How to record a Roland MC505 Sequencer??

What you have to do is just create an AUDIO track and arm it for recording. Select your Apogee Duet audio-input as an input source for that track by click-holding an Input selection slot under I/O section on the track's channel strip (either in Mixer or at the left side of the Logic window).

Highly recommend at least skipping through the beginning of Logic's User Manual, especially recording section and working with tracks. No offense, but I see questions like yours on a regular basis and I wonder what makes people so unaware of having all information they need at a few clicks of their mouse...

If you want a quality answer to your question, do formulate it correctly then! You said you wanted to "record sounds" and haven't mentioned MIDI at all.

In this case, I'd say nothing more except that you must spend some time studying both Logic's and MC-505's manuals, as well as the corresponding terminology. It will only do you good my friend. Good luck!

It would help to understand that MIDI and AUDIO are absolutely two different things. You don't 'hear' midi, you only 'hear' what audio the midi is triggering. It seems like you want to record midi to logic express in a way that triggers the sounds in the 505's 8 different channels on individual tracks in logic. MIDI is the computer information or 'data' that is sent from your controller keyboard (Either some other keyboard, or the 505 itself) that triggers the sounds in the device that you want to hear the sounds from. It seems as if you know how to hear your 505 audio in logic express already, but it seems as if you would like to know how to trigger each and all of the 8 individual channels of sounds from your keyboard or controller in a way that allows you to record the midi data or info into logic express on individual tracks so that you can edit the midi information of those individual midi tracks in logic and that allows the midi info you've recorded into logic express to trigger the corresponding channels on the 505 in a way in which you can hear it play on the 505? To put it more simply, you want to use logic express to record or sequence the midi data that will trigger any channel on the 505 from logic express so you can do your editing, not from the 505 but from logic express? Is this right? (know I crazily repeated myself above) - Reub.