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ER-101 – peoples choice panel (black–on–metalphoto)

Indexed Quad Sequencer

The ER-101 is an externally clocked and resettable 4-track sequencer. Each track consists of 2 analog control voltage outputs referred to as CV-A and CV-B, and, one digital output referred to as GATE.  The ER-101’s purpose is to provide the musician with a tool for creating and manipulating clock-synced control voltage contours of great length and complexity.  Probably the most traditional (but still very relevant) patch for a track’s output would be something like this:

Pitch Control:         CV-A to the 1V/octave input of a VCO (voltage-controlled oscillator)
Velocity Control:     CV-B to the level input of an EG (envelope generator)
Note On/Off:         GATE to the gate input of the same EG

Patched this way, the ER-101 gives you the ability to create almost any 4-part harmony in any scale with arbitrary dynamics and rhythm (up to the clock period). Really. The ER-101 can be a tool that enables you to inject just the right of amount of structure, repeatability, and control into your stormy creations.  On the other hand, the ER-101’s randomization and jittering operations, it’s penchant for complex phasing in time across tracks, and its ability to store thousands of steps for seemingly infinite variation, can be used to make just a few VCOs and VCFs sound like a huge workstation synthesizer.


– 4-track sequencer
– stepped and smooth voltage transitions
– each track has 3 outputs: 2 CVs + 1 gate
– each track has its own adjustable loop points
– each track contains up to 100 patterns  and each pattern can contain up to 100 steps
– each step can be individually adjusted to have 0-99 clock cycles in duration
– each gate can be individually adjusted to have 0-99 clock cycles in duration with or without ratcheting
– gate outputs are 0-10V which is perfect for pinging filters and LPG’s
– CVs are chosen (indexed) from voltage tables of which there are 2 per track (A & B)
– built-in voltage tables: 12-tone equal tempered, 22 shrutis, linear 0-8V, exponential 0-8V, linear-exponential 0-8V and others
– voltage tables are user-editable and have 100 entries per table
– voltages between 0.000-8.192V at 2mV increments can be dialed in
– smoothing can be enabled for individual steps, entire patterns and/or entire tracks
– smoothed transitions are NOT simply slews but are adjusted to match the current tempo in real-time
– hold feature (complete double-buffering of device state) allows smooth musical edit-commit-at-will while the sequencer is running
– while in hold mode, committing changes to a running sequence can be either immediate or quantized to the beat
– reset can be either immediate or quantized to coincide to with the ending of the current track, pattern, or step
– stores up to 16 snapshots of the state of the entire device
– arbitrary insert/delete of patterns/steps with clipboard style copy/paste
– math button allows you to specify a mathematical operation to apply to a step, a pattern or a track.
– note repeat (aka ratchet) any step
– shuffle (aka swing) any step
– expansion port
– firmware upgradeable via USB


Width: 26hp
Depth: 2cm from the back of the faceplate
Current Consumption:
(There is a switch on the back that lets you choose the +5V source.)
  • If +5V source is internal REGulator then approx 120mA from +12V.
  • If +5V source is the BUS then approx 95mA from +5V and 25mA from +12V.

Digital Inputs: x2 (clock and reset, threshold=2.5V)
Digital Outputs: x4 (gates, LO=0V HI=9.9V)

Analog Outputs: x8 (CV-A and CV-B, 0-8.192V at 12-bit resolution or 4096 levels)
Max Total # of Patterns: 400 per snapshot
Max Total # of Steps: 2000 per snapshot


Other modules by Orthogonal Devices | ER-101 – original flavor panel (black–on–grey) | ER-101 – nostalgia panel (white–on–grey)