Comrex DH30 Digital Hybrid

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Designed with both AES/EBU and analog inputs and outputs, the DH30 can interface with the latest digital and analog consoles. To ensure quality sound in studios that have open speakers and microphones, the DH30 was created with an acoustic echo cancellation feature.

The DH30’s digital signal processing (DSP) has multiple adjustable parameters to provide you with the best send and caller audio signals. New audio processing features such as the compressor and downward expander functions ensure that the best audio reaches your audience. All audio processing features are programmable via the front panel controls. For the deepest, most reliable hybrid null, and the best quality caller audio for your application, the DH30 is the answer.

Easy to use and install, the DH30 has simple front panel controls and remote control capability. These controls put the On, Off, Rec, and Cue functions right at your fingertips. The DH30 also includes a 2W monitor amp with volume controls right on the front panel. The Rec function sends a start/stop signal to your external recording device. The Cue function allows you to control which audio signal should be sent to the caller, allowing you to switch from the Send input to the Cue input at the touch of a button.


  • Remote controllable presets
  • Password protected
  • 24-bit digital signal processing (DSP)
  • AES/EBU digital or analog audio input and output
  • Record and Cue functions
  • Selectable auto mix-minus
  • Selectable acoustic echo cancellation
  • Selectable auto answer and disconnect
  • Integrated monitor amp with front-panel volume control
  • Remote control via contact closures or RS-232
  • Adjustable caller control (ducking)
  • Adjustable three-band equalizer
  • Adjustable compressor and expander
  • Bass boost
  • Microphone send and cue preamps
  • Automatically accepts all worldwide voltages
  • Three selectable presets for customized audio
  • Worldwide compliant including FCC, CSA, CE, CTR 21

Technical Specification

Technical Specification

Cue In: XLR Female
Mic/Line selectable, -55 or 0 dBu
nominal, adjustable, balanced bridging, 20k Ohm impedance, selectable 12VDC phantom power
Caller Output: XLR male
0dBu nominal, adjustable, balanced, 50 Ohm impedance

Aux Output: XLR male
0dBu nominal, adjustable, balanced, 50 impedance

Telco Line: RJ-11 connector
POTS (plain old telephone service) line or analog extension from a PBX or dry line (no DC offset voltage). A-Lead
supervision provided

Telco Set: RJ-11 connector
A-Lead supervision provided

Telephone Transmit
All measurements referenced at -15 dBm level on the phone line
Frequency response: 250 Hz to 3.5 kHz, 1 dB
SNR: >70 dB
Distortion: <0.15%

Telephone Receive

All measurements referenced at -15 dBm level on the phone line with caller processing options bypassed
Frequency response: 250 Hz to 3.5 kHz, 1 dB
SNR: >70 dB
Distortion: <0.1%

Remote: DB-25 Female
Remote Send Input:
0dBu nominal, adjustable,
unbalanced, 20k Ohm impedance
Remote Caller and Aux Output:
0dBu nominal, adjustable
unbalanced, 50 Ohm impedance
Control Inputs:
Remotely activate any of the following functions with a simple switch
closure to ground: On, Off, Cue, and Rec along with preset selection controls
1,2, and 3 or with Send, Caller, and
Monitor Mute controls
Status Outputs: Remotely check the status of the hybrid using the On and Off status outputs. Status outputs are open collector outputs rated at 30VDC and 40mA maximum

Monitor Output: 1/4″ stereo jack
Tip=+phase, Ring=ground,
Sleeve=ground, 1W output into an 8 Ohm load

Send Input: XLR female
Mic/Line selectable, -55/0 dBu nominal,
adjustable, balanced, bridging,
20k Ohm impedance

Echo Cancellation/Mix-Minus
Tail time: 120 milliseconds
Null: 50 dB

Telco Cancellation
Tail time: 32 milliseconds
Null: 55 dB

Operating Temperature

0-80 percent

LCD programming display, ENTER/ESC/st programming buttons, Monitor volume control,
Send-level LED bar meter,
Caller-level LED bar meter,
Record, cue,
Hybrid On/Off,
Buttons with status LEDs

Power: IEC Type
Auto Adjusting 100-240VAC, 2A, 50/60 Hz, 30W

Send-to-Caller separation: 55 dB nominal
Tail time: 32 milliseconds

Pin 1=ground,
Pin 2=+phase,
Pin 3=-phase; 32, 44.1, or 48 kHz sample rate

Pin 1=ground,
Pin 2=+phase,
Pin 3=-phase; 32, 44.1, or 48 kHz sample rate

RS-232: DB9 Female Connector
9,600 baud rate, used for status and
control via a PC or other RS-232

Record Control: DB9 Female
Start, stop, and enable outputs are open collector outputs rated at 40VDC and
50mA maximum

Dimensions (LxDxH)
17.125″ x 10.125″ x 1.75″
43.5 x 25.7 x 4.44 cm
Rack mount included for installation in a 19″ rack

6.7 lb/3.04 kg (dry)
11.2 lb /5.08 kg (shipping)

Note: Specifications are subject to change without notice.

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