Korg SQ-10 (c. 1978–1980)

A row of big white buttons, twelve knobs, and no memory at all. Korg's analog sequencer makes you play it rather than program it.

Overview

The Korg SQ-10 is an analog step sequencer, and it arrived alongside the MS-20. Korg's own iMS-20 documentation notes the SQ-10 "was also introduced in the same year" as that synthesizer. It was designed for the MS series, and the surviving MS-20 owner's manual spells out the workflow plainly: set the SQ-10 to determine the pitch and tone color the MS-20 produces at each step, then let the sequencer's internal clock run through the steps for automatic control. The manual also describes a live-performance patch where the SQ-10 advances one step and changes tone color every time a key is played on the MS-20. This is not a box that sits in a rack doing its own thing. It's a control-voltage brain for a semi-modular synth.

Production is generally placed at approximately 1978 to 1980, though the sources admit exact years aren't firmly recorded. Equipboard describes it simply as "an analog sequencer from the 1970s," and MusicRadar calls it "the classic Korg SQ-10." Physically, it's a panel of step switches and knobs with no pattern memory whatsoever. You program it by turning knobs and setting switches, the way early analog sequencers were always programmed. Nothing is stored. Nothing is recalled. The pattern exists only as long as the knobs stay where you left them.

Depending on what you want from a sequencer, that's either the dealbreaker or the whole appeal. For players coming from the MS-20, it's the appeal. The SQ-10 turns a monosynth into a pattern instrument, and the random mode in particular has a reputation for producing material you wouldn't have dialed in deliberately.

Key Features

Three Rows of Steps — A, B, and C

The front panel carries a row of 10 step switches and 12 knobs, organized into three rows of step positions labeled A, B, and C. Rows A and B each run 10 steps. Row C is shorter at 7 steps, with a repeat step (R) at the end that can serve as a gate or trigger sequencer. That truncated third row lets you run a shorter cycle against the longer A and B rows, so the pattern shifts against itself over time. Sources conflict here - one description gives the unit as having 2 rows of 10 steps rather than the three-row A/B/C layout - so treat the row count with caution. The three-channel output is described as allowing pitch, tone color, and timing variation, which is a fair summary of what the A/B/C structure buys you.

Sequencer, Alternate, and Random Scanning Modes

The SQ-10 offers three scanning modes: sequencer, alternate, and random. The random function gets singled out. It was noted as a surprisingly musical feature, and owners have long described the unit as capable of creating interesting pattern-based music in real time. With the output feeding a synth's pitch and filter, it generates phrases that feel composed without being predictable. The alternate mode gives you a back-and-forth motion through the steps rather than a straight run.

Eight CV Outputs and Eight Trigger Outputs

The SQ-10 provides 8 voltage control outputs (C1-C8) and 8 trigger outputs (T1-T8). The CV outputs aren't limited to pitch. Vintage Synth Explorer notes they can be connected to the oscillators, VCF (filter), or LFOs of MS-series synths for additional modulation tricks. So you can run one CV output to a filter and another to pitch, and the sequencer is animating two parameters at once. The trigger outputs handle gating and clocking duties, and the service manual's function tests walk through this kind of routing, connecting trigger outs to an MS-10's trigger input to verify that a pulse lands only on the correct step.

Internal Clock from 80Hz to 20kHz, Plus External Clocking

The internal clock runs from 80Hz to 20kHz, and the unit can also be clocked externally through a CLOCK IN input. The service manual documents the clock knob's behavior directly: turned fully counter-clockwise, the cycle slows to somewhere in the 10-to-40-second range, and turned clockwise, it speeds up. There are also dedicated inputs for voltage-controlled clock speed. The manual lists jacks where an incoming control voltage from an MS-10 changes the clock rate, speeding up toward +5V on one input and slowing down toward +5V on another. That makes the sequencer's tempo another patchable parameter.

Screwdriver-Adjustable Voltage Scale Adapter

A screwdriver-adjustable voltage scale adapter calibrates the SQ-10 to the MS-20's Volts/Octave system. The scaling is set to match the MS-20's tracking, and it's adjustable rather than fixed. For driving other gear, Vintage Synth Explorer notes that a CV/Gate converter allows the SQ-10 to be used with other Roland, Moog, Sequential, and even MIDI synthesizers.

Edit Switch for On-the-Fly Changes

An edit switch lets you pick a particular step to change while the sequencer is running. On a machine with no memory, this is the performance interface. You're not recalling a stored pattern, you're reaching into the running sequence and moving a step. The service manual's step-test procedure describes the step button advancing the sequence through its positions, and the big white start/stop and step buttons are called out as a distinctive physical feature of the original.

Analog Mixer Section

The service manual documents an analog mixer built into the unit: the sum of the IN 1 and IN 2 voltages should appear at the OUT voltage. The manual's example connects an MS-10's output to IN 1, the SQ-10's multiple trigger out to IN 2, and an MS-10 CV input to OUT, so the trigger signal modulates the pitch of a note while the IN 1 voltage shifts the entire pitch. It's a small utility section.

Historical Context

The SQ-10 was designed for the MS series synthesizers, and its introduction is tied to the MS-20's arrival. Semi-modular synths and outboard sequencers were being sold as a system then, and the MS-20 owner's manual devotes a section to expanding the system with the SQ-10. It describes both automatic control of the MS-20 from the sequencer and a live-performance patch where playing the MS-20 keyboard advances the sequence a step at a time.

Its influence outlasted its production. Korg's own iMS-20 app includes a 16-step analog sequencer "designed based on this SQ-10," and Behringer's BQ-10 is described by MusicRadar as "an analogue semi-modular sequencer based on the classic Korg SQ-10" and by Synthanatomy as "a clone of the Korg SQ-10 sequencer." Gearnews offers a more measured view, suggesting the BQ-10 is "perhaps more closely based on the modern-day KORG SQ-1 than on its predecessor from the 1970s." Coverage of those clones notes that originals "are going for premium prices and they are selling."

Collectibility & Value

The SQ-10 has a real market, and the numbers are not small. A current eBay listing for a unit, titled "KORG SQ-10 Analog Sequencer 12 Step 3 Channel CV Gate Vintag," carries an asking price of $2,236. The "12 Step" claim in that title conflicts with the 10-step description elsewhere. It's a single listing, not a settled market value, and Reverb maintains an estimated-value price guide page for the model without publishing a figure in the sources available.

Buying advice is thin in the documented record, but a few practical notes survive. The unit requires an external power source, with no built-in battery option, so a complete example should include its supply. A DIY repair write-up flags that reassembly involves an infinite number of small screws to align with the frames, and that it's very easy to go wrong and have to disassemble a panel again to make everything fit. Photograph everything first. The service manual survives as a PDF on the Internet Archive, and owner manuals are available through ManualsLib and Vintage Synth Explorer. Common failure points aren't named in the sources available.

It's a well-built analog sequencer, designed as a system partner for the MS line, with a random mode and a physical interface that resists automation.

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