Arturia iSem User Manual
Arturia / Oberheim
iSEM User Guide:
Table of Contents
Introduction ............................................................................................................................................... 4
From the first Oberheim synthesizer up to TAE® .................................................................................... 4
A better emulation thanks to TAE® ............................................................................................................ 10
Main UI Controls...................................................................................................................................... 12
Loading & Saving Patches ............................................................................................................................... 12
Browse Presets ................................................................................................................................................................. 12
Load ...................................................................................................................................................................................... 12
Save ....................................................................................................................................................................................... 13
Importing Presets ........................................................................................................................................................... 14
Controls ................................................................................................................................................................. 15
Potentiometers ................................................................................................................................................................. 15
Selectors and Buttons .................................................................................................................................................... 16
Virtual keyboard .............................................................................................................................................................. 16
Keyboard functions ........................................................................................................................................... 16
Octave: ................................................................................................................................................................................. 16
Scale: ..................................................................................................................................................................................... 17
Key: ....................................................................................................................................................................................... 17
Hold ....................................................................................................................................................................................... 18
Chord .................................................................................................................................................................................... 18
Zoom ..................................................................................................................................................................................... 18
Scroll ..................................................................................................................................................................................... 18
Poly ....................................................................................................................................................................................... 18
Modulation and Pitchbend Levers ............................................................................................................... 19
Inverting the levers ........................................................................................................................................................ 19
CONNECT .................................................................................................................................................... 20
WIST ..................................................................................................................................................................................... 20
GLOBAL TEMPO ............................................................................................................................................................... 20
MIDI ........................................................................................................................................................................ 21
MIDI Channel selection ................................................................................................................................................. 21
MIDI Learn ......................................................................................................................................................................... 21
BACKGROUND AUDIO ....................................................................................................................................... 22
MAIN PAGE ................................................................................................................................................ 24
VCO .......................................................................................................................................................................... 25
Frequency Controls ........................................................................................................................................................ 25
Oscillator Modulations .................................................................................................................................................. 25
Pulse Width ........................................................................................................................................................................ 25
Oscillator Sync .................................................................................................................................................................. 25
Sub Osc ................................................................................................................................................................................ 25
Oscillator Mixer .................................................................................................................................................. 26
VCF .......................................................................................................................................................................... 26
Envelope Generators ........................................................................................................................................ 27
ENV 1 .................................................................................................................................................................................... 27
ENV 2 .................................................................................................................................................................................... 27
Low Frequency Oscillators ............................................................................................................................. 28
LFO 1 .................................................................................................................................................................................... 28
LFO 2 .................................................................................................................................................................................... 28
Effects mix/Output ............................................................................................................................................ 29
Output Level ...................................................................................................................................................................... 29
Soft Clip ............................................................................................................................................................................... 29
Arpeggiator .......................................................................................................................................................... 30
Rate ....................................................................................................................................................................................... 30
Sync ....................................................................................................................................................................................... 30
Play Mode ........................................................................................................................................................................... 30
Octave Range ..................................................................................................................................................................... 30
Enable Switch ................................................................................................................................................................... 30
Portamento ........................................................................................................................................................................ 30
2. Mod Matrix ........................................................................................................................................... 31
Mod matrix Enable/Disable ........................................................................................................................................ 31
Operation ............................................................................................................................................................................ 31
Mod amount ...................................................................................................................................................................... 31
3. Voice Programmer ............................................................................................................................. 32
Activate/Deactivate Voice Programmer ................................................................................................... 32
Polyphony ............................................................................................................................................................. 32
The Barlines......................................................................................................................................................... 33
Changeable destination and activation switch ................................................................................................... 33
Allocation modes ............................................................................................................................................... 33
4. FX ............................................................................................................................................................. 34
Overdrive:............................................................................................................................................................. 34
Chorus .................................................................................................................................................................... 35
Delay ....................................................................................................................................................................... 35
5. Perf (Perform) ..................................................................................................................................... 36
Introduction
From the first Oberheim synthesizer up to TAE®
Thomas Elroy Oberheim was born on July 7th 1936 in Manhattan, Kansas. His first
attempts at building electronic equipment came after leaving UCLA, when he built an
amplifier for the PA system of his friend's band, the United States of America. Once that
was completed, the singer for the United States of America asked Tom if he could build
them a ring modulator- so he set to work researching how to create it. Thanks to an article
by Harald Bode, Oberheim was able to hand build a model suitable for musical
applications. This was the very first piece of his legendary music equipment, and the
beginning of a long career in the crafting of unique and fabulous sounding electronic
instruments. The ring modulator was an instant success and became widely used in
music production, most notably in the soundtrack of the film "Beneath the Planet of the
Apes".
Eventually, his ring modulator was released to the market as Maestro Ring Modulator
RM-1A, garnering widespread positive feedback and used by many musicians like Herbie
Hancock, Jan Hammer, John Lord and more.
The Maestro RM-1A Ring Modulator
A few years later, Mr. Oberheim became very interested with the sound of instruments
played through a Leslie rotary speaker. This fascination inspired him to plan and construct
a phase shifting effect which was intended to imitate the Leslie speaker sound: it was
released as Maestro PS-1. It too was a true success and sold nearly 25,000 units.
The Maestro PS-1A Phase Shifter
In 1969, he founded “Oberheim Electronics”.
At the NAMM show in 1971, Tom Oberheim approached Alan Robert Pearlman of ARP
Instruments, Inc. and asked him to become an ARP dealer in Los Angeles. After a
positive conversation, Oberheim Electronics became the first dealer of ARP on the west
coast of the U.S. and sold ARP synthesizers to many musicians including Leon Russel,
Robert Lamm and Frank Zappa.
While working for ARP, he noticed that ARP2500 had the possibility of playing
two notes at the same time (known as duo phonic); he found this much more
interesting and powerful than regular monophonic synthesizers, and so he
decided to modify the ARP2600, empowering it with the same duo phonic
potential as the ARP2500 in 1973.
In addition to being an electronics wizard, Tom Oberheim was also an
educated computer engineer and subsequently designed the DS-2 digital
sequencer to control ARP or Bob Moog’s synthesizers. This pioneering device
was a huge step forward because the DS-2 was one of the very first digital
sequencers, and was the first step towards making his Synthesizer Expander
Module (or SEM).
The Oberheim DS-2A digital sequencer
In May 1974, he showed the SEM, that he designed with the help of Dave Rossum of Emu Systems, at the Audio Engineering Society Convention in L.A. The SEM was the first
synthesizer with the name “Oberheim Electronics” on the market.
The Oberheim SEM
Tom expanded its concept again with the help of Dave Rossum and Scott Wedge (Cofounder of E-mu Systems) by creating polyphonic synthesizers that were in effect
combinations of the SEM with a digital keyboard in one carry-case.
They were known as the “Oberheim 2-voice (TVS-1)” and “Oberheim 4-voice (FVS-1)”
synthesizers, and were released in 1975.
He realized that operating these polyphonic synthesizers in real time was not practical
from a musician’s standpoint so he began to think of an alternate solution, something that
would render the instruments more straightforward and easy to use. The answer he came
up with was the Polyphonic Synthesizer Programmer, which could store the synthesizer's
sound settings. This was the first voice programmable synthesizer, and a huge step in the
world of sound synthesis.
The Oberheim 4-Voice
The Oberheim 4-Voice synthesizer had a notable feature: it was the one of the
first electronic instruments to boast multi-timbral operation. The 4-Voice was
organized with the group of independent monophonic synthesizers (SEMs),
which were controlled by master controller section that handled the main
global controls (it couldn't however set the all parameter values i.e. OSC
waveform, filter resonance, filter type).
This specification- while already a major innovation in the world of
synthesizers- made it slightly unpractical to edit the machine in real time. On
the other hand if the player wanted to have different sounds for every single
note in the chord, it was possible- making it a truly powerful and unique
electronic instrument. Therefore, when player played a lead, different sounds
would be produced, in a cyclical manner- a very different approach to
synthesizers by today's standards. It is worth noting that this feature made
key split and unison available as well.
The next machine Tom created, the “Oberheim 8 voice” was very similar to
the 4-voice, and can be summarized basically as the FVS-1 plus 4 externallycombined SEM modules. It released in 1977.
The Oberheim 8-Voice
Afterwards, Oberheim Electronics continued to be a prolific synthesizer
company, releasing the OB-1, OB-X, OB-Xa, OB-8, Xpander and Matrix6 and
12, all highly regarded and influential machines.
In 1985, Oberheim Electronics closed, however Gibson Guitar Corporation
continues its brand and some Oberheim products. Tom recently began
producing hand-made updated SEMs and has announced the release of a
successor to his original 4-voice available in the next few years.
A better emulation thanks to TAE®
TAE® - standing for True Analog Emulation - is a new technology dedicated to the digital
reproduction of analog circuits.
When implemented in software code, TAE® algorithms guaranty the respect of hardware
specifications. This is why the Oberheim ISEM offers an unparalleled quality of sound.
In detail, TAE® means:
Aliasing-free oscillators:
Standard digital synthesizers produce aliasing in high frequencies, and also when using
Pulse Width Modulation or FM.
TAE® allows the production of totally aliasing-free oscillators in all contexts (PWM, FM...),
and at no extra CPU cost.
Aliasing
Linear frequency spectrum of an existing well-known software synthesizer
Linear frequency spectrum of the Oberheim oscillator made with TAE®
Better reproduction of analog waveforms:
Original analog oscillators used capacitor’s charge and discharge cycles to produce
common wave shapes (saw tooth, triangle, square). This means that waveforms were
slightly curved. TAE® allows the reproduction of the capacitors discharge.
Temporal representation of a waveform on a Oberheim SEM
Temporal representation of the Oberheim ISEM waveform thanks to TAE®
In addition, original analog oscillators were unstable. Actually, their wave
shapes were always slightly different from one period to another. Also, due to
analog hardware sensitivities, new period trigger times varied with the
temperature and other environmental conditions.
TAE® simulates the instability of oscillators, helping to create warmer sounds,
often given the affectionate term of “fat”.
Better reproduction of analog filters
TAE® allows the emulation of analog-designed filters in a much more precise way than
any existing digital filter. In particular, TAE® has managed to reproduce the legendary
Oberheim -12dB low-pass resonant filter with great respect towards the original.
Implementation of soft clipping
In analog synthesizers, particularly Oberheim's, the resonant filter at the VCA uses a
current limiting function, preventing the signal from being too loud (soft clipping).
TAE® reproduces this current limiting function, making the sound more natural. It also
allows filters to enter self-oscillation like original hardware synthesizers do.
Soft-clipping transfer function
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