# Confusion with 102 Group

Hi
I am new to 101/102 and probably should go much slower…and I may have a complete wrong understanding of the group section of 102

Here is what I try to do:

1. Create a track with 4 steps
2. On group 1 select step 1 and use group modifiers low x to change CV-A
3. On group 2 select step 1 and use group modifiers low x but change CV-A to another pitch

My understanding is that by changing the group between 1 and 2 I should be able
get the different modifiers… means the values i gave to CV-A should change, but this
is not the case…

it only works when:

1. Select Group 1
2. invert, now the modifier changes to the invertet Group 1 Value
3. Select Group 2
4. press invert 2x, now the modifier changes to the invertet Group 2 Value

somehow i have the feeling that the Group is not “updating” when changing.
I only can see the change on the display but not hear it by CV-A
(when focus the group modifiers and changing between Group 1 and 2.)

Thanks for any help,
Pe

ok, i give up for now…just can’t get my head arround this.
Would be very nice if someone makes a video which shows the diffrent Groups (not only number 1) and how to use it.

its a mystery right now to me.

best, Pe

It sounds like the only thing that you are missing is the fact that group modifiers compose. A step can be a member of multiple groups. The final modification of the step will be the composition of all of the group modifiers in which it is a member.

So in your example, where step 1 is a member of group 1 and group 2, the final modification is:

`modified_step_1 = G_2(G_1(original_step_1))`

where G_n represents the (active) modification for group n. The G_n modification is itself a composition of the X, Y, and Z modifiers. The ability to overlap groups is crucial to getting the most out of the 3 mod channels (X, Y, and Z).

Take this usage case as an example: You want to use mod channel X to transpose the pitch of an entire sequence and channel Y to alter the gate duration of all the down beats. You could add the entire sequence to group 1 and add only the steps that fall on a down beat to group 2. These down beat steps will also be part of group 1. Group 1 modifier will arrange for pitch transposition via channel X and the group 2 modifier will arrange a modification to gate duration under channel Y control.

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excellent.

i can’t say that i fully grasped the whole concept / application yet, but i enjoy the challange…

thanks! for pointing in the right direction. i need to settle in

pe

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I’m still on the ER101 side of things too.
Don’t understand much how things work on the 102 side, I’ll just leave it and maybe one day I’ll understand how things work.
What I really would like to see is some vids about the whole process, step by step.
Wondering why nobody made a tutorial on YT.
I really believe in the power of this sequencer but it’s hard to get my head around the mathematical approach.

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Hopefully someone as affable as @NeilParfitt will pick up doing tutorials for the ER-101/102. While the ER-101 was straightforward the 102 is a bit elusive.

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I also find the 102 difficult to fully grasp :-/

I should also mention that I’m dyslexic so I find reading my way through big chunks of text difficult.

Some video tutorials would be very welcome but I do appreciate making them takes a lot of time and effort.

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Thinking in layers help for me. Like in Photoshop, all layers alter the one image.

now lets practice

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Thank you, unfortunately I’m not so familiar with Photoshop although I do understand the layers needed to build.

visualizing the process may be less abstract…although i can’t say that i can speak as an authority… : )

Layers in Photoshop are like transparent sheets, each sheet can act as an filter, altering only defined parts, or the complete image. Now you can stack as many layers you want on top of the image.

Regading 102: The layer would be the group and the image the track.

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Eureka, things finally fall in place.
Parts en Groups are clear to me, although I’ll still have to make it my own…practice,practice
This week the Recording section is up.

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Question: is only one Group active at a time, or are all defined Groups acting simultaneously? I suspect only one group at a time is active, but what I can’t figure out is how to switch to a different Group. I can scroll through the different Groups, but only Group 1 has the little dot in the numerical LCD lit…

Thanks!

All groups are active simultaneously and it’s the sum of all the differences of the group transforms that are finally added to the value.

"the order of transformations across groups and channels does not matter because transforms are always applied to the original parameter value, then the original value is subtracted from the transformed value, and these differences are accumulated. Finally, the accumulated differences are added to the original parameter value to get the modified parameter value.

…if there where two groups with all three X, Y & Z transforms on both groups then the `FinalCV-A = OrigCV-A + G1Xdiff + G1Ydiff + G1Zdiff+ G2Xdiff + G2Ydiff + G2Zdiff` where `Xdiff` etc is the individual transform differences

For those who care: the motivation for the above method was to combine the transformations in such a way that one group/channel transform would not magnify or diminish the effect of another group/channel transform. This automatically implies that the effects of the transforms should be superimposed (like waves). Hence, you get the above procedure."

Here’s the pseudo-code Brian provided with the discussion:

Code:

``````# Accumulate transformations and gradients for the current step about to be played.
Let orig[P] = original parameter value for the current step
Let final[P] = final parameter used to render the current step
Let transform[P,G,C] = current selected HI/LO transform for parameter P, group G, channel C
Let gradient[P,G,C] = slope assigned to parameter P, group G, channel C
Let mod[C] = control voltage present at the CV input of mod channel C

for P in {cv-a, cv-b, duration, gate} do
sum = 0
for G in {groups containing current step} do
for C in {X,Y,Z} do
sum += transform[P,G,C](orig[P]) - orig[P]
end
end
# final parameter value
final[P] = orig[P] + sum
end
``````
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thanks for that. I’ll have to read more closely and continue to experiment. So what does the little dot in G1 signify…just that G1 maybe has steps added?? So if I had steps/transformations, will the dot appear there as well. I’ll play around with it some more. I’m pretty early on with it, but I can see how this is an absolute beast! So clever and cool! I didn’t think anything could give the Monome apps a run for their money, but this combo plays in the same neighborhood.

Cheers.

Yes, the dot means that a step or steps for that track are assigned to that group.

I agree, the potential for complexity using groups is huge - have fun!

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One more question…is there an easy way to turn a Group on and off? I suppose one way is to pull any cables out of the xyz inputs, and avoid assigning any transformations to the ‘low’ setting.

There is a setting in the CONFIG.INI that might be of use to you:

``````[Groups]
; Should the mod CV be gated by its associated mod GATE?
;
; true | false
gate-mod-cv = false
``````

Setting this to `true` will allow you to block the mod CV signal when the mod GATE signal is low. You will still need to keep the low transform as the identity (empty) transform but at least you won’t have to resort to pulling cables.