Q-VX – Voice Selection Expander Kit

CAD $15.00


Q-VX, a member of London Power’s Q-system of switching kits, is required when more than four system “voices” must be controlled in a guitar rig, but where the user interface is remote.

  • up to four incoming voice control lines
  • up to four output function control lines
  • can use DIPs for programming (order up to four Q-DIP)
  • voice LED driver (4 LEDs)
  • 12Vdc required if LED driver is used

In a guitar system, the combination of preamp channels, effects, reverb, etc comprise the “voices” of the system. Q-LATCH provides direct random access to those voices, but only up to a choice of 1-of-4. Adding more Q-LATCHes allows the remote foot switch to be expanded, but at the amp end those extra voice control lines must be interfaced with relays, jfets and other devices. Such an interface can be accomplished by adding more Q-RLY and Q-FET control boards, but this is unnecessary in most applications. Rather, it is typical that a few functions must be accessed by a multiplicity of inputs. Q-VX expands the number of voices that can control or access a given function in the amp or system when Q-LATCHes are not present at the amp end.

Each of the four control blocks within Q-FET and Q-RLY has an XF pad, “expand function”, where a fly lead can be soldered linking from the output of Q-VX so that up to eight voices can access the given function. Add another Q-LATCH at the remote foot switch and another Q-VX in the amp for up to twelve voices accessing each function.

The incoming control lines typically correspond to “voices” of a guitar system, and Q-VX has an onboard voice LED drive circuit. This is useful when the Q-LATCH voice selector is wired in a remote location: the Q-VX provides local annunciation of the voice selected while Q-LATCH provides the same for the remote position.

Of course, Q-VX can be used independently from the other Q-system cards in creative fashion to interface custom circuit requirements.

Assembly of Q-VX is quick and easy with the high-quality PCB and kit notes. The mounting holes are designed to line up with those in Q-LATCH, Q-RLY and Q-FET so that the boards can be stacked if required.

Q-VX is programmed by soldering jumpers where the DIP switches would otherwise go, if Q-DIP is not used.There are four XF output pads, so four positions for DIP switches to access up to four functions.

The stock LEDs are round 3mm green standard brightness.

Kit requires assembly.

PCB size: 3 x 1″, 76 x 25mm

See also:

Q-DIP – 4-way DIP switch

For more information:
– see our page, About Our Switching Kits
– download our informative PDF: London Power Switching Kits Selection & Application (135 kB, 22 pages)