[sdiy] DOTCOM Analog Sequencer.. next project startup..

Fri Jul 24 20:33:11 CEST 2020

> I think you'd want your processor to implement some sort of "speed multiplication" for your rotary encoder(s).  If you're at C0 and you want it to be C8, that could take a while to get there (assuming that going > > below C0 doesn't wrap around to C8)  Either the faster you turn it, the more values it skips, or maybe having a "shift" button that would put the encoder into 5x range or something.

Every encoder increment/decrement would be a semitone.
So to change one note of a sequence would be fast enough (I think..)

> I don't understand what you mean by "change any CV 'on the fly' when playing a sequence". 

I meant turning any pots or encoder on a specific column

And change its CV value while the sequence is playing.

> Would not selecting a step via a button and turning the (single) encoder fit this?  

Yes it would nicely.

De : Chromatest J. Pantsmaker [mailto:chromatest at azburners.org] 
Envoyé : 24 juillet 2020 13:12
À : Jean-Pierre Desrochers
Cc : SYNTH DIY
Objet : Re: [sdiy] DOTCOM Analog Sequencer.. next project startup..

I think you'd want your processor to implement some sort of "speed multiplication" for your rotary encoder(s).  If you're at C0 and you want it to be C8, that could take a while to get there (assuming that going below C0 doesn't wrap around to C8)  Either the faster you turn it, the more values it skips, or maybe having a "shift" button that would put the encoder into 5x range or something.

I don't understand what you mean by "change any CV 'on the fly' when playing a sequence".  Would not selecting a step via a button and turning the (single) encoder fit this?  Or do you mean to change any step from an external CV?

Surely, the MCU would generate the CV 'on the fly' no matter if the note was set via analog pots, a bank of encoders, or a single directable encoder.

On Fri, Jul 24, 2020 at 6:50 AM Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:

>  Are you wanting to break out of the traditional and frankly pretty boring play-every-note / all-notes-same-length vibe of "normal" step sequencers?

Yes. I need adjustable step durations with forward, backward or random playback availability.

>  Smooth encoder or detented encoder?

Doesn’t matter..

>  What maximum clock rate are you aiming at?

Around 16Hz max sequence speed (micro-controller running at 20Mhz)

>  One feature of the Doepfer A-155 (easily my favourite "traditional" step sequencer, particularly with the A-154 sequencer controller attached) that I really, really like is the ability to change the pot range — fine >  >  control when you need it, or wide span when you need it.

A rotary encoder would be a fixed and very wide span CV adjustment on each steps.

Still thinking.. (computing..)

Jean-Pierre

De : john slee [mailto:indigoid at oldcorollas.org] 
Envoyé : 23 juillet 2020 22:33
À : Jean-Pierre Desrochers
Cc : SYNTH DIY
Objet : Re: [sdiy] DOTCOM Analog Sequencer.. next project startup..

Are you wanting to break out of the traditional and frankly pretty boring play-every-note / all-notes-same-length vibe of "normal" step sequencers?

Memory requirements should be negligible with any modern microcontroller, considering the number of steps and the resolution required — even if you added pattern and song storage, which would work well with rotary encoders.

I have assumed you will have a microcontroller regardless of pots/encoder choice, as you'd not need to add many features before the micro was cheaper than the equivalent CMOS logic.

Smooth encoder or detented encoder?

What maximum clock rate are you aiming at?

One feature of the Doepfer A-155 (easily my favourite "traditional" step sequencer, particularly with the A-154 sequencer controller attached) that I really, really like is the ability to change the pot range — fine control when you need it, or wide span when you need it.

John

On Fri, 24 Jul 2020 at 10:09, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:

I'm starting to think about my next DOTCOM analog module:
a 16 steps sequencer (maybe 32 steps).
So far I'd have 2 choices for the final number of steps CV adjustments.

- Standard CV pots sequenced with gates
  pros: cost is cheap, the note value is physicaly kept by each pots
  cons: bad note precision on large span (I'd like a 61 notes span on each
CV adj),
              span must be kept not too large..

- Rotary encoders
  pros: Very large CV span can be achieved on each steps (beyond 61 notes), 
             quantization easy to be achieved on each steps adjustments. 
  cons: expensive (are they all ?), need for data memory to keep every note
values (micro-processor needed)

All the gates could be generated by the same micro or
from a precise adjustable master clock

What do you think from your past experiences ?

Jean-Pierre

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