to change the bass you need to insert a bass synth(cakewalks studio instruments/bass guitar is perfect for this.
but to be honest you would better far with a keyboard or the piano roll.
those bass accompanyments <<that, are great.
as for synching its easy.
but first you need to explain what you want to do here ..is sonar the master or the slave?
have you set up your drum machine to send midi signals?
if you dont then this isnt going to work.
its not about MMC is about midi synch.
under PROJECT in the preference menu,select MIDI.
look over to the right and you see the part where it says "SEND MIDI SYNCH" ??
you need to check the first two boxes:
(TRANSMIT MIDI START/STOP and USE START NEVER CONTINUE.)
also the menu on this part has a section where your drum machine must be checked( a tick mark )
youll see it,depending on the devices you are pluging in it may only have your drum machine and your audio interface,
make sure the drum machine is the only one checked or sonar will go bananas looking for other data and will possibly crash.
thats it,dont go messing with any other buttons or anything.
simple.
but make a note so when your done,you know which buttons to switch back,butcause you need to un tick the boxes when your done synching because heres what happens.
when you hit the start button in sonar,your drum machine will begin playback.
what you need to do is experiment a little bit.
because not for nothing what is simple for some is a little indepth for others.
midi signal doesnt send any sound,so your bass is just an impulse and nothing more,its not a sound,sonar could care less about what your sound is,thats up to you to determine.
so think of it like that.
here comes an impulse...what are you going to do??
well set up the catcher mit and catch it with a bass synth instrument.
P.S.- you cant do the bass and the drums at the same time so make sure when your sending your midi data from your drum machine to sonar your not sending both(drums and bass midi)
because even though the bass is an instrument,its still going to send impulses and those will make sonar think you want these impulses as drum parts...so you will have drums flying every where.
remeber set up your drum machine to send midi messages.
if you are already using the machine with session drummer or something,then it should already be sending them.
it might be worth it to mention in the drop down list in the track box look for your drum machines drum map,sonar comes with alot of drum maps already in memory.
do your drum track,then your bass track.
by making sonar the master like i have explained here your tracks will line up perfectly and you will love your life....and me for giving you this in depth tutorial on midi.