It is possible to make your own using a 20k ohm linear taper potentiometer. See the schematic on the VR2 data sheet.
The VR 2 provides a simple "pot-on-a-wall" solution to adjust volume from a remote location for products having 0-5 VDC level inputs. The VR 2 fits in a standard US electrical box and can be paired with a Decora™ plate. It contains a linear taper potentiometer with a single Euroblock screw terminal for each of the pot’s three conductors, the Vr terminal, the Vc wiper terminal, and the ground terminal. It is compatible with these units:
The VR 2 remote assembly mounts in a standard U.S. electrical box with a minimum depth of 2.25" (5.5 cm). Use the flat head #6 screws supplied with the kit to mount the remote assembly and silk-screened front panel to the electrical box.
Turn the power to the unit off until all connections are made. Connect the VR 2's control voltage Vc (wiper) connection(s) first. Then connect the voltage reference - “Vr” on the VR 2 (“REF” terminal on a RPM unit). Connect the GND (ground) terminal last. Double and triple check your wiring before applying power to the MA 4 or RPM since improper wiring can and will cause permanent, irreparable damage to the VR 2, requiring replacement of the remote. Such damage is not covered by Rane's warranty; checking the wiring is easier than a second trip to the job site with another remote.
It is important to ensure that the Remote Ports are not subjected to sustained voltages outside the range of 0 to 5 volts DC or high levels of static. Inputs are protected, however, caution is the better part of... you know. It is a good idea to install the wiring, connect it to the Remote and then make the final connections at the Remote Port. Do not short the Vref pin to ground. This pin is current limited, however, excess heat is generated in the 5 volt supply if a short occurs. Never subject the Vr pin to voltages above 5 volts.
Install the knob so the line on the knob is properly aligned with the silk-screening on the front panel of the remote. Install any Decora plate of your choice. For a secured installation, you may wish to leave the knobs off and use a blank Decora plate to cover the remote after adjustment.
You may use 5-conductor unshielded remote control signal cable for shorter runs (less than 200 ft.) or 4-conductor (2 pair) shielded remote control signal cable (use the shield as the GND return) for longer runs (200 to 1000 ft.). The type of wire required is influenced by your installation and local electrical codes. Variations in wire type do not greatly affect the performance of the remote controls. Rane Corporation does not provide or source cable. Please contact your local retail or wholesale outlet, not the Rane factory.
The following is a short list of suitable cable types:
CONSOLIDATED ELECTRONIC WIRE AND CABLE
Unshielded remote control signal cable CAT. #9896
Shielded remote control signal cable CAT. #9877 or #9852
WEICO WIRE & CABLE INC.
Communication and control cable:
Multiconductor, unshielded CAT. #7606
Communication and control cable:
Multiconductor, unshielded CAT. #1175C
Unshielded remote control signal cable CAT. #88741
Shielded remote control signal cable CAT. #88723
Note: the VR 2 has the same appearance as the VR 1, it just uses a different value pot.