The V4 is a handy one-into four MIDI Thru unit, which you can use to convert one conventional MIDI Out (connected to the IN socket of the V4) into four cleverly buffered parallel Outs (available at the THRU sockets of the V4).
You will find that the V4 MIDI Thru Unit is a convenient pocket-sized gadget. Its dimensions are just 58mm x 69mm x 23mm.
Powered from the line
The power for the V4 buffer circuit is derived from the MIDI connections at its MIDI In socket. This circuit configuration inevitably makes certain assumptions about the master MIDI device: it assumes that the screen connection on pin 2 is the zero volts of the associated MIDI driver circuit; it assumes that the source connection on pin four is derived from a five volt power supply; it assumes that the MIDI driver current switch is connected via pin 5. As the design of the MIDI master device could fail (for good reasons) to meet any of these criteria, compatibility problems can occur with any line-powered MIDI gadgets; problems are however rare.
It may seem counter-intuitive to have what is effectively an amplifier powered from its own input signal! Please be assured that, with suitable circuit design, sufficient power can indeed be derived from the MIDI master device.
This Philip Rees V4 is in Excellent Condition and comes with it’s Original Box and User Guide.
Picture is of the actual item.