A transfer function / curve would be by far be the most flexible and would allow the user to make some awesome complex things within one single window/curve interface. If you want to check out the best/most comprehensive implementation of this very feature, check out Alchemy 2.0, the synth in Logic Pro X. It's got a very clever curve system (they call it a ModMap). HERE is a direct link to the Logic Pro X Alchemy ModMap in the manual.ultra_audio wrote: Sun Dec 28, 2025 11:15 amThanks for trying it out. By the way, we are thinking of enhancing the mod system. I've realised that we need some kind of curve control for each link between the source and the destination.bmanic wrote: Sun Dec 28, 2025 6:38 am I don't have Ultra demo installed any more as the simplistic modulation system is just not my cup of tea...
If we had something similar on the aux, that would be enough to adjust how much the aux affected it. Or perhaps the Vital approach is simpler? I'd be keen to hear your thoughts.
That still leaves you with a single "Aux" modulation slot per modulation.. which in my humble opinion is way too little considering how powerful your synthesizer could be. For instance, what happens if you have an Envelope modulating the filter cutoff and you want to modulate how much the envelope modulates that filter through velocity, keytracking and also with an LFO.
It is _very_ common for some basic functions to have at least two layers deep modulation. Most notably envelopes by velocity. This is why I always recommend to developers that they should implement a bi-directional "Depth" control, for instance +/- 100%, for all modulation sources. This is extremely important for synthesizers that only have a very shallow mod matrix that only goes 1 layer deep, like the one in Ultra synth. That way you have another access point for secondary layer modulation when needed, without having to expand the mod matrix capability.
Of course this is not as flexible as having a true 2 or 3 layer deep mod matrix. Personally I always prefer mod matrices that allow deep layering (so a modulation that is modulated, which in turn is also modulated, aka 2 layers deep).
The main benefit of multiple layers is that it gets much easier to create sounds that are immensely satisfying to play on a keyboard as the sound designer can carefully tailor how the full range of the keyboard affects the sound. Especially important, and often neglected, is keyboard tracking. It is in my opinion THE most important modulation source right after velocity. Keyboard tracking combined with a good modulation mapping system (the "curve") is extremely powerful.
It's even more powerful if the ModMapping can be forced to operate in "octaves" mode, like in Alchemy, where you can divide it into 12 sections so that you can get exact values for each key in an octave. This allows you to make crazy cool things like tailor made LFO rates, consistently for every key over the whole keyboard. This also allows you to exceptionally accurately set filter cutoff points per key so that the sound always plays musically and optimally. Now if you also add a standard parametric EQ in the filter section, so that it's polyphonic, it allows the user to completely reshape the sound accurately over every single key.. something that to this day only very few synthesizers allow. Alchemy being one of the very few ones.
Why is this so powerful?: Well imagine you got the almost perfect sound with your oscillators, modulators and filter sweeps.. but there's this annoying ringing "mud" in the sound, especially in certain key ranges. A polyphonic parametric EQ + mod mapper with easily dividable "per key" snap system makes it incredibly easy to get rid of the annoying frequencies, per key. For the user who plays the sound it's all just seamless and the sound just feels super polished and sits within the mix perfectly.
This is far more powerful than having a parametric EQ in the FX section and cutting out some mud. That's usually throwing out the baby with the bath water type of deal and may just fix a few keys in a very narrow key range. With a polyphonic EQ + mod mapping, that solves the problem immediately and always reliably.
Here are some very common things sound designers may want to control the "curve" of:
Velocity
Modwheel
Aftertouch
Envelopes (to modify their default slope and behavior)
LFO (to skew their shape or force random LFOs to dump values in a binary manner)
Keyboard tracking (to force the range into what is needed for the task)
A mod mapper also easily allows for the reversal of modulation sources while at the same time they are linearly mapped to something else. So for instance sweeping the Modwheel may normally go linearly form 0 to 100 to one target whereas at the same time it may map from 100 to 0 to another, thus creating the exact opposite values. Very handy. Or to make it only work for a particular section of the synth when modwheel is about 50% into it's movement and then fades out before it's set all the way to 100%. Modulation remapping/curve is such a super flexible thing that I'm always very glad to see such a system. It expands the capabilities of a synthesizer immeasurably!
Anyhow, sorry I went off on a tangent there and wrote a way too long post, as always. If you do ever need veteran help with sound design or especially ideas for implementations for your synth, don't hesitate to contact me via PM. I've got quite a long record when it comes to synthesis.
