ART 442 EQ & 452 EQ Graphic Equalizer User's Guide

Equalizer Overview – Features and General Information

Model 442 Two Channel 15 Band 2/3 Octave Precision Graphic Equalizer

The Model 442 features constant Q circuitry with a 3% center frequency accuracy. Special features include 60MM full range precision Sliders, LED metering, selectable range 6dB or 12dB, active balanced and unbalanced input/output connectors, RFI filters, variable input level control, passive bypass switch, clip level indicators, ground lift switch, and selectable line voltage switch.

Model 452 Single Channel 31 Band 1/3 Octave Precision Graphic Equalizer

The Model 452 features constant Q circuitry with a 3% center frequency accuracy. Special features include 60MM full range precision Sliders, LED metering, selectable range 6dB or 12dB, active balanced and unbalanced input/output connectors, and RFI filters. The unit also has variable Hi Pass (low cut) and Low Pass (high cut) filters, variable input level control, passive bypass switch, clip level indicator, a ground lift switch, and selectable line voltage switch.

Installation

The Model 442 and 452 Equalizers are designed for mounting in a standard 19" equipment rack or one of the many rack type portable cases available on the market. The vertical measurements are 3.2 inches. Both models are 8.5 inches in depth.

Power Connectors

The Model 442 and 452 Equalizers have internal power supplies and are designed for operation from 120-240 volt, 50-60Hz mains supply. Power consumption is 12 watts. In new installations and portable sound systems, or any situation in which the mains power is in question, it is wise to confirm the voltage and select the appropriate line voltage switch BEFORE connecting the equalizer to power sources.

Input/Output Connections

The Model 442 and 452 Equalizers have three paralleled input and output connectors. XLR and 1/4" TRS are actively balanced with pin 2 or the tip being Hi (Hot), Pin 3 or the ring being Lo, and Pin 1 or sleeve being ground. Unbalanced operation requires using the RCA phono connector or use Pin 2 of the XLR or tip 1/4" TRS as ground.

Balanced output requires using Pin 2 of the XLR or the tip of the 1/4" TRS as output Hi (+) and using pin 3 of the XLR or the ring of the 1/4" TRS as Lo (-). It does not require pin 1 or signal ground. The signal exists differentially between the two balanced leads. Ground is used only for shielding to prevent potential hum. Paralleling inputs and outputs may be accomplished by using any of the three connectors. Note: 1/4" TRS are normally used.

Signal Levels

Signal levels from -10 dBu to +4 dBu are considered normal and 20dB of headroom exists above these levels. Do not connect microphones directly to the equalizer. Microphones require a preamp.

Chassis Grounding

The Model 442 and 452 Equalizers are equipped with a rear panel Ground Lift switch. After setting up your system, if the system exhibits excessive hum or buzzing, the problem may be a ground incompatibility between your equalizer and other equipment in the same system. There are several combinations that can be attempted. NOTE: ALWAYS TURN YOUR AMPLIFIERS DOWN BEFORE CHANGING GROUNDS. Try different combinations of lifting grounds on units that are supplied with ground lift switches or make sure all chassis are connected to earth ground, either through the AC Power cord ground or by the front panel rack mount screws.

Operating Instructions

Before starting to equalize your sound system there is some information you should know and procedures you should follow. Your equalizer is equipped with a bypass switch. The bypass switch, when activated, lights the LED and cancels all equalization settings while allowing signal to flow through the unit at unity gain.

Also included is a range selection switch with LED indicators, 6dB =green, 12dB= yellow. In addition to the range selection switch there is a level control potentiometer. The level control operates between off and +6dB. Note: If there is too much gain your equalizer has a red LED Clip indicator. The Clip LED illuminates when signals reach 5dB prior to clipping. If this situation occurs and the overload LED flashes occasionally, this is okay. However, if the overload LED is steadily on, you must readjust the level control.

Initial Setup Tips

1. Set channel levels to the center detent 0dB on the front panel.
2. Bypass the equalizer (Note: Select the bypass switch and press - the red LED is on).
3. Set the frequency slide controls to the center detent or 0dB.
4. Select the 6dB range switch (green LED on).
5. Apply signal to the system.
6. Release the bypass switch, red LED off.
7. If the Clip LED is on you must turn down the input level control.
8. You may now start equalizing your system.
9. If you do not have enough gain for your needs, switch the range switch to the 12dB setting.
10. If the Clip LED lights continuously, turn down the level control until the LED is off most of the time.

Front Panel Controls

Dual 15 Band Graphic Equalizer (Model 442)

The front panel displays two identical channels. Each channel features 15 vertical sliders for frequency adjustment, labeled from 25Hz to 16kHz. Above the sliders are input level indicators and controls. Each channel has a POWER button, an EQ OUTPUT MONITOR section with a LEVEL control, a Range/Bypass switch with associated LED indicators (green for 6dB, yellow for 12dB, red for bypass), and CLIP indicators. The ART logo and "APPLIED RESEARCH AND TECHNOLOGY" are prominently displayed.

31 Band Graphic Equalizer (Model 452)

The front panel features a single bank of 31 vertical sliders for frequency adjustment, labeled from 20Hz to 20kHz. It includes a POWER button, EQ OUTPUT MONITOR section with a LEVEL control, a Range/Bypass switch with LED indicators, a CLIP indicator, a HI PASS FILTER control (labeled 40Hz), and a LOW PASS FILTER control (labeled 10K). The ART logo and "APPLIED RESEARCH AND TECHNOLOGY" are also present.

1. POWER SWITCH: A push-button switch, likely with upper and lower portions for ON/OFF. Caution is advised to turn the equalizer ON before amplifiers and OFF after amplifiers.
2. FILTER LEVEL CONTROLS: These are the 15 or 31 sliders, each controlling the output level of its respective bandpass filter. The center detent is noted for flat response.
3. FILTER RANGE SWITCH & INDICATORS: A switch (likely shared per channel or globally) that selects the boost/cut range of the sliders between +/- 6dB (green LED) and +/- 12dB (yellow LED).
4. BYPASS SWITCH & INDICATOR: A switch that, when activated (red LED illuminated), bypasses all equalization circuitry, routing the signal directly from input to output at unity gain.
5. OVERLOAD INDICATOR: A red LED that illuminates when any equalizer section is within 5dB of clipping. Occasional flickering is acceptable, but steady illumination indicates a need to reduce level.
6. HI PASS FILTER (LOW-CUT FREQUENCY CONTROL): A rotary control to adjust the roll-off frequency for unwanted low frequencies, adjustable from 10Hz to 250Hz.
7. LOW PASS FILTER (HIGH-CUT FREQUENCY CONTROL): A rotary control to adjust the roll-off frequency for unwanted high frequencies, adjustable from 3kHz to 40kHz.
8. LEVEL CONTROL: A rotary control for adjusting the input signal level. Turning it to the center detent sets unity gain.
9. LED Metering: An LED array meter on each channel showing the output level, used for setting proper levels to subsequent equipment.

Rear Panel Connectors & Controls

Dual 15 Band Graphic Equalizer (Model 442)

The rear panel features various connectors and controls for system integration.

31 Band Graphic Equalizer (Model 452)

The rear panel features various connectors and controls for system integration.

1. POWER CORD: A captive, three-pin polarized AC power cord for connecting to the mains supply. The center grounding pin should not be removed.
2. FUSE HOLDER: Houses the AC primary fuse. Specific fuse ratings are mentioned: 0.6Amp for 100-103VAC and 220-240VAC.
3. AC VOLTAGE SELECTOR: A slide switch to match the unit to the local line voltage supply (95-130VAC or 190-250VAC).
4. GROUND LIFT SWITCH: A switch to disconnect the signal ground from mains and chassis earth ground, used to resolve hum caused by ground loops.
5. INPUT/OUTPUT CONNECTORS:
   • 1/4" TRS: Balanced connectors, wired Tip=Hi (+), Ring=Lo (-), Sleeve=Ground.
   • XLR: Balanced connectors, wired Pin 2=Hi (+), Pin 3=Lo (-), Pin 1=Ground.
   • RCA PHONO: Unbalanced connectors, wired Tip=Hi (+), Sleeve=Ground.

   Note: Only one type of socket should be chosen for audio connection at a time.

For Balanced Connections

Wire the connectors as follows: Phone Jack: Connection: tip = high, ring = low, sleeve = ground.

For Unbalanced Connections

Use 1/4 inch tip-ring-sleeve or mono phone plug connectors or RCA phone jack connectors wired as follows: Phone Jack: Connection: tip = high, ring = no connection, sleeve = ground.

Applications

Graphic equalizers may be used wherever modification of the frequency contour of a sound system is needed. A graphic equalizer is a solution to any number of sound problems or creative urges.

• Typical reinforcement application of a two channel equalizer: This diagram shows a stereo setup where a mixer feeds two separate channels of equalization (one for each channel of the 442 EQ), which then drive two power amplifiers, each connected to a speaker.
• Equalization of audio signals from a mixer: This diagram illustrates how an EQ can be inserted into an auxiliary send/return loop of a mixer. The mixer sends a signal to the EQ, and the EQ returns the processed signal to the mixer.
• Equalization of a musical instrument: This shows a single instrument's output being fed into an EQ unit, which then connects to a power amplifier, and finally to a speaker.
• Equalization of a guitar effects loop: This diagram depicts a guitar signal going through a preamp, then into a stereo effects loop, followed by an EQ unit, and finally to an amplifier.

Warranty Information

Limited Warranty

Applied Research and Technology (ART) warrants to the original purchaser that this product and its components will be free from defects in workmanship and materials for a period of three years from the date of purchase. ART will, without charge, repair or replace, at its option, defective product or component parts upon prepaid delivery to the factory service department or authorized service center, accompanied by proof of purchase date in the form of a valid sales receipt.

Exclusions

This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs. This warranty is void if the serial number is altered, defaced, or removed. ART reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufactured. ART shall not be liable for any consequential damages, including without limitation damages resulting from loss of use. Some states do not allow limitations of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific rights and you may have other rights, which vary from state to state.

For units purchased outside the United States, an authorized distributor of Applied Research and Technology will provide service.

Service

The following information is provided in the unlikely event that your unit requires service:

1. Be sure that the unit is the cause of the problem. Check to make sure the unit has power supplied, all cables are connected correctly, and the cables themselves are in working condition.
2. If you find the unit to be at fault, write down a complete description of the problem, including how and when the problem occurs. Please write down a description of your complete setup before calling Customer Service.
3. Call the factory for a Return Authorization (RA) number.
4. Pack the unit in its original carton or a reasonable substitute. The packing box is not recommended as a shipping carton. Put the packaged unit in another box for shipping. Print the RA number clearly on the outside of the shipping box. Print your return shipping address on the outside of the box.
5. Include with your unit: a return shipping address (we cannot ship to a P.O. Box), a copy of your purchase receipt, a daytime phone number, and a description of the problem.
6. Ship only your unit and its power supply (keep your manual!) to: APPLIED RESEARCH AND TECHNOLOGY, 215 TREMONT STREET, ROCHESTER, NEW YORK 14608, ATTN: REPAIR DEPARTMENT, RA#.
7. Contact Customer Service at (585) 436-2720 for your Return Authorization number or questions regarding technical assistance or repairs. Customer Service hours are 9:00 AM to 5:30 PM Eastern Time, Monday through Friday.

Specifications