Anyone know how I can edit sources from both mono and stereo (12 and 16 bit) in the same project in Premiere 1.5 without acheiving tinny or muffled sounds?
Is it possible to duplicate the mono sounds to make them sound nearer to stereo or is there a simple way?

Thanks

ok, open a new 48khz project (48khz is the sample rate for 16bit) in the screen aspect you desire,
import your footage as normal, the 12 bit footage will capture but will require to be rendered from 32khz to 48khz on the timeline (when you drag a 12bit 32khz clip ontot he timeline it will appear with a red line above it, go into sequence, then render)

12 bit can be stereo at source, usually 12 bit is used where you want to have two audio layers (much like on a dvd when you can select a different dubbed language or directors commentry)

On many cameras the bias between each track can be altered at the playback stage so that you hear either all of one layer, all of the other, or a mix of the two. If you consult your camcorder handbook it will tell you how to adjust this setting, this may beef up the sound of your desired track by giving more emphasis to it.

Once you have your clip on the timeline highlight the clip then go into 'effects controls', go into audio filters and you should have a command to duplicate left, or duplicate right, mono recordings are usually on the left channel, this will give you linear stereo (i.e. identical sound from both speakers, no stereo overlap or phasing) you can also find pan controls within the 'audio mixer' window if you want to shift the ballance to suit your subjects orientaton in the frame.