[sdiy] Alternatives to Faders

Wed Mar 7 16:08:42 CET 2007

Ball? No

you know the pitch-bend and modulation wheels you normally get on synths?
Thats the way Im going at the moment...although the wheel Im using is okay, 
Im having problems finding wheels / dials that are similar to modulation 
wheels so if anyone knows of any, I would be very grateful. They need to be 
roughly 10mm wide and the same diameter (or close to it) as modulation or 
pitch-bend wheels.

The wheels are arranged so that rather than pointing left to right...they 
point up and down (i.e front to back) and that you rotate the wheel forwards 
to increase the level and backwards to decrease the level.

Underneath the panel, the wheel rotates the optically encoded disc which 
interupts the LED to Photo transistor sensor setup and this sends - via the 
drive chip - data to whatever logic or chip you've get setup to handle your 
little "desk"

Ive done some experiments with this now and I like the way it performs. 
Basically, it is very low resistence so you can literally "flick" the fader 
to maximum....or drag it very slowly for very accurate low rate changes.

One of my findings is that a "Hold" or "select" button should be used for 
each fader. This enables / disables the fader and prevents it being moved by 
accident.
Another potentially useful function that Im going to play with later on is a 
"rate" button.

The beauty of this system is that it is very compact (the wheels Im 
experimenting with are only 10mm wide and 50mm in diameter), and the rate 
can be adjusted to suit individual needs. Also, because there is no contact 
between the dial / wheel and the sensing mechanism, wear isnt an issue.

The only issue Ive found is that the level display is inadequate for fine 
control. Consequently, Ive come up with the following idea:
for each track, 2 x 3 digit 7 segment displays, one above the other. The 
upper one should be the level (i.e 0 to 255 or 0 to 100) with the lower one 
displaying "fine tune" (again 0 to 255 or 0 to 100). Using both 0-255 gives 
us 16 bit level control and coupled with a rate button, this gives us a 
reasonable amount of control with enough to response rate to make them 
practical.

If anyone wants copies of my CAD work or docs, let me know.

EK

----- Original Message ----- 
From: "phillip m gallo" <philgallo at attglobal.net>
To: "Synth-DIY" <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, March 07, 2007 7:08 AM
Subject: RE: [sdiy] Alternatives to Faders

> Haven't tried the technique.  Do you expect to use a ball interface in the
> vertical as well as horizontal mounting plane?
>
> regards,
> p
>
>
>
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Edward King
> Sent: Tuesday, March 06, 2007 7:42 AM
> To: Synth-DIY
> Subject: [sdiy] Alternatives to Faders
>
>
> Ive been playing around with my panel design for a little while (taking a
> break from soldering, woodwork, metalwork and the fiddly business of 
> slotted
> switches).
>
> One of the things that has always bugged me about any board that Ive 
> bought
> is the limit of channel / track controls.
> Since most synths are limited to 16 MIDI channels, this is usually what 
> you
> get. Plus a master volume control.
>
> Further, most workstations provide track / channel control through up/down
> buttons or in the case of newer DAWS, faders on a touchscreen.
> Neither of these options are very friendly and certainly dont provide a
> level of fluidity required for smooth control of tracks.
>
> The alternatives are of course faders, but herein lies the problem:
> What if you have more tracks / channels than you can cater for with 
> faders?
> They do - after all - take up a reasonable amount of space and the decent
> ones (of which I think Penny and Giles are probably the creme de la creme)
> cost a bomb. Quality does matter. A basic 100mm 0.50 pence fader will last
> only a few thousand operations before degredation is really noticeable. A 
> 50
> dollar fader will last a lot longer (probably the lifetime of the machine)
> but would you really spend 800 dollars for faders on a homebuilt?
>
> The problem remains though that if you have more tracks than faders, you
> have to abstract this out and use a bank switching arrangement. This
> introduces problems of its own...if you have fader #1 moved to 70% and 
> then
> switch banks so that fader #1 is now covering track #17, the fader will
> still be at its 70% position and this will cause a jump from whatever 
> value
> track 17 was at before to the 70% mark its controller now is.
>
> The only practical way around this I can tell is to use motorised faders
> that - when you switch fader banks - move the faders to reflect the values
> of the tracks they now represent.
> These are even more expensive and take up even more board real estate
> though, not to mention the increase in power and control and interfacing
> requirements.
>
> So, Im open to ideas (especially ones which enable me to use 16 faders to
> represent multiples of 16 tracks).
>
> I have a few of my own and this is the current favourite:
>
> I was playing around with a ball mouse, cleaning out the gunk from the
> rollers when it suddenly occurred to me that the sensing mechanism was 
> quite
> hardy, but very compact. I dont know if its common knowledge, but the
> sensitivity of mice can be adjusted from the mouse as well as the 
> operating
> system.
>
> So I set up an experiment to see whether I could get the right 
> sensitivity -
> versus - input ratio and it more than suffices.
>
> I figured that since pitch-bend or modulation wheels are commonplace on
> synths, they are immediately identifiable as control surfaces and have a
> proven track record.
> They are also the right size (ish) and becuase nearly 50% of their area
> would sit above the surface of the panel, they are reasonably compact.
>
> Of all the ball mice sensing components, some use an analogue led and
> phototransistor setup (which is then converted by the electronics), but 
> most
> use a logic output. Both types have drive electronics (usually in the form
> of a single chip).
> A quick search of components suppliers puts these sensors at a cost which
> provides a cheaper and more flexible solution than all of the above. 
> Funnily
> enough though, it works out cheaper to buy 50 ball mice (which obviously
> contain 2 sets of sensors and electronics) than it is to buy the sensors
> themselves.
>
> Has anyone tried this method?
>
>
>
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