Genos: Needed DSP improvements

Posted on by

I’ve really enjoyed playing Genos. The Super Articulation 2 (SArt2) voices take emulative synthesis to a new level of realism.

Although Yamaha have added the new rotary speaker effect to the Genos, there is still work needed to make the drawbar organ experience realistic and competitive with Hammond clones. Yamaha needs to bring the drawbar experience up to the same level as SArt2.

The current drawbar organ implementation is much the same as the previous Tyros and S-series drawbar organ mode. The drawbar signal chain consists of a tone generation stage followed by the rotary speaker effect:

                                 Rotary
    Drawbar tone generator ----> Speaker ----> Mixing Console
                                 Effect

The output is sent into the usual Genos/Tyros/PSR Mixing Control and system-level effects architecture.

The drawbar tone generator has an eight level volume control that determines the level of the pure drawbar signal. The user sets this level using a virtual drawbar in the drawbar mode graphical user interface (GUI). So, the signal that hits the input of the rotary speaker effect is constant at the level set by the user. In Genos-land, the foot pedal sets XG MIDI channel volume, i.e., changes the post-effect volume level of the organ’s channel in the Mixing Console.

Problem is, that’s not the way the real-world works. On a Hammond, for example, the foot pedal changes the signal level hitting the rotary speaker. The foot pedal does two things:

  1. It changes the overall volume level of the instrument (i.e., what the audience hears), and
  2. It changes the signal level hitting the rotary speaker pre-amp.

The second point is crucial for realism as the amount of pre-amp distortion changes with the signal level. A higher signal produces more distortion and a low-level signal is relatively clean.

The existing Genos drawbar implementation does not do this. The amount of distortion is set once and is constant. The amount of distortion does not change with the organ volume. The way the expression pedal changes channel volume sounds unnatural and is not realistic.

Many of us, including Uli and Stuart on the PSR Tutorial Forum, have tried to work around this problem. We also find the drive in the new rotary speaker effect to be, well, wimpy. So, we have tried inserting a distortion effect before the rotary speaker effect, etc. and have run into several limitations and roadblocks. These issues have to do with DSP effect chaining, access to DSP effect parameters and control of DSP effect parameters.

Here’s a short list of issues:

  • Be able to control the signal level from the drawbar tone generator into the rotary speaker drive effect. The distortion level must track the input level in order to accurately emulate real world distortion.
  • Be able to insert a distortion block between the drawbar tone generator and the rotary speaker in order to make up for the wimpy drive in the new rotary speaker effect.
  • Be able to edit parameters of a DSP effect when more than one DSP is assigned to a part. Only the last DSP in the chain is displayed in voice and can be edited. In Firmware v1.02, there was an edit button in DSP assignment dialog. Please bring this feature back. [Thanks for this one, Uli!]
  • Be able to edit more than 16 DSP effect parameters, including the missing parameters for the UNI COMP and new rotary speaker effect.
  • Be able to use the foot pedal to control all user controllable parameters for all DSP effects that have them, not just the WAH effect.
  • Provide access to the UNI COMP side-chain input, i.e., a way to connect a signal to the side-chain input.

Yamaha’s own engineers are getting ahead of the Genos developers by designing effect algorithms with more than 16 parameters, side-chain inputs and so forth. These features are currently hidden or inaccessible to Genos users. For example, we cannot change the slow-fast and fast-slow times of the rotor nor can we connect a signal into the side-chain input of the UNI COMP compressor.

The XG architecture has always provided for effect parameters which can be controlled by an assignable controller (e.g., AC1). Yet, the only two Genos effects which may practically be controlled in this way are the WAH effect and rotary speaker speed. Yamaha need to unleash the power of Genos’ assignable sliders, knobs and buttons by generalizing control. Please let us assign any MIDI controller to any parameter in any effect block. (Rotary speaker speed only affects the rotary speaker block in the drawbar signal chain.)

So, I hope Yamaha takes these suggestions into consideration and makes them part of a future update. These improvements would make Genos truly competitive against other premium-priced keyboards — clones, not just arrangers.

DSP effect signal flow

When Yamaha’s Genos developers design the graphical user interface (GUI) to manage chained DSP effects, they should call their colleagues at Line 6.

The Helix Native plug-in has a spiffy signal flow window (see image below) in which a Helix user creates and edits a virtual pedal board. The user creates effect blocks and interconnects them. Genos should have a similar visual interface for creating and managing DSP effects that are chained. Touching an effect block should open the detailed parameters for the block. The Genos touch panel would be a natural for this kind of interaction.

[Click image to enlarge.]

Slider value pick up

I have to thank Simon Sherbourne’s review of the Aturia KeyLab Essential for inspiring the following suggestion. His review appears in the February 2018 issue of Sound On Sound Magazine.

The Genos sliders are noticeably jumpy. Their behavior has prompted several complaints on the PSR Tutorial Forum.

Simon likes the value “take over” implemented in the Arturia KeyLab Essential. Quoting Simon’s review:

“Take over is always smooth. … Sliders take over using Ableton-style scaling. As soon as you move a slider the software knows where it is and draws a ‘ghost’ fader showing the hardware position. Any movement will produce relative adjustment of the mapped parameter until the physical and virtual sliders come together. Clever!”

The Arturia manual calls this “Pickup” behavior: “the faders in your DAW will gradually move to match the current position of the fader on your controller as it moves.”

Yamaha should add pickup behavior to the Genos sliders. Slider mode should be selectable by setting either a utility parameter or a controller function setting.