Audio Setup

The audio mixer box controls all the audio in the system. It has two stereo inputs: the main input is controlled by the editor switch. The secondary input is directly from the laserdisc player.

The master volume control (the blue knob) controls output audio level, which is sent both to the speakers and to the audio inputs of all the other components.

Audio Inputs

The four black knobs control the input to the mixer. When an individual knob is pushed in, its input is connected through to the output. When it is pulled out, it is not connected to the output but it is connected to the mixer's headphone jack. Rotating the knobs controls the relative volume of each input source. The pan knobs should always be set all the way to the left for left audio inputs and all the way to the right for the right audio inputs.

The first two knobs control the left and right stereo inputs coming from the editor switch, the second two control the left and right stereo inputs coming directly from the laserdisc player. Normally the editor switch knobs should be in (i.e. connected), the laserdisc knobs should be out (i.e. disconnected), and the volume should be set to 10 on all knobs. Use the blue master control knob to change the overall volume.

If you have already dubbed a voiceover onto a tape and want to add music from a CD, you will then want to use the laserdisc inputs as well as the editor switch inputs. Then adjust the individual volume control knobs until the voice and music channels have the right relative volume.

Recording a voiceover on your tape

Executive Summary

Ambient noise

The video room should be as quiet as possible when you record a voiceover on the tape, otherwise all the background noise is also recorded which sounds quite tacky. Turn off the power on the Lyon-Lamb scan converter (rightmost rack column, bottom (under the table!), power switch on front) and the NTSC encoder (leftmost column, under the table, power switch in back). These devices have loud internal fans.

Important! The ventilation system for the video room is quite loud, so you want to turn it off while making the voiceover. You also want to shut the door. However, if the video room is unventilated for too long the decks start to eat tapes. (Technically, if humidity in the room gets too high, moisture condenses on the tape heads, which causes the tape to stick to them instead of smoothly rolling past. The air conditioning for the building is also a dehumidifying system.) The ventilation system can take several minutes to turn off or on. But the door is trivial to open and shut. So when you're actually recording, have the door shut. When you're playing back to see how it turned out, or thinking about what to say next, open the door! Monitor the temperature in the room. If it feels really hot or the thermometer goes above 72 degrees consider cooling the room down before continuing. Do not forget to turn the air conditioning system back on when you are done audio recording! (Turn the knob to -4, which is maximum cooling.)

Microphone

A simple way to put a voiceover onto your tape is to use the audio dub functionality of the play 3/4" deck. (The one on the left, not the usual one you use for recording on the right!) The audio DUB/CH-1 button allows you to record your voice into audio channel 1 without disturbing the video track. Plug the microphone into the CH-1 microphone input in the lower left corner of the deck. (The microphone is usually stored in the cabinet along the left wall, with the proper cord plug into the deck. It's got a 3-pin audio jack on the end that connects with the microphone and a "phono" type jack on the end that plugs into the deck.) When you hit the button, you're recording audio. The tape does not preroll, it starts from right where you are. The CH-1 AUDIO LEVEL knob controls the volume level that you record at. I've had good results around 3 or 4, your milage may vary. The needle on the gauge above the knob can go into the red zone on the right occasionally, but should never "peg out" on the extreme right side. Whenever it does so the recorded voice is disorted. It's easy to incrementally record your narration, but it's hard to go back and fix a mistake in the middle of things. I highly recommend that you check after every edit to make sure that everything sounds right before going on. (Note that the audio meter only works when you're actually recording or the deck is at a full stop. It will not work when you're in pause mode.) Also remember that when you're recording the speakers must be turned all the way down or else you'll have feedback problems.

The complicated way to use the microphone is useful if you need to do insert audio editing: that is, go back and fix something up in the middle of a track. You use the the editing board to control exactly where you want to record the signal. Plug the microphone into audio input 4 in back of the audio mixer. Turn the pan knob to the middle. Turn the editor switch knobs (the two leftmost ones) all the way down to 0. You'll need to fiddle with many different knobs: the "microphone" knob (presumably audio input 4) and the blue master knob on the audio mixer, and the audio level knobs on the 3/4" record deck. I've had good results with

Your milage may vary, always check the tape after recording a little bit to make sure it's both undistorted and loud enough. Make sure the speakers are turned all the way down when you're actually recording to avoid echo. Remember you'll have to turn them back up when checking the sound levels.

Tone

If you are making a videotape with an audio track, it's nice to put 1 KHz tone on top of colorbars at the beginning of each segment. (Then anyone who later might need to copy your tape onto a compilation can easily set the audio levels.) To do this, set the Oscillator switch to On. If you've set the editor switch to colorbars then the main audio input should be empty, but you might have to turn off the laserdisc inputs (i.e. pull the rightmost two knobs out). Polite video rack users will set the Oscillator switch back to Off when finished.

Tamara Munzner & Phil Lacroute/Jan 5, 1996

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Last modified: Wed May 29 20:13:18 1996