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This article is based on a PreSonus manual and are used with the kind permission from the people at PreSonus.

WikiRecording thanks PreSonus for their support of our community.

The original manuals can be found at PreSonus's Technical Support Website.

FEATURES

The following is a summary of your DEQ 624s features:

24-Bit Digital Signal Processing

The DEQ 624 utilizes 24-Bit resolution for accurate processing of analog signals.

Dual 31 Band Equalizers

Each channel of the Graphic Equalizer section of the DEQ 624 is comprised of 31 digital EQ encoders. These digital EQ encoders are centered in 1/3rd octave increments from 20 Hz to 20 kHz.

Separate High Pass & Low Pass Filters for each channel

Each channel of the DEQ 624 is provided separate High and Low Pass filters. The Low Pass Filter is variable from 10kHz to 20 kHz. The High Pass Filter is variable from 10 Hz to 410 Hz.

Expander

Both channels have separate Expanders with Ratio and Threshold controls for minimizing system noise.

Limiter

Each channel of the DEQ 624 is equipped with a Brick-wall limiter (Ratio=Inf: 1) with a Threshold control to provide protection from extreme transients. This feature is designed to protect the system components and the listener.

HI Q

Selecting HI Q alters the characteristics of the equalization of the DEQ 624. The center frequency remains fixed for both Normal Q and HI Q; however, in HI Q the effect on adjacent frequencies is less pronounced. Normal Q is 1/3rd octave bandwidth (Q=4.32) and Hi Q is1/8th octave bandwidth (Hi Q=11.54)

==Range== The degree of control of the digital encoders in the DEQ 624 Graphic Equalizer section can be altered by engaging the Range control switch located in the Dynamics/Master control section. A choice of + / dB dBand dB can be chosen by pressing the Range switch. The selected Range is indicated by LEDs located at the extreme left side of the Graphic Equalizer section. Changing the Range selection for a channel changes the range for all EQ encoders on a channel.

Bypass

Engaging the Bypass switch routes the signal from input to output by way of a hard-wire bypass (On-board metering continues to monitor processed signal; not bypassed signal).

User-Programmable Presets

Four user-determined setups can be stored in the DEQ 624. This is accomplished by storing a snapshot of the settings of the various controls of the front panel of the unit into one of the four preset positions provided for this purpose. A Store switch and a Preset switch can be found in the Dynamics / Master control section to activate this feature. Pressing the Preset switch cycles through the Four Presets and the Manual position.

Front Panel Security Lock-Out

The security lock-out feature allows the operator of the DEQ 624 to defeat the front panel controls of the unit when in Preset mode. Inadvertent or intentional alteration of the units controls will have no effect on the Preset governing the signal being processed. Entering a user-created three-switch code combination restores complete operation of the units front panel controls.

AHC-Adaptive Hum Cancellation

This is a proprietary feature of the PreSonus DEQ 624. Annoying 50 Hz /60 Hz system hum caused by grounding problems can be greatly reduced without effecting program content by simply by engaging AHC. Channel A Master. The Channel A Master switch slaves the controls of Channel B to Channel A for ease of set-up.

FRONT PANEL BASIC LAYOUT

The front panel of the DEQ 624 is divided into two sections:

The Dynamics / Master control section of the DEQ 624 occupies the right side of the front panel and contains the Limiter, Expander, Filters, Gain control, HI Q switch, Range switch, Bypass, Channel Master A, AHC, Program LEDs, Preset switch, Store / Security switch, Output Level Meter and, Gain Reduction Meter for both channels.

The Graphic Equalizer section contains Range LED indicators, 31 EQ encoders for each channel and the 31 HI Q Active LED Indicators.

Dynamics/Master Control

Output Level Meter

The output of each channel of the DEQ 624 can be monitored by way of dual twenty segment LED meters contained in the Dynamics / Master section. These meters display the output of channels A and B, respectively, from 42dBu to +22dBu . A peak hold function has been incorporated into the output meters to facilitate monitoring extremely fast transients. The peak hold lasts for approximately 3 seconds. The Output Level meter continues to monitor processor activity in Bypass mode.

Gain Reduction Meter

The Gain Reduction Meters of the DEQ 624 monitor the activity of both the Expander and Limiter. These 10 segment LED meters are calibrated in increments from dB to dB and show the amount of Gain Reduction applied by the dynamics processors. The Gain Reduction meter continues measuring processor activity in Bypass mode.

Filter High Pass / Low Pass

HIGH PASS FILTER

The High Pass filter control is variable from 10 Hz to 410 Hz. The High Pass filter is always active. Signals above the user-selected frequency point go through, i.e. pass unaffected. The variable filter control can be rotated fully counter-clockwise (10Hz) to effectively take it out of the spectral range of audio.

LOW PASS FILTER

The Low Pass filter control is variable from 10kHz to 20 kHz. The Low Pass filter allows signals below the user-selected frequency to pass. The 20 kHz position on the variable frequency control is located at the fully clockwise position and is labeled-Off. Intuitively the Off label is correct as the bandwidth of the DEQ 624 is 20 Hz to 20kHz, therefore, selecting 20 kHz allows all frequencies from 20 kHz and below to pass through unaffected, effectively turning the Low Pass filter Off.

Expander

The DEQ 624 Expander is provided to eliminate system noise. The Expander is controlled by selecting a threshold point for downward expansion to begin and by selecting a ratio, which controls the amount of downward expansion.

THRESHOLD

The Expander Threshold control is variable from dB to Off .

RATIO

The Ratio control is variable from to Infinity.

Limiter

A Brick Wall Limiter is available to each channel of the DEQ 624. The limiter will protect system components and listeners from destructive transients by providing an electronic barrier which signals rising above the user-determined threshold will not be allowed to cross.

THRESHOLD

The Threshold control for the Limiter is calibrated from dBu to Off.

Gain

A Gain control on each channel of the DEQ 624 is the last controller in the signal path and is used to compensate for signal level loss from dynamics processing. The control is centered at and with a Cut / Boost capability from dBu to dBu.

Bypass

A Bypass switch on each channel redirects signal to a hard-wire bypass connection that takes the DEQ 624 circuitry out of the signal path. This switch lights up when Bypass is ON. The DEQ 624 metering system continues to monitor processor activity in Bypass mode.

Range

Each channel has a Range switch for selecting the range of control for the graphic equalizer sections digital EQ encoders. One of three LEDs per channel located at the extreme left side of the face of the unit light up when selected to indicate the current range for the graphic equalizers digital encoders. A lighted Red LED indicates a range of or dB; a lighted Amber LED indicates an available range of or dB and a Lighted Green LED indicates a selected range of or dB. The selected range for a channel is applied to all digital EQ encoders in Manual mode or when setting up a program to be stored in a Preset position. If a set-up procedure is begun and a change in the range of control of the encoders is desired, it is probable that any EQ encoder choices made before the alteration in range will require resetting. Range selection for each channel is global and is applied to all channel EQ encoders.

HI Q

Normal Q (Q of the DEQ 624 is divided into bandwidths of 1/3rd octave from 20 Hz to 20 kHz. HI Q (Qresets the bandwidth to 1/8th octave. The center frequencies remain unchanged while the effect on adjacent frequencies is less pronounced in HI Q. Pressing the HI Q switch lights the switch and indicates HI Q is now available to be selected. A row of 31 Red LEDs labeled HI Q can be found on the Graphic Equalizer section between the two rows of digital encoders. These are the HI Q Active indicators, which do not light unless a frequency has been selected for applying HI Q.

SELECTING AND SETTING HIQ

Begin by pressing the Channel A HI Q switch. This will light the Channel A HI Q switch in the Dynamics / Master Control section. This enables HI Q select /deselect mode for Channel A and disables Channel B HI Q switch and the Preset switch. Any HI Q Active LEDs below any of the Channel A equalizer encoders in the Graphic Equalizer section that have HI Q enabled will now be lit.

The Graphic EQ section digital encoders are used to enable or disable HI Q. The speed at which the encoder is moved is used to select it for HI Q mode. Moving the encoder slowly does not select the encoder for HI Q but rather allows it to be read and updated normally. Moving the encoder quickly causes the Red HI Q Active LED beneath the encoder to blink and the Store / Security switch in the lower right-hand corner of the faceplate to blink. Pressing the Store / Security switch at this time latches the selected EQ encoder into HI Q. The HI Q Active LED beneath the selected encoder stops blinking and remains ON indicating the encoder is now in HI Q and the Store / Security switch light goes off. Adjusting the EQ encoder in HI Q mode results in a more focused manipulation of the selected frequency with reduced effect on adjacent frequencies.

The following example illustrates enabling and disabling HI Q for the 1kHz EQ encoder for Channel A.

EXAMPLE Enabling HI Q for 1 kHz (Channel A)

(HI Q is not enabled for any of Channel As EQ encoders at the start of the sequence).

1. Press the Channel A HI Q switch. The Channel A switch lights up and none of the HI Q Active LEDs in the Graphic Equalizer section are lit.

2. Move the Channel A 1 kHz EQ encoder quickly. This will start the HI Q Active LED beneath the 1 kHz EQ encoder of Channel A and the Store / Security switch light to begin blinking slowly.

3. Press the Store / Security switch. The HI Q Active LED below the 1 kHz remains on continuously and the Store / Security switch light goes OFF. The 1 kHz EQ encoder is now in HI Q.

4. Pressing the Channel A HI Q switch turns off both the HI Q switch light and the HI Q Active LED indicator beneath the Channel A 1 kHz EQ encoder. The resulting HI Q Boost / Cut of the Channel A 1 kHz EQ encoder remains. Disabling HI Q

(The sequence begins with only the 1 kHz EQ encoder of Channel A HI Q enabled.)

1. Start by engaging the Channel A HI Q switch. The HI Q switch and the HI Q Active LED indicator below the 1 kHz EQ encoder of Channel A light up and remain ON.

2. Next, move the 1 kHz EQ encoder of Channel A quickly. This will cause the HI Q Active LED indicator below the 1 kHz EQ encoder of Channel A and the Store / Security switch to blink rapidly.

3. Pressing the Store / Security switch results in the HI Q Active LED indicator below the 1 kHz EQ encoder of Channel A and the Store / Security switch light to go OFF. HI Q has now been de-selected for the Channel A 1 kHz EQ encoder.

4. Pressing the Channel A HI Q switch results in the Hi Q switch light going OFF and the unit to exit HI Q set-up mode. EQ encoders are updated when HI Q mode is selected. The effects of Boost / Cut are audible during this process. During HI Q mode, any EQ encoder may be toggled ON/OFF by repeating steps 2 and 3 of the preceding examples.

SOME IMPORTANT THINGS TO REMEMBER ABOUT HI Q:

1. Only one EQ encoder at a time may be selected.

2. Once an EQ encoder has been activated it may be de-activated by: A. Pressing the Store / Security switch B. Turning the HI Q mode off by pressing the HI Q switch

3. The HI Q non-volatile memory is updated when the HI Q mode is switched OFF.

REMEMBER: Selecting Channel A HI Q disables the Channel B HI Q switch and the Preset switch. Conversely, selecting the Channel B HI Q switch disables the Channel A HI Q switch and the Preset switch.

Channel A Master

The Channel A Master switch is located in the upper right-hand corner of the faceplate. When the Channel A Master switch is selected, all EQ encoders, controls and switches for Channel B are disabled. Selecting the Channel A Master switch forces Channel B to use all of the settings of Channel A. When the Channel A Master switch is turned OFF, all of Channel Bs controls become active.

Channel B

Channel B of the DEQ 624 is a duplicate of Channel A. All controls, encoders and LED indicators found on Channel A are found on Channel B.

REMEMBER: When Channel Master A is engaged, all of Channel Bs controls are disabled!

Adaptive Hum Cancellation (AHC)

Adaptive Hum Cancellation has been incorporated into the DEQ 624 for the express purpose of reducing 50 Hz or 60 Hz line noise. This very common audio artifact is typically caused by ground loops and can be successfully removed by AHC. AHC is in learning mode when turned OFF. While in this mode, AHC monitors the noise/hum level. Corrective waveforms are continuously updated based upon noise/hum coming into the unit. When AHC is turned ON the last corrective waveform is applied to the audio data. Should the noise level change and AHC become ineffective in controlling the noise/hum, it is then necessary to turn AHC OFF for a few seconds so it can adapt to the new noise level and then be selected again by pressing the switch to the ON position to resume operation.

Presets

The DEQ 624 can store up to four programs. Stored programs can be recalled by selecting the desired program with the Preset switch located at the right end of the front panel of the unit. Pressing the Preset switch repeatedly cycles through the four Preset positions. Stopping on a program for approximately three seconds causes the stored program in that position to load and the unit to operate in that Preset mode (NOTE: All EQ encoders, controls, and switches with the exceptions of the Store / Security switch and the Preset switch are disabled when a program is recalled).

STORING PRESETS / PROGRAMS

The Store / Security switch is used to store Programs (Note: Programs cannot be stored if Channel A HI Q, Channel B HI Q or the Preset switch are in the ON position).

Press and release the Store / Security switch. Notice that the Store / Security switch and the Program 1 LED are blinking rapidly. You can cycle through all 4 Program positions and back to Manual mode by simply pressing and releasing the Store / Security switch.

Go through set-up of the DEQ 624 to suit your requirements. After you have finished, be sure that Channel A HI Q, Channel B HI Q and Preset are not engaged. To create and save the current set-up as a program in position 1, press and release the Store / Security switch. This will cause both the Store / Security switch and the Program 1 LED to blink rapidly. Next, press and hold the Store / Security switch until the Preset switch lights and the Program 1 LED stops blinking and remains ON. The system set-up youve just completed is now stored in the Program 1 position and can be recalled by pressing Preset until the Program 1 LED comes ON. Four separate set-ups can be stored and recalled in this fashion.

It should be noted that updating a stored program is only possible if the unit controls have not been changed. If you want to tweak a stored program, you would have to first restore the controls to the position they were in when the original snapshot of the controls was stored to memory and then make your adjustments.

To clear all stored Presets. Turn the power to the DEQ 624 OFF. Power the unit back up while pressing the Channel A Master switch. This restores the four Preset positions of the unit to the factory default setting of Zero for all settings and overwrites all stored information.

Security

The controls of the DEQ 624 can be locked to prevent intentional or inadvertent alteration. The DEQ 624 must be in a Preset mode to utilize this security feature.

LOCKING THE DEQ 624

To lock the DEQ 624, make sure the unit is in Preset mode. Now, while holding down the Store / Security switch; push any three switches in the Dynamics / Master control section. You can choose to push the same switch three times, one switch twice and one other switch or three separate switches. Any combination of three switches while holding the Store / Security switch locks the front panel.

UNLOCKING THE DEQ 624

To unlock the DEQ 624, hold down the Store / Security switch and repeat the three-switch combination that was used to lock the unit.

(It is possible to over-ride the lockout feature. If you should forget your combination, you can power the unit OFF and power it back ON while holding down the Store / Security switch. This will restore full operation of the unit.)

31 BAND EQUALIZER SECTION

• 31 Digital Encoders per channel

• 6 dB (Red), 12 dB (Amber), 1224 dB (Green) RANGE LED Indicators per channel

• 31 HI-Q Active LED indicators

BACK PANEL BASIC LAYOUT

Both channels of the DEQ 624 XLR inputs and outputs, TRS inputs and outputs and a Barrier Strip with inputs and outputs for versatile system connectivity.

POWER SUPPLY

The Power Supply for your DEQ 624 has been Factory Configured to use the voltage of the electrical current for the country of retail sale (USA = 115V). WARNING: Attempting to operate this unit at voltages for which this power supply was not designed will void the manufacturers warranty and may result in damage to the unit and injury or even death to the operator.

TECHNICAL

DEQ 624 Technical Specifications:

Number of Channels: Two Dynamic Range: >105dB Noise Floor: -95dBu Signal to Noise: 90dB Power Supply Rejection: 98dB Headroom: +22dBu Frequency Response: +/- 0.5dB 10Hz to 22kHz Channel Gain: 20dB to +20dB THD + Noise (Un-weighted): 0.005%

Input

Input Impedance: 12K Input Connectors: XLR,1/4”TRS, Barrier Strip

Output

Output Impedance: 51 Output Connectors: XLR,1/4”TRS, Barrier Strip

Metering

Level Meters - 20 Segment LED 42dBu to +22 dBu Gain reduction – 10 Segment LED -0.5dB to – 12 dB

Power Supply

Type: Linear Input: 115 / 230VAC (Factory Configured) Power: 20 WATTS Main Connection: IEC receptacle Size: 2U Rack Dimensions: 19” X 9” X 3.5” Weight: 14 lbs. Chassis: Steel/Aluminum

Categories: Manuals | PreSonus Manuals