Antex electronic DMX-4 user manual General description

DMX-4 USB Mixer User Manual

General description:

The DMX-4 is a 4 channel microphone preamplifier with

4analog to digital converters (A/D). The DMX-4 connects to a PC via a USB 2.0 connection so that audio can be recorded onto the PC’s hard drive. There are 2 configurable monitor outputs, which can be independently set to be a mix of any combination of the

4input channels. The monitor outputs can be used to connect to a PA system or for video/teleconferencing.

All level adjustments are solid state; there are no mechanical knobs on the unit. Level adjustments are made by moving virtual slider controls in the Antex Mixer Program running on the PC. This allows for settings to be stored and retrieved as a “scene”. Also, if the PC connected to the DMX-4 is connected to a LAN, adjustments can be made from a remote computer somewhere on the LAN.

The microphone inputs are professional balanced XLR connectors. The differential input impedance is 2K. Phantom power of +14 volts can be turned on under control of the Antex Mixer Program. Phantom power is connected through a 1K resistor on each line. In “microphone” setting, all 4 inputs have a gain range of +10dB to +85dB. Note that 65dB of gain is done in the analog circuitry, and the additional 20dB is done in the digital domain. As you increase the gain on any input, the level of this audio will get louder in the monitor output and in the recording level. However, once you exceed 65dB, the recording level will continue to increase, but the audio in the monitor output will not increase any further. Input channels 1 and 2 have a

DMX-4 USB Mixer User Manual

fixed gain of 0dB in “line” setting. Inputs 3 and 4 have an adjustable gain of –8 to +31.5dB in “line” setting. (Although the circuitry is capable of a lower gain setting than –8dB, the setting is limited in the Antex Mixer Program to –8dB so that it is not possible for the analog circuitry to go into clipping before the A/D.)

The monitor outputs are single ended RCA jacks, capable of a 2VRMS signal (+6dBV). The level adjustment range is from –102dB to +25.5dB. The output has a 560 ohm internal series resistance to protect it from short circuits to ground. The equipment that the monitor output is connected to should have an input impedance of 2K or greater.

The A/D converter sample rate can be set to 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, or 48KHz. This allows for optimization between file size and audio fidelity. All 4 inputs are digitized separately, and 4 tracks may be recorded to hard disk. The inputs may be mixed in any combination to the 4 record channels using the Antex Mixer Program. On your PC, the 4 record channels are accessed as 2 stereo Wave Devices. Record channels 1 and 2 are left and right of Wave Device 1, respectively, and record channels 3 and 4 are left and right of Wave Device 2.

Power input to the DMX-4 can be from +5 to +15 VDC. Power consumption is about 5 watts. The unit is supplied with a 9V international wall adapter, but can also be powered by battery packs or from an automobile accessory plug (“cigarette lighter”). The power indicator LED changes gradually from green at 12 volts to red at 5 volts so the user can note a color shift on battery power when the battery gets low.

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