Hi Nico,
the Juno is BBD based chorusing. It's using MN3009 BBD chips which produce delays ranging from 0.64 ms to 12.8 ms according to the datasheet for that chip.
Taking a look at the circuit, TriceraChorus isn't set up the same way so you won't be able to do an exact model with just one (The L/C/R LFOs are 120 degrees rather than 180 degrees apart), though you might be able to do it with two in series provided that the second one is receiving stereo input from the first. That would be a luxurious way of doing it, though, so here are a few other suggestions that may get you closer to the sound you're looking for using one TriceraChorus:
- Use a 50/50 wet/dry mix
- To mimic different L/R speeds, you can try having the BBD chorus only on the Left, and then have the Detune set to 0 L -4 R (or something similar — key thing is having the left at 0) with Detune Mix at 50%. The detuning effect will work differently in different registers, so you may notice the "rate" on the detuned side seem to shift if you go up an octave or two. One caveat here: you do need to be using stereo input and output for this to work. (In mono to stereo, TriceraChorus will send the modulated signal to the left and the dry signal to the right when only the L voice is on, which is not what you want here)
- Roll off the high end a little and boost the output gain to make the sound warmer
- Try different instrument sources in the H9 settings. The synth source (not synth bass) will be brighter than the guitar source. The bass will have a similar profile to the guitar, but with more low end.
- Try delay settings in the range indicated by the datasheet. In chorus mode, the delay knob sets the minimum delay.
- You might also experiment with chorale mode for the more active I+II sound, since that uses three LFOs per voice. Two of the LFOs are fixed rates, one fast, one slow. If you use low rates, you can minimize the effect of the voice's main LFO. One other thing to be aware of is that in chorale mode, the delay time for a voice is going to be inversely proportional to the depth. At 25% depth, the shortest delay will be approx 75% of the delay time.
This site may also be useful: http://www.florian-anwander.de/roland_string_choruses/
