There’s a lot of mystery beneath the hood of the Oberheim OB-8. From the hidden page two parameters to the OS B5 DSX / Midi parameters and Reassignable Mod / Pitch bender orientation. I figured I’d put a post together to cover a few of these and repost some arcane knowledge about Oberheim’s almost most advanced synthesizer. Consider this my first Synth-wiki-dump:
Article one:
======================================
NON-OBVIOUS FUNCTIONS OF OBERHEIM OB-8
======================================
The OB-8 has many functions that a user would never guess existed from
looking at the control panel labeling. This is a cheat-sheet to avoid
constant reading of the manual. Most of these functions are hidden by
virtue of requiring some combination of simultaneously held buttons,
or some other such thing that doesn’t seem obvious.
* Change split point:
Pressing the SPLIT button normally takes you in and out of keyboard
SPLIT mode, but you can also hold down SPLIT while pressing a key to
change the split point. Split points are non-volatile, and will
survive patch changes and shutdowns. However, they are also stored
with split patches, so selecting a new stored split will recall its
stored split point as well, overriding whatever is currently set.
* Transpose keys on LOWER keyboard:
The keyboard may be transposed by any interval, but the “lower” part
in a split/layer can only transpose upward. (Nevermind that in a
layer, both patches cover the whole keyboard — there’s always one
patch that is assigned through the UPPER button and one that’s
assigned with the LOWER button.) The reason the “lower” patch can
only go upwards is because the interval is selected on the keyboard
relative to C0, the lowest C. Press and hold down SPLIT or DOUBLE
(as appropriate) and LOWER at the same time, and select the upward
interval above C0 on the keyboard you’d like to transpose to.
* Transpose keys on UPPER keyboard:
This is the same, except transposition can go up or down because the
reference point is now Middle C (C3). It’s true even if you’re
transposing a layer (“double”), and both patches are covering the
keyboard. Hold down SPLIT or DOUBLE (as appropriate) and UPPER at
the same time, and select the interval above or below Middle C.
Transpositions of both the UPPER and LOWER components of a split or
layer _are_ stored with a split or layer patch! Recalling a split
or layer that was saved with transpositions active will also recall
the transpositions!
* Detuning one side of a split or layer:
The “lower” side (the patch assigned with the LOWER button) in a split
or layer can be detuned relative to the upper one by holding down the
LOWER button and turning the OSC2 DETUNE knob at the same time. This
control is only active for LOWER. (You can’t hold down UPPER.) Like
the other special hidden settings of splits and layers, this one too
is actually stored with the patch. Recalling a split or layer that
had a relative UPPER/LOWER detuning in effect will also recall that
detuning interval.
* Reset all split/layer settings to defaults:
To reset the split point to Middle C, cancel all traspositions,
relative detuning, etc.), hold down whichever button applies
currently (SPLIT or DOUBLE), and press the MANUAL button.
* Recalling/writing splits and layers:
Contrary to the way patch selection normally works on Oberheims when
not in split or layer mode, in this case, the GROUP buttons (which
are similar to Roland’s concept of “bank” buttons, to select a bank
of 8 patches) now behave just like regular patch buttons. That is,
they don’t select a bank of patches, they just select a single patch,
and have equal weight to any of the eight regular patch buttons.
This means that in split or layer mode, rather than having as many
possible patch storage locations as there are GROUP button combinations
_multiplied_ times the regular patch buttons (which on Rolands would
typically be 64), here you only have the 4 GROUP buttons _plus_ the
8 regular patch buttons, for a total of 12 patches. In split or layer
mode, a GROUP button is just another patch button, and it selects a
split or layer all by itself, not in combination with a button from
the regular buttons. However, your 12 splits and 12 layers do not
share slots, and you always have 12 patch locations of each (12 stored
splits and 12 stored layers).
To recall a stored split or layer hold down SPLIT or DOUBLE as
appropriate, and press one of the GROUP or regular patch buttons,
keeping in mind that any of them is just a patch button as far as
splits and layers are concerned. (There are no “groups” or “banks”.)
To write one, do the same thing, but hold down the WRITE button until
its light comes on first, and then do it. All transpositions, detunes,
split points, etc. will be stored with the split or layer.
* Modulation lever peculiarity:
The modulation lever on an Oberheim has a spring-loaded center
position like a pitch wheel, but does nothing if you push it away
from you. That’s just normal Oberheim behavior.
* Pitch bend lever peculiarity:
Contrary to the norm adopted by every other synthesizer company, on
Oberheims, pushing the pitch bend lever forward makes the pitch drop,
and pulling back on it makes the pitch rise. This is completely
backwards, but it can’t be changed without rewiring the potentiometer.
That’s also just normal Oberheim behavior.
* Modulation lever’s LFO waveform selection:
This is perhaps the finest example of hidden control panel functions
the OB-8 has to offer! First off, the RATE and DEPTH knobs near the
pitch/modulation section of the keyboard _pull up_. Yes, that’s right,
you can pull up on the knobs like the headlight switches on older cars,
which turn but also pull out to turn the headlights on. (Bet you would
have never even thought of trying that…) Naturally it’s not labeled.
And here’s now you select LFO waveforms for modulation:
Triangle Wave Push down the RATE knob while doing
doing nothing with the pitch bend.
If it was already down, pull it up
first so you can then do it.
Square Wave Pull up on the RATE knob while doing
nothing with pitch bend. If it was
already pulled up, push it down first
so you can, and then do it.
Rising Sawtooth Wave Pull up on the RATE knob while pulling
back on the pitch bend lever. See
above for if the knob was already up.
Falling Sawtooth Wave Pull up on RATE knob while pushing the
pitch bend lever forward.
White Noise Push the RATE knob down while pulling
back on the pitch bend lever.
Sample & Hold Push the RATE knob down while pushing
forward on the pitch bend lever.
This is really how you select waveforms for modulation lever LFO’s.
Okay. You can stop laughing now.
* Setting non-zero amounts of modulation all the time:
Since Oberheims have a spring-loaded lever for modulation rather than
a non-spring-loaded wheel like everybody else, it’s not possible to
just park the modulation setting at a non-zero position and leave it
there while playing on the keyboard like it would be anywhere else.
However, there’s a DEPTH knob, which if turned up, will let you set
how much modulation you’d like to have running all the time, even when
you’re not pushing the lever. The trick here is, it doesn’t do
anything at all when it’s not pulled up like a headlight switch.
(That’s why I’m filing it under non-obvious.) The advantage to this
is supposed to be that you can find a setting you like, and jump to it
immediately by just pulling up.
It may be worth noting (though it’s not as unconventional — lots of
synths have this feature), that there is a third source of modulation
control possible, beyond the lever and the pullable depth knob, if you
have a variable pedal connected to the MODULATION jack on the back.
In that case, you modulation amount would be a sum of the current
lever position, the DEPTH knob position (if it’s currently pulled up),
and the pedal.
* Setting pitch-bend range:
The vaguely labeled “AMOUNT” button near the pitch bend lever is a
toggle that can run in one of two modes, depending whether it is lit
or not. When it is off, the pitch bend range is fixed, and is always
a whole tone up or down. If you turn AMOUNT on, the pitch bend range
is programmable. Doing that is, of course, another hidden function.
Hold down AMOUNT, and at the same time play any key in the lowest
octave of the keyboard up to C1. This will let you set the pitch
bend range anywhere from a semitone up to a full octave. The setting
becomes non-volatile, and will take effect whenever the AMOUNT light
is on. Pressing the AMOUNT button again takes it back to its fixed
nature, which is always one whole tone up or down, and you can toggle
between the fixed setting and the user-defined one that way any time.
* Accessing the arpeggiator controls:
The buttons and knobs that control arpeggiator funtions are mostly the
same buttons and knobs that control pitch bend and modulation lever
functions. The MODE button switches the meanings of those controls
between the two roles; when the light is on, you’re looking at the
arpeggiator settings.
* Keyboard HOLD function with the arpeggiator:
You might not think to try this, but the KBD and HOLD buttons can be
made to come on at the same time. This way, the arpeggiator will
arpeggiate notes held down by the HOLD function _AND_ notes being
held down manually on the keyboard, both. You must hold KBD and HOLD
down together, because normally pressing one makes the other go off.
* Arpeggiation types:
The UP and DOWN buttons do individually what you would expect — UP
makes the arpeggiator play upward, and DOWN makes it play downward.
Less obvious is that you can have them both on to make it play up
then down, and having them both turned off puts it in random mode.
Also, random mode tries to give slight preference to the first note
played, on the presumption that it may be your tonic.
* Using arpeggiation ranges:
Another wonderfully obscured function, the OB-8 arpeggiator can
memorize and recall any of five programmable transposition settings,
which then become used only in the arpeggiator. (They have nothing
to do with regular keyboard usage.) Also, there is a sixth mode for
not using any arpeggiator tranposition, which is the default.
It’s hard to explain what this does. Obviously, when you’re in the
default mode, the arpeggiator plays what you played. This is selected
(if you’re not already in that mode) by holding down MODE and pressing
the LEFTMOST of the six buttons below the pitch/modulation levers.
(That’s the one labeled HOLD, the first button in that row.)
Ignore the labeling on the buttons; these functions are totally hidden
and have nothing to do with any of those six buttons labeled functions.
But if you hold down MODE and this time press the SECOND button in that
row (labeled KBD), you enable the first tranposition. Since the OB-8
comes with all the transpositions we’re talking about here set to
octaves, that means the arpeggio will spread out over an octave beyond
the spacing at which you actually played it. However, that interval
can be user-defined (see below) to whatever you want.
If you hold down MODE and press the THIRD button in that row (the one
labeled OSC2 ONLY, but disregard that label for this), you’ve enabled
TWO arpeggiator transpositions — the one described in the last
paragraph, plus this one, and the two intervals combine. So now if
all your arpeggiator transpositions are still set to octaves as they
are at factory settings, your arpeggios are spreading out over two
octaves beyond what was actually played. If they’re something user-
defined though, then it’s your first user-defined interval plus this
second one.
Hold down MODE and press the FOURTH button (labeled, irrelevantly,
“AMOUNT”), and you enable the first THREE transpositions for the
arpeggiator — the two described above, plus this one. At factory
settings, that makes your arpeggios span three octaves further than
actually played. You get the idea. It goes this way for all six
buttons below the pitch bend and modulation levers, without regard
to their labeled functions, so long as you hold down MODE while
you’re selecting them, and so long as you remember the leftmost
one is the one that turns these transpositions off (its programmed
interval is NO INTERVAL), which means pressing that combination
makes the arpeggiator play your arpeggio unmodified.
Almost makes you wonder why they bothered labeling the control panel.
Half the functions on the OB-8 have nothing to do with anything it
says, and are accessed by holding down this and this and pressing
that while you play something else.
* Programming arpeggiation ranges:
As mentioned above, although OB-8’s came pre-programmed with all five
of the user-definable arpeggiator transposition intervals set to one
octave, giving up to a five octave spread to a played arpeggio pattern
(remember the first of the six buttons turns the feature off, and is
not an interval), those intervals can be changed individually to
something other than octaves. To do that, hold down the MODE and
ARPEGGIATOR buttons at the same time, and then play five notes on the
keyboard, one at a time, not as a chord, while holding down the two
buttons. Those five notes will become the new transposition intervals
for the arpeggiator, and will become non-volatile, and independent of
any currently selected patch (i.e., a global setting of the keyboard).
* Pedal sustain time:
It is labeled on the control panel (at least on OB-8’s that have their
PAGE2 funtions labeled), but it’s still worth noting that unlike every
other keyboard’s sustain pedal policy, on the OB-8, the time that a
note will sustain while the pedal is down is a programmable parameter
of a patch. On any other keyboard, holding the pedal down is simply
equivalent to holding the note down indefinitely.
* Arpeggiator sync:
The arpeggiator sync jack on the back of the keyboard is completely
undocumented in the manual. I have heard from one source that it
expects a +5V trigger, and I have also heard that sending a loud
note from a drum machine into that port will suffice. Although the
OB-8 can support MIDI, there is no function to sync the arpeggiator
to MIDI clock, and that continues to be true even if the factory
MIDI is replaced with the Encore retrofit. (The Encore retrofit for
the Roland Jupiter-8 _does_ sync the arpeggiator to MIDI clock though.)
* Waveform selection:
When setting the waveforms for oscillators 1 and 2, selecting sawtooth
or pulse is done as expected with the buttons so labeled. However, it
should be noted that turning both SAW and PULSE off selects a triangle
wave, and turning them both on creates a composite wave from both the
sawtooth and the pulse wave.
* Square waves:
Square waves can be obtained by selecting pulse wave, and turning the
PULSE WIDTH knob fully to the left.
* Individual oscillator control of pulse width:
More unlabeled joy! You can change the pulse width of OSC1 or OSC2
individually by holding down the PULSE button of the oscillator you’d
like to change, and turning the PULSE WIDTH knob while it’s held down.
Normally, the knob changes pulse width for both oscillators at once
(provided they both are set to a pulse wave as far as waveform
selection for each oscillator goes). Once the two oscillators have
been given differing settings this way, they can be made them same
again by turning the PULSE WIDTH knob all the way to the right or
left while _not_ holding down anything.
* Switching oscillators on and off:
The buttons to turn oscillators 1 and 2 on and off (allowing you to
create simpler one-oscillator-per-voice patches if you’d like) is in
a rather confounding place — in the FILTER section. Don’t ask me
why they’re not in the OSCILLATOR section. Also, OSC2 has the option
of being on at either HALF or FULL volume. (Don’t worry, there are
labeled buttons for that. You don’t have to hold anything down.)
Also, there’s a white noise generator, and it’s turned on in the
FILTER section too, right where you’d expect a noise generator to be.
* ATTACK settings:
This isn’t related to the control panel, but is an important fact about
the OB-8 nonetheless: The factory documentation distributed by Oberheim
for calibrating the envelope generators is _WRONG_, and if followed,
will result in the OB-8 being incapable of generating fast punchy
attacks. The OB-8 has actually gotten a reputation for having slower
attack than its predecessor keyboard, the OB-Xa, because of the number
of OB-8’s that have been incorrectly calibrated _following Oberheim’s
own instructions_. In the service manual, where it says to calibrate
the EG’s to as close to 0.000 volts as possible, that should actually
read “as close to -0.256 volts as possible.” That is because there is
a 0.256 volt difference between the reading your voltmeter will get
while the system is running in calibration mode and the setting it
will have after the calibration is finished and it is returned to
normal operating mode. That will manifest itself as sluggish attacks.
This only affects the calibration of the EG’s (i.e., the ADSR). All
the other calibration instructions should be followed literally.
* Envelope reset:
In a bizarre but nifty feature, the ADSR cycle of any sound can be cut
short as it fades out (the RELEASE stage) by hitting the WRITE button,
the button normally used for writing patches. If pressed quickly and
not held down, that button serves as a cutoff for still-dying sounds.
* Sampled Vibrato LFO
The LFO’s aren’t too badly labeled, but on thing that’s not too obvious
is that all three of the waveform selectors can be on at once, and in
that case, it will do sample & hold from the separate LFO generated by
the modulation lever (rather than from noise as normal S&H would do).
For regular noise-derived S&H, turn the bottom one on as labeled on
the panel.
* Portamento bend:
In PAGE2 mode (which is itself an alternate control panel mapping,
before we even start talking about hidden stuff), there is a button
labeled PORTAMENTO BEND, which makes all notes gliss from a
programmable interval above or below the actual note played to the
actual note. Naturally, programming that interval requires holding
the PORTAMENTO BEND button down (while in PAGE2 mode) and playing
the desired interval on the keyboard, using C2 (the third C on the
keyboard) as a reference point.
* Reset all PAGE2 parameters:
If your PAGE2 settings have become simply mad, you can reset all PAGE2
parameters to defaults and retreat to the relatively simple world of
the OB-Xa (which had no PAGE2 mode) by pressing the PAGE2 button twice,
holding it down the second time, and while it is held, pressing the
button (for this purpose, irrelevantly) labeled F-ENV, which in this
context functions as a PAGE2 parameters reset.
* Loading cassette dumps made on other OB-8’s
Some of the calibration settings on an OB-8 are handled by the CPU, and
are thus actually non-volatile software settings rather than physical
positions on trimmers on the circuit board. Because of this, those
parts of the calibration that are done that way are lost when the
battery gets replaced.
Oberheim wanted to save keyboard techs from having to go through a
calibration just to replace the battery, so they made it so that every
cassette dump also includes the non-volatile calibration parameters in
the dump. Since every tech already knows to save the customer’s
patches before replacing the battery (if it’s not gone already), it
makes getting your CPU-managed calibration settings back afterward
happen more or less automagically.
The bad part is that anyone wanting to use the WAV files on the
Internet which contain recordings of the binary tape leader tone and
data from an actual cassette dump of the OB-8 factory patches to get
the original factory patches on their OB-8 will also be loading the
calibration settings of whoever that OB-8 belonged to. That probably
will not sound very good. It also strongly discourages trading of
patch banks between users using cassette dump as the medium.
If you ever do load someone else’s cassette dump, you will want to
review all parts of the calibration procedure that are not made with
a physical trimmer adjustment (i.e., all software-driven settings)
after you get the sounds loaded.
It is probably a much better idea to trade sounds with sysex dumps,
however:
a) Not all OB-8’s had MIDI at all, from any source.
b) The original Oberheim MIDI could only sysex dump single patches,
and had no function for sending a whole bank in one dump.
c) The Encore retrofit can send whole banks, but it was undocumented
in earlier versions the printed manual, and you might only know
you can even do it if you’ve looked at the PDF file manual now
available on Encore’s web site.
So cassette dump is the only way of saving patch banks that all OB-8
owners can do, but you still probably don’t want to do it unless you
don’t mind checking your calibration afterward.
Article 2:
OB-8 MIDI IMPLEMENTATION VERSION B-5
TRANSMITTED DATA — CHANNEL VOICE MESSAGES
Status Data Bytes Description
1000 xxxx 0kkk kkkk Note off. (See notes no. 1-2.)
0vvv vvvv 0vvv vvvv = note off velocity: always 40H.
1001 xxxx 0kkk kkkk Note on. (see notes no. 1-2.)
0vvv vvvv 0vvv vvvv = 40H
1011 xxxx 0ccc cccc Control Change. (if enabled).
0vvv v000 0ccc cccc = Control number (01=mod lever).
0vvv v000 = control value.(range 0-78H. Lowest
3 bits are ignored).
1011 xxxx 0ccc cccc Control Change. (if enabled).
0vvv vvvv 0ccc cccc = Control number (40H = Sustain
footswitch)
0vvv vvvv = control value.(0 = off. 7FH = on.)
1100 xxxx 0nnn nnnn Program select. (if enabled)..
0nnn nnnn = 0 through 77H.
1110 xxxx 0vvv vvvv Pitch 0end change LSB (see note 3).
0vvv vvvv Pitch Bend change MST
TRANSMITTED DATA — SYSTEM MESSAGES
1111 0000 0H System Exclusive Oberheim I.D. no.
0ddd dddd Device number. OB-8 = 01H
01H Command Byte 1 : Program data dump follows.
0ccc cccc Command Byte 2 : Program number.
data Program data. (see note 4)
F7H End of System Exclusive Status Byte.
OB-8 MIDI Implementation Version B-5 August 15,1984 Page 2
RECOGNIZED RECEIVE DATA — CHANNEL VOICE MESSAGES
Status Data Bytes Description
1000 xxxx 0kkk(kkkk Note off. (See notes no. 1-2.)
0vvv vvvv 0vvv vvvv = note off velocity: ignored
1001 xxxx 0kkk kkkk Note on. (see notes no. 1-2.)
0vvv vvvv 0vvv vvvv = 0: Note Off.
0vvv vvvv not = 0, velocity ignored.
1011 xxxx 0ccc cccc Control Change. (if enabled).
0vvv v000 0ccc cccc = Control number (01=mod lever).
0vvv v000 = control value.(0-78H. Lower 3 bits
are ignored.)
1100 xxxx 0nnn nnnn Program select. (if enabled).
0nnn nnnn = 0 through 77H
1110 xxxx 0vvv vvvv Pitch Bend change LSB (see note 3).
0vvv vvvv Pitch Bend change MSB
RECOGNIZED RECEIVE DATA — CHANNEL MODE MESSAGES
1011 xxxx 0111 1011 cccc cccc = 123 (7BH) : All notes off.
0000 0000 vvvv vvvv = 0. The OB-8 turns off all notes that
were turned on by MID!.
1011 xxxx 0111 1100 cccc cccc = 124 (7CH) : OMNI mode off.
0000 0000 vvvv vvvv = 0. The OB-8 turns OMNI mode off and
turns off all notes that were turned on by MIDI.
1011 xxxx 0111 1101 cccc cccc = 125 (7DH) : OMNI mode on.
0000 0000 vvvv vvvv = 0. The OB-8 turns 0MNI mode on and
turns off all notes that were turned on by MIDI.
1011 xxxx 0111 1110 cccc cccc = 126 (7EH) MONO mode on.
0000 0000 vvvv vvvv = 0. The OB-8 has no M0NO mode. When
this command is received the OB-8 switches to
OMNI on / POLY mode and turns off all notes that
were turned on by MIDI.
1011 xxxx 0111 1111 cccc cccc = 127 (7FH) P0LY mode on.
0000 0000 vvvv vvvv = 0. The OB-8 is always in P0LY so no
mode change occurs. All notes are turned off that
were turned on by MIDI.
OB-8 MIDI Implementation Version B-5 August 15,1984 Page 3
RECOGNIZED RECEIVE DATA – SYSTEM MESSAGES
1111 0000 10H System Exclusive Oberheim I.D. no.
0ddd dddd Device number OB-8 = 01H
01H Command Byte 1 : Program data dump follows.
0ccc cccc Command Byte 2 Program Number
data data (see note 4 for data format)
F7H End of System Exclusive Status Byte.
1111 0000 10H System Exclusive Oberheim I.D. no.
0ddd dddd Device number OB-8 = 01H
00H Command Byte 1 Program data dump Request.
0ccc cccc Command Byte 2 Program Number
F7H End of System Exclusive Status Byte.
1111 0110 – System Common Message : Tune Request
OB-8 MIDI Implementation Version 8-5 August 15,1984 Page 4
NOTES:
I. xxxx : Basic Channel number minus I. i.e. 0000 is CH.1. and 0001 is CH.2.
range : CH.1-8.
2. kkk kkkk = note number. Range 24H-60H
3. Sensitivity of the pitch bender is selected in the receiver. Center
position (no pitch change) is 2000H, which is transmitted ExH-00H-40H.
Maximum transmitted value is 7F40H. (The 6 lsb’s are not looked at by the
OB-8).
4. 00ERHEIM OB-8 PROGRAM BIT MAP :
Sent as 4 bit nibbles, right justified, LS nibble sent first.
: BIT 7 : BIT 6 : BIT 5 : BIT 4 : BIT 3 : BIT 2 : BIT 1 : BIT 0 :
———————————————————————————-:———-
BYTE 0 : VCF REL (6 BITS) : LFO WAVE :
: : 2 1 :
————————————————————————- :———-
BYTE 1 : VCA REL (6 BITS) : :UNISON:
: : 0 : :
——————————————————————————————— BYTE 2 : VCF DCY (6BITS) : FILTER: OSC 2:
: : FM : FM :
———————————————————————————————
BYTE 3 : VCA DCY (6 BITS) :OSC2 WAVEFORM:
: : I : 0 :
———————————————————————————————-
BYTE 4 : VCF ATK (6 BITS) :OSC1 WAVEFORM:
: : I : 0 :
———————————————————————————————-
BYTE 5 : VCA ATK (6 BITS) : OSC 2 : OSC 1 :
: : PWM : PWM :
———————————————————————————————-
BYTE 6 : VCF SUS (6 BITS) : NOISE : 4 POLE :
: : : :
———————————————————————————————-
BYTE 7 : VCA SUS (6 BITS) : OSC 2 : OSC 2 :
: : ON : HALF :
———————————————————————————————–
BYTE 8 : VCF M0D (6 BITS) : OSC 1 : TRACK :
: : ON : :
———————————————————————————————–
BYTE 9 : VCF RES (6 BITS) : PW1 : VC01 :
: : 180 ‘ : 180 ‘ :
————————————————————————————————
BYTE 10 : VCO 1 PW (6 BITS) : VCA : F-ENV :
: : MOD : :
————————————————————————————————-
BYTE 11 : LFO FREQ (6 BITS) : SYNC : OSC 1 :
: : : FM :
————————————————————————————————-
OB-8 MIDI Implementation Version B-5 August 15,1984 Page 5
————————————————————————————————-
BYTE l2 : FM AMNT (6 BITS) : : :
: : 5 : 4 :
————————————————————————- VOLUME —
BYTE 13 : PWM AMNT (6 BITS) : : :
: : 3 : 2 :
————————————————————————- —
BYTE 14 : PORT AMT (6 BITS) : : :
: : 1 : 0 :
————————————————————————————————–
BYTE 15 : VCO2 DETUNE (6 BITS) : VCO 2 PW :
: : 5 : 4 :
————————————————————————– : —
BYTE l6 : VCF FREQ (6 BITS) : : :
: : 3 : 2 :
————————————————————————– : —
BYTE l7 : VCO2 FREQ 6 BITS) : : :
: : 1 : 0 :
—————————————————————————————————
BYTE 18 : VC01 FREQ (6 BITS) : SPARE : LEGATO :
: : : PORT. :
—————————————————————————————————
BYTE l9 : RETRIG POINT (6 BITS) : RETRIG LFO WAVE :
: : 2 : 1 :
————————————————————————– :————–
BYTE 20 : PEDAL SUSTAIN (6 BITS) : : PORT :
: : 0 : BEND :
—————————————————————————————————
BYTE 21 : FM VIB RAISE (6 BITS) : LFO : FM DLY :
: : TRACK : INVERT :
—————————————————————————————————-
BYTE 22 : PWM VIB RAISE (6 BITS) : PORT : PORT :
: : QUANT : MATCH :
—————————————————————————————————-
BYTE 23 : FM VIB DELAY (6 BITS) : 180 ` : 90 ‘ :
: : : :
—————————————————————————————————-
BYTE 24 : PWM VIB DELAY (6 BITS) : PWM DLY : PWM :
: : INVERT : QUANT :
—————————————————————————————————-
BYTE 25 : VOICE DETUNE (6 BITS) : EXPO : CONST :
: : PORT : PORT :
—————————————————————————————————-
BYTE 26 : BEND AMOUNT (6 BITS) : LFO RATE : FM :
: : DELAY : QUANT :
—————————————————————————————————-
OB-8 MIDI Implementation Version B-5 August 15,1984 Page 6
MODES
The OB-8 defaults to 0MNI ON upon power up. If the OB-8 is a receiver, it will receive on all channels. If the OB-8 is the transmitter, it will transmit on one channel. (selectable)
The OB-8 may also be operated in OMNI OFF mode. If the OB-8 is a receiver, it will now receive ONLY on the selected Basic Channel. If the OB-8 is used as transmitter, it will now transmit the upper half of the keyboard on the Basic Channel, and the lower half will be transmitted on the Basic Channel + 1. Pitch bend, progam select, etc. will be transmitted on both channels. The Channel Split Point is the same as the regular Split Point. (default is middle C.) THIS MODE IS INDEPENDENT OF SPLIT MODE.
The OB-8 is always in POLY MODE.
FRONT PANEL SELECTABLE FUNCTIONS (ON PAGE TWO OF FRONT PANEL)
NOTE: Functions must be enabled on source AND destination machines to work.
Switch Function
A Enable/Disable program change and program dump.
Power-On default: disabled.
B Enable/Disable Pitch bend and modulation controls.
Default: disabled.
C OMNI ON/OFF. Toggle OMNI status. Power-On default is OMNI ON
(led is lit.) (see MODES)
D Channel display/select. Press and hold down D button to display
or select the Basic Channel.
WRITE Dump current STORED program to MIDI. NOTE: SWITCH “A”, “PROGRAM
ENABLE”, MUST BE ENABLED FOR A DUMP TO OCCUR.
TRACK Sequencer Re-Enable / Turn off MIDI Notes.
IMPORTANT: The OB-8 cannot RECEIVE MIDI info and be run by the
DSX sequencer simultaneously (due to hardware design.) So, to
prevent MIDI data errors, the sequencer is DISABLED upon
receiving any data from MIDI IN. This condition is displayed by
the TRACK led on page 2. When you no longer wish to use the OB-8
as a receiver, and you want to use the DSX, disconnect MIDI IN
and press the TRACK button. The led will go out, the sequencer
will work normally, and any notes turned on by MIDI will be turned off.
Power-On default: TRACK light off, Sequencer Enabled.
Article 3:
OB-8 Revision B5 Software
Operation Guide
8/15/84
This revision of OB-8 software (version B5) has been made to improve the operation of the OB-8 with the DSX, as well as to add some new MIDI features. For a complete explanation of the OB-8’s existing features, please refer to the OB-8 Owner’s Manual and the OB-8 Revision B3 Software Operation Guide. To verify the software version number of an OB-8, press the PAGE 2 button twice and hold it down the second time it is pressed (the PAGE 2 led should now be lit). Wile holding down the PAGE 2 button, press and hold the SYNC button. While holding both switches down, the PROGRAMMER leds will display the OB-8’s software version number. If the B led in the GROUP section and the 5 led in the PROGRAM section are now lit, the software version is B5. This version has all of the features of version B3, as well as the following NEW FEATURES:
1. The Sustain Footswitch on the OB-8 has now been added to the MIDI interface. This means that when two OB-8s are connected together through MIDI, the Sustain Footswitch on th MASTER OB-8 (the one using MlDI OUT) will also control the Sustain on the SLAVE OB-8 (the one using MIDI IN). This feature can also be used by other synthesizers that transmit and recieve Sustain Footswitch information on MIDI.
2. When an OB-8 with MIDI is connected to a DSX Digital Sequencer, the MIDI output of the OB-8 will send out the notes played by the DSX through the MIDI output. This allows additional synthesizers with MIDI to play the same thing that the OB-8 is playing from the DSX. Now with version B5 (and a DSX with version 3.00 or above), it is possible to have the DSX control the OB-8 AND a synthesizer connected to the OB-8’s MIDI OUT INDEPENDENTLY. By assigning the DSX’s CV outputs to the OB-8 MIDI (see “DSX REVISION 3.00 INSTRUCTIONS”), the DSX will send whatever the DSX’s CVs are playing to the OB-8’s MIDI OUT without the OB-8 playing it. The notes that the OB-8 are playing will NOT be sent to the MIDI OUT, so that the two synthesizers can play completely independently. This also means that when this feature is used, and the DSX is not playing anything on the CVs, no notes will be sent to the OB-8’s MIDI OUT regardless of what is being played on the OB-8.
3. The overall speed of operation on the OB-8 has been increased to allow the DSX to communicate with the OB-8 faster, resulting in increased accuracy of the timing of notes played by the DSX.
4. The range of vibrato lever has been changed for better compatability.
Article 4:
Oberheim OB 8 Improved sound mod!!!!
This is from the archives of Haible Juergen
As I posted before, the main difference in sound between the
OB-8 and the OB-Xa is a bass loss of the OB-8 due to a 22Hz
highpass in the signal path.
While 22Hz don’t look that dramatic, remind You that the phase
is fucked up at much higher frequencies. You can see the saw
wave distorted to an exponential slope instead of a linear one
for the entire low octave. The pulse has extreme overshots
(differentiated), and the triangle is hard to describe, but not a
triangle at all anymore.
In my earlier posting I suggested increasing coupling capacitors,
but this affects the autotune routine which is optimized for speed
and will produce errors with the enlarged time constants.
Last night I tried an alternative method: Compensating the phase
shift of the voices in the output stage (after the autotune loop).
The “bad guy” actually is the coupling between the VCF and VCA:
it’s a 75kOhm resistor in series with a 100nF capacitor.
To compensate for this, we have to put a similar network into the
feedback loop of an opamp.
To avoid additional stages, I decided to change the frequency
response of the opamp that converts the final VCA’s output current
to a voltage.
Now here’s the way to go:
(1) Replace the resistors R505 and R506 (100k) with 1M resistors
on both voice boards (4 resistors in total). If You stand in front
of Your open OB-8, these resistors are located near the right
edge of the board, next to a TL082 opamp. Cutting them out
is easier than desoldering them on the 2-sided pcb.
(2) Now build a small network of a 120k resistor and a 56nF cap
*in series* and connect the whole network *in parallel* to the
new 1M resistors (solder it right on top).
That’s all. If You want to do an A-B crosscheck, modify one voice
board first and cycle thru the voices. You will hear the difference,
and You will also see it at a scope.
If You find the original OB-8’s sound more pleasant, just short the
four 56n capacitors. Or solder 4p1t switch across the caps to have
immediate access to both sounds.
For my part, I have the change hardwired, without a switch. If I want
less bass, I can do this with the mixing console …
DISCLAIMER:
Though this works fine on my OB-8 (and I don’t know any reason why
it shouldn’t ob Yours as well), I guarantee for nothing.
Article 5:
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- Oberheim OB-8 Page2
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- OB-8.mulitmode.filter
::: IF :::
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