HQ-231 DUAL CHANNEL 31 BAND 1/3 OCTAVE GRAPHIC EQUALIZER with FDC™ - Feedback Detection Circuit USER’S GUIDE
GENERAL INFORMATION HQ-231 DUAL CHANNEL 31 BAND 1/3 OCTAVE GRAPHIC EQUALIZER WITH FDC™ Congratulations on the purchase of your new ART equalizer. This professional equalizer is perfect for all applications and is also well suited for signal processing in situations where feedback is possible. It’s features include ART FDC™ (Feedback Detection Circuit), and constant Q circuitry with a 3% center frequency accuracy.
FDC can also be employed as a simple spectrum analyzer along with its primary use with the equalizer. This will allow you to identify “hot” spots – area of potential feedback – and attenuate accordingly before feedback occurs. Of course, during a musical performance, FDC will help you quickly locate and eliminate feedback if it occurs. Be careful when running a sound system close to its feedback limit. Feedback can damage equipment as well as hearing.
1/4" Phone connections may be used balanced or unbalanced. When balanced, the tip is High (+), the ring is low (-) and the sleeve is ground. To use unbalanced use a mono phone cable, this will automatically ground the ring to the sleeve. RCA connections are always unbalanced. 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.
readjust the level control. INITIAL SET UP Here are some tips to help you with the initial set up: 1. Set channel levels to the center detent 0dB on the front panel. 2. Select the Bypass switch to bypass the equalizer (Note: The red LED is on). 3. Set the frequency slide controls to the center detent (or 0dB). 4. Select the 6dB range switch (Note: The green LED is on). 5. Apply signal to the system. 6. Release the bypass switch (Note: The red LED is off). 7.
boost/cut capability. At 6dB the green LED will illuminate, and at 12dB the yellow LED will illuminate. 4. BYPASS SWITCH & CLIP INDICATOR LED Bypass Switch: When the red LED is illuminated, this indicates that the unit or channel is in the bypass mode. Signal is routed directly from the input to the output without passing through any circuit (often referred to as ”hard-wire bypass”).
loses power (which causes the unit to go into bypass), the signal will be equal or lower than the active eq gain. This will ensure that a signal with undesirably higher levels will not be passed inadvertently. 8. FDC LED INDICATORS Each frequency band of the equalizer has a Feedback Detection Circuit LED, showing its relative feedback level. These LEDs glow red, then become brighter as feedback begins to occur.
sound systems, or any situation in which the mains power is suspect, it is wise to confirm appropriate voltage and line polarity BEFORE connecting the instrument to power source. 13. GROUND LIFT SWITCH This switch is used to disconnect the signal ground from the mains and chassis earth ground. You may set the switch to the LIFT position if ”Hum”, caused by a ground loop, can be heard at the speakers. 14.
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.
WARRANTY INFORMATION Limited Warranty Applied Research and Technology will provide warranty and service for this unit in accordance with the following warrants: Applied Research and Technology (A R T) warrants to the original purchaser that this product and the components thereof will be free from defects in workmanship and materials for a period of three years from the date of purchase.
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.
SPECIFICATIONS EQUALIZER Bands Type Accuracy Travel Range 2 x 31, 1/3 Octave ISO Spacing From 20Hz to 20kHz. Constant Q 3% Center Frequency 45mm (Positive Center Detent). +/- 6dB or +/- 12dB (Selectable) INPUTS Type Connectors Impedance Maximum Level Active Balanced/Unbalanced 3-Pin, 1/4” TRS (Balanced), RCA (Unbalanced) 20k.
APPLIED RESEARCH & TECHNOLOGY 215 TREMONT STREET ROCHESTER, NEW YORK 14608 USA (585) 436-2720 – Voice (585) 436-3942 – Fax www.artproaudio.com E-mail: cserve@artproaudio.
