ATI MX100 User Manual

MX100 MX100C

MX101 XP100

MONO OUTPUT MIXERS

OPERATING AND MAINTENANCE MANUAL

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PURPOSE

The MX101 is a three input miniature mono mixer designed for demanding in-the-field use in broadcast ENG (Electronic News Gathering) and Field Production applications. The MX101 incorporates most of the features requested by news professionals, sports announcers, and film and video sound engineers into a tiny and rugged package.

The MX100 and MX100C Studio Mixers are lower cost, high quality studio mixers for applications, which do not require the full feature complement of the MX101 field mixer. The MX100C adds an output limiter to the basic MX100 features.

The companion XP100 Input Expander provides an additional four switchable microphone /line inputs and can be used with any of the mixers.

The MX101/ MX100/ MX100C Mixers may be used alone or in combination with the XP100 Expander for any application requiring a compact, rugged and professional sounding, mixing or input selection system. Several XP100 Expanders may be added for up to a 23 input system with minimal noise buildup in the mixing network. The MX100 or MX100C alone makes an efficient stereo-to-mono combiner, a simple voice-over PA driver with inputs for noise masking and background music, or simply a very clean and quiet mike or line input mixer

Several power modules for field use are available including both replaceable and rechargeable 24V battery packs, DC/DC converters for 6 to18V automotive or belt pack battery power and plug-in 24VDC wall supplies. An optional rugged Field Pack carry bag includes side protection plates for the mixer with quick-change slide mounts for the battery packs.

DESCRIPTION

MX101 MONO FIELD MIXER

Three XLR INPUTS with phantom power and front panel MIC/LINE switches drive low noise instrumentation preamplifiers with a wide range of internal dip switch selectable preamp gains from 60 to 0dB to accommodate either high or low output microphones and line inputs. Phantom power can be individually Dipswitch selected for each input and is automatically switched off in the line input mode. Front panel switches activate individual LO-CUT FILTERS to reduce bumps, thumps, and wind noise and bass buildup.

A switched TEST TONE oscillator and a SLATE microphone easily mark takes. An intense LED bargraph VU meter monitors the line output and is easily viewed even in bright sunlight. A LIMIT indicator and switch shows peaks and limiter action. The MX101 provides a high-level line output that will drive either balanced or unbalanced external loads of 600 ohms or higher. The XLR output may also be jumper-plug

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programmed for microphone level output. A HEADPHONE switch selects either full program or split program and cue. A recessed, thumbnail operated headphone level control minimizes panel clutter and once set, tracks the MASTER output. A pre-fader cue from input one or an external director’s CUE INPUT from a rear panel jack feed the headphone cue circuit thru an internal trimpot.

An EXPANSION INPUT to the mixing buss allows interconnection of two mixers or the addition of one or more companion XP100 Mic/Line Input Expanders. All panel controls and connectors are clearly labeled.

MX100, MX100C STUDIO MIXERS

Both the MX100 and the MX100C also provide three inputs with front panel selection of microphone or line input levels. Phantom power and input stage gain is dipswitch programmable for any input. Phantom power is disabled in the line input mode. The MASTER level control feeds a high level output stage which comfortably drives either balanced or unbalanced output loads of 600 ohms or greater. A bright LED VU meter and headphone amplifier monitor the program output. The output may be set to line or microphone level by moving an internal jumper plug. The MX100C adds a switched low distortion compressor / limiter and a peak indicating LED to the basic MX100 Mixer. A rear panel Expander input allows interconnection of two mixers or the addition of one or more companion XP100 Input Expanders.

XP100 INPUT EXPANDER

The XP100 Input Expander provides an additional four MIC/LINE switchable inputs and plugs into the Expansion Buss input of the mixer. 24V phantom power is available for each input via internal jumper plug selection. The XP100 inputs provide a fixed 40dB microphone gain and unity (0dB) gain for line inputs. The XP100 is supplied with interconnecting expansion cables for the audio and DC connections to the MX101, MX100 or MX100C.

POWER

A mixer and up to two companion XP100s can comfortably share a single external WA100, 24VDC / 400mA. wall mount AC/DC power supply. A mixer and a single expander can be powered from a DCA100 DC converter or a PPA-1 or 2 rechargeable battery packs.

MOUNTING

Up to three amps will mount side-by-side in only one rack unit high using the available

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rack mounting kits. They may also be neatly stacked or mounted side-by side on your desk with the available angled desk mounting kits. Extra knob caps are provided to allow you to color code the input controls. Yellow, red and green caps are supplied in addition to the gray and blue caps on the units. To replace the caps, gently pry out the old cap and press in the new one.

CIRCUIT DESCRIPTION

INPUT STAGES

The inputs of the MX101, MX100 and MX100C are identical. They are designed around a very low noise and low distortion, balanced and floating input instrumentation amplifier. The SSM2017 is one of the latest generations of devices designed specifically for use as a low noise microphone amplifier. In addition to ultra low noise and distortion, it features a very high slew rate of 17V/µs virtually eliminating slew induced Transient Intermodulation Distortion. The three preamp input stages can be individually set for gains of 20, 40 or 60dB for microphone inputs and 0 or 10dB for line inputs using the internal rocker Dipswitches S11,

S21 and S31, position 2 (ON - 60dB) and position 3 (ON - 40dB) (turn both positions OFF for 20dB) for microphone inputs and position 4 (ON - 10dB, OFF - 0dB) for line inputs. The preamps will have an input clipping level of +18dBu minus the selected gain, e.g. -42dBu input clipping at 60dB gain (8.5mV peak) , -22dBu at 40dB (85mV peak) and -2dBu at 20dB gain (.85V peak). The gain should be set such that the maximum microphone output level is always below the input clipping level. Some shotgun type microphones are designed for very high sensitivity to give them the necessary reach and can easily overload a high gain input when used in a close talking application. Set the preamp mic. gain to the lowest usable level to avoid overload or select a microphone with a built-in, switchable attenuator which you can switch in for close talking use.

The XP100 has a fixed input gain of 40dB for microphone inputs and 0dB (unity gain) for line inputs. The XP100 is best used with normal studio type microphones with peak outputs below -22dBu (85mV peak).

The MX101 incorporates switchable single pole low-cut 125 Hz filters on each input to help block wind noise.

PHANTOM POWER

Phantom power at regulated +20.2VDC through an equivalent 1.66Kohm is supplied to a microphone when the appropriate rocker dip switch (S11, S21, S31 position 1) is selected ON and the MIC/LINE pushbutton is in the MIC position. This voltage level is more than adequate for most (not all) phantom powered microphones even though they may be

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labeled 48V phantom power. Check the microphone specification sheet for 9 to 52V or 12 to 48V ratings (includes almost all electrets type condenser microphones). Those few RF condenser microphones requiring a full 48VDC for phantom power will need an external power source (generally available from the microphone manufacturer).

On the XP100 only, 24VDC phantom power is individually selected for each input with a jumper plug P1, P2, P3 or P4. Moving the jumper plug closest to the P1, P2, P3 or P4 marking selects phantom power for the corresponding XP100 input. Of course, dynamic microphones don’t care if there is phantom power or how much there is of it or whether it’s even turned on or not so long as they are properly wired with their coil across pins 2 and 3 of the XLR connector (shield to pin 1). If they are not wired correctly they may sound real funny with the phantom power turned on (or not at all…maybe ever again).

LEVEL CONTROLS

Each of the three inputs is controlled by its' own audio taper potentiometer. These controls preferably operate in the twelve-to-four o'clock range. If you consistently run the input fader below the ten o’clock position, you should probably reduce the preamp gain setting one step with the internal dipswitches to assure maximum headroom and control resolution. If you have a preferred position for a particular input, you can pop out the knob cap and reposition its' reference indicator line to the twelve o'clock position. A selection of colored knob caps is included with the unit to allow you to color code the inputs.

The Master control adjusts the Line Output as indicated by the LED meter. The Master gains and output stages add 32 dB of additional gain. The Master control should normally operate above the two o'clock position to maximize internal headroom and optimize noise performance.

LINE OUTPUT

The output stage of the mixer, A5, utilizes a unique active balanced output driver IC, the SSM2142, that can sense whether the connected load is balanced and floating or is unbalanced due to either side being grounded. A balanced output load will be driven with equal and antiphase levels on the HI and LO output lines. An unbalanced (one side grounded) load will cause the driver IC to shut off the signal output to the grounded side of the load and double the output level applied to the other side, thus maintaining equal output to either type of load. The output stage will drive loads of 600 ohms and higher. Nominal output is +4dBm with clipping at +22dBm into balanced loads. Maximum output at clipping is reduced by 6dB when driving an unbalanced load, since the full output swing of only one driver is available. A jumper plug, P1 located just behind the output XLR connector selects either +4dBm line level or -50dBm microphone level output.

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