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Juno 6/60 emulation(s)

Discussion in 'REAKTOR' started by colB, Nov 30, 2018.

  1. colB

    colB NI Product Owner

    We were throwing another thread way off track getting into discussion on this so...
    I've been working on a Juno based synth for a while now as a side project, and it's getting to the point where some parts are working out pretty well. It's hard to tell though without access to the actual hardware.

    Various stuff like:
    *what the combination waveforms look like (saw+pulse) and with different levels of sub...
    *what the rules are for the arp - does it reset as soon as you hit a key, or wait for its clock, when does it reset its clock after you release the last key... how does the external sync work...
    *curves for various controls
    *max/min settings for LFO rate.
    *how does the PW slider effect the pulse width when its set to LFO?

    when you stack the different waveforms does it get louder?
    What about saturation? if you crank up the VCA with all the waveforms on, does it get crunchy, or warm up? if so what impact does that have on the high registers, particularly if chords are played...

    Thanks for the offer to help with a few examples - that would be great.
    Basically, any elements you can isolate in different ways would be very useful. Single notes with different oscillator settings
    It would be good to hear some different intervals held for a few seconds each with saw, and maybe octaves... The envelope with different settings... the noise all by itself... all sorts :) Maybe the LFO on minimum rate, maximum rate and with the dial set to half way...
    It would be interesting to hear your thoughts on where various models are not so close to the original, and where they are pretty accurate (I'm assuming you already have some thoughts on that being a lucky owner of the real thing).
    Even if you just post a few of your absolute favourite patches with a few notes, so I can see if I can get close to the sound of them - that would be a lot of fun.
    Last edited: Nov 30, 2018
  2. colB

    colB NI Product Owner

    I also posted some very quickly thrown together examples on the other thread which I'll repost here. These are of my current WIP compared with the Juno from the Reaktor 3 legacy library - thanks for the tip Paule. The R3 version is definitely one of the better Junos in Reaktor land so a good benchmark for me.

    The third example has synth A dry then synth A with it's chorus, then synth B dry, then synth B with it's chorus
    The settings tweaked to get the sound as similar as possible on both synths
    I'll call them synth A and synth B

    Mostly IIRC, these are all pulse with pwm and some Sub. filter is mostly removed to be fair to the old library unit (Reaktors filters are way better now)
    example 1 is A,B,B,A,B,A
    example 2 is A then B
    example 3 is A dry, A with chorus, B dry, B with chorus

  3. colB

    colB NI Product Owner

    I'd like to hear opinions about the chorus as well - not how good it is, but more like what its characteristics are.
    e.g. some juno models have really full-on digital style chorus, it sounds great, but it's a massive effect.
    Is it really full-on in this way, or is it more subtle and nuanced in its feel ? Does the volume dip, rise or stay the same when chorus is engaged?
  4. m3m

    m3m NI Product Owner

    Awesome, got some work on this morning but I'll have a play with some of that over the weekend?
  5. ZooTooK

    ZooTooK NI Product Owner

    Not sure what kind of feedback you are looking for and what A and B represent but A sounds better to me in all cases, including the chorus. The B chorus is not very pleasant to my ears.
  6. colB

    colB NI Product Owner

    Any feedback is great thanks.
    Best for me would be what sounds more or less like a Juno.

    I don't really mind so much which sounds 'better'. e.g. The UL 'juno' that uses multiple detuned oscillators sounds great and really 'fat' but nothing like a Juno to my ears.

    In comparison 1, there are two different ensembles playing roughly the same thing with similar settings. (A is 1st 4th and 6th, B is 2nd, 3rd and 5th). In this clip, the figure being played is a single note line, with pulse and sub both on. 'A' sounds different because the sub and pulse are separate oscillators (not what's happening in a Juno), in 'B' the sub is phase locked to the pulse reset (much closer to the hardware behaviour).

    In comparison 2, this is maybe even more noticeable. The first synth is A in this clip, and the fact that the sub is a separate oscillator with uncorrelated phase with respect to the pulse means that the sound is much thicker and more even, whereas B is slightly thinner and more open, but maybe a bit grittier and with a more obvious octave separation - certainly a significantly different sound considering the settings are similar. (there is pulse width modulation in this clip)
    Last edited: Dec 1, 2018
  7. m3m

    m3m NI Product Owner

    Hi all - here's a first attempt at recording some Juno 6 behaviour:


    It's a Zip file containing a bunch of WAVs:
    • Notes an octave apart played with Square, Saw, and Sub oscillators
    • Octaves played with Square + Saw
    • Playing a note with a Square wave, and mixing the Sub into it (0%, 25%, 50%, 75%, 100%)
    • Mixing Sub into Saw wave
    • Mixing Sub into Square + Saw wave
    • Effect of PWM on Square wave (manually increasing PWM depth from 0 to 100% in 10% steps)
    • Noise with LPF cutoff right up
    • Noise: reducing the LPF cutoff in 10% steps from open to almost-closed (NB the final two, almost-closed steps are very quiet but in EG Audacity you can see there's a signal there still that isn't just circuit hiss)
    • Noise: increasing the High-pass Filter cutoff, 10% steps
    • Square: one note, sweeping LPF cutoff up and down 10 times, increasing filter resonance for each sweep
    • Square wave (LPF not quite open): chorus off, then chorus type I, then chorus type II
    • Square wave: chorus with type I and type II buttons both pressed
    • Square wave (higher note): chorus off, then type I, then type II
    • Saw: chorus off & on, both types
    • Noise: chorus off and on, both types
    • Arp: 3 note chord, type "Up", 1 octave range... sweeping the arp frequency/rate.
    • Arp: same chord, type "Up", 1 2 and 3 octave range
    • Arp: "Down", 1 2 and 3 octave range
    • Arp: "Up/Down", 1 2 and 3 octave range
    I hope that helps. For me, what's at the heart of the Juno is the waveforms, the character of the filter, and the chorus circuit. The machine's old, and I haven't had it serviced so I can't guarantee whether it's still behaving like the ideal Juno 6. I guess that gives if part of its character. Also, I don't want to

    EG when the filter resonance is up, during a filter sweep, the sound gets louder as the resonant frequency of the filter matches the frequency of a waveform harmonic. That makes sense... but also, I think I hear something like distortion; I don't know if that's to do with the cutoff frequency wobbling around the frequency of the harmonic, or even due to gummy potentiometers. But it's a lovely sound.

    But also... the square wave isn't at all like a Reaktor square wave, and the sawtooth is curvier than a mathematically perfect sawtooth... and the shape of the waves changes with pitch... part of that might be that, even though the High-pass filter cutoff is turned down, it's still affecting the audio?

    Let me know if any of that sounds helpful; and where the hugest gaps are... I can do a few more recordings if you think it's worthwhile.

    Cheers, have a good week!
    • Like Like x 3
  8. colB

    colB NI Product Owner

    Magic, I'll get stuck into that asap.
  9. m3m

    m3m NI Product Owner

    No worries, no pressure... interested to hear what you make of the chorus recordings though - to my ears the hardware effect sounds enormous and wild, way bigger than the digital models. I can't be sure, but I think whatever modulation it's doing changes rate unpredictably?
  10. colB

    colB NI Product Owner

    I've been playing through the examples, and they are superb - exactly what I needed. I was pleased to hear that I can get close to most of the sounds. It seems I'm on the right track. I noticed that your Juno is a lot cleaner than some of the other examples I've heard, so I was able to reduce the levels of the various noise processes I'm employing, which is a relief :)

    Chorus wise, single note held means it's much easier to get a grip on the modulation rate and stuff like that - but you don't get such a feel of the power of the effect without chords I suppose. I suspect that the big enormous wild result is a sum of the parts rather than just the chorus. I have been playing with this type of chorus - at least in terms of emulation attempts - for years, and also had various chorus pedals in hardware. The BBD ones sound great, but when A/B'd with a good digital one, the digital unit usually seems bigger and lusher to me. The BBD ones have a more organic feel though - it's just a different effect, it's thicker and less 'open'. The Juno's oscillators can produce lots of nice harmonics because of the possible combinations, but there's lots of space in there because there is still only one oscillator per voice - just a clever one. So that thick organic chorus is a perfect match, filling up the spaces in the oscillator sound - nice! However, if you had a synth with multiple oscillators per voice, I wonder if it might be a better match for the wider more open/spacious sound of a digital chorus

    One thing that's missing from the examples you uploaded is hearing intervals played simultaneously, particularly octaves. So if you ever get a chance when you're doing some recording - no big deal if you're too busy.
    The reason this is something I want to hear is that assuming the oscillators are free-running, (most) digital synths do a funny phasing thing when the pitches are locked to an interval, and it's most obvious on unison and octaves. Depending on the phase offsets between the two oscillators when the notes are initialised, the result can be extremely different each time. Analog synths behave differently in this context because the pitch is never locked, and always out by some small amount... and always changing by some tiny amount as well.
    The Juno's are an interesting case because they use DCOs. So there is a very close timing relationship between all six voices

    I want to find out if the pitches are locked enough to get that digital style phasing thing when hitting octaves, or if the variation due to the analog parts of the circuitry is enough so soften it, or if there is nothing like that effect at all in which case, at least I know I have work to do :)

    Thanks again for the examples.
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  11. m3m

    m3m NI Product Owner

    Wow, my J6 sounds CLEANER than others? That's a surprise, thanks for letting me know! Also, it's interesting you've spent some time thinking about the chorus circuit - my understanding is that the Juno sound came from Roland economising on the oscillators to make polyphony affordable, then fattening up the sound with chorus? It's definitely key to the sound, it's not just a peripheral add-on thing.

    With the intervals... I guess you want the notes triggered as close to simultaneously as possible? I can have a go over the next few days, but I'm not 100% sure how effective it'll be - the J6 has a MIDI kit retro-fitted, although I don't know how perky or reliable the timing is. Maybe you can work it out based on multiple examples?

    Anyway, good luck with them, have a great day!
  12. colB

    colB NI Product Owner

    That's not really important. The ideal thing would be to have a few stabs at the same octave in a row to see what variation there is from one to the next.

    Something else I'd like your opinion about is the envelope. I've read that there is some thing 'special' about it, something distinctive... but no further details. Is that something you have noticed? Or just part of the mojo myth that always builds up around vintage equipment?

  13. colB

    colB NI Product Owner

    I've read that the chorus introduces a LOT of noise, but yours sounds pretty clean as BBD stuff goes.
    Also just listening to pure square/pulse wave output, yours has a bit less grit than some I've heard... less noise related pitch tremble. I suppose it's a subtle difference that I'm tuned into at the moment :)
  14. sellotape

    sellotape NI Product Owner

    Many interesting questions i've had asked myself for many times. If you try to catch the character of a certain synth you have to figure out so many details that it's kinda impossible to get the right spice. It's not just one or two parts that are coloring the sound. You will find it in the whole signal flow. Eg when you mix oscillators or waveforms, input level of the filter, saturtion behaviour of the resonance, the vca and the voice sum up, range and shape of modulation signals, simply just everything. A bbd chorus is a story for itself. But even if this topic is way to complex and wont lead to a pefect emulation it will let us understand what really makes the different in sound and how we can achieve a at least more interesting or detailed sound.
    For the arp sync, it works on pulses usually send by a clock but you also can use trigger signals to make more rhythmic arps. In other words it always moves the arp one step further when the clock input goes above a certain current. Btw lots of details like lfo ranges can be found in roland's service manuals and if you're familiar with schematics you often get an idea of how things are working.
    The most annoying part is not having the real thing to test and compare so it'll be nice to expand this topic to more synth recordings just to figure out some of their behaviours. Some things might be trivial like most of the waveshape bending that in most cases occurs in dc filters but other things you never thought of will be very significant.
    Think there are many interesting things to explore and as i've already spend ages on a/b comparing and testing for very little details i'm very interested in this topic. Let's explore the devil of detail.
  15. m3m

    m3m NI Product Owner

    The devil's always in the detail - I think this is part of what interests me about ColB finding that my Juno 6 is on the quiet side (chorus-hiss wise).

    I'm guessing that individual, real instruments vary subtly in their sound, and maybe more so as they age to 30 or 40 years old? So... if you made the world's most accurate model of an individual piece of hardware, that would necessarily NOT sound like a lot of other instruments of the same class. All versions of Monark will issue the same numbers if they're configured, and their random numbers seeded, in the same way. But no 2 Moog Model D's will ever issue exactly the same flow of electrons?
  16. Paule

    Paule NI Product Owner

  17. colB

    colB NI Product Owner

    Yeah, I'm really thinking more about the I ternal clock, if external sync is not active. So when you hit a chord, does the arp start immediately, or wait for a tick from a free running internal clock?
    If it restarts the clock on a 'fresh' chord, how long does it take to reset after all notes are released. Details like this are important :).
    I've also noticed some 'interesting' arp behaviour on one or two demos. Most arps have little idiosyncracies that enable little tricks and neat discoveries. It would be nice to nail those.
    Yes, I am very familiar with the service manuals and the schematics therein :)
    I've updated my oscillator again, so I'll post some more A/B examples for you to cast you critical ear over!

    The chorus is another thing. In some ways I'm getting closer, in others it's still miles away from authentic.
    One of the problems is that the noise and aliasing from a BBD is completely different from the aliasing in a DSP system, so to get a truly authentic model, you would need to remove the DSP aliasing, then add in the BBD aliasing, then if that's being filtered in some way, model the filtering...

    Not sure it's worth it though going to that extreme. The main thing is a good chorus that recreates the overall feel of the original. So a twin rate-variable delay core with a triangle LFO inverted for the second channel. Then tuning the LFO range and delay time's until it's close.
    Possibly some companding if the original has companding - have to check those schematics again.
    Someone suggested elsewhere that there may also be a sine LFO in the chorus adding some more modulation. Not sure about that, but again, worth a look.
  18. Chet Singer

    Chet Singer NI Product Owner

    Fwiw, the Yamaha choruses of that era often mixed two LFOs together, a fast one and a slow one. Their units often had three BBDs and each LFO had three outputs of 0, 120, and 240 degrees.
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  19. colB

    colB NI Product Owner

    Ok, another quick look at the schematics, and some scope twiddling with m3m's examples and it's getting closer.
    Here's another comparison.

    Two sounds, one of them is m3m's Juno the other is my work in progress, both playing a saw waveform through chorus mode 2. See if you can tell which is which.

    Of course, this is just a single note. I expect there are many other challenges ahead when multiple notes start getting played together... and then there's the filter :eek:
  20. colB

    colB NI Product Owner

    IIRC, Jimmy Page used a Yamaha chorus pedal!