Connecting Ribbon-Controller with 2.3 kOhms to MBox Plus?

[SLP]

Hi,

I'm going to build a MidiBox Plus as a universal MIDI-Controller.

This means:

6 Faders (2 red Buttons / 4 black Buttons)

6 Pots    (2 20mm Aluminium Buttons / 4 12mm Aluminium Buttons)

2 joysticks OR footswitch, XY-Pad, Ribbon-Controller (XY and Ribbon are free samples from Spectrasymbol)

Yesterday I've recieved  my Ribbon-Controller and noticed that it's got a resistance of 2.36 kOhms

instead of 10kOhms as the usual pots. Can I use this too?

...And what happens, If I remove my finger from the Ribbon (removing the Signal Pin from a pot)?

thx Matthias

[illogik]

hi;

the pots on ain work as voltage dividers; they deliver a voltage ranging from 0 to 5V to the analog inputs. Another value pot does the trick but with another resolution i guess. Try it out with a low value pot.

BUT;

...And what happens, If I remove my finger from the Ribbon (removing the Signal Pin from a pot)?

then the ain pin is floating (not connected to ground/a voltage) and will cause jittering of mididata. check the forum though there is a topic on the xy-pad maybe there is allready an nice solution for this

good luck

edit; this topic

http://www.midibox.org/forum/index.php?topic=5023.msg32241#msg32241

quote form rafael

You have two possibilities:

1. Add the resistor between GND and the Fader tap (the one which is connected to the AIN) and you will get an output of 0 if you dont`touch the pad.

2. Add the resistor between +5V and the Fader tap (the one which is connected to the AIN) and you will get an output of 127 if you dont`touch it.

[SLP]

Thank you for answering my question that fast.  :)

I think I'll use a switch to switch from the Ribbon-controller to a definite Resistor to avoit jittering.

Matthias

[Wilba]

I've been thinking about a ribbon controller myself... the reverse side of Mini DV tape is a good resistor (but fairly high resistance, 100K per cm!)

One thing to be wary of with these ribbon controllers - if you are using them as a simple voltage divider, like a slide or rotary pot, the first major difference is that the "wiper" can be off the strip, the SECOND major difference is that the "wiper" is not just one point - you can touch at multiple places and "short" up to the entire strip. That is, you can touch at the start and end of the strip and effectively short your power rails. It is unlikely you will intentionally do this, but it might happen accidentally.

To fix difference #1, you can do it the simple way (I'm guessing here, unproven) - ground the wiper through a big resistor. That should stop the jitter, and when your finger is off, AIN input should be zero. If the resistor value is much, much greater than the strip resistance then its effect of reducing the resistance of the strip between the wiper contact and ground will be minimal. The more complex way is doing something fancy like this: http://www.paia.com/LabNotes/index.htm

To fix difference #2, if you don't mind sacrificing a little of the range, put some small resistors between each power rail and the strip ends, so that making a "short" across the entire strip still will go through these resistors instead of shorting the power rails. Or, do it the fancy way (see above link).

[SLP]

I'm not building a MBox 64 or something. I'm not using those AIN-Things.

I'm going to use it as a realtime-Controller for some softsynths (CS-80V).

I don't mind difference #2, but I'll try out your 1st suggestion to avoid jittering.

 

[illogik]

I'm not building a MBox 64 or something. I'm not using those AIN-Things.

yes you are..  ;D

midibox plus is kindof the older version of Mbox 64; this has more/better options. It's still on the site as reference for the people who built this in the past, but it will not be supported in the future.

The MB64 doesn't have to have 64 pots; it's a maximum, so you can build it the way you like.

every pot/fader/ribboncontroller needs to be connected to a AIN, so you will need this afterall

good luck

[SLP]

Hm... after having a closer look at the schematics of the AIN-Module and the MBox Plus, I notice that It's quite the same  :o ( multiplexers). But for me, the MBox Plus offers enough analog inputs to controll the most important things of a softsynth.

If i need more a. inputs and if i earn more money then now ;) , i'll think about building another MBox 64.

Matthias

[SLP]

hi again,

today I wanted to connect the Robbon-controller to my MBox but the only signal I get is "0" when I don't touch it and "127" when i touch it. It douesn't make a difference where I touch it, it's always the same... :-\

can you help me?

matthias

p.s.: Dear admin, as this thread now turns into a "troubleshooting"-thread, could you please move into the troubleshooting-folder?

[audiocommander]

have you measured the behavior with an ohm-multimeter before connecting it to the MB?

If the ribbon-controller is okay: how did you connect it?

[SLP]

>:( oh man, I'm that stupid.

the nice guys from spectrasymbol just changed the pin-order.

In a normal pot the signal-pin is in the middle but in my

ribbon it was on the left side.

thank you anyway  ;)