Local On/Off Switch in USB mode

[horsegrip]

G'day, Why, when in USB mode is the Local switch turned Off and not recommended for use? Also, which buffer size is recommended under USB mode?

[annikk.exe]

If Local is on, pressing keys on the Virus keyboard causes the synth to produce output.

If Local is off, pressing keys on the Virus won't produce any output.

When you have the synth plugged in via USB, and you have Virus Control up with a patch selected ready for playing, here is what happens when you press a key:

1. Key pressed. A message about the key press is sent along the USB wire into the computer.

2. The computer registers that a key has been pressed, and if you are recording at the time it will then add a note in the appropriate midi track.

3. As well as this, it also sends a message back to the Virus along the USB cable, saying "hey, this note has been played. you should make some output for it"

4. The virus then produces the output specified by the host software.


So if you had local switched ON, then the note would be played twice - once when you press the key and the virus plays the note on its own, and then again after the message has travelled into the DAW and sequencer software, then back out to the Virus.

Another possible hazard would be if you are using the Virus to control another VST, say a sampler with a piano patch in it. If local is On, then when you play the piano notes your Virus will also be outputting whatever patch it happens to be on! So in my case I would get nice, soft piano notes mixed with .EXE l34D patch, which is a searing digital lead =P

So that is why. :>

Access actually recommend that when playing in a part, you change the Virus output mode from USB out 1+2 to Analog out 1+2. This is because it takes some time for the message to travel along the USB cable, be processed in the host, and then travel back to the Virus again. It results in some latency while playing, so when you hit a note it takes a noticeable fraction of a second to actually produce the output.
If you set the output to the analog outs then it avoids this latency, which makes it nicer to play in notes whilst recording a riff or whatever.
[Note that most hosts compensate for the latency during midi playback - this issue only affects live playing]


On buffer size, the lower you set it, the lower the latency we just discussed will be.
If you are lazy like me and can't be bothered switching the output type all the time and just want to keep it on USB out 1+2, then my advice would be to set the buffer size as low as possible. If you set it too low, you will start to notice unwanted blips and other artefacts appearing in the music. It doesn't do your Virus any harm to experiment with a low setting though, so try different settings until you are satisfied :>


Hope this helps..


-Annikk