In simplest terms a master keyboard guides the sounds to your equipment using MIDI - a sort of creative control center used to play your own sounds in the sequencer or as a control unit for your sound modules or cards.
A master keyboard normally offers very few built in sounds if it offers any at all. Instead the focus is on easily useable keys, buttons, and other controls for MIDI such as sound selection, pitch bend, modulation, volume, etc.
Music teachers often suggest their students switch to a good keyboard as soon as possible or simply start with a piano keyboard as it is extremely important for learning proper playing technique. For this reason those who work mostly with MIDI recording are increasingly opting for sound modules instead of fully equipped keyboards. Because the money that is saved by purchasing the modules makes up about half the price of a good master keyboard with weighted keys.
The same conclusion is often reached by people who have experienced how prone to issues the keys of some synthesizers are when compared to the other elements. That is to say: when something breaks it’s usually a key. When this happens you usually have to send the entire device in for service. During this time it isn’t possible to even play pre-recorded songs because your sound generator is missing!
Regardless of which reason has led you to choose a master keyboard you should keep your fingers away from keyboards with mini keys! Learning to properly play on one is nearly impossible. These models are meant for vacations, the street and for those with a shortage of space but not as a main keyboard.
Apropos shortage of space: Recently there have been more and more models entering the market with only 25 keys - these have full size keys though and come with a considerable number of controls considering their size. These should be particularly interesting for those short on space (as mentioned) or for people who travel a lot but don’t want to compromise on key feel. While they are still no replacement for a full size one these mini-midi-keyboards can be used to record a quick chord or tune.
Normally the MIDI Out of the keyboard is connected directly to the MIDI In on the MIDI interface and the MIDI In connectors of the individual samplers are connected to the MIDI Outs of the interface. In this case the sequencing program takes care of the data transfer to the sampler, with the advantage being that you can set the MIDI channel, octave position and dynamics directly in the program.
First, check if any MIDI data is present at the MIDI In connector of the MIDI interface (most sequencing programs provide a display, if necessary, you can also start recording and check your program's Event Editor for notes being recorded). If this isn't the problem, then check if the MIDI Out connection of the master keyboard is correctly connected to the MIDI In interface and that the MIDI interace is correctly installed.
When data enters the sequencing program it needs the ''MIDI thru function'' in your sequencer to transfer the notes in real time over the MIDI out port to the connected sampler or internally to the sound card. This function has to be on! You can usually set which MIDI channel you want to control by changing the MIDI channel of the currently selected track. Similarly, you can also transpose via the sequencing program or change the touch dynamics.
Since your master keyboard is not connected directly to the sampler(s), only via the MIDI interface, your sequencing program is needed to transfer the played notes to it or the built-in sound card. Many MIDI interfaces offer the option of transferring the MIDI data directly when the computer is off if they don't do it automatically. For others though you will need a MIDI adapter (just connect MIDI In to the interface via the adapter with MIDI Out).
If you would like to use the built in sounds of your synthesizer or the sounds from another sampling device (sound modules, sound card etc.) in your sequencing program, then you need to set your synthesizer to ''Local: Off'' mode. This function is normally located in the basic settings of your synthesizer (where you can also find the MIDI send channel). In ''Local: Off'' mode, pressing the keys produces no sound but the notes will be transfered like normal over the MIDI Out port to the connected equipment (probably the interface in this case). However, signals at the MIDI input of the synthesizer are played back normally.
If the function ''MIDI Thru'' is active in your sequencing program then the data will be automatically trasnferred to the connected sampler, sound card or to your synthesizer. You can then set the output or the MIDI channel and choose which notes are transferred to your sequencing program, and your synthesizer will only play them once the data is sent back to it.