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CCRMA Seminar Room

The CCRMA Seminar Room (Knoll 315) is a small room with a large conference table, ideal for small classes and meetings or short projects requiring lots of surface area.


Photo of the Seminar Room showing the conference table, chairs, Linux machine, cookie jar, audio mixer, document camera, and Kramer rack.

In this room you should see:

Audiovisual Selection

Use the Kramer system to plug in and choose one video source.

Use the mixer to mix the audio (including stereo from the selected HDMI source).

The Kramer VP-551x HDMI switcher and some of its input sockets.

Audio System

We now hear the mix of a few audio sources via a K-Mix Blue digital mixer:

The first two mixer channels are currently reserved for future microphone inputs, or live signals from the Stage.
Whatever stereo audio the selected HDMI source may contain.
Stereo sound, in analog, from the Linux machine’s connected Tascam audio interface (affected by the Tascam’s LINE OUT 1-2 and MONITOR BALANCE volume knobs)
From the dangling stereo audio cable with a 1/8 inch (aka 3.5mm) TRS unbalanced analog stereo connector, meant to plug into the headphone jack of a laptop, phone, etc.).

Operating the K-Mix

We use only a fraction of the capabilities of the K-Mix; this diagram shows which parts of the user interface we do and don’t use in the Seminar Room:

Labeled K-Mix front panel. We ignore most of the interface’s buttons. The power switch and A/Main buttons should be lit. The lower-left VU button toggles whether the visual metering for the 8 channels and overall mix will show the virtual fader levels (how much each track is turned up in the mix) versus being VU meters that display in real time the changing volume of the source material.

Each of the mixer’s 9 faders is touch-sensitive; just rub your finger up and down to control volume.

Channel trims have been adjusted so that a computer’s 0 dB just barely doesn’t clip and is approximately identical in loudness when switching between HDMI and headphone jack (at least on one particular laptop).

The HDMI, Linux, and Analog inputs are “paired into stereo channels”; adjusting either (left or right) volume will always control both equally.

Each fader is also a 12-segment LED display. The VU button in the lower left corner toggles between the two modes of what these meters display:

We recommend VU on, because it lets you see visually which mixer channels correspond to the sound you’re currently hearing, so you know which faders will adjust the volume.

K-Mix in VU mode: note the lit blue VU button in the lower left and that all the meters are displaying zero (showing that all mixer inputs are currently silent)
K-Mix not in VU mode: note the unlit VU button in the lower left. We see from the meters that the HDMI, Linux, and Analog inputs are at 0dB (barely “touching” the red) and that the Overall output volume is a bit lower.

This page of CCRMA documentation last committed on Mon May 15 10:57:07 2023 -0700 by Matthew James Wright.