[sdiy] Alternatives to Faders

[Edward King]

Beer is always an issue :o)

Some great points raised, thanks.

I think I may have given the wrong impression though....

My synth design is almost all digital (I plan to put an analogue board in 
it, but havent designed that yet).

So the "rotary faders" wouldnt be controlling analogue gain, but the gain 
controls at the mixing processor.

As regards the position, I planned to use 3 x 7 segment displays at the top 
of each "fader" to indicate numerical value and bargraph LEDs (the panasonic 
level meter ones from digikey) for approximation. Also, at the bottom of 
each "fader" another 2 x 7 segment display to indicate the channel / track 
number.

I was looking into how to display which fader is controlling which channel / 
track (sort of better version of a scribble strip), but could only think of 
7 segment displays for the track number.
Any ideas for alternatives?

Edward

----- Original Message ----- 
From: <harrybissell at copper.net>
To: <edwardcking2001 at yahoo.co.uk>; <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, March 06, 2007 7:00 PM
Subject: RE: [sdiy] Alternatives to Faders


The sensing method would work well...

Issues might be the 'zipper noise' that digital
gain control might cause... these are not analog.

Another issue might be if you needed to know the
approximate position of the fader.

I think you could make a linear control fader with
a belt of perforated material (think of old 8mm film
around two rollers... one with the optical sensor
attached.  Bargraph LEDs might go under the band...with
the 'recalled' position shown as you change memories.
As the band is endless... you could always turn it
'up' or 'down' from the present position.

Probably would not work well with beer spilled on it...
if that is an issue    ;^P

H^) harry


>
>
>
>---- Original Message ----
>From: edwardcking2001 at yahoo.co.uk
>To: synth-diy at dropmix.xs4all.nl
>Subject: RE: [sdiy] Alternatives to Faders
>Date: Tue, 6 Mar 2007 17:41:48 +0200
>
>>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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