V/Bar (meaning Volt Per Bar and pronounced VEEBAR) is a standard used by all Adroit sequencers and time related modules. It uses voltage as an analogue of time just like V/Octave uses voltage as an analogue of pitch. This offers several advantages over conventional clock based sequencing that uses a regular pulse to represent the advance of time.
V/Bar sequencing is conceptually simple, very flexible and works at sample level precision due to the 64 bit implementation. V/Bar sequencers can handle micro-timing adjustments, cope with everything from glacial to audio rates and will even run backwards just as happily as forwards. Also, as there is no need for reset or start/stop signals, wiring is simplified and sequencer behaviour is far more reliable than in a clock based system.
The V/Bar standard uses one volt to represent one bar (measure). This means that a quarter note duration is represented by a 1/4 of a volt difference. Eight bars is an 8 volt difference. In a song the beginning of the 12th bar will be represented by 12 volts. In a long song the voltage available at the global V/BAR OUT socket of the Song Control module might get higher than 100 V but there is no danger of being electrocuted! It is just a number and Voltage Modular sets no upper limit even though the standard voltage range is – 5 V to +5 V.
All Adroit sequencers wrap around voltages and simply repeat when fed high voltages.
The Adroit V/Bar standard also provides a simple means for switching sequencers on and off. If a zero voltage is fed to a sequencer it will disable it. This means large numbers of sequencers, perhaps configured in long chains, can cooperate – passing control to each other as required in a computationally efficient manner.
To gain some insight into how V/Bar sequencing works let’s look at some graphical examples of V/Bar voltages as seen by CV Watcher…
The green voltage trace above shows the input voltage varying from 1 to 4 volts over four bars. The top two traces show how the Time Split 2 module splits the voltages into two parts each driving a separate sequencer for a single bar at a time. Notice how the voltage for one output drops to zero when the other output is active.
The Time Split 4 traces above show how the same principle can be extended to four outputs feeding four sequencers over four bars This time the input voltage is in magenta.
Finally here’s an example using the Time Split Fills module…
Here the green trace shows the input voltage again over four bars. The red trace shows the BARS 1-3 output and the yellow trace shows the BAR 4 OF 4 output. Notice how the top line traces from one to three volts over the first three bars and then gives way to the other output for the final bar in every four bar loop.
Note that Song Part modules work in the same way as time splitters except that the number of bars is user selectable rather than hard wired.
Combinations of Song Part, time splitter and Time Flow Changer modules can produce all manner of interesting V/Bar manipulations.