The KSR Ceres ONE is a mini preamp pedal from KSR Amps, a reimagined version of the company's Ceres preamp in a small format. KSR describes the Ceres line as distilling the KSR sound into a small package, with the Ceres ONE coming in at about half the size of the original, measuring 2.7″ x 4.7″ and weighing 1 lb1. In terms of tone, KSR says it picks up where the original Ceres left off by adding gain, more usable low end, and increased dynamics and touch sensitivity1.
The pedal is manufactured completely in KSR's Cincinnati facility, with CNC machining, powder coating, laser etching, silk screening, and circuit board assembly all performed under one roof, with no outsourcing1. As of October 2026 it is listed at $249.002; earlier product pages in January 2026 listed it at $279.001.
The controls
The Ceres ONE carries many of the same functions present on KSR's full-size amps, in an enclosure measuring 2.7″ x 4.7″. Two toggle switches, the Mode switch and the Feel switch, and the familiar knob rows do most of the work14.
| Control | Positions | What it does |
|---|---|---|
| Mode switch | Up / Center / Down | Up = Ares/Orthos Crunch, Center = Artemis/Gemini Red Mode, Down = Colossus Lead 14 |
| Feel switch | Up / Center / Down | Up = Thick, Center = Tight, Down = Fat; the opposite of the original Ceres4 |
| EQ knobs | Full sweep | Function as on full-size KSR amps, with the full sweep of each control totally usable4 |
| Gain knob | Continuous | Operates like the full-size KSR amps and the original, without the unwanted top-end artifacts typically associated with solid-state circuits4 |
| Footswitch | Press / hold | Press activates the gain channel; hold activates mute1 |
The Mode switch positions are named after KSR amplifier channels, so players familiar with the company's amps can map the pedal's voices onto the amps they reference. All modes have added usable gain on tap compared with the original Ceres1.
The Feel switch is worth a close look for anyone coming from the original pedal: KSR notes that its positions are the opposite of the original Ceres, so Up is Thick and Down is Fat rather than the reverse4.
Bypass modes and the Clean channel
The Ceres ONE includes KSR's exclusive Bypass Mode switch, offering True Bypass, Buffered Bypass, and Clean Bypass1. Each suits a different place in a rig:
- True Bypass: for hitting a clean amp further down the chain on your pedalboard, with no tonal coloration5.
- Buffered Bypass: also operates with no tonal coloration5.
- Clean Bypass: enables the top row of Tone and Volume knobs, accessing the pedal's Clean channel, which can drive a power amp directly5.
That third mode is the one that sets the pedal apart from a straightforward drive box. Instead of the bypass signal being untouched, Clean Bypass turns the bypassed state into a second, clean preamp voice controlled by its own Tone and Volume knobs, which KSR positions as a way to drive a power amp directly5.
Power and connections: 9V, 100mA
The Ceres ONE runs on a standard 9V DC input that requires at most 100 mA to function1. KSR lists a compatible 9V, center negative, 500 mA power supply for its pedals, so the pedal follows the common center-negative convention used by most pedalboard power supplies1.
The 100 mA draw means the Ceres ONE can share a typical isolated power supply output, but the 9V DC input is a power jack, not a battery compartment; the pedal needs an external supply.
Jack placement is designed for pedalboard integration. Looking at the front of the pedal, the top right jack is the input, then the 9V power in, then the output, all top mounted so patch cables and power run along the back edge of the board1. The external Control port sits on the bottom left side5. Top mounted jacks allow for easy integration into an existing pedalboard4.
The Control port itself is a 3.5mm (1/8″ headphone) TRS jack that allows control of the pedal's channels and future expansion via momentary contact closure relays4. In practice, that means an external switching device can change the pedal's channels, with the relay-based design leaving room for KSR to add functions later.
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Questions
Is the KSR Ceres ONE true bypass?
It offers three bypass modes through its Bypass Mode switch: True Bypass, Buffered Bypass, and Clean Bypass. In True and Buffered bypass the pedal operates with no tonal coloration, so True Bypass suits hitting a clean amp further down the pedalboard. Clean Bypass instead engages the top row of Tone and Volume knobs to drive the pedal's Clean channel.
Where is the KSR Ceres ONE made?
It is built completely in KSR Amps' Cincinnati facility. CNC machining, powder coating, laser etching, silk screening, and circuit board assembly are all performed in house, with no outsourcing.
Which KSR amps does the Ceres ONE Mode switch reference?
The three positions reference KSR's amplifier lineup: Up is the Ares/Orthos Crunch sound, Center is the Artemis/Gemini Red Mode, and Down is the Colossus Lead 1. All three modes carry added usable gain compared with the original Ceres.
What does the Control port on the Ceres ONE do?
The Control port is a 3.5mm (1/8 inch) TRS headphone-style jack that allows control of the pedal's channels and leaves room for future expansion via momentary contact closure relays. It sits on the bottom left side of the pedal.
Does the Ceres ONE have a mute function?
Yes. The footswitch button activates the pedal's gain channel, and holding it activates a mute function.
Sources (5)
- IN STOCK! Ceres ONE™ Orange Matte Black knobs, KSR Amps, 2025-11-03
- Home - KSR Amps, KSR Amps, 2017-02-22
- Home - KSR Amps, KSR Amps, 2017-02-22
- IN STOCK! Ceres ONE™ Black Matte Orange knobs, KSR Amps, 2025-11-03
- IN STOCK! Ceres ONE™ Midnight Fade, KSR Amps, 2025-11-03
