Similar in design to the M3, the TB4M provides facilities to act as the control room monitor source selector & adds a host of features making it a studio communications control module as well. The control room signal path is completely passive, with a four gang stepped attenuator, that tracks within ±.05dB. The TB4M includes an independent cue & talkbalk system with independent level controls, a mono sum, selectable headphone monitoring, microphone & remote switching.