The Telefunken AR-51 is designed in the tradition of the classic mics of the past, utilizing the same circuit design as the classic Telefunken ELA M 251E. The AR-51 employs new cost-efficient manufacturing methods to meet a price point suitable to any recording studio, from major World Class facilities to voiceover rooms and home project studios. The new R-F-T AR-51 utilizes only premium components, including a vintage New Old Stock (NOS) tube that has been rigidly tested for noise and microphonics, as in the ELA M 251E. The AR-51 also features a globally-sourced power supply and capsule, both rigorously tested prior to installation.

As with all products in the R-F-T range of Telefunken Elektroakustik microphones, the circuit board has been designed for superior current handling, permitting the amplifier to have full access to the necessary "power on demand" for handling low frequency and transient information. Modifications have been made to the amplifier circuit to optimize the performance of the capsule and a signal path that includes the same European manufactured output transformer found in every ELA M 251 E built since 1960.