I just got my Duo today (actually 2 - 1 for me, 1 for a friend).
I am disappoint.
The 2 VCOs on both of the Duos I have will lock together if they are closer than a few Hertz in frequency, or if the 2nd VCO is set to a multiple of the 1st VCO. This makes it near impossible to get the type of slowly detuning synth sounds that people tend to like. I can tune things somewhat close to a nice slowly beating unison, and then the waveform will suddenly leap to a static pulse wave, that often sounds quite nasal.
I'm not sure if this is a "feature" of the Duo, in order to get specific intervals, or if it is due to coupling of the VCOs through the power supply. Probably the latter. Regardless of the cause, it makes it much more difficult to get the types of slowly beating sounds I like in my synths. I could use my own signal processing to fatten things up (ValhallaÜberMod makes unison sounds out of simple synth waveforms), but this kinda defeats the point of having a 2 VCO synth. Plus, the sound of a single waveform synth through a chorus will be different than hearing the 2 VCOs beating through a nonlinear VCF.
Has anyone else got their Duos yet? If so, have you found this to be the case?
I wonder if there are any simple mods that could reduce the coupling. I'm no expert on analog (far from it - my soldering skills are pretty poor), but it seems like there could be some improvement with isolating the VCOs from the power supply. Or maybe there is only so much you can do with the 3.3 volt power suppy that those 2 AAA batteries provide. I tried sticking some fresh Duracells in there, and had the same issue.