M404A — Hi/Lo Pass Filter

FEATURES: The M4OAA Hi-Lo Filter is a plug-in, high performance module designed to be compatible with the Ward-Beck group of modular console components: Individual controls provide ten cut-off frequencies for the high and low frequency spectrum: The rate of attenuation is 18dB/octave_ Active circuitry uses operational amplifiers introduces no loss. 1OLF cut and 1OHF cut positions at 18dB/octave Low frequency cut (high-pass) is effective at the following 3dB points: 70Hz , 1OOHz , 150Hz , 250Hz,500Hz, 1kHz, 2kHz, 3kHz, 4kHz, and 5kHz_ Solid-state audio switch rapidly inserts/removes filter circuit in transient-free mode High frequency cut (low-pass) is effective at the following 3dB points: 5O0Hz , 1kHz , 2kHz, 3kHz, 4kHz, SkHz, 6kHz , 8kHz , 1OkHz , and 12kHz.

Panel status lamp indicates filter operation A mode selector provides a third rotary control function which permits the use of the Hi only, Lo only or simultaneous Hi-Lo circuits to achieve a pass-band effect. The transient-free controls may be pre-set or operated directly during program transmission: A unique solid-state audio switch rapidly inserts or removes the filter elements from the system program path.

Balanced circuit design The M4OAA utilizes operational amplifiers and is entirely balanced and lossless. The active circuit operates with 38dB gain to enhance the flexibility of this unit as a filter /mix-amplifier within a console system: The use of a simple external resistive network adapts the M4OAA for unity gain operation. Low profile, compact design , mounts directly on console panel in-line with mixing attenuator

FEATURES: The M4OAA Hi-Lo Filter is a plug in, high performance module designed to be compatible with the Ward-Beck group of modular console components_ Individual controls provide ten cut-off frequencies for the high and low frequency spectrum: The rate of attenuation is 18dB/octave. Active circuitry uses operational amplifiers introduces no loss_ 1OLF cut and 1OHF cut positions at 18dB/octave Low frequency cut (high-pass) is effective at the following 3dB points: 70Hz, 1OOHz , 150Hz , 250Hz,500Hz, 1kHz, 2kHz, 3kHz, 4kHz, and SkHz.

Solid-state audio switch rapidly inserts/removes filter circuit in transient-free mode High frequency cut (low-pass) is effective at the following 3dB points: 500Hz , 1kHz , 2kHz, 3kHz, 4kHz , SkHz, 6kHz, 8kHz , 1OkHz, and 12kHz _ Panel status lamp indicates filter operation A mode selector provides a third rotary control function which permits the use of the Hi only, Lo only or simultaneous Hi-Lo circuits to achieve a pass-band effect_ The transient-free controls may be pre-set or operated directly during program transmission.

A unique solid-state audio switch rapidly inserts or removes the filter elements from the system program path. Balanced circuit design The M4OAA utilizes operational amplifiers and is entirely balanced and lossless The active circuit operates with 38dB gain to enhance the flexibility of this unit as a filter Imix-amplifier within a console system_ The use of a simple external resistive network adapts the M4OAA for unity gain operation_ Low profile, compact design_ mounts directly on console panel in-line with mixing attenuator

FEATURES: The MAO4A Hi-Lo Filtet Is a nlug-in; high performance module designedd b8 compatible with the Ward Beck group modular console components: Individual controls provide cuf-off frequencics for the high and Iow frequetev spec[cur, Therate altenualion 1BdB/actave: Activa circuitfy HS pperational amplifiers introduces no lass; 1OLF cut and IOHF cut positions 18dB{octave Lot frequency cut (high-pass) etfective at the following 3dB points: Z0Hz, |OOHz 1SOHz , 250Hz, 5OOHz , IkHZ, 2kHz, 3kHz, 4kHz , and SkHz: Solid state audio switch rapidly inserts/removes filter circuit aFansient-tree mode High frequancv cut (Iow-mxass] effeclive al the following JaB points; SCOHZ, IkHZ; 2kHZ, 3kHz; AkHz, SkHZ, GkHZ, BAHz, IOkHZ; &nd 12kHz.

Pariel stalus latp) indicates filter operation mode selector provides third rotary control function which nermits the USE of the HI only Lo only or simultaneous Hi-Lo circuits achiave pass-band effect The transient-free controls may pre %1 opurated direcily during program transmission; unicue solid-state audio switch rapidly inserts Or removes the filter elements from the systen pregram path: Balanced circuit design The M4OAA utilizes operational amplifiers nid entiraly balanced and lossle55 The active circuit operates wiIm 384B gain enhance flexibility this unit #ilter {rix-Ariplifier within coiola system: Tne Use of simple eXIATAl resistive [lelwor adapts tha M4O4A for unity gain operation; Law prafile, compact design, FICUFIS direcily on console pane in-line with mixing atienualol;

MATCHED GAIN 38dB FREQUENCY RESPONSE + 0.SdB from 20Hz to 20kHz (effects controls at zero position) EQUIVALENT INPUT NOISE C115dBm 1OHz to 1O0kHz bandwidth) HARMONIC DISTORTION Less than 0.5% from 3OHz to 20kHz (measured at 18dBm output level) SOURCE IMPEDANCE 150/600 ohms balanced or unbalanced INPUT IMPEDANCE 50/600 ohms + 10% INPUT LEVEL ~38dBm nominal, ~2OdBm maximum LOAD IMPEDANCE 600 ohms OUTPUT IMPEDANCE 600 ohms 150 ohms available) + 10% OUTPUT LEVEL 18dBm maximum PHASING The low terminal number of the input pair and the low terminal number of the output pair are in phase_ EQUALIZING CHARACTERISTICS In accordance with specified curves within + 0.5dB POWER REQUIREMENTS 48 volts dc, regulated from M648 or equivalent 1OOmA AMBIENT TEMPERATURE 0?

to 60'c DIMENSIONS 1.58W 6.625L x 6D (depth below panel) inches WEIGHT 1l Ibs. Net ACCESSORIES: WARD-BECK SYSTEMS INC WARD-BECK SYSTEMS LTD; 290 Larkin St; Buffalo, New York 14210 841 Progress Ave; Scarborough, Ont M1H 2x4 (416) 438-655O Telex: 06-23469 Telephone: WBS

MATCHED GAIN 38dB FREQUENCY RESPONSE t 0.5dB from ZOHz to 20kHz (effects controls at zero position) EQUIVALENT INPUT NOISE -115dBm (1OHz to 1OOkHz bandwidth) HARMONIC DISTORTION Less than 0.5% from 3OHz to 20kHz (measured at 18dBm output level) SOURCE IMPEDANCE 150/600 ohms balanced or unbalanced INPUT IMPEDANCE 150/600 ohms 10% INPUT LEVEL ~38dBm nominal, ~2OdBm maximum LOAD IMPEDANCE 600 ohms OUTPUT IMPEDANCE 600 ohms 150 ohms available) + 10% OUTPUT LEVEL 18dBm maximum PHASING The low terminal number f the input pair and the low terminal number of the output pair are in phase EQUALIZING CHARACTERISTICS In accordance with specified curves within + 0.5dB POWER REQUIREMENTS 48 volts dc, regulated from M648 or equivalent 1OOmA AMBIENT TEMPERATURE 0" to 60'c DIMENSIONS 1.58W x 6.625L x 6D (depth below panel) inches WEIGHT 1h Ibs_ Net ACCESSORIES: WARD-BECK SYSTEMS LTD_ WARD-BECK SYSTEMS INC_ 841 Progress Ave,Scarborough,Ont_ MH 2x4 290 Larkin St; Buffalo, New York 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS

MATCHED GAIN 38dB FREQUENCY RESPONSE t0.5dB from 20Hz to 20kHz (effects controls at zero position) EQUIVALENT INPUT NOISE ~115dBm ( 1OHz to 1OOkHz bandwidth) HARMONIC DISTORTION Less than 0.5% from 3OHz to 20kHz (measured at 18dBm output level) SOURCE IMPEDANCE 150/600 ohms balanced or unbalanced INPUT IMPEDANCE 50/600 ohms 10% INPUT LEVEL -38dBm nominal, ~2OdBm maximum LOAD IMPEDANCE 600 ohms OUTPUT IMPEDANCE 600 ohms 150 ohms available) t 10% OUTPUT LEVEL 18dBm maximum PHASING The low terminal number of the input pair and the low terminal number of the output pair are in phase EQUALIZING CHARACTERISTICS In accordance with specified curves within + 0.5dB POWER REQUIREMENTS 48 volts dc, regulated from M648 or equivalent 1OOmA AMBIENT TEMPERATURE 0" to 60'c DIMENSIONS 1.58W x 6.625L 6D (depth below panel) inches WEIGHT 1h Ibs_ Net ACCESSORIES: WARD-BECK SYSTEMS LTD_ WARD-BECK SYSTEMS INC_ 841 Progress Ave,Scarborough,Ont_ MH 2x4 290 Larkin St;, Buffalo, New York 14210 Telephone: (416) 438-6550 Telex: 06-23469 WBS

The M404A is designed to mount directly on mixing console front panel- The dimensions are such that the unit may be mounted in line with standard straight line mixing attenuator associated with each mixing channel cutout 1.56w 6L and two tapped holes will be required as shown in drawing 404-04-010 _ The escutcheon of the M404A will overlap the cutout and holes External connections are made to the 22 Pin PC connector in accordance with drawing 402-02-011 For optimum results, use insulated, shielded twisted pairs for both input and output wiring Dress al1 audio cables apart from ac and power supply wiring Ground shields at one end only and use separate ground return wire to the system common ground for the power supply and shields as shown in the System Wiring Diagram B402-02-012 The metal frame of the M4O4A equalizer should be bonded to the system ground_ In this case it is permissible to loop through each unit with common ground wire connected via pin 19 When used in systen, such as an audio mixing console, the M4O4A equalizer should be operated from separate power supply than the ones used to provide dc power to program amplifiers cue amplifiers or other similar units operating at high output levels The latter units produce large current swings and the possibility of instabilitya noise or crosstalk should be avoided in systems which combine high gain and wide-band amplifiers CIRCUIT_DESCRIPTION Refer to schematic diagram B404-02-0l0 _ The M404A has three main active circuit sections low noise preamplifier, equalizer networks and output amplifier The equalizer section, resistor- capacitor networks and FET isolation amplifiers, has unity gain and is switched in and out between the pre-amplifier and output amplifier via pushbutton SW4 -4

The M404A has four operating controls These transient-free controls may be pre-set or adjusted during the operation of the unit_ The selectable frequencies associated with the HF and LF cut controls may be used independently or cumulatively to achieve multiple or combined effects_ depending on the position of the HI-LO/LO-Lo selector switch (SW2 ) HF CUT X 1K control SW1 ) This control produces rapid roll-off commencing at the high frequency audio spectru to achieve low-pass filter characteristics The frequency designations indicated on the photo-etched escutcheon Inust be converted X 1K (10oo) to correspond t0 the operating frequency The nomenclature applies to the ~3dB point on the attenuation curve E.G 12-12,000 Hz , 5=5,00O Hz and 5=500 Hz , etc.

In the OFF position the equalizer exhibits flat frequency response characteristics within 0.5dB to 2OkHz _ 6

The M4O4A is designed for dependable, trouble-free service; however, as with all high quality electronic equipment, regular schedule of inspection should be established_ Any accumulation of dust should be periodically removed with soft brush and vacuum hose = -7