The BSS DPR-504 is a 4-channel professional noise gate which has been designed for simple and intuitive use. It incorporates modern integrated circuit technology for high packing density and long term reliability. Ingenious proprietary techniques are employed to make the engineers life easier without compromise to performance or versatility. 

•Four independent channels that are linkable to give either one or two stereo linked master/slave modes 
•Flexible parametric Key filter for frequency conscious gating with absolute precision. The parametric EQ approach provides a higher degree of control for accurately rejecting spurious unwanted gate triggers than similar shelving filters. 

•Key listen provides operator with the facility to hear the effect of Key side- chain EQ or other processing effect as an aid to setting up. 
•Dual metering system which indicates both average and peak responses simultaneously and gives the operator precise information regarding the signal levels around the threshold point. Separate 'gate open' marker LED, linked to gate dynamics, continually monitors interrelation between gate activity and the actual signal. 
•IN switch which allows the operator to force open the gate, in the absence of signal, to check the integrity of the signal lines, and observe set dynamics. This also functions as channel bypass. 

•Selectable 'Fast and auto' attack modes which have been optimized for accurate and transparent performance over the widest variety of program material. Self adjusting Auto mode deals cleanly with varying dynamics whilst a super fast mode is available for demanding percussion and synthesizer transients. 

•Simple to operate, combined Hold and Release control which has special audio-tapered characteristics to give subtle 'musical' envelope shaping. 

•Rear mounted electronically balanced XLR input and output connectors. 

•Rear mounted 1/4" jack socket allows access to external side-chain key input for uses such as external EQ, delay or keying by and unrelated signal.