digital artifacts

i've noticed a few different areas where audible high frequency artifacts appear. i don't know if fixing them is beyond the limits of the processor, or if they are purposely left in for extra "digital" character, or if there are any more significant firmware updates planned, but i'll document them here. i'm using 0.36.

1. knob zipper noise. i hear this on the overdrive in the mix section, when rapidly turning the drive knob. slewing the knob value would be a typical fix.

2. envelope noise. i hear this most pronounced on the snare and clap envelopes, set to zero repeats, with a moderately fast attack time.

3. auto-panning noise. this may essentially be the same as the first two since they all have to do with amplitude changes. if i set a sine or tri lfo to control panning, i hear zippers as it changes direction.

4. triangle phase offset. does the triangle waveform not start at zero? with no attack i hear a click at the start of the sound.

5. separate from number four, the already documented phase reset clicks on overlapping amplitude envelopes still exists. i program my envelopes around it, but it sneaks back in when i morph. no real workaround until the envelope level check gets implemented.

6. sine artifacts. i hear high frequencies in low sines, probably due to wavetable size or sample rate limitations. not a biggie for me.

there are probably other zippers and clicks having to do with lfos and amplitude that i havent noticed yet.

i enjoy some of the artifacting that happens. i appreciate the extreme ranges that allow intentional destruction (very low pitches, or parameter switching on kit morph for example), but it would be nice to see some of the simpler more obvious ones cleaned up.

i'd take a stab if i could get the tools to install on my ancient computer.


  • edited October 2015
    I can confirm (maybe) all of these. 
    I have some things written in a txt file @ home, will check it out when I get off work.

    By far the biggest issue for me is the phase reset clicks. 

    Also, another thing that bothers me, though unrelated to these artifacts, is the tuning of the FM oscillator (mix mode). It's detuned by -50 cents from the main oscillator. A workaround would be to detune the main osc by -50 cents, but then your whole LXR won't be in tune with other synths so that isn't ideal. We should have a fine tune for the FM osc as well, or at least have it in tune with the main osc by default. Can anyone else confirm this?
  • good catch. i just tried it out: i have a single step, decay that lasts almost as long as the pattern for amplitude and fm (no mod env), same coarse settings, and i hear the beating finally stop when i get the fin setting down to -63 (which i believe is -50 cents, right?). i was wondering why i could never get consonant fm sounds.
  • also sounds like the fm oscillator doesn't reset, since i'm getting clicks even with no overlapping envelopes.
  • thanks for trying it out. indeed, -63 is -50 cents. and yes, i can confirm the phase reset clicks for the fm oscillators as well.
  • Yeah i'm noticing all that clicks too unfortunately. They are present in every track with LXR. I doubt Julian will fix this stuff :(

    It is more likely Brendan Clarke could look into this within his custom fw i guess.
  • is there a reason why Julian might not fix this or at least give us any info about all these problems?
  • He is too busy i guess
  • Brendan Clarke has phase reset fix in his to-do list
  • Hi! Just to check in after some back and forth with theandru - I have a 'proof of concept' firmware (based on my custom one) that forces the oscillator to not reset on retriggers. It only works on drum sounds - and keep in mind that there may be several reasons for a 'click' at the beginning of a sounds. But you should be able to make a continuous tone with retriggers that doesn't click by setting the main osc to a sone or something, attack 1 or so, some large decay and turning everything else off. It's far from done as it introduces several other issues, so be warned!

    It also retunes the FM, this isn't difficult, but will need to be discussed more since this change will alter how patches sound (particularly, I suspect, hi-hats and cyms).
  • Yeah. I tried this FW and clicks are still present when you retrig kick for example. I guess it is here because kick tail is being cut abruptly without any fade out. 
    When i do similar things with nord micromodular everything works just fine without any clicks.
  • there are several reasons you might get a click, this eliminates one of them - again, it's not meant to be a useable firmware, just to show that the osc phase reset can be switched on and off. Things like setting attack to 0, using a filter, or any of the mod sources may also cause clicks on retrig. I'll look into those - some may be desirable.
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