I generally steer clear of early MIDI accessories. The
MIDI standard was introduced in 1983, and many MIDI implementations
from the early days were either misinterpreted (IE the infamous "All
Notes Off" on Roland keyboards and Yamaha DX-7 maximum velocity
response less than 127) or not implemented in the spirit of
"universal control". The Oberheim XK was introduced in 1985
and falls under the latter. While it is a MIDI controller,
Oberheim chose to optimize it for their Xpander and Matrix-12
products as
will be explained later. Its MIDI implementation doesn't fit
the definition of a "universal controller". The XK does not
implement MIDI features added to the standard later, such as NRPNs or
14 bit controller messages.
By the way, while the rear panel badge identifies the model as the
Oberheim XK-1 it has zero relevance with the Hammond XK-1.
In the 80s rock band I am playing in, the Andromeda gets a lot of use
and its own 61 note keyboard is often not enough with all the sounds I
have to
play.
To remedy that, my Hammond XK3 in my offsite rig doubles as a MIDI
controller for my Alesis
Andromeda when I am not playing organ
parts. Since I am using my Kurzweil MIDIBoard as a
master MIDI
controller for the entire system, I only need note-on & note-off
MIDI messages from the XK3 to trigger the Andromeda. All other
MIDI messages are filtered
using my JL Cooper MSB+ to keep the system glitch free, which can
happen too easily in a complex MIDI matrix system!
Since my stage rig is a compact duplicate of my studio system, I do my
sound design development in my studio carrying only my Andromeda
instead of the entire stage rig. This saves a lot of time and a
lot of stair climbing to my basement studio. I sought a good 61
note MIDI controller for my studio to emulate the dual function of my
XK3 so I could configure Andromeda mixes for the stage. None of
the modern MIDI controllers met my needs (to be frank, most of them are
cheap plastic toys). I became aware of the
Oberheim XK MIDI controller only recently - after a review of its
capabilities I decided this would fit my needs.
Features
The XK is a ruggedly built controller with non-weighted 61 note long
fulcrum keybed that
features attack AND release velocity, and mono aftertouch. While owners
have complained about the XK's unreliable Panasonic keybed like that in
the OB8 (as well as Moog Memorymoog, Korg Poly-6, others), mine does
NOT have the Panasonic keybed - perhaps Oberheim
changed to a better keybed in its later years? The keybed feels
like the same one in my Oberheim Matrix-6, and even though it is
non-weighted I like its feel better than a lot of other
keyboards. The XK features the Oberheim "levers" for pitch bend
and
modulation, a slidepot controller right above them, and octave shift
buttons conveniently above those controls. Like the
OBX/OBSX/OBXa/OB8, it includes HOLD
and CHORD functions (handy for a MIDI controller). The unit
weighs 15 pounds and is a low profile
case - I could easily add a couple of straplocks and use this as a
"keytar". On the rear panel are jacks for footswitch and external
clock.
100 user patches (known as "master programs") can be configured in the
XK, with each patch capable of three MIDI zones that can be split or
layered. The XK has a "block copy" that allows you to define a
"default" user patch configuration then copy it to a block of patches
(this eliminates copying your default parameters to every patch by
hand). MIDI Parameters for each zone include channel number,
patch number, multipatch number, upper limit, lower limit, voice limit,
transpose, slidepot CC#, mod lever reverse CC#, switch# for footswitch,
mono mode (not "unison"), levers on/off, aftertouch on/off, velocity
sensitivity, and arpeggiator. Velocity sensitivity is offered in
two curves (only one is really useful), plus fixed velocity.
Release velocity uses the same sensitivity selection. Patch numbers are
only assignable from 0 to 99 (not the MIDI max of 127), and Pitch bend
and aftertouch CC# are fixed and cannot be reassigned. Pitch bend
resolution is only 9 bits not 14 as the MIDI spec permits.
The arpeggiator can be set to one zone at a time and can be externally
clocked from the rear panel jack but its maximum rate is 40hz (reduced
to 20hz in OS version 1.4, see below). The arpeggiator can be
combined with the HOLD function, which latches the notes so you don't
have to hold them down. The CHORD function can also be used to
arpeggiate a chord using a single key press. Arpeggiator
intervals are "global" and are not stored with a user program.
Multipatch number is only useful with the Oberheim Xpander/Matrix-12
products.
START, CONTINUE, STOP, AUTOTUNE, and ALL NOTES OFF
MIDI controls are available but not as dedicated buttons thus they
require a two button press. Song Select is available, again
requiring
two button press and is not programmable. Aftertouch sensitivity
can be adjusted, the value is global and is retained with power off.
Spillover is possible on the XK using the voice limit parameter.
When the parameter is set to a value other than 16, the XK will
transmit note messages for the first Nth notes, then each succeeding
note is transmitted on the next adjacent MIDI channel. This was
optimized for the multipatch feature of Oberheim products like the
Xpander/Matrix-12 but is not useful for other products. This is
what I mean when the XK is not optimal as a "universal
controller". Unfortunately there is no facility in the XK to
configure patch numbers for the other MIDI channel. If you
perform the factory reset procedure, the default patches have zones
programmed to odd numbered MIDI channels. This is to ensure that
a spillover operation does not cross into another zone.
"Mono mode" begs some clarification. This does not turn the XK
into a monophonic controller. What it does is implement Mode 4 of
the MIDI specification. The usual operation of a zone is to
transmit MIDI notes on the same MIDI channel (barring the spillover
option). MIDI Mode 4 transmits each succeeding key press to the
next adjacent MIDI channel. On the XK the voice limit forces the
channel to "roll over" when the number of voices is exceeded.
This is intended to operate as a multitimbral system, where each MIDI
channel can have a different sound called up. Of course this
requires an adequate set of MIDI devices for the receiving end, or MIDI
devices capable of multitimbrality. Since the XK modulation
controls (pitch bend, mod wheel, slidepot, aftertouch) are mono only,
every MIDI channel gets the same modulation amounts.
Unfortunately there is no facility in the XK to configure patch numbers
for the other MIDI channels. top
Not a "master controller"
In my assessment, the Oberheim XK does
not fit the definition of a master MIDI controller. Its
feature set for configuring a MIDI setup is pretty shallow.
Missing parameters for a master MIDI controller are setting
preset volume, modulation depth, and other MIDI parameters such as
filter cutoff and envelope generator transient times. The lack of
ability to reassign aftertouch to a different MIDI CC#, missing ability
to configure patch numbers for "spillover" operations, and no SYSEX
patch archiving are big problems. I may be spoiled by my
MIDIBoard, but it did teach me parameters that are valuable for a
master controller.
I have to say I am not a fan of slidepots for modulation
controls. Slidepots have a short life, and finding a replacement
slidepot is hard because the pins have to line up with the footprint on
the PC board (there is no industry standard). I am very tempted
to modify my XK to use a control other than the slidepot. top
Caveat Emptor
I have two very big beefs with the XK:
NO PATCH ARCHIVING!
Only a MIDI output is provided and there is no SYSEX patch data
transmission/reception implemented. There isn't even a tape
interface for archiving patches. You must record your
configurations on pen and paper, and the owners manual failed to
provide a blank user patch template. In my book, this is a stupid
omission!
WALL WART I DESPISE wall
wart power supplies with the non-locking plug as they slip out too
easy. Wall warts are too fragile for the harsh rigors of gigging,
and are a PITA to pack up. Since I am a gigging musician, I
refuse to use wall warts in my stage rig. This means the XK is
delegated to studio use only. top
Firmware revisions
Firmware rev 1.4 adds some features:
The HOLD/CHORD functions are separate per zone
The action of the pitch bend can be reversed (I greatly preferred
the reverse orientation where pulling the lever towards you is bend
down)
Arpeggiator gate time is changed to minimize missing or sticking
MIDI notes with fast tempos. It also reduces the maximum tempo
from 40hz to 20hz.
Modulation lever (pulled toward player) CC# can be reassigned but
is global.
Velocity curves can have a maximum velocity value to accommodate
the Yamaha DX-7 and other keyboards whose maximum velocity response is
less than MIDI velocity=127.
There is no way to tell what version is in the XK other than attempting
the new features or opening the hood to inspect the marking on the
EPROM chip that holds the firmware. top
Factory Reset
If you acquire a used XK you should perform a factory reset procedure:
turn off power
press & hold MASTER PROGRAM button
turn on power
press STORE
two "_" characters will appear in the display
press "9" twice
display will count down from 99, resetting all user patches in
memory.
No undo is possible, so archive your patches before a reset. top
Epilogue
While it is an adequate MIDI controller, don't use the XK as a master
MIDI controller as its feature set is rudimentary and it lacks some
crucial features. Lack of SYSEX patch archiving is a serious
omission that takes it out of the running for a master
controller. Since this product uses a coin battery on the circuit
board to retain user patches when power is off, these batteries are due
for replacement as they are over thirty years old and can cause
potentially irreversible damage to the circuit board if the battery
leaks. If you acquire one of these, take it to a competent tech
right away to replace the battery (this is not a job for the novice,
and the procedure is not expensive for a tech). On the plus side,
a numeric keypad is provided for data entry - I abhor interfaces with
only increment/decrement buttons for adjusting data. If you have
a synthesizer non-keyboard module with MIDI, the XK is a good
controller. top
