• 1x CTD-4125
• 1x AC Power Cord
• 1x Quick Start Guide
• 4x Input Connector (GREEN)
• 2x Output Connector (GREEN)
• 1x GPI Connector (BLACK)
• 1x Fault Relay Connector (BLACK)
• 1x Rear Support
• 2x Rear Support Screws Type I M4x6 (Philips)
• 2x Rear Support Screws Type II 10-32 0.75 (Philips)
• 1x Rack Ear
• 1x Half Rack Extension Ear
• 6x Rack Ear Screws M5x8 (Philips)
• 2x Bottom Mounting Plate
• 4x Bottom Mounting Plate Screw M4x6 (Philips)
• 4x Rubber Feet

Dimensions: (DxWxH) 14.1 x 8.6 x 1.7 in. (358 x 220 x 43 mm)
Weight: 7.1 lbs (3.2kg)
Shipping Weight: 9.1 lbs (4.1kg)

You can access the WebUI by entering the amplifiers IP address in your browser, the device will need to be on the same network as the amplifier.  You can also access it from the AVX Manager software.

For additional information, please check the following article:
Accessing the WebUI | Crown Comtech D-Series Amplifiers

1. Analog Audio Inputs:
   The amplifier features four balanced analog inputs using 3.5mm pitch 3-pin terminal blocks.
    
2. Network & Dante (Digital Audio):
   There are two RJ45 ports on the rear panel for primary and secondary network connections.

• Control: Use the Primary port to connect to your network switch for WebUI access and HControl (AMX/BSS) integration.
• Dante/AES67: These ports also handle digital audio.

3. Speaker Outputs:
   Output connections use 5.08mm pitch 4-pin terminal blocks.  Each block handles two channels.
    
4. GPI (Control) & Fault Relay:
   GPI Port (6-pin 3.5mm).  Connect external switches or potentiometers here.

The CT-D Amplifiers can be controlled via the built in WebUI, AVX/Manager software, Dante Controller, GPIO and API/HControl integration.

1. Access the WebUI.
2. Go to System settings.
3. Under “Power and Fan Management” you can select Auto Standby to Enabled/Disabled.
   Time to Auto Standby can be set anywhere from 3 to 60 minutes.
    

The Channel LED's indicate channel signal and health.
The Status LED's indicate the status of the Data/Network, Audio/Dante and Health.
The Power Button LED indicates the Power status.

Supports Dante with AES67 interoperability, offering Split, Redundant, and Switched network modes across its dual Ethernet ports for flexible control, redundancy, or daisy chaining.

Choose the network mode based on your system requirements.  Use Redundant mode when Dante audio redundancy is required.  Use Split mode when control traffic and Dante audio must be separated.  Use Switched mode to daisy-chain devices using a shared connection.

For additional information, please check the following article:
ComTech D Series Amplifiers: Dante Network Setup and Best Practices

Use Redundant mode when Dante audio redundancy is required. 
Port A = Dante Primary + HControl. Port B = Dante Secondary.
Both ports can also support control and monitoring.

Use Split mode when control and Dante audio traffic must be separated. 
Port A = HControl. Port B = Dante Primary audio.

Use Switched mode when daisy-chaining network connections between devices.  In this mode, Port A and Port B share a single IP address used for Dante audio, control, and monitoring.

AES67 is an Audio-over-IP interoperability standard.  When enabled on a Dante device, it allows audio to be shared with non-Dante, AES67-compatible equipment using RTP multicast streams.

1. Launch Dante Controller.
2. Navigate to Device View.
3. In the Device List, double-click and select ComTech Amplifier.
4. Open the RTP Configuration tab.
5. Choose the desired mode:
   - To Enable, set RTP Mode to AES67.
   - To Disable, set RTP Mode to None.
6. PTPv2 warning will prompt, select OK.
7. Power-cycle the amplifier if prompted.

Yes, depending on the network mode.  In Redundant mode, Port A (Dante Primary) and Port B (Dante Secondary) may use APIPA with separate address ranges.  In Switched mode, Port A and Port B share a single IP address in the 169.254.0.0/16 range.  APIPA is not recommended for Split mode.

CT-D amplifiers use the Dante Embedded Platform.  Version numbering differs from Dante hardware products and does not indicate outdated or incompatible software.

Yes, supported speaker tunings can be loaded and managed through the WebUI.

For additional information, please check the following article:
Comtech D Series Amplifiers: How to apply Speaker Tunings

Power Sharing is the CTD-4125’s ability to dynamically distribute a shared 500-watt power pool across each set of four channels so that any channel can draw wattage as needed if the group’s total remains within 500 W.

For the CTD-4125:
•    Total available power = 500W
•    That power is shared between Channels 1 to 4.

Power Sharing is measured by the total output power drawn from the amplifier’s single shared channel group (Channels 1–4), verified using standardized burst power tests (typically 1 kHz, 20 ms burst at 0.1% THD), where the combined output of all four channels must not exceed 500 W, regardless of how the power is distributed among them.

You can access the amplifier from the AVX Manager software.  When a firmware update becomes available on our remote repository, an update firmware icon will appear in the Firmware Version column.

For additional information, please check the following article:
Firmware Update | Crown Comtech D-Series Amplifiers

No, the Dante Embedded Platform firmware should not be updated.  It is maintained as part of the system and should remain unchanged unless specifically directed by the manufacturer.

No, firmware downgrade is not supported.

To do a factory reset make sure the amplifier is turned on, then press and hold the reset button on the back of the unit for at least 10 seconds.
 

Yes, the CTD-4125 uses a universal power supply, supporting 100–240 VAC, 50/60 Hz operation without requiring manual voltage selection.

ComTech D Series amplifiers use internally bridged, differential (floating) speaker outputs in all operating modes.  Neither speaker terminal of each output is tied to chassis ground or earth ground.

When configured for 100V operation, ComTech D amplifiers produce approximately 93 Vrms at the output.  This is normal operation and is by design.

Please reach out to our HPRO Parts Department for spare parts availability and pricing.

Phone: 844-776-4899 Option 1
Email: hpropartsusa@harman.com

The ComTech D Series have a 3 year warranty.