HMS Audio Tutorial

HMS Audio System Tutorial

This tutorial describes the common usage of the audio system (part of the video editing system) at HMS. The main control of the audio system is located on the rack next to the UMatic and VHS player/recorder. The mixer system is labeled as 'ALESIS Studio 12R'. The patch bay is located right below the mixer, and labeled as patch bay.

Layout

Patch Bay (Left Half)

o/p of individual systems

i/p to mixer

  9800     VHS    9850    -  Mic  Octane  Midi
  o   o   o   o   o   o   o   o   o   o   o   o
  1   2   3   4   5   6   7   8   9   10  11  12
  o   o   o   o   o   o   o   o   o   o   o   o
  9800     VHS    9850    -  Mic  Octane  Midi

Top row [1-12] is output of individual systems. So connecting cable to one of these jacks is equivalent to connecting cables to the audio-out of the individual systems (on their back panels). Bottom row [1-12] is input to the mixer. By default, the output of individual system automatically flows down to mixer inputs. So, for example, consider this.

  9800
  o   o ...
  1   2 ...
  o   o ...
  9800

Now, if nothing is connected to bottom set, then output of 9800 automatically flows down internally to bottom row, i.e. now 9800 is automatically connected to mixer input [1-2] without any external cables. However, if we were to connect cables from other devices to mixer input [1-2], then, the mixer no longer gets input from 9800, but gets it from external device.

Patch Bay (Right Half)

o/p of mixer [13-14]

i/p of individual systems

  Mixer
  o   o   o   o   o   o   o   o   o   o   o   o
  13  14  15  16  17  18  19  20  21  22  23  24
  o   o   o   o   o   o   o   o   o   o   o   o
  9800     VHS    9850    Octane  -   -    Amp

In the top row, only 13 & 14 are used as mixer output. Connecting cables to these two jacks is equivalent to getting output from the mixer. Jacks in the bottom row are input to the individual systems. For instance, connecting cables from 13 & 14 [top] to 15 & 16 [bottom] is sending mixer output to VHS. This audio signal can be recorded in VHS. Unlike the first 12 sets of jacks, those jacks [13-24] don't flow signals down automatically, i.e. when there is no cable between 13 & 14 [top] to 13 & 14 [bottom], 9800 will not get the mixer output automatically.

Mixer Control

Each channel of the mixer can be controlled separately as follows.

Trim Knobs (Red):: Pre-amplifier. We use this knob to control the balance of the input signal so that all the input signals to the mixer is almost the same level.
Two Band Equalizers (Green):: Emphasizes or cuts certain frequencies of the sound. (80 Hz is input cut off). If sound is boomy or muffled, then cut off low. Pull low down if using microphone. Dropping high reduces hiss in sounds.
Auxiliary out (blue):: Not hooked up.
Stereo balance (black):: Balance for stereo. Changes the balance of audio signal to go left and right (13 & 14 of output [top row] of the patch bay).
Volume Sliders:: When recording sounds from the system corresponding to the channel, pull up the sliders (usually both the one correspond to left and the one correspond to right at the same time) to 0dB. All other channels should have this slider set to the bottom.

In presence of sound, if LEDs at the upper right corner of mixer don't light up to even half, try adjust the "Trim" and leave volume sliders as is.

To Listen to Audio

Listening to 9800:

Unplug all the cables from the patch bay. Bring slider of channel 1 & 2 up to 0dB. Keep sliders of all other channels to the bottom.

1	2	3	4	5	6	7	8	9 & 10	11 & 12

Press play button of 9800. Observe that when there is audio signal from the tape, the LEDs at the upper right corner of the mixer panel flash. When there is audio signal, slowly adjust the trim knob of channel 1 & 2 to the the best audio level.

Listening to VHS:

Unplug all the cables from the patch bay. Bring slider of channel 3 & 4 up to 0dB. Keep sliders of all other channels to the bottom.

1	2	3	4	5	6	7	8	9 & 10	11 & 12

Press play button of VHS. Observe that when there is audio signal from the tape, the LEDs at the upper right corner of the mixer panel flash. When there is audio signal, slowly adjust the trim knob of channel 3 & 4 to the the best audio level.

Listening to 9850:

Unplug all the cables from the patch bay. Bring slider of channel 5 & 6 up to 0dB. Keep sliders of all other channels to the bottom.

1	2	3	4	5	6	7	8	9 & 10	11 & 12

Press play button of 9850. Observe that when there is audio signal from the tape, the LEDs at the upper right corner of the mixer panel flash. When there is audio signal, slowly adjust the trim knob of channel 5 & 6 to the the best audio level.

Using Headphone:

Before playing any sound, turn the speaker off by pushing the speaker power button (bottom of the mixer). Plug headphone to the headphone jack. Play the audio source device and adjust the audio level. Turn the speaker back on when done.

Monitor Recording:

When monitoring audio copy / video recording, trim knob should not be used to adjust the monitor audio level. Use phone / monitor knob to adjust monitor audio level in this case.

How to Record

When copying audio:

Connect patch bay cable from 13 & 14 (mixer out) to input (bottom row) corresponding to the recording device, e.g. 15 & 16 (VHS). Slide up the slider corresponding to the source device, e.g. 13 & 14 (9800). Adjust the sound level by checking the LEDs at upper right corner of the mixer and controlling the trim knobs. Also check the destination device to see if the audio signals are in the right level (all three video player/recorders have input signal meter). Make sure the audio recording (both left and right) of the destination device is set to on.

When copying from multiple sources:

Connect patch bay cable from 13 & 14 (mixer out) to input (bottom row) corresponding to the recording device, e.g. 17 & 18 (9850). Slide up the slider corresponding to the source devices, e.g. 1 through 4 (9800 and VHS). The mixer panel should look like this.

1	2	3	4	5	6	7	8	9 & 10	11 & 12

Adjust the sound level by checking the LEDs at the upper right corner of mixer panel and controlling the trim knobs (of channel 1 through 4). Also check the destination device (e.g. 9850) to see if the audio signals are in the right level.

To record into octane:

Connect patch bay cable into 19 & 20 bottom (from 13 & 14). Slide up the corresponding sliders of the mixer.

Quick dubs (by bypassing mixer):

Connect directly from output of one system to input of the second system. This can be done by connecting the patch bay cable from e.g. 1 & 2 9800 into 15, 16 (VCR2).

Listen only to the audio (bypassing the mixer):

Connect e.g. 3 & 4 (VCR) output to 23 & 24 input (amplifier).

Warnings

Don't connect input cable to e.g. VHS and increase volume slider of VHS. This will result in hiss (since this will make a look-back of the sound signal).
After finishing your work, leave the speaker on if you turned it off.
Control the speaker output using the phones / monitor knob (right side of the mixer panel).
Keep the master slide (the slide not associated with any channels and located at the right side of mixer panel) should stay at 0dB all the time. No need to change this.