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 Forum index » Clavia Nord Modular » Nord Modular G2 Discussion
Module bugs and undocumented specs
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Electromagnetic Wave

Joined: Apr 28, 2013
Posts: 263
Location: Kebek
G2 patch files: 37

PostPosted: Sun Feb 11, 2018 9:34 pm    Post subject: Module bugs and undocumented specs Reply with quote  Mark this post and the followings unread


I often read important details about the G2 which I forgot with time or I do not remember well. That's why I did this gathering. The forum search tool (or search engine with advanced options) remains a very efficient way to get information. But this gathering can be useful to guide the construction of a patch and the choice of modules to be used. Or to understand how to correct gaps in a patch without reading several topics and then do something else and lose the workflow!

I thought that including the module bugs and undocumented specs booth is a good idea. Because sometimes the solutions are not in the topics of the bug section but in the G2 Discussion section.

Feel free to add more module bugs (with solutions when available) and undocumented specs here.


Undocumented module specs

dx modules
The real DX7 envelopes have some 'bugs' that never seem to get copied in emulations. That is why the factory patch watergdn won't sound the same without fiddling

The module seems to be incorrectly named because the D is really the R....The Attack-Hold-Decay envelope is an envelope with three stages: Attack, Hold and Release

FltLP 6db
the NM's 6db/oct LPF has a tendency to react to it's input dropping to a steady zero by (sometimes?) going unstable and outputting either a positive very small value or some sort of noise
some filter topologies don't like too short word lengths (low resolution) in the internal filter states, which can lead to the filter getting into an unstable region when you feed it very low frequencies

Classic filter
The Classic filter has a little bit of compression built in, which is absent on the other filters

Saturate module
soft clipping is used in the G2 Saturate module

Clavia may have done something clever to keep from loosing those bits, and calling the output a "gain" would not accurately describe what's going on inside the module...My guess is that Clavia actually "gains up" the signal to a full 24-bits *before* the compression, then divides it down before the output, which is where it needs a reference level to translate to, rather than a simple gain measurement.

Bug :

the envelope retriggers every time a key is pressed or released which seems very odd. I could see it possibly retriggering for each key down, but not on a key up. For instance, I can hold down a note, hear the envelope sweep, keep holding that down and press another key the envelope sweeps, release the key and the envelope sweeps again.
use the monokey module in the FX section to trigger/gate the envelope (and disable it's auto trigger/gate)

X-fade Multiplexer
If you feed a blue line into Mux 1-8 and 8-1 modules, they will only change values when the input crosses over the lower positive quarter of the value range. If the complete blue range is -64 < x < +64 (if memory serves), then a mux 1-8 will slide from 8 to 1 when x goes from +32 to 0.
So if you want to constantly change mux routings with, say, a random module, you need to route it through a mixer set to linear 50 or a multiplier set to 0.5.
This doesn't apply to, for instance, SeqCtr modules

it's control input does not use the same range as any of the other mux control input (8-1 or 1-8 out). looking at the help file, it should.
rather, I have to amp the singal by over 2x to get it to track like the others

the problem seems to be the the drum synth actally, it's not completely shutting off it seems but it needs the pitch shifter and a lot of amplification to make that audible .. when you toggle the mute button of the drum synth the effect comes and goes ... when you add a noise gate after the drum synth the problem is solved

Osc Percussion
hearing noise would mean repeated triggers for the perc osc
very quickly after the positive edge immediately a negative one follows

the stock G2 filters do nothing in the most upper frequency range settings. Shocked I mean, they simply stop working altogether, regardless of slope setting.

There was another remark in the article ... about at high frequency settings the filter no longer working as a filter ... didn't the Clavia filter have this issue too?...
Yes, the FltLP module has this problem
Yes, but strangely the FltHP doesn't. I suspect it's just a scaling error.

allpass filter
I have been playing a bit with Nord G2's allpass filter(the multimode filter set to 6db and use BP output). But from how I understand allpass filter and how I have used them before, it doesnt really act like an allpass filter.
The G2 SVF in allpass mode does indeed have unity gain issues, probably because of the way the integrators work in a SVF topology (only conjecture, would have to tinker to be sure)

Sequencer Rec Input
there is a problem with the sequencer modules control level and logic signal outputs being delayed well after the clock signal arrives to advance to the next step. But, signals patched to the value and trigger/gate inputs pass through the sequencers immediately with each calculation cycle, so the delay problem is with the step advance, and not completely with the outputs
Add a logic delay module to keep everything in synch. Even the minimum delay time of 0.10ms can be enough time for the sequencers to catch up.

When assigning the length of a sequencer to a morph knob, changing variations will cause the sequencer to restart at position one, even if the morph is at the exact same position in both variations
sequencer resets when you change length

when any input is connected to Rec Enable, or Rec Input, the value output is set AFTER the trigger event goes from low to high. And in some cases even set to a wrong value.
The workaround to the problem of wrong notes in NoteSeqBug1 is to add a delay of 0.09 msec

in the SeqCtrl, when you change the value of the right slider from the select one, it modify the output (of course xfade is off).
An example: the seqctr out is currently positionned on the slider 1,
if you move the slider 2, when its value reach the slider 1 value, the output value is increased by 1
Fix :
by inserting another seq module before. The value from the other seq can be set at 64 (bipolar) or 1(unipolar). These values have no effets on the other sequencer (altering the sum from the 2 sequencers). Just be sure to use the same mode uni/bi polar on the 2 sequencers.

switch 8-1
The switch 8-1 module is not sending correct CC values when you Dump CCs useing shift/patch on keyboard. Values sent when clicking on switches:
Switch______Val clicking switch_____Val on DUMP CC

midi control send modules
I have lots of midi control send modules linked by the yellow send/receive pairs the G2 starts to loose resolution on the CC's it sends
The problem seems to be much less present if you turn patch to monophonic, or you move as many as possible ctrl send modules into FX area (that is monophonic)

it appears as though when on 1/96 that the patch start time is slightly variable and causing me some problems
changing the division from 1/96 to 1/16 will fix it

clocked delay module
clocked delay module was only timing to the maximum value of the delay module (0.5sec, 1sec, 2sec etc) and ignoring the clocked value selected. Even setting it to very low values resulted in the maximum delay time.
turn off/on the 'MIDI Clock Receive' parameter from the System menu

Only the 4-tap delay has a "direct" output that is not modulatable. The G2 delays suck, as all the modulatable tap outputs increasingly degrade the signal (probably through buggy interpolation) when used for looping.

some background noise built up to an audible level in just a few minutes...
When the feedback level is set below 100%, the original sound decays to silence but the artifacts remain audible indefinitely...
If we call the maximum output before clipping 0db, then the output of a sine wave oscillator is down 2 bits at -12db. A delay module with internal feedback, such as Delay A, decays to silence without producing any lingering artifacts whenever the feedback parameter is set at or below 50 (64). At a setting of 50.8 (65) after the source signal has decayed to silence the artifacts are at -78 db. When compared to the original signal at -12 db this yields a s/n ratio of 66 db. Keeping in mind that these artifacts persist indefinitely, any patch using a delay like this can have a s/n ratio as low as 66 db... At higher settings it gets worse, up to 16 db worse, yielding a s/n ratio of only 50 db. When the feedback loop is set to unity, I can't measure the noise floor because the source signal is still present, but by listening I guess that the artifacts are only about 20 db quieter than the source signal. So much for 24 bit audio

Demo Bug :
The TriSaw waveform is unipolar.
The Demo Software has this bug, but the G2 1.4 OS appears not to have the problem

the LFOs seem to hold sync quite well at low bar multiples/bpms but lose it as the LFO gets slower



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Joined: Feb 28, 2005
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PostPosted: Mon Mar 26, 2018 11:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Nice post, good info there.
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