Topic: What parameters are modulated by velocity in Pianoteq?

I don't entirely trust my hearing about this question, since the parameters interact so closely, so I'll ask the question. Obviously some of the parameters are modulated by velocity, such as the amplitude of the hammer strike, but are others, such as:

1. Overtones as adjusted on the sliders. (Of course they rise in amplitude as velocity increases, but do they rise at the same rate as velocity increases, so that if I raise the amplitude of the 2nd harmonic by two decibels, is it always two decibels louder than the default setting, regardless of the velocity?)
2. Soundboard impedance, cutoff fq, and Q.
3. Global resonance
4. Sympathetic resonance. (Sometimes the resonance sounds a little too much for low  velocities, contributing to a syth-like tone.) 
5. Direct sound duration.

If some of these are modulated by velocity, is the scale linear for each or are there velocity curves for each?

I'm asking so I can have a better understanding of what to expect when I adjust these things, and because the effect of some of the parameters seems to be hard for me to predict. I'm not always sure, as I experiment with the various knobs, what to try to adjust, and the relative effect of each parameter on low and high strikes.

What I may be leaning towards is requesting a way to control the relationship between velocity and each of these parameters--a scaling knob for each, possibly, or ideally, drawable velocity curves. Such controls would be particularly valuable for parameters such as the overtone sliders, since it would let the user better define the rate at which the brightness of the instrument increased.

Thanks for any insights.

Last edited by Jake Johnson (24-09-2007 20:50)

Re: What parameters are modulated by velocity in Pianoteq?

Jake Johnson wrote:

I don't entirely trust my hearing about this question, since the parameters interact so closely, so I'll ask the question. Obviously some of the parameters are modulated by velocity, such as the amplitude of the hammer strike, but are others, such as[...]

It is not easy to answer to your questions because there are many different situations. There are however some general rules that can serve as guidelines. For example, soundboard impedance, cutoff fq, and Q are mechanical properties of the soundboard, so they are not concerned by velocity (wood properties of the soundboard like Hooke's tensor do not depend on what is happening at the hammer or strings level). Other features like overtone relative amplitudes or sympathetic resonances are modulated by velocity, because they depend on what is happening to the strings. There are however no direct velocity curves for each feature, as it is driven by the model itself. Thus it would be difficult to provide direct control w.r.t. velocity for all features.

Re: What parameters are modulated by velocity in Pianoteq?

I'm clearly wading in over my head. As you know, I'm slowly learning about the physics of acoustics. These concerns may have been addressed long ago as part of the model. Sorry if I'm still trying to understand some of the basics.

About the soundboard impedance, cutoff fq, and Q: My thought was not about what was going on with the strings directly, but instead that velocity contributes to force. The greater the force applied to the strings, the greater the force transmitted to or reflected off the soundboard, depending on its impedance\resistance\inertia. So isn't velocity tied to directly to the soundboard vibration in that sense--for the frequencies the soundboard can absorb, lower velocity strikes will not overcome the impedance and instead be reflected off the soundboard, while harder velocity strikes (with a greater force) will overcome the soundboard's inertia and be more absorbed, resonating the soundboard, though also, because of the greater force they apply to the strings, air, soundboard, et al, louder. We now have control over the soundboard impedance and fq cutoff. The ability to set velocity curves for just the impedance would let us control just how hard we had to hit the keys to overcome the impedance. (The problem is not in the model, but with midi keyboards and our, or my, ability to control low strikes precisely.)

AND: Similar user-drawable velocity curves for the harmonics would give us an enormous amount of control over the timbre of the instrument. This is where I wander off into the world of fantasy again: Configurable velocity curves for each overtone, and ideally, again for each overtone, an envelope with points for pre-Attack amp, Attack time, Decay amp and time, Sustain amp and time, and release amp and time, with the possibility of setting negative and positive points (so each point could rise above any initial setting on the slider.) Knobs for controlling the extent to which each overtone's envelope responded to velocity. Knobs controlling the ratio of velocity to amplitude. In other words, make the conventional synthesizer amp envelope controls (but not just the newer reduced ADSR envelope on Romplers) available for each frequency in the note.  A fantasy that would be a nightmare for processor load?   

Again, my apologies for these long posts and questions and requests. The problem is partly that Pianoteq opens up all of these staggering possibilities. I should be spending my time learning to play the piano better.

Last edited by Jake Johnson (19-02-2008 07:55)