Border Patrol Control Unit valve pre- amplifier 

The Control Unit pre-amplifier is the result of a long and protracted design process during which many circuit topologies and components were rigorously evaluated and selected on a purely musical basis. Many manufacturers simply prescribe a collection of 'audiophile' components and assume that incorporating them into their product will automatically ensure good sound. This is usually far from the case. Each component has to be evaluated, regardless of reputation, and selected only if it blends into the whole. The operating conditions of the valves need to be carefully tuned in, and the qualities of each part of the circuit need to be harmonically in sympathy with each other. The aim, like in all BorderPatrol products, is not to produce an amplifier that excels in one particular audiophile area but one which has balanced and integrated musical qualities.

The Control Unit is equally at home playing classical, rock, jazz, ethnic, technology or any other music genre and we are sure that it's musical capabilities will more than exceed your expectations.

The Control Unit uses a single 5687 triode valve for each channel configured as an anode follower. This valve is chosen for it's low gain, low output impedance, low microphony and low noise. Hovland Musicap capacitors are used for signal coupling. No negative feedback is employed and the circuit is hard wired into un-printed boards. A double section choke input filter, EZ80 valve rectified H.T. supply with Black Gate capacitors provides the high voltages for the circuit and unusually, and perhaps uniquely, a similar choke input filter supply is used for the filament supply, though this time Hexfred diodes are used as rectifiers. Input and output sockets are mounted on a copper ground plane. The chassis is made from 2mm copper plate. A phono version is available featuring a 2 stage hard wired triode phono stage that uses a ECC83 and 6922 double triode.