Re: How do I connect V-Drums to computer by MIDI
i) MIDI stands for Musical Instrument Digital Interface. It was standardised in 1983 by a group of companies all agreeing to use the same standard for communicating between electronic instruments. MIDI is simply a series of numbers (data) that tell an external device (e.g. a computer) which notes are being played, on which instrument, when and how loudly. It's a very simple system. I suggest reading the Wikipedia article on MIDI.
ii) On electronic drums, a sensor (called a piezo - won't go into the details) picks up your playing and turns it into an analogue electrical current. This is in turn passed onto your electronic kit's 'brain' (I prefer 'module') and converted into the MIDI data. The stronger the playing, the stronger the current from the piezo and the higher the 'velocity' data number is (0-127) on the converted MIDI data. The MIDI data then triggers the sounds on the module (or external device).
iii) If you want to use MIDI data in recording drums (e.g. using virtual instruments), you will need to output the MIDI signal from your TD-4 into a computer. There are plenty of MIDI interfaces out there that will take the signal from your drum kit and allow the computer to read the MIDI data.
iv) You will need some kind of DAW software and the associated virtual drum software. There are plenty of good packages out there. Superior Drummer, BFD2, etc. DAW software depends on platform (e.g. PC or Mac). I use a Mac with Cockos Reaper, which is a very good-value DAW platform that works on both Mac and PC. Before I used Reaper, I used Logic Pro and there are other DAW platforms out there like Cubase and Sonar.
v) If you want to record the sounds from the drum module, then you can ignore all of the above. All you would need then is some form of stereo input into the computer (many come with a basic jack input) and the associated cables to plug into the audio output from the TD-4. Recording that onto a computer can be achieved using a basic wave editor like Audacity without the need for a complex DAW.
vi) VST is one of the formats of what are generally called 'virtual instruments'. Virtual instruments are just that. Computer-based sound packages. There are other formats, e.g. AU (on the Mac) but VST is a more common format. Remember, VSTs are virtual instruments but not all virtual instruments are VST-based. If you want to use virtual instruments, you open your DAW software, select the MIDI input (your drum kit - but it won't be labelled as such - it'll be easy to find in the MIDI input menu of your DAW package) and then open the virtual instrument, e.g. BFD2 or Superior Drummer.
vii) Samples are quite simply, 'samples' of real, recorded sound. These are often used in virtual instruments. For instance, in BFD2, the 'snare drum' options will be real, recorded snare drums that have been filed and stored in a particular format to work within the virtual instrument. It is also possible to use samples without virtual instruments. If I were to record my voice and use a snippet of it in a composition, I have effectively 'sampled' my voice.
I hope that helps.