Creating a "volume pedal" with nonlinear taper

iOS
1

I’ll state my ultimate question first, here:

How are other people achieving volume-swell volume pedal configuration on iOS, for guitar sounds?

I ask this because I’m not fully satisfied with any of the methods I’ve thus far tried, and maybe others have figured out something simple I’ve missed. I have tried a number of ways to create a full-sweep “volume pedal” in AUM on iOS using both MG3 and plugins; for example, I can connect a CC7 or CC11 expression pedal to:

  • The channel volume on an AUM audio channel;
  • An audio bus send amount on an AUM audio channel;
  • The output volume parameter of some plugins (e.g., IK’s MixBox);
  • Cascaded instances of the native Gain plugin in AUM; or
  • The output volume of the MG3 mixer.

While these all, technically, work, none are ideal. The first three options can certainly sweep from minus-infinity (or at least minus-enough) to 0dB in one go, but only with a linear “taper” on the expression pedal’s sweep. Volume swells a la Fripp / Hackett / Lifeson really need a nonlinear taper to sound right and be intuitively “playable”.

MG3 can configure a nonlinear taper quite nicely, which is awesome, but even this isn’t ideal because, using MG3 as a plugin in AUM, that plugin comes before the amp sim (to give me the pedalboard FX I’m after), where a volume pedal affects the amount or distortion/saturation during the sweep. I want foot volume it after the amp sim, where the quantity of dirt is the same throughout the volume sweep. Also, I want my volume pedal to come after any noise gates, not before them; an aggressive gate will ruin the bottom part of the sweep.

I’ve lately been experimenting with using the native Gain plugin in AUM, cascaded over multiple instances, to try and get the effect of a nonlinear taper to the sweep. The native Gain plugin will only go down -24dB, but three of them, all tied to the same expression pedal, will certainly go down below the audible threshold, and if I play a little bit with the exact start points of each one (e.g. they all sweep up to 0dB in the end, but if the first one sweeps only from -10 to 0, the second from -20 to 0, and the third from -24 to 0, it does seem to get me a little better taper than a single sweep using a different method. Theoretically one could add as many cascades as necessary to get the taper desired, but that whole enterprise just seems clunky.

I’m not sure why I haven’t been able to find an obvious “volume pedal plugin” that would have a finely configurable taper, or at least a mapping like you can do with, say, MG3 or with curves in the SWAM plugins, but maybe I’m missing something obvious.

Which brings me back to the question I started with: how are other people solving this problem?

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Using MG3 to remap expression pedal curves
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Welcome to the iOS volume pedal woe club. There is no such plugin, AFAIK. Like you said, simply using gain plugins or assigning MIDI controllers to the mixer faders does not quite cut the mustard.

This is on my list of plugins to make once I figure out how to make plugins :slight_smile:

Some guitar amp sim/fx siuites have volume pedal models (Amplitube, TH-U and ToneStack Pro) but they also do not have useful automation/MIDI functions when used inside a host like AUM.

You could use a real volume pedal in your signal chain, though hitting the front of your audio interface like that seems like trouble to me.

The plugin situation for modelling a volume pedal on macOS is much better.

3

I was afraid this might be the case. The absence of an atomic foot volume plugin seems…conspicuous, somehow, doesn’t it? Any idea why nobody has put one out yet?

You could use a real volume pedal in your signal chain, …

Indeed. I have tried, with my limited gear, to do this. It’s not a “real volume pedal”, but I do get noticeably improved tactile response using the foot volume module on my Boss MS-3 with an expression pedal. Using a simple 1x1 iRig USB as my audio interface on one of the MS-3’s effect loops, I can put the MS-3’s volume either before or after the interface. This works, but again is not ideal. If I put volume after the interface, where I’d usually want it, then I have to handle any post-volume effects (e.g. delay, reverb, looping) either onboard the MS-3, or with additional hardware units; or with a second send to an interface. If I put foot volume before the interface, I can use dirt pedals on the MS-3 and mitigate the “volume affects distortion level” problem at least somewhat, but a VP in this position means the only noise gate I can lean on, is the one on the MS-3, which again isn’t bad, but it’s limited.

I’ve also thought about getting an active volume/wah pedal, and placing it in the effect loop of my NUX Amp Academy. This might be a good answer for guitar sound, since you can place both the gate and send/receive blocks before or after amp and dirt pedal, and that will cover both volume and wah applications, but this also has limitations with interweaving the guitar chain with software/plugin effects. (And ironically, it is mostly MG3, with its pitch-shifting and overtone possibilities, that most makes me want to place a plugin before dirt, amp, and volume…otherwise I’d be reasonably content with sending a hardware-driven guitar sound on to plugins to handle rack and looper effects. :nerd_face: )

All this just starts to sound a lot more messy than being able to do it all-in-the-box.

4

A little experimenting wound up with some revelations that I think warranted a more generalized post, but as an update, I think the way forward for a true "audio volume pedal” is actually to use an atomic instance of MG3 with a simplified preset.

In a nutshell, this preset has MG3 take the expression pedal’s raw input, remap it to a nonlinear curve like MG3 can do with its Patchbay nodes, and then send that nonlinear output to the Gain plugin on an audio Chain. (Gain seemed smoother than connecting to the Mixer.) I had to tweak things a bit (e.g. configure the curve to not go above unity gain, find the right shape for a good volume swell sound, etc.) but it’s by far the best solution I’ve seen so far, and I think worth further experimentation.

And that’s where things got more generalized. I remembered–duh–that I might be able to take that remapped curve, and instead of sending to to Gain internal to the MG3 preset, send downstream as outbound MIDI–and therefore making it available to other elements in AUM. That discussion is elaborated further at the other post, but at least for now I think I have an acceptable “volume pedal” solution to go with! :nerd_face:

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