Envelope Opening Noise - Minitaur

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CleverConQueso
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Envelope Opening Noise - Minitaur

Post by CleverConQueso » Mon Jun 30, 2014 3:17 pm

Folks -
Any advice on how to minimize the clicking or popping sound you get when a note first attacks on the Minitaur? If a patch is bright, you don't notice it, but if you're delving the depths, it's very present since the pitch of the pop is higher than that of the note. It's particularly noticeable when I use a sequencer since it plays faster so there are more note events.
Thanks,
CCQ

CleverConQueso
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Re: Envelope Opening Noise - Minitaur

Post by CleverConQueso » Mon Jul 07, 2014 8:47 pm

I'm playing around with oscillator sync via the editor and that's making some gains but isn't quite it. Does no one else hear a click when they try to play a very dull low note? If I post the patch and a mp3, would you check it out on your Minitaur?

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stiiiiiiive
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Re: Envelope Opening Noise - Minitaur

Post by stiiiiiiive » Tue Jul 08, 2014 3:02 am

I'm sure you know that but have you tried to increase just a little the attack time on both envelopes?

CleverConQueso
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Re: Envelope Opening Noise - Minitaur

Post by CleverConQueso » Tue Jul 08, 2014 2:16 pm

Thanks, Stiiiive. I have but it gets to the point where the swoop of the envelope just gets too obvious. I've got two examples attached to this message where I think I'm getting close. Is this an issue you come across?
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stiiiiiiive
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Re: Envelope Opening Noise - Minitaur

Post by stiiiiiiive » Tue Jul 08, 2014 7:05 pm

Well I don't have any Minitaur actually. If the envelope attack can be heared as too long, then I guess the problem is elsewhere.

EMwhite
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Re: Envelope Opening Noise - Minitaur

Post by EMwhite » Mon Jul 21, 2014 11:01 pm

This is a common problem, or better put, an artifact of the way that most analog VCAs operate.

There is a phenomena which has been described as "zero crossing" and occurs when an Oscillator's voltage each phase is anywhere EXCEPT zero volts; it's the nature of a cycling waveform which becomes problematic the moment a decidedly quick attack VCA opens. It's more obvious with subtle textures such as sine waves or timbres with lower or no resonance.

If you've ever sampled audio then cut it up (slicing) and played resulting clip, you'll hear an obvious CLICK at the very beginning and sometimes at the end. To fix this, simply bring the sample into an editor and change the start point to a place along the x-axis at zero volts. Job done. Because there are so many samples per second (44,100 likely) you won't mess up the length of the sample or the fact that it might have been on beat from a rhythm syncing prospective. You've just moved the starting point ahead a few tens of thousandths of a second.

It's not so easy with an Oscillatorwaveforms because a) you don't have the luxury of hand editing at any point where you decide you'll strike a note and b) similar to a sample being played back, the frequency is pretty fast, even a 4th octave "A" is running 440 cycles per second... go ahead and try to press a key in the two places that the voltage crosses zero per second without looking; it's nearly impossible. And sure, compensating with a slow attack will help but it sort of loses that punch that you desire.

On more aggressive waveforms it may actually be masked by the sound or even contributed to a click/clack of a percussive and highly resonant timbre.

I've read suggestions of multing up a trigger to the sync input of your OSC (assuming you've got a modular), but I could never get this to work.

So get your hands on a zero crossing VCA, which uses digital logic to track the waveform voltage, it can 'open' ONLY at crossing where negative voltage turns to positive and positive turns to negative to avoid that 'click'. WMD sells one and STG sells one for MU; they aren't cheap but modular is not cheap. For the rest of us, or for poor minimoog and mintaur owners :D it's there aforementioned tricks and only moderate improvement. :(

Check out F Major in this old MASCHINE video on slicing; at ~1:21 of https://www.youtube.com/watch?v=QMrFPhGj1r4 you can hear how these click are obvious on a sliced up audio clip. When MASCHINE does "Detect" mode, it does choose a zero crossing point. Obviously, MASCHINE's sample slicing and an Oscillator VCA envelope are apples and oranges but the same theory applies.
'76 Minimoog, Taurus 3, Oberheim FVS + Son of 2-voice; Sequential ProOne; Juno 106; Moog Model 15; Kurzweil 250; Hammond M3; and a handful of Fender Basses Flickr!

psynthetic
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Re: Envelope Opening Noise - Minitaur

Post by psynthetic » Tue Jul 22, 2014 2:36 am

EMwhite, that was very enlightening and makes perfect sense.

Presumably this is the same thing that can cause clicking with very fast (eg: microsecond not millisecond) attack times on an analogue gate then?

I knew that fast attack times etc could cause clicks/artefacts, but never really put to much thought into exactly why, but for some reason I thought it my head it must've been some kind of distortion of the signal itself (eg: attack time going past the maximum "slew rate" of the amp or something? I don't know much about electronics, i was just taught that the slew rate of an amp is important to dynamic response etc) it's comforting to know that it's not really the device "failing" or running outside spec that causes it but more like a mechanical failure of the speaker to keep up by the sounds of it? Like popping on a square wave without clipping..?

I don't suppose you'd know/care to touch on how this relates to terms i've heard like "Hysteresis" in relation to gating etc?

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stiiiiiiive
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Re: Envelope Opening Noise - Minitaur

Post by stiiiiiiive » Tue Jul 22, 2014 4:28 am

Thank you for explaining, EMwhite. That makes perfect sense: lower pitches will be more likely to produce that.

From what I know, hysteresis is nothing related to this, but I may be wrong.
Hysteresis is the phenomenon by which a given parameter doesn't take the same "values route" when being increased or decreased.

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_DemonDan_
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Re: Envelope Opening Noise - Minitaur

Post by _DemonDan_ » Tue Jul 22, 2014 10:40 am

CleverConQueso wrote:Folks -
Any advice on how to minimize the clicking sound you get when a note first attacks on the Minitaur?

I'm not near a Minitaur right now but...

If the hidden NOTE SYNC parameter (CC# 81) forces both oscillators to start from zero then this is your solution.

If it only forces OSC 2 to slave to OSC 1's current phase then it will be of little help.

Someone who has one up and running will have to tell us if that works.
_ :twisted: _DemonDan_ :twisted: _

EMwhite
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Re: Envelope Opening Noise - Minitaur

Post by EMwhite » Thu Jul 31, 2014 10:51 am

No, that doesn't work Dan.

Yes it sync's OSC 2 to OSC 1; but OSC 1 is free running (at least according to my scope).

Drifting/beating OSCs give a nice phasing sound but the punch of having both OSCs hit at the same time is obviously why Moog added the feature.

But back to the zero crossing issue above, I've successfully patched up the WMD technology and it sounds great. Mine is in MU format and I have three of these in one module. At first I thought that I would need to actuate the filter envelope externally as well but I can just let Minitaur use it's normal VCA with no attack and let the Filter run according to Minitaur's envelope, then further attenuate the amplitude using the zero crossing module.

At present, I'm using an Midi->CV interface and patching the gate output (triggered and held open by Midi note) into the CV input of the Digital Attenuator but I'm fairly certain I can do this with audio patched into the side-chain input; I just haven't messed with it.

But it's click/pop free :D

Is it worth the $$ and complexity ? Probably not. Can Amos add a new feature in future to provide a sync option to eliminate the click? (maybe but maybe not); the WMD architecture uses a dedicated micro controller per cell so there are three of them which run autonomously... And it's only good up to about 14 kHz or 15 kHz which is pretty high. Think about it, in order for this to work, it's got to digitally track the waveform and then trigger at the precise moment that zero crossing occurs. The Minitaur is very busy with other activities such as watching for midi interrupts, running and calculating an LFO, executing envelopes, etc. On the other hand, if the Minitaur code can programmatically reset the phase of OSC2, maybe it can also do OSC1... or maybe not... depends on how the VCOs are implemented in hardware.
'76 Minimoog, Taurus 3, Oberheim FVS + Son of 2-voice; Sequential ProOne; Juno 106; Moog Model 15; Kurzweil 250; Hammond M3; and a handful of Fender Basses Flickr!

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