Alphatrack Clone

[John E. Finster]

Hi,

 

this is a little something I whipped up today.

The Frontier Alphatrack was my favorite midi controller and I used it a lot until it broke down some day.

Today I´m into something a little bigger, but I always thought about integrating some parts of the Alphatrack protocol into my Midibox. So I created a MB_NG Patch that emulates the Alphatrack, which I want to share.

 

 

The Alphatrack´s host message sits on the right side of the screen. The other stuff on the left side (Volume bar, Solo/Mute/Rec state and "Vpot"assignement) I put in, because I created this script with my SEQ4 and this looks more clean than using the SEQ4´s leds.

 

For the Alphatrack clone a 2x16 character lcd is sufficient, but I think it doesn´t hurt to have a little more lcd space for custom labels.

 

Instead of the fader I´m using an encoder, the volume level can be reflected on the lcd, the touch sensor is replaced with a buton event.

 

The original Alphatrack features touch sensitive encoders, which is a very nice and handy feature. In my design I also replaced these touch sensor events with simple button events, but with some metal-shaft encoders and metal encoder knobs one can easily build some touch sensitive encoders.

 

All other buttons and leds are assigned in the NGC script, just the hw_ids would have to be adapted.

 

The MB_NG Firmware has to be modified a little bit, inside mbng_event.c a number has to be altered:

 

	 u8 x_wrap = (*stream == MBNG_EVENT_SYSEX_VAR_TXT56) ? 56 : 64;

     has to be changed to:

	 u8 x_wrap = (*stream == MBNG_EVENT_SYSEX_VAR_TXT56) ? 56 : 16;

 

So that the variable ^txt can set the cursor to the second line after 16 characters.

 

Then the MB_NG source has to be compiled again and uploaded onto the Midibox.

 

I tested it with Reaper (using the genius Alphatrack-Pro extension) and with Reason 5, no problems so far.

 

 

 

There are some issues I couldn´t find a solution for yet:

 

1. Using an encoder (or a fader) for volume doesn´t work completey. One can send the volume value, and the midibox somehow "picks up" the right volume value from the daw, when the encoder is moved. But the Midibox doesn´t receive this value, when it is just sent by the daw.

 

2. I wasn´t able to recreate the touchstrip from the Alphatrack. I can create 2 buttons with the events for a 1-finger touch and a 2-finger touch, but when I tried to emulate the touchstrip movement with an encoder, it didn´t work

 

I believe this has to do with the pitchbend values. The fader would need to send/receive a 10bit pitchbend value and the touchstrip a 5bit pitchbend value. But the MB_NG only provides a 14bit pitchbend value.

This is not really a problem for me, since I wouldn´t use any of those 2 features for my own box, but for a complete clone, those issues would have to be resolved.

 

Maybe someone has an idea for a workaround?

 

 

Anyway, perhaps this can be of some use to someone.

 

My regards

 

 

Midibox_Alphatrack.zip

 

 

P.S. Inside the Zip are the .NGC script and a .NGL script for the extra labels I use on the left side of the lcd.

Edited August 17, 2013 by John E. Finster