Comrex DH20
Digital Hybrid Single Line Telephone Interface


Our Price: $955.20List Price: $995.00
(Low Price Guarantee)

In Stock

The DH20 is a high quality single line telephone interface that interconnects a standard telephone line and your audio equipment, allowing you the ability to send audio to and receive audio from a connected telephone line. The DH20 is ideal when the very best audio quality is required for talk shows, news feeds, production, recording studios, and internet applications.

Comrex's newest DSP technology delivers better and more reliable sound quality. The DH20 delivers the deepest and most stable hybrid null, ensuring maximum isolation between the send and caller audio. That means no echo and no "bottom of the barrel" sound.

In addition, Comrex has added selectable automatic gain control(AGC) and caller ducking. With AGC, each call will be delivered to your equipment at the same level. Caller ducking reduces the caller's audio level when the announcer speaks, providing a more "controlled" environment. There's also a speaker amplifier so you can connect a speaker directly to the unit and monitor callers without headphones.


  • DSP digital technology ensures the very best audio quality and thedeepest, most reliable hybrid null
  • Easy to install, simple to operate
  • Built-in speaker amplifier
  • Balanced audio in and out
  • Mic or line input
  • Selectable AGC ensures every caller is at the same audio level
  • Selectable caller ducking
  • Selectable auto-answer/auto-disconnect compatible with most telephonecentral offices including loop current interruption and busy/reorder tones
  • Remote control and status
  • Automatically accepts all worldwide voltages
  • Worldwide compliant, including FCC, CSA, CE and CTR21
  • Dry line capability


  • Caller Output: XLR male, 0dBu nominal, adjustable, balanced, 50½ impedance
  • Aux Output: XLR male, 0dBu nominal, adjustable, balanced, 50½ impedance
  • Telco Line: RJ-11 connector
       POTS (plain old telephoneservice) line or analog extension from a PBX or dry line (no DC offsetvoltage).
       A-Lead supervision provided
  • Telco Set: RJ-11 connector, A-Lead supervision provided
  • Telephone Transmit:
       Nominal send input of 0 dBureferenced to -15 dBu onto the telephone line.
       FrequencyResponse: 250 Hz to 3.5 kHz, ±1dB
       Signal to noise ratio:>56 dB
       Distortion: <0.2%
  • Telephone Receive:
       Nominal telephone line level of -15dBu referenced to caller output of 0 dBu
       Frequency Response:250 Hz to 3.5 kHz, ±1 dB
       Signal to noise ratio: >56dB
       Distortion: <0.2%
  • Remote: DB-25 Female
       Remote Send Input: 0dBu nominal,adjustable, unbalanced, 20k Ohm impedance
       Remote Caller andAux Output: 0dBu nominal, adjustable, unbalanced, 50 Ohmimpedance
       Control Inputs: Remotely activate any of thefollowing functions with a switch closure to ground: On, Off, and MonitorMute
       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
  • Mix-Minus, Caller-to-Send separation: 50 dB nominal, Tail time: 32 milliseconds
  • Operating Temperature: 32-100°F/0-38°C
  • Humidity: 0-80 percent
  • Controls: On/Off Buttons, Volume Up/Down Buttons
  • Status LEDS: On Status, Off Status, Send Audio Presence, Caller Audio Presence
  • Adjustments: Send Input Level, Caller Output Level, Auxiliary Input Level, Auxiliary Output Level, Burst Adapt Select, Mic/Line Select, Caller Boost Select, Momentary/Latching Select, Auto Answer/Disconnect Select, Caller Control Select (0, 6, 12, or 18 dB), AGC Select, Auto Mix-Minus Select, Aux Mix Select
  • Power: IEC Type, Auto Adjusting 100-240VAC, 2A, 50/60Hz, 30W
  • Null, Send-to-Caller separation: 55dB nominal, Tail time: 32 milliseconds
  • Dimensions (W x D x H): 17.125" x 10.125" x 1.75" (43.6 x 25.7 x 4.44 cm)
  • Weight: 6.35 lbs. (2.88 kg)

HACKER SAFE certified sites prevent over 99.9% of hacker crime.

Secured by Thawte

Full Compass is an Upfront Merchant on TheFind. Click for info.

Copyright © 2014 Full Compass Systems, LTD. All rights reserved.
Please read our Terms of Service, Privacy Policy and Conditions Statement.
We are not responsible for typographical errors in pricing or product specification inaccuracies in our catalog or web site. Prices are subject to change without notice.

Proud Member of:
Full Compass Systems, Ltd. BBB Business Review Logo: AES Logo: GSA Advantage Logo: National Association of Broadcasters Logo: NSCA Logo: Society of Broadcast Engineers
Logo: InfoCOMM Logo: NAMM
Full Compass is a national leader in Professional Audio, Professional Video, A/V, Lighting and Musical Instrument sales. Since 1977, our goal has been to provide the best possible value with exceptional customer service. We offer over 700 top equipment brands including, Shure, Yamaha, Panasonic, Sony, JBL, Sennheiser, Canon, QSC, Audio-Technica, Crown and much more. We also provide services such as computer systems integration, lighting design, and rentals (rentals available in Wisconsin only). Full Compass is an authorized service center and parts distributor for most of the major manufacturers we carry.