Worth knowing: I’m writing this as someone who has never used an octatrack.
It’s a fascinating device as the audio quality is extemely high, yet it’s a machine that seems always ready, even eager, to get very noisy indeed (and through the multimode digital and optional analogue filters alone, there are many different ways of doing this). But it can stay clean if preferred.
When I bought one, my choice was between an LD3 and an octatrack. In the end my main reasons for choosing LD3 were its 8-note polyphony, its allowing stereo sampler configuration and its heavy focus on granular processing. The LD3 is significantly more expensive than an octatrack, especially with analogue filters, extra audio routes and CV system added. But I don’t regret picking it.
Although it can be confusingly deep owing to its versatility, LD3 is mostly easy to learn. One distracting aspect to it is that it uses potentiometers instead of rotary encoders. Its eight control knobs are important in setting up patches and fine-tuning the unit’s many, many parameters, and to have these settings jump around when you enter a menu and turn a knob can be irritating. It certainly doesn’t ruin the experience for me, but I can’t help feeling that rotary encoders (like on octatrack) would have been more sensible.
The on-board effects are unusual, perhaps the reverb most of all, because they mostly seem to be derived from the same granular engine. Thus the reverb effect resembles an actual reverb only with a specific combination of parameters, and otherwise sounds completely different. The granular engine is unlike anything else I’ve heard - grain envelopes are by and large not smooth and don’t crossfade very well, resulting in lots of clicks and glitchy textures. I feel that this rough, glitchy style ties into the readiness of the unit to be noisy - I think Gotharman likes to make a nice racket and has engineered this thing to do that first and foremost and indeed very well. Creating smooth granular pads, as I’ve spent a lot of time learning to do, is possible but can require careful patching. I don’t know how octatrack compares in this regard.
Thus the time-stretch effect can often sound very crispy/crackly and not that clean, although at certain settings (short stretch, high sensitivity) you can get incredible elastic sounds that I enjoy very much. I’d be happy to record a demo later if you like.
I like the stretcher, pitch shifter, pitchshaper, resonator and output granulator effects most of all. It has also a very versatile EQ, but this gives no information about frequencies - nearly all parameters across the unit use the same 0-511 value ranges. I think that’s weird and awesome.
The sequencer is quite interesting. It is limited to 64 steps, but it is possible to morph (with a knob or by modulation) between two sequences in the same preset, and it is also possible to play back ‘songs’ comprising chained presets, which load without any latency, seemingly thanks to the unit’s low-level assembly coding. You could therefore have the unit play an entire composition back for you, if you take the time to create all the presets and record or dial in the sequences.
You can modulate parameters such as gate length, note values and even note positions (aside from grid and step views of notes, they can be viewed also from a cool parametric perspective to determine where in the sequence they appear). However you can modulate only one such parameter at a time per sequencer. You can set (and modulate) swing, microtunings. You can set sequencer trigger probability and random offset timing. You can set the number of steps for each sequencer, allowing polyrhythms; whatever their length or resolution, they all follow a single internal or external BPM.
Samples are easy to load onto the unit via a USB dongle; I haven’t yet tried recording them directly. It processes live audio as well. It can of course be used as a regular looper rather than as a sampler voice, but I’ve found that it prefers to be the latter. It hasn’t too much space for very long files, but it can still load anything instantly once it’s on the device.
I’ve rambled a lot and kind of lost my train of thought. I’ll see if anything else comes to mind. I’m happy to try and answer any other questions or post any specific audio demos. Felix (@NightMachines) is a bit of an expert with the LD3 and the new SpazeDrum devices, so I’m sure he could chime in with videos and advice too.