loud over the air, and for keeping daddy from accidently setting the levels wrong when recording baby's first birthday party, but it's death to classical music.

3. Poor microphone placement. A camcorder located to see what needs to be seen isn't usually in the best place to hear what needs to be heard. Most TV camera operators use clip-on microphones, or hand-held microphones held close to the source, rather than camera-mounted microphones. You can tell when they don't do this--the sound is crappy.

But the audio capabilities of Hi-Fi video are actually excellent. Hi-Fi VHS uses depth multiplexing to record the sound in very high bandwidth along with the video signal, rather than in separate linear tracks with much less bandwidth.

I used to do quite a few field recordings of musical groups using two microphones, a mixer and a Hi-Fi VCR, just as Joe suggests. I turned off the automatic volume control (an absolute requirement), and set the levels so that the loudest passages are a little above 0 dB on the record-level indicators. Thus, you need a camcorder that has the capability to turn off the automatic volume control and also some indication and adjustment of record levels (or a mixer that does so). You also need microphones that can take the sound pressure level of your instrument (or group) without breaking up.

Nowadays, I record on a mini-disc recorder using an Audio-Technika AT-822 stereo microphone and no mixer, with results even better than the Hi-Fi video. You don't, of course, get pictures with that.

Rick "who thinks consumer camcorder are designed for baby birthday parties" Denney


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