say your doing transient work..you load up session drummer 3 to use as kick replacement..now all of a sudden you want to replace the snare to..do you just load up another session drummer 3 track and make your computer work harder???no,you insert a midi track and route it to session drummer and yse that synth instead.

1 Midi Track + 1 Audio Track = 1 Simple Instrument Track (soft synth track).
Just a different route to the same results.

Like others, before X1 I found the simple instrument track too limited for my liking. Now with the improved inspector in X1, it works really well.

Ok so you guys are explaining how a synth output track and midi track put together is an instrument track, but Im not sure the question posted has been answered...


A midi track is a track in there is nos sound, only data. Everything in that track is midi data that tells whatever the source is that the data is put into, what to do, such as what notes tio play, modulation, pitch bend data, velocity, pedals, etc... 
Midi being a data language, the track is simply what holds that language.

You need to make the output of the midi track set to be to the input of whatever softsynth you are wanting that midi data to be used by.

The synth output track is the track associated with the actual softsynth and puts the midi data "through" that softsynth for processing. It also can determine what output on the softsynth the sound created with the midi data in the softsynth comes out of (this is if a softsynth has multiple outputs).

One thing that is cool about having them separate is that you can see both the midi data and a waveform preview(when activating this view in the synth output track) at the same time.

And not to forget, there's the "original" use of a MIDI track : simply to send the data to an external (hardware) synth. Don't know if anybody are using that kind of thing anymore, though :-)

I mainly use a hardware synth, a Roland Sonic Cell and I occasionaly use some sounds on my old Casio keyboard. It has a great sounding piano.

You are so right about that casio keyboard, ill take certain piano tones on my wk-200 over any pianos on any of my soft synths, i just dont practice enough anymore, my timings off so i dont record audio, i need the step sequencer...

Thanks for all responses by the way

Going by how often questions are asked about it, the so-called "simple instrument track" can be confusing to recording newbies, because the user doesn't get a clear picture of what's going on.

Even with the added improvement of having both the audio and MIDI Inspector visible on a track, I still can't stand simple instrument tracks.  So set in my ways I guess - I just Gotta see the two separate things, the MIDI track, and the audio track, so I still work the "old" way.

RB

Just to add more to this thread:

MIDI is in a sense a "Control language". it can control;

Hardware. eg synthesizer, keyboards, control surfaace, lighting controllers, in fact just about any hardware that needs switching can be controlled by MIDI. often usesd in live shows to control lights, projectors and a host of other hardware devices. Of course the hardware needs an interface between the MIDI data stream and the device that translates the commands into action.

Software. eg softsynths and other control software that interfaces the above hardware.

So in our applications its usually used to write "music" in a form that is sent to either a software or hardware synth which, with a bit more processing converts it to the audio we hear.

So MIDI always has 2 components. the data (MIDI information itself ) and the device that translates/processes the data into action; in our case the action is converted to audio.

SONAR allows you to make this whole process more transparent and hide info from the user if they choose to by displaying a "Simple instrument" track. If you choose to see more of the information you can, either by using the Inspector or by using the older SONAR way of viewing things by showing a MIDI track (all the data) and an audio track (where the sotfsynth is inserted) which results from the MIDI data being processed through a softsynth.
 
If your MIDI data is controlling a hardware module (synthesizer, keyoard or sound module) external to SONAR, there is no need for an audio track for a softsynth. Instead you will likely have an audio track/s that recieves the incoming audio from the hardware module. If on the other hand, the MIDI is controlling a lighting rig and cueing the turning on and off of lights, dimmers and other device, then there would simply be a MIDI track in SONAR into which that DATA was written.
 
one of our forum members is in a band that puts on a full show where SONAR is used to automate controls for lighting, cuing projectors, sound modules and the keyboard player uses it to generate his live sounds as well.
 
MIDI, despite it's relative simplicity (as far as computer languages go), is a very powerful and flexible means of contolling a vast array of devices.
 
Hope this helps more than confuses.

Couldn't agree more about the power of MIDI. My whole one-man rock cover live show is controlled with MIDI.

All I do is start & stop the sequencer, all patch changes for guitars and vocals are then MIDI controlled. No more jumping on foot pedals, all I have to concentrate on is playing and singing, both of which are hard enough for me, never mind both at the same time.