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Category: Reviews

The VAXMIDI by Infinite Response

In 2015 a Kickstarter was created for a project called “VaxMIDI” – a MIDI keyboard controller with attractive features, including polyphonic note pressure detection or “aftertouch”, a feature that traditionally has been difficult and expensive to produce, and/or protected by patents.

The second really interesting thing about this project is that it would be shipped in kitset form, to keep costs to a minimum.

The folks behind this project were reputable (read more about Infinite Response and the VAX77 keyboard). Strictly speaking, I did not need another keyboard controller in my studio, but as an engineer/musician, the project intrigued me.

I backed the project at the top tier, in for a 8-octave unit.

After the project reached its funding goal, we had to wait for the kit to be developed and manufactured before eventually receiving our kits. I was in the second wave of beta testers, and early 2017 I came home to a large box on the front doorstep.

I took over the dining room table for several months, assembling and testing each of the four 2-octave units.

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Each base is an extruded aluminum section with a complicated cross section, supplying rails for the keys to swivel and rest on, and a clever mechanism of hammers that are flipped up by each key, and pass a slotted blade through an optical detector.

The aftertouch sensor is a long slot that widens as the blade is pulled through the sensor as the key is depressed more firmly.

There is quite a few places where this can go wrong: The sensor strip (of 22 detectors) can be misaligned; the distance between the hammer rail and the sensor base can be too high or too low; the felt on which the key steel rests can be too high… all these things have to be just right in order to position the slots correctly for the note and pressure detection to work correctly.

Additionally, there are challenges in assembling each base into the chassis and connecting the system circuit boards so that it stays together in a robust and stable configuration. Also, there are bugs in the firmware such that spurious patch changes were being emitted during testing.

Bottom line: My assembled unit is back in its big brown box, in my garage, until such time as we get some updates on how to address these issues. It’s looking more and more as though they will not be forthcoming. I think the company has long burnt through their Kickstarter funding, and combined with family health issues, I don’t foresee this project coming to a good conclusion.

That’s sad, because it shows a lot of promise. Technically, I think it can work, but it is really sensitive to manufacturing tolerances, and the skill and ability of the assembly technician (i.e. me) to overcome them only goes so far.

Review: K&K ProST Dual Channel preamp

Last post I described my experience setting up my Stick to have bass strings on both sides of the fingerboard. One roadblock is that the Stick uses a stereo output jack to carry each side. This is cool for independent processing of bass and treble registers, but if you’re trying to play both registers as a single bass instrument, you might want to treat the output as a single mono source, without switching cables around.  (Basically, I wanted to mess round with chords without messing around with cords. Heh. I slay me.)

This topic comes up quite a lot on the forums. What equipment to use with the Chapman Stick’s dual channel design? Many people invest a lot of money in capable, sophisticated and expensive processing units, but it seemed to me that I really just needed a simple two-channel active mixing device.

After much searching on the web I found Gollihur Music, and after absorbing the information on Bob’s site, I ordered a K&K Pro-ST Dual Channel Pre-amplifier, for $124. It seemed like the ideal thing from the specs.

It arrived the other day. It’s a nice, compact black box with two knobs (volume for each channel) and three jacks (stereo input, main mono out, and a second output that splits the output and retains the channel separation. So basically if you want to keep the pre-amp feature but process the two channels independently, you can. This seems like the best of both worlds.

There’s a small screw at the side that you have to remove to take the lid off. This thing is very solidly built, it feels very reliable.

Once the lid is off, you can plug in the required 9-Volt battery, and adjust the channel gain and EQ pots. There is even a little metal “screwdriver” for this purpose, tucked away inside with velcro to keep it from knocking around.

Yes, this device allows you to set the gain and bass/mid/treble for each channel independently. Perfect for my situation, where the treble side of the Stick sounds a bit too trebley, despite the bass strings that are used.

I plugged in the Stick and experimented with adjusting the EQ.

With the volume turned all the way up, it seems as though the default available gain is about 120% unity. 

If you’re looking to amplify a piezo pickup or similar (I have a Dean Markley acoustic pickup I was thinking of using with my Wendler bass, for example) then you can change the amount of gain on each channel using adjustments to the mini-pots. They are set half-way by default.

I ended up knocking back the treble pot a little to even out each side of the Stick. I couldn’t get it perfect – the two registers just sound different, that’s just the way it is, but I could get a definite improvement over the flat response, so it was worth it.

With the stick hanging off my military-style web belt, the preamp’s handy belt clip lets me use a short TRS “patch cord” to direct the Stick’s stereo output to the preamp input. Then my regular “Monster” mono instrument cable takes the preamp output away to my POD, etc, for recording.

Initial tests are very promising.

Still in use, November 2017

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