CTR2-Max-5

October 24, 2026

1. CTR2-Max units are back in stock! All units now ship with v2.00.00 firmware that removes WiFi and Bluetooth functionality, and adds support for AetherSDR CTR2 Relay and AetherCTR2. More about this change can be found here.
2. USPS has changed the way it handles international shipping costs. Please see my post here for more information.

CTR2-Max (Max) is the latest addition to the CTR2 controller family. Because the display used in CTR2-Max has not been FCC certified, Bluetooth and WiFi modes have to be disabled in order to sell it. Max now operates as a USB-only device. It supports MIDI control over USB and works with many radio control apps like SmartSDR for iOS/MacOS, AetherSDR, RimuSDR, OnlineRemoteRadio, and RemoteTx, etc.

It also supports direct Flex radio control over USB using the new AetherSDR CTR2 Relay feature. You can find this mode in AetherSDR v26.10.3 and above, under the Settings->Controllers->CTR2… menu. This mode provides the same functionality as Flex WiFi mode does in other CTR2 controllers, but uses USB instead of WiFi. In addition, it supports a new app from AetherSDR called AetherCTR2. This app replaces the stock CTR2-Max firmware with a modern user interface and directly supports many of the features found in AetherSDR like CW decoding and audio graphics. It is pre-installed on all CTR2-Max units shipped after October 23, 2026. AetherCTR2 was created, and is supported by, the AetherSDR development team. AetherCTR2 is shown in the last photo in the photo gallery.

CTR2-Max features a much larger touchscreen display (2.8″ compared to 1.28″ on the Quad), one additional knob, and two additional buttons.

In Flex mode, Max connects to your radio as a non-GUI client using the CTR2 Relay feature released in AetherSDR v26.10.3. In this mode, Max runs in parallel to the AetherSDR GUI client connected to the radio.

Unlike previous CTR2 controllers which use a piezo buzzer for sidetone (when operating in direct Flex control mode), Max produces a true sinusoidal sidetone with full pitch and level control. The output of the codec feeds a 1.2 watt amplifier that drives an internal speaker. Not only is the sidetone easier to listen to, an optional sidetone audio interface option allows you to patch transformer-isolated sidetone from Max to your headphones, powered speaker, mixer, or PC sound card. See the limitations of this option below.

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Please enter your call sign in the Add a note to your order section on the Checkout page so I can create your registration key.

Failure to do so may delay your order.

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Select the mode you want your unit to boot into from the options below. You can change the boot mode at any time in the Settings menu.

Also, if you’re planning on using CTR2-Max in MIDI mode with a radio control app, let me know which app you’re running in the Add a note to your order section on the checkout page and I’ll load that app’s configuration into your unit. This way, you’ll  only need to import your app’s MIDI map from the CTR2-Max Config Files page to be ready to go.

You can find the list of control apps I have configurations for, and the map files for them, on the CTR2-Max Config Files page.