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The A90 appears to be measuring its velocity from the counter weight... a neat
idea but is it good physics? “Somewhere between the mechanism and the code
that interprets its movement is the problem.”

This review is based on A90 serial# 2K16708 H

How is the key stroke made into a midi note.

Two methods: measure velocity of the key stroke (between two points) or
measure the impact (at the bottom of the stroke). The A90 appears to be
measuring the velocity of its counter-weight.

For the past 13 years, I’ve used a Kurzweil Midiboard for all my tracks. The
feel is kinda okay and for its day it wasn’t bad. It’s the only controller I
know of that will transmit on 8 midi channels at the same time (although the
midi output is way to slow thru its one port out). It is also one of a very
few controllers that has polyphonic aftertouch. This means you could have
independent vibrato per each note being played if you prefer.

However, The Midiboard has one major flaw... key bounces at the bottom of the
stroke when playing softly. Kurzweil never really solved this problem because
it would require redesigning the sensor system. So they used some software
routines in attempts to minimize the problem and it made the problem a little
more tolerable.

The Midiboard differs from most controllers in that it uses the impact of the
key at the bottom of the stoke to determine the velocity number sent 1-127.
Most controllers actually measure velocity (usually measured by the time it
takes the key to travel between two points).

With the Midiboard’s impact sensor come advantages and problems for keyboard
players. Notes can stop short if the key bounces on the bottom of the stroke
making editing the midi stream a necessity. And when those notes cut off
they are a distraction. But with a little getting used to this controller the
key bouncing issue is tolerable although still there. But I haven’t found any
controller that is better at getting the performance dynamics right.

What I’ve been looking for is a controller that feels like a real piano and
would get my hands back in shape for performance. Despite the fact that the
Midiboard has wooden keys and some weights it still doesn’t have enough
resistance to get your hands in shape for a real piano.

The A90

When I first played the A90, I was impressed with its piano-like feel. With
its weighted action I felt sure this would be the answer. The only negatives
I noticed were two things. First, you couldn’t buy it without the internal
sounds in it. Second, the action which felt so great, was incapable of doing
fast repeats where occasionally you might like to twiddle a note with one hand
alternating fingers in rapid succession. At the time I didn’t realize that
the problem of fast repeats was another symptom related to a major engineering
problem. But, I was willing to give up the fast repeating for that nice stiff
piano-like feel. Besides, I thought with a little practice I might be able
to get my hands in good enough shape to get those repeats.

The dynamics of its own internal piano (custom tweaked for the action) seemed
good. So, I brought one home on approval... hooked it up and loaded one of my
stock piano disks. When I began to play, a big smile appeared over my face.
After the first few crashing chords and some runs, I began to play my heart
out....feeling those keys vibrate under my fingers, I felt like I had found
THE controller I had been looking for! I could almost feel the jacks slipping
out from under the hammers as they were being launched toward the strings. I
called the store and told them the A90 had found a home and that I would
continue some exploration and call later to seal the deal. (close call.)

Of course with the thrill of playing I had noticed some quirks with soft play
but attributed them to my hands being out of shape. I decided to record some
tracks with the A90 since with all the clunking noise of a controller as
you’re playing it, it’s impossible to hear nuances of what the recording will
be like. It was then I noticed something strange about my playing...
something that I couldn’t blame on my hands not being used to a real piano.
Soft delicate passages were dynamically inconsistent. Some notes were louder
than intended and some were softer. It all added up to something I didn’t
intend to play. So I began tinkering with V-curves. I had been suspicious
from the beginning that reducing the large display and superb programmability
of the curves in the A80 (the A90’s predecessor), to a small miniature display
and preset curves (with preset anchors for adjustment) had been accomplished
for budget reasons.

Problem

The A90 appears to be measuring its velocity from the counter weight... a neat
idea but is it good physics? By measuring the velocity there ...the
linearity of response depends on the mechanical design of that mechanism.
Somewhere between the mechanism and the code that interprets its movement is
the problem. After 3 days of comparing the same passages played with the
Midiboard and the A90 and analyzing the midi data stream we found this A90
failed the accuracy test. With the curves set for a heavy touch, we noted
some velocities on soft play were off by as much as 40 midi velocity steps
(127 total) that’s a 31% error. That was significant. We tried adjusting
every curve, every parameter and the best remedy was leave the action with a
light curve. Although this improved the accuracy, it still didn’t get the job
done right. The curves/mechanism cause both over and under reaction to
dynamic passages where accurate expression is essential.

By the time you get arpeggios to sound right the action is too light. Lower
velocities are affected without any ability to affect uppers except for curves
6 & 7. 6 is useless; 7 comes close but not it.

I think in redesigning the A80, Roland’s engineers were creative in their
approach and developed many great and useful features but the product
development failed to yield what a good controller should have... accuracy.

And I should mention this. This is not a case of a particular controller not
working with a particular sampler-- the Midiboard just had a much better
capability of rendering intended dynamics than the A90. This is not intended
to make people go right out and look for a used Midiboard... but it does show
that in some cases 13 year old technology is better.

The A80

In my disappointment after returning the A90, I looked for and found a brand
new (still in the box) A80. One of my former students had an A80 so I took
him up on his offer to bring it down to the studio and we could check it out.
This unit has the best software for fitting a curve to your equipment and
playing that I’ve seen. The display is great... the feel is okay. But the
A80 suffers from a common engineering problem that occurred in the early days
of designing velocity controlled Synths (late 70s).... the sharp keys play
louder than the naturals. So much for the A80.

O1W Pro X

I had one of these in the studio and I must say its accuracy and playability
was excellent and it measures velocity from the key. It’s only flaw is that
we couldn’t find any adjustment for the velocity curves for external devices.

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