[FIXED] Using CV Input 1 to clock Table not reliable

[SynthBu]

Excited newbie here. I’m trying to do Steve Reich’s Piano Phases using NerdSeq plus Pamela’s New Workout for generating clock ticks. I’m a pianist who loves modern music, which makes me very detailed oriented, and I want to duplicate Reich’s intent as much as possible. I’ve seen the XOR video on Piano Phases using Nerdseq but I want to do it differently. 

Reading through the forums I found that one can control steps in a table by using CV Input. Yes, the Nerdseq is all powerful! Therefore I created a trivial Pattern with just a single note C-2, and then transposed that note in the Table to get the 12 note loop needed for Piano Phases. 

And it almost worked perfectly. But it turns out that roughly 1 in 20 times the clock tick from CV Input 1 is missed and the note sounds for two ticks, completely throwing things off. 

Being an engineer I of course debugged:

• Using Nerdseq clock as input to the table works perfectly (though then can’t do Piano Phases). This means that using a Table should be okay. 
  
• Using other inputs such as CV Input 2 did not work in same way
  
• Looked at the input signal using a scope and it is very clean
  
• I thought perhaps the voltage level was insufficient so added a VCA to boost it from 5V to 7V but that did not make a difference. Plus I found by turning down the voltage the clock still worked same way until dropped to about 2V. So seems it can’t be voltage level.
  
• I tried using the clock output that never varies to make sure the Nerdseq wasn’t trying to adjust a varying clock.
  
• I tried slowing down the clock ticks but behavior was still not reliable.
  

Video showing the problem is at https://youtu.be/90QGaSApuaM . You can see and hear how the stepping is not consistent due to sometimes missing clock ticks.

The simple Project file that defines the Pattern and Table can be downloaded from https://drive.google.com/file/u/0/d/1pzz...ring&pli=1

Hope someone can provide some insight on either what I’m doing wrong or if there is a bug.

[mgd]

Hi SynthBu,

I have not yet looked at your project or video (will do that later), but you can find a NerdSEQ file for Steve Reich's Piano Phases under https://forum.xor.eu/showthread.php?tid=1791

Kind regards,
Michael

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I’ve seen the XOR video on Piano Phases using Nerdseq but I want to do it differently.

Care to explain how? (as in: what do you mean by differently?)

Yes, the Nerdseq is all powerful! Therefore I created a trivial Pattern with just a single note C-2, and then transposed that note in the Table to get the 12 note loop needed for Piano Phases.

This seems to indicate you plan to drive two tables with slightly differing clocks via e.g. CV1 and CV2 and thus create the phasing. Programming or manually controlling those two clocks seems somewhat complicated but should work.

And it almost worked perfectly. But it turns out that roughly 1 in 20 times the clock tick from CV Input 1 is missed and the note sounds for two ticks, completely throwing things off.

Seen that in the video. Which Firmware version are you using?

Using other inputs such as CV Input 2 did not work in same way

What do you mean by that? Using any of the CV1...4 should give the exactly same behaviour (though I have not tried that...)

I tried using the clock output that never varies to make sure the Nerdseq wasn’t trying to adjust a varying clock.

What do you mean by that? Have you tried to plug the clock out of the NerdSEQ into e.g. CV1? (I won't know why that shouldn't work)

I tried slowing down the clock ticks but behavior was still not reliable.

Not sure if steepness of the rising edge in CV1 is relevant (I'd expect not!) but you might try to pass your clock signal through a slew circuit to slow it down ever so slightly just for testing purposes.

If your CV1 behaves differently than e.g. your CV2...4 then something seems weird.

I have not looked at your project (downloaded it though) but your description is simple enough and the video seems clear as well (read: no obvious mistakes there). Maybe Thomas has an idea as to what might be the problem.

Kind regards,
Michael

[SynthBu]

Sorry, I couldn’t figure out how to quote snippets from the message from Michael so I’ll just do my best.

How differently: I wanted to make the number of measures variable for where the tempo is different. Also, I was trying to learn what can be done with Pamela’s New Workout. Using the Nerdseq was really secondary, just for creating the actual notes. And lastly, I wanted to do it in a “modular” way as to a kind of “programmatic” way. I should mention too that as a pianist I actually tried playing Piano Phases on a piano, but utterly failed because couldn’t vary my speed appropriately.

Two tables with slightly differing clocks via e.g. CV1 and CV2: Exactly! But I discovered the problem after creating just the first table so I haven’t yet bothered to create the second.

Firmware: 2.01 A, which I should have of course mentioned in my original post.

CV1...4 should give the exactly same behaviour: Indeed. I tried multiple CV Input channels and they all behaved the same (some ticks were randomly missed).

I tried using the clock output that never varies: I meant that I was using Pamela’s New Workout to create two clocks. One was completely steady at 200BPM. The other one was sometimes sped up slightly. I could see how a varying clock could possible cause problems with the Nerdseq so I tested using the steady clock.

Have you tried to plug the clock out of the NerdSEQ into e.g. CV1? Brilliant idea! I’ll try it and report back.

Not sure if steepness of the rising edge in CV1 is relevant: I’m somewhat doubtful that this could be the problem because I’d expect sharp rising clock to actually be more ideal than a slewed clock. But perhaps Thomas can weigh in on this.

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Important update: I tried using a cable to connect the Nerdseq Clock Out to CV1 Input and some clock ticks were still not being processed by the Table. So definitely not a voltage level issue.

[XORadmin]

I need to test this out myself but right now I am in Superbooth mode which means I only can make time for really critical stuff.

But I will look into this when I am back. I expected it to work well but maybe it doesn't and I need to dive in. Steepness should definitely be no issue.

[SynthBu]

I need to test this out myself but right now I am in Superbooth mode which means I only can make time for really critical stuff.

But I will look into this when I am back. I expected it to work well but maybe it doesn't and I need to dive in. Steepness should definitely be no issue.

I definitely expected Superbooth to take priority. Looking forward to your investigation when you have time. 

Note that in my previous reply I mentioned that the issue is super easy to duplicate simply by feeding the Nerdseq clock output into CV1 Input. No need to duplicate the external clock that I originally used.

[XORadmin]

I should probably send you some feedback and just want to let you know that I fixed it. Actually I saw directly what was wrong :-)
Will be in the next version.

[SynthBu]

I should probably send you some feedback and just want to let you know that I fixed it. Actually I saw directly what was wrong :-)
Will be in the next version.

Excellent! I was just about to ping you to see if the problem was on my side. I'm looking forward to doing my Reich Piano Phases experiment once I get the software update.

Do you have an approximate idea of when the the next software version will be available to me?

SynthBu