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 Forum index » DIY Hardware and Software
Velocitizer: A different approach to adding velocity to ADSR
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Ricko



Joined: Dec 25, 2007
Posts: 209
Location: Sydney, Australia
Audio files: 23

PostPosted: Sun Feb 20, 2011 6:45 am    Post subject: Velocitizer: A different approach to adding velocity to ADSR Reply with quote  Mark this post and the followings unread

I was reading this conference paper:

"Expressive Articulation for Synthetic Music Performances"
by Tilo Haehnel and Axel Berndt:
http://www.educ.dab.uts.edu.au/nime/PROCEEDINGS/papers/Paper%20P1-P5/P277_Haehnel.pdf

They look at Leopold Mozart's book on early classical/baroque articulations, and do some measurements of instruments. So I thought I'd have a stab at a circuit in SPICE. Here is it, in case anyone is interested.

Basically, we run the ADSR through a multiplier and then into the same kind of sine shaper diode circuit that VCOs use. The result is that at low velocity, a linear ADSR input comes out err linear. But at higher velocity, the input is bent into a curved shape, filling out the note without altering the timing.

Anyway, attached is the circuit, a sound simulation (synthedit), and an eg waveshape.


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Last edited by Ricko on Fri Feb 22, 2019 12:07 am; edited 1 time in total
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emdot_ambient



Joined: Nov 22, 2009
Posts: 667
Location: Frederick, MD

PostPosted: Mon Feb 21, 2011 3:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

It's a really simple circuit...would be interesting to hear it built and tested on a synth voice articulating it with something other than veolcity (like a sequencer output).
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Ricko



Joined: Dec 25, 2007
Posts: 209
Location: Sydney, Australia
Audio files: 23

PostPosted: Fri Feb 22, 2019 12:06 am    Post subject: Velocitizer Reply with quote  Mark this post and the followings unread

Just to say that Elby Systems now have released this circuit as a kit and built, as Velocitizer, see http://www.elby-designs.com/contents/en-us/p1057_ASM322_-_Velocitizer.html It is a simple build, less than an hour all up: through hole, 4HP and my build worked first time.

Not only can it be used for adding velocity dynamics, where the shape as well as the level changes, it also works on audio signals, as a waveshape animator/chorus effect, as it turns out! UPDATE: video at https://youtu.be/EjKQMTWaeyY

Laurie from Elby has tweaked some components and values in his BOM. For example, in the schematic above I used 1N148 germanium diodes (by mistake!), while Laurie uses BAT42 Schottky diodes. In my built module, I just use vanilla 1N4148. (I think Laurie alters the value of a resistor too. Lots of room for variation.)

I have some demos and info up on Muff at
https://www.muffwiggler.com/forum/topic-214038.html

Last edited by Ricko on Fri Feb 22, 2019 7:15 am; edited 3 times in total
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MusicMan11712



Joined: Aug 08, 2009
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Location: Out scouting . . .

PostPosted: Fri Feb 22, 2019 6:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Interesting article! One of the staples of electronic music experimentation has long been timbral variation which can be created in many different ways. This article provides insights into ways that timbral variations have been achieved by non-electronic musicians. The idea of simulating those techniques without relying on samples/multisamples of non-electronic instruments is intriguing! Thanks for posting the link.
--Steve

Quote:
Conclusion:
Articulation, if not reduced to a mere tone duration feature, offers a big potential for synthetic music performances.
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Ricko



Joined: Dec 25, 2007
Posts: 209
Location: Sydney, Australia
Audio files: 23

PostPosted: Fri Mar 08, 2019 1:09 am    Post subject: Reply with quote  Mark this post and the followings unread

OK, so now I have tried it with different diodes: Silicon (1N4148), Germanium (1N60), and Schottky (BAT85) which have progressively lower voltage drops so different responses in this fixed circuit.

Works fine with all of them, and each have slightly different feels and output levels, but I cannot really characterize them, or pick a favourite. I think the Schottky gives a sharper attack or something, but I cannot say. I will probably stick with the Germanium, merely because I am tired of unsoldering. It would be neat to have a switch to select between different diode types.

I have put up another little audio demo on Muff Wigger Eurorack forum (search Velocitizer), with the Velocitizer pinging a Low Pass Gate. That demo uses the Germanium. The LPG does not get excited by low CV signals, so it works well with the Velocitizer, giving more of a range than a normal VCA does.
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Ricko



Joined: Dec 25, 2007
Posts: 209
Location: Sydney, Australia
Audio files: 23

PostPosted: Thu Mar 28, 2019 3:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

Here is an audio example of the Velocitizer played from a keyboard, to show how the velocity alters dynamics. (The LPG makes everything sound like a banjo, it seems?)

KCV ->VCO -> my pulse forming waveshaper -> LPG in -> out (slight reverb added)

Gate -> ADSR -> Velocitizer (germanium) ->passive mix -> LPG cv

Velocity -> Velocitizer


In this example, you can hear a variety of different note shapes: no knobs were twiddled all the variation is from playing.

One effect that is noticeable is that the sustain is set to 50%: from the action of the Velocitizer, it means that low velocity notes have an effective sustain of 25%, while notes played loud have an effective sustain of 75% (very roughly).

Another effect, sightly more subtle, is that the high velocity envelopes are fatter than the low velocity notes, not just louder, which is the primary intent of the circuit (distinguishing it from a normal 1Q multiplier.) This is not just that I am holding the notes longer, but that the louder velocity envelopes are soft-limited by the Velocitizer to give a fatter envelope. (The LPG adds another layer of dynamic variation on this, of course.)


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