Celsus SP-ONE

Active model: MSRP $499 USD; Passive model: MSRP $399 USD

Spacious sound stage, commanding bass, exemplary coherence and musicality

The Celsus SP One stands above bookshelf speakers in its price range for its superior sonic characteristic and stunning good looks. The enclosure is made of a dense, premium-quality, naturally finished bamboo. The bamboo cabinet changes its hue with variations in room and natural lighting. One cannot fully appreciate this until he or she sees the speaker up close. It asks to be caressed. The grey anodized aluminum front panel and carbon fiber driver complete the stylish look.

Size notwithstanding, the Celsus SP-ONE speaker can fill a room with audiophile-quality sound. The SP-ONE’s expansive soundstage, commanding bass and overall musicality puts it at the forefront of bookshelf designs. For more personal applications, the SP-ONE’s excellent nearfield characteristics, especially at low volume settings, makes it the perfect desktop companion.

Celsus SP-ONE comes in two models. The Active model includes power amplifier and bluetooth wireless audio where it can be used as a standalone wireless speaker or to receive music from external source device. For audiophiles who want to get the best performance out of SP-ONE's unique speaker driver and acoustic design, they can consider using an external high performance amplifier with the Passive model.

Note: A small batch of the initial production has right speaker with logo on the lower right corner and left speaker with logo on the lower left corner. For subsequent productions all the left and right speakers will have logo on the lower right corner.

Features that enable SP-ONE to outperform similar speakers

  1. 1. Deep Bass Carbon Fiber Woofer:
      a) Carbon fiber cone: A carbon-fibre cone woven from thousands of ultra-fine carbon fiber yarn features these advantages:
    • The rigidity (Young's modulus) is three times that of glass fiber, twice that of Kevlar fiber, and 20 times the strength of iron. It effectively inhibits split-vibration frequency distortion, resulting in minuscule dynamic deformations.
    • Low mass (lighter than aluminum) permits high electro-acoustic conversion efficiency with the ability to closely follow the electrical signal's transient response, with the added benefit of high sensitivity and an impressive SPL.
    • High damping factor
    • Insensitive to changes in humidity and temperature, thus offering excellent stability over long periods of time.

The carbon-fiber cone produces dynamic and powerful bass, smooth, detailed sound and a wide sound stage.

b) Patent pending folding ring design.

Typical Design

SP-One Woofer Design

For small and mid size speakers, the traditional folding ring design has a deficiency that resulted in 10dB frequency curve valley in the 2kHz region. This will affect the vocal richness of the music. The Celsus Sound folding ring design solves this dynamic nonlinear distortion problem and improves overall frequency response.

  1. 2. Tweeter: soft dome, horn-loaded driver for a wide dispersion of highs – a design that lowers the crossover frequency in order to achieve a flatter frequency response. The soft-dome tweeter’s high-energy magnetic flux and self-cooling capability together produce an audibly clearer signal.
  1. 3. Frequency Division: Cross over design using premium parts

  2. 4. The SP-ONE’s double cavity allows for a bass reflex design capable of delivering powerful dynamics.

  1. 5. CD-quality Bluetooth sound: together, the 4.0 Bluetooth transmitter and receiver module with aptX technology plus the SP-ONE’s noise-reduction circuit deliver CD-quality sound.
  1. 6. Optimized Active Speaker Design: the SP-ONE audiophile-grade power amplifier‘s specific compatibility with speaker and Bluetooth module bring to life a vast, imposing soundstage rich in the music’s smallest details.


  • Enclosure is made of a dense, premium-quality, naturally finished bamboo*
  • Carbon Fiber Woofer with folding ring structure and custom-designed magnet together produces 50Hz deep bass and the most coherent sound.
  • Soft dome, horn-loaded tweeter for a wide dispersion of highs
  • Double cavity cabinet design allows for deep bass and powerful dynamics.
  • Optimized active speaker design

*Many lookalike speakers use bamboo designed skin on MDF wood

Passive Speaker Specifications:

Frequency Response: 50Hz to 20kHz Impedance: 6 Ohms Power Rating: 60W Sensitivity: 88db
Dimension (H x W x D): H195 X W130 X D180mm Weight: 2Kg/unit Package Weight: 6.2Kg/pair    

Active Speaker Specifications:

Frequency Response: 50Hz to 20kHz Impedance: 6 Ohms Power Rating: 60W Sensitivity: 88db
Inputs: Bluetooth & Line In Power Supply: AC adapter (DC19.5V, 3.16A) Dimension (H x W x D): H195 X W130 X D180mmrong>    
Weight: 2.3Kg/unit Package Weight: 6.7Kg/pair 5V DC charging Port for external accessory