Improved assemblies, systems, and methods provide an electrical signal processor for acquisition and processing of electric signals from tissue. The electrical signal processor is sized and configured to be implanted in subcutaneous tissue. The electrical signal processor includes an electrically conductive case of a laser welded titanium material. Control circuitry is located within the case, the control circuitry including a rechargeable power source, a receive coil for receiving a first radio frequency wireless telemetry to recharge the power source, and an antenna for receiving a second radio frequency wireless telemetry for communication with the electrical signal processor.