The AXiS-49 Revealed

The Axis keyboards from C-Thru music are potentially the most keyboard innovative instrument to come out in several centuries (8 to be exact), for reasons discussed elsewhere on this site. No one else has the magical combination of velocity-sensitive, 2-dimensional array, ergonomic, isomorphic and inexpensive keys this thing has.

My gang of DIY music keeners (a.k.a. totally nuts music nerds) really wanted to see the inside of the new Axis-49. I volunteered to be the fall-guy.  So here is what I found.

1. Cute Feet.

AXiS-49-bottom

The bottom of the unit has rubber feet that can be put in several places,
to stick out to a different degree and thus change the unit's tilt. This is a simple, robust way to adjust tilt that I wish PC keyboards had, as the hinge system many of them use is prone to collapse.

2. Clean PCB design.

AXiS-49-bottom-PCB

The underside of the PCB is the expected simple design: no surprises here. Its basically a sensor array under the keys the detects the closing & opening of two switches under each key. The opening and closing of the switches is offset in time, and the difference in time is converted to midi velocity.

3. 2 Chips to run it all.

AXiS-49-chips

The whole thing is driven with only 2 chips, the USB interface is a PIC18LF2450-I/SO, and the dsp chip  is a dsPIC33FJ128 GP310-I/PT, a nice 16-bit, 40-MPS Microchip chip. Both chips are quality chips, and relatively expensive, I believe.

4. Inexpensive quality.

The buttons (technically membrane switches) are like the Yamaha DSP that I took apart a year or two ago. But these oft-maligned switches are much better, with real disks of graphite, and gold, not copper contacts. The thick membrane is probably high-quality silicone, which does not degrade with time. The throw is a decent 1 mm. not the .05 as in the Yamaha toy. I'm impressed. These should last many years and should always be accurate.

5. Possible Key customization.

Finally, here are the key-posts. I do not recommend that you pull them off - you may not get them fully back on the fastener, and may hurt the switch underneath. Instead disassemble the unit to get at the keys. 

Note that you should take great care in taking the top of the PCB. Turn the unit on edge, with the USB jack port on the bottom edge. Take your time.

Put the unit back together the same way, and ensure the membranes go all back exactly into place.

It should be possible to put in a light spring, felt washer or some such to quiet the keys, too.   

6. A modest Mod.

AXiS-49-recolored

I re-arranged and partly recolored one bank of keys for playing in Wicki (folded major scale) mode. C in Green, E is dark blue.

In summary, this is technically a very well built instrument.

Comments

[Shinxis]

Very nice! I'm wondering if I could use some of these photos on my thesis concerning alternative keyboards..?

[Wilba]

[this is good] a bit late, but... Thanks for showing the key construction, I always wondered if they were mechanical or membrane.

[Jim Plamondon]

[this is good]

This key mechanism is what Thumtronics should have used in the Thummer.

[MusicScienceGuy]

I assume you are talking about the instrument you were talking about on DIYKeyboard.org. I wouldn't call your very interesting project a "toy" - it looks very unique and has possibilities for cool enhancements.

But the Axis-49 is definitely no toy. While the people making them place them as a smaller, casual-use device compared to the Axis-64, I think that two of the units (one for each hand), plus a cheap Korg NanoPad or E-MU Xboard 25 would make for a really top-end musical instrument.

I have questions about just how easy it's velocity-sensitivity is to use, but I'll wait a few months until I know the keyboard better.  Stay tuned for posting on how I find learning it.
Ken.

[Bug]

What I meant to say, was: this makes my project look like a toy.

[Bug]

[das ist gut] Wait, so these _are_ velocity-sensitive?

-.-;

[MusicScienceGuy]

To answer some of the above questions,
1.
What are your initial thoughts about making a similar device?

It's time to learn to play it, not build more.

2. ...does anybody know who their manufacturer is...?
When I rebuild my keys to the jammer colour pattern, I'll look to see if it says on the switches.

BTW, thanks, HarperJohn for cross-posting the link to the C-Thru forum.

Ken.

[esskay]

those dual contact membrane switches must be a standardized component of some sort right? does anybody know who their manufacturer is or where to get em? I'm searching mouser for em but coming up dry

[William Croft]

It makes sense for C-Thru to do this with membrane switches to keep the cost down.  But as you say, the build quality here looks excellent.  I recall photos of the larger C-Thru showed large hunks of machined aluminum key bottom plate, etc.  This is the right way to go...

[William Croft]

[c’est top] Ken, thanks for cracking it open!  Here are the controller data sheets:

dsPIC33FJ, the key scanner

PIC18LF, the general controller and USB interface

[harperjohn]

[this is good]

Thanks for being the "fall guy"! Very interesting info!

I got my AXiS-49 on 3/26/09.

!! NOTE !! I had trouble installing it on one of my computers. It turns out the "class compliant" midi devices can have a conflict with logitech web cams...

">http://www.vyzor.com/support/viewtopic.php?f=45&p=736">
http://www.vyzor.com/support/viewtopic.php?f=45&p=736

This solved the problem.

Anyway, I had some time to play with the "49" this weekend and I like it a lot!!!

What are your initial thoughts about making a similar device?