[sdiy] What do you like in a synth control surface?

[Tom Wiltshire]

I think there are various ways to do it, but you have to think about the basics of any interface:

Providing information to the user, both about what parameters there are, and what values they have.
Not overwhelming the user with needless detail, or maintaining a good hierarchy of important -> not so important.
Easy access to anything you need to get at frequently. Access to "set and forget" type parameters can be more fiddly without hurting things.

Personally, I like the knob-heavy interfaces on a lot of the classic polysynths. You can see what you can do (good overview of available parameters) and you can see what values things are set at (assuming it's got a "manual" mode and we're not looking at the knobs but hearing a patch from memory).
Larger knobs and more space around them makes for a luxurious feel and is ergonomically a joy to use, but decreases the amount of parameters you can fit on a given area. Trade-offs, as ever.
Screens-plus-encoders like on the Oberheim Xpander or (more recently) John Bowen's Solaris are a reasonable compromise, if you've got buttons which give you access to each screenful of parameters. Looking at the buttons gives you an overview of the synth, or ought to. Bonus points if you arrange the buttons to give you an idea of the signal flow on the front panel. This is one thing Dave Smith got right on the recent Prophet 12 - the panel is virtually a map of the signal flow from left to right. Very intuitive. For a pretty deep synth, I think it's impressively clear.
Mention was made recently of button-plus-indicator-LEDs for switched options. This is a good solution, and copes with programmable synths too, which knobs don't.

I agree with Gordon's comment about modular synths. The flexibility is great, but the wires get in the way as soon as you've got more than one row of modules. If it's Eurorack, the problems are identical, but you also need pixie fingers to tweak anything. Even at the single-module level, some Eurorack modules have the worst examples of interface design I'v ever seen. Mostly where the controls appear to have been randomly scattered across the front panel (because we're cool and don't like to be stuck in the grid, man) and are labelled with meaningless esoteric nonsense like "Humdinger", "Frolick" or whatever. Gack! Give me a clear layout of function and tell me what it does so I don't have to decode the panel using the manual!

I also agree with Florian's point about the range and response of controls being very important. Having a "frequency" control on an oscillator that was linear in character would be utterly unusable! Many controls need a exponential or log response. And sometimes the best response is tweaked beyond a neat equation. I recently worked on a project where we needed to extend the slow end of an envelope, but as Florian mentioned, mostly you don't need curves that long, although it's nice to be able to use them occasionally. The solution was to break the control response into various sections, so that you had detailed control over the shortest range, reasonable control over medium length curves, and more limited control in the last third of the pot's rotation of the very longest times. This kind of thing is a lot easier with digital (where there's usually a lookup table for it), but's it's at least worth thinking about with analog circuits, even if you eventually decide it's not practical in a given situation.

HTH,
Tom


On 23 Feb 2015, at 13:07, Jack Jackson <jackdamery at hotmail.co.uk> wrote:

> So excluding modular synths, how do you like a hardware synth interface to be?
> 
> Preferences such as sliders/rotary pots. slide/rotary/pushbutton+led switches, spacing, colour etc.
> 
> Any feedback welcomed.
> 
> Best Regards,
> Jack 		 	   		  
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