Editing MIDI Files
Firstly, you can only 'tweak' a recording while it is a .mid file - before you alter it to a .wav, then an Mp3. Recorded songs could be vastly improved if they were edited in the arranger section before letting them loose for the listeners to hear. OK - you cant do this 'live' - but a recording (like a studio version of a song), should be a lot better than 'live', simply because, like a recording studio - you have a mixer, and although more primitive, everything you need to make a studio quality recording is built into the 'Arranger' section of your keyboard.
Many of us often use external programs, like Sonar, Cubase, Evolution, Reason, etc, etc. to do this editing in the computer - these programs, besides being very hard to learn and use, are not really needed, or essential for most players (although they do a lot more than the arranger section in the keyboard, for more advanced sequencing, etc..).
Firstly, 'Highlight' the .mid file that you are going to 'Tweak', and then go to the 'Mixer' Screen. You can choose there by moving through screens, whether you want to change Instruments, or adjust Volume, EQ (Top and Bottom Frequencies), or 'Panning' (Where that track or instrument is placed from left to right) - This helps to separate the instruments from each other. I personally leave the lead (usually on tracks 1 - 4) and Bass (usually on track 11) together with the drum track (on Track 10) in the middle - but if there are two drum tracks, I pan one of them slightly to the left to give the drums some 'movement.
I find on most songs, that the 'Style' tracks (usually 9 - 16) have been left as they are. They will nearly always benefit from some editing. Drums are usually the XG Format (Std Drum Kit 1) ones, and will in most cases benefit being changed to 'Live' ones - plus turning up the High EQ to hear the SShhh of the brushes and Cymbals, Hi Hats, etc. The Bass on Track 11 will nearly always benefit from an increase on the same High EQ as well. You will learn a lot by listening, as you go, to what effect you get by moving controls. Little tricks, like, for example - Growl Sax really 'Kicks Butt' if you turn up the High EQ to almost Max, and the low EQ to '3 O'Clock' Most 'Steel' type guitars also come 'out of the woodwork' with some added 'Top end' EQ. If there are two 'similar sounding'Instruments in a file, I pan them to opposite sides to separate them too, also in the lead, where there are instruments changing, I move them apart, so that they 'Answer' from each side. I think many accept the settings in styles and leave them alone, after they have recorded their .mid, but quite often they can be improved beyond recogntion by a bit of 'tweaking', even, in some cases by instrument changes.
While you are carrying out these adjustments, you can hit the 'Play' button, and listen as you go along, to hear the effect you are having as you change things. Before changing any volumes, remember that if you alter these, and the .mid has any Auto Volume changes, it will be lost, so watch during playback for the sliders on the volume to move, if they do - then dont alter volume. This also applies to fade outs at the end (they don't fade out!). If the mid has no auto volume, you can adjust the volumes, OK to get your balances between different tracks right. If it has Auto volume, you can still raise the tracks, by raising both the high and low EQ on that track. Also, If the lead tracks (on 1 to 4 usually) change instruments (Registration Changes), any Adjustments to Panning, EQ and Volume will apply to all instruments that play on that channel .... Sometimes you can get by with a 'compromise setting' that will work OK with all the instruments, as they change on that track. Also, If you change a voice on one of these tracks, the other voices in the registration will play as just the one that you have chosen, and not change instruments on that track.
Lastly, hit the 'Execute'button, then save your new version (preferably with a slightly different name, so that it won't overwrite the original, in case you have gone backwards, rather than forwards (and we all do at times!).
When you have done all the above - it is time to record the .wav, and convert to Mp3 - your recording should be perfect! Just remember, however - you have set up all the sounds to your sound equipment - whether it be at night with the headphones on, or through your 500 X 500 Watt Power Amp and Speakers. When someone else listens to your song, whether it be on Mp3 or .mid - IT WILL NOT SOUND THE SAME as it did on your system, and with your specific EQing etc of your keyboards amplifier! Geeesh! Nothing is perfect in this world.
This is just 'My take' - others may not agree with me, or what I say, or how I do it, but why not start 'Messing with Midies' - once you get the hang of it, and fluent with the operations, it is great fun, and you will end up with far better recordings ! !