Let’s get the obvious out of the way. OP-1 field has one new engine, one new FX, one new “sequencer” and one new “LFO” to support velocity. It has BlueTooth support, short-range FM broadcasting and velocity sensitive keys. There are also 3 additional tape types, support for tape “projects” and each tape track is fully stereo. Everyone who wants to know this already knows this. However, there are many smaller features that either don’t get mentioned at all, or get barely mentioned.
Somewhat less obvious things
Pre-tape panning with shift + red.
Renaming and deleting of patches. Long overdue. I still hope they add it to original OP-1. Drove me nuts, since I spend a lot of time playing with sound, rather than melodies.
Endless, finger and pattern LFOs record velocity now, so theoretically you can combine that with velocity LFO to sequence a parameter change. Not exactly cutting-edge compared to automation lines in other synthesizers, but it’s something that was completely impossible previously.
EQ section has now a dynamic frequency distribution graph. Useful during mastering.
Some tape types have somewhat different tape tricks and “rewind” effect.
Both samplers now have cross-fade for the looping section.
Drum sampler can be stereo or switch between A and B samples in the same slot. (Kind of annoying that there is no way to record those separately on the unit itself, though.)
You can finally set overall patch velocity in shifted envelope screen. Really important feature. Volume discrepancy in patches was driving me nuts on OP-1.
You can finally set the range for “bend” function of the keyboard. For some bizarre reason, though, it’s only settable to 1, 2, 4 and 7 semitones, plus a full octave. Why not just give us the full range?
Non-obvious things
Value LFO now supports 4 LFO shapes: sine, square, ramp and saw.
Random LFO can be routed to individual values, while on OP-1 it only affected all values at the same time.
Random LFO can now be routed to meta-parameters (AMP volume, pitch or pan, or all at once). This effect is polyphonic! Many interesting new possibilities.
It doesn’t sound like much, but these three changes above radically expand what is possible within patches on the device.
EQ settings can now be toggled, individually or together, by clicking encoders on EQ screen. This is mentioned in the manual (I checked), but I would have never noticed without it being mentioned by Son Wu in one of his videos.
During recording and playback you can how lift the recording head by clicking the blue encoder on tape screen. During playback it cuts off all tape sound without muting the keyboard. During recording it disengages all sound sources from being committed to tape. Haven’t seen this mentioned anywhere at all.
Lost features
For completeness sake, let’s list what is missing too.
Hidden Iter engine. Not a big loss, imo.
Hidden multifilter FX. That one I will miss. Extremely powerful effect.
They’ve changed how pitch parameter works with Element, so now a lot of crazy ambient patches that were possible on OP-1 will not work on Field. This is not a complete loss, though, it’s just different functionality.
Bend and crank LFOs. You might have never used them, but Crank routed to while meta-parameter produced pretty cool distortions that you couldn’t get in any other way.
Chop lifter game. It will be missed. I’ve rarely played it, but I like having it in OP-1 anyway. It was a nice nod to old-school games, which clearly inspired something in OP-1’s UI. Maybe field has another hidden game somewhere.
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Reply with more new features if you find them or if I missed something.