Let's expand on the topic a little bit of midi controllers.
The general rule of thumb is: As long as the device (regardless of what the device is) has got a midi OUT, and your DAW has a midi IN, that device can be a controller.
People have been asking whether this keyboard can be a good controller or whether this brand is better, etc, etc., blah, blah, blah. My take is if you feel comfortable using that particular keyboard, then use it. Doesn't matter (well, ultimately it does) if the keyboard is a cheap Casio or a very expensive Novation or Korg, as long as it has midi ins and outs and/or a USB connection, you're 50% good to go.
Of course, you need to control something. A sound/drum module, softsynths, or even a DAW mixing environment, all of these can be controlled by midi in one form or another. A controller with USB midi is the most convenient for most since the midi interface is already built-in; no need for a separate midi interface. It has one caveat, though. Most USB midi interfaces are bus powered, they derive their power from the USB bus connection. My beef with this is that some vendors DO NOT supply the AC power adaptor, you have to buy them separately. My second peeve is that when bus powered, they do not output midi thru the midi ports; the only time they do is when powered thru the AC adapter. So be forewarned:
When buying a usb controller, make sure an AC adapter is included, if not, make sure to buy the approved adaptor.Next, of course are keyboards with midi IN and OUT ports. Not all portable keyboards (Casios and Portasounds) come with midi ports. Those that do can pull double duty as a controller keyboard. There are caveats: these sometimes send out strange midi or sysex messages when you press a button, some of the more affordable units don't even have a pitchbend wheel (if they do, the 'dead spot' is horrible), some don't even send out data from their internal sequencer (not really critical for most but if you want to transfer your sequences to your pc, you're screwed).
How about old keyboards with midi? You CAN use these but you have to be somewhat familiar with the way they operate, plus you HAVE to have a form of midi interface (which can be a simple joystick port midi cable or USB multiport interface). There are some gotcha's with old keys, however. For example, the Yamaha DX-7 CAN be used as a controller BUT it's max velocity peaks at 100 - full midi velocity goes up to 127; in some modules, the sound timber changes at velocities higher than 100 so make a note of that when using a DX-7. I personally use my Korg Prophecy now as a controller, I can actually use all 3 of my keys since they are all midi'ed up to my DAW, but I prefer using the Prophecy because of it's additional controls, which brings me to...
Additional controls. Pitchbend wheels, modulation wheels, joystick controllers, aftertouch (w/c is quite different from touch response; touch response really is velocity sensitivity), knobs, sliders, ribbons and pads. All of these additional controls often add to the expressiveness of a patch or sound. The Prophecy, for example, has pitch bend and mod wheels, aftertouch, a 3rd wheel (called a log) with separate control destinations for +Y and -Y, a ribbon controller in the center of the log, 5 knobs that can send 4 separate controller messages EACH. Now you know why the Prop has become my main controller. It's one shortcoming? It only has 3 octaves! Anyone who has played keys long enough will tell you that sometimes, 61 keys is not enough - sometimes I long for that 76 or 88-key Kurzweil with that long 18" ribbon on top - damned expensive for a keyboard controller, though. And let's not forget the <smirk> STRAP-ONS
like the Roland AX-1 (now AX-7) controller.
Keyboards are not the only controllers. There are drum pads, wind/breath controllers for emulating wind instruments, guitar midi controllers like the Roland GK-2A/GK-3 in combination with the GI-10/GR-33, and loads more. All of these are meant to control sound modules, whether in hardware of software.
So why doesn't everyone use cheap Casios for controllers? It all boils down to feel. How does the keyboard feel when playing? Are the keys noisy? Are they too heavy or too light to the touch? Are the controller values too coarse? All of these and more affect how you play and how expressive you want your sound to be. If all you want to do is enter notes, then a simple Casio (or portasound) will do, but if you're looking for more expressiveness in your playing, then a dedicated controller is what you're after.
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