Amphion BaseOne25 System Passive Subwoofer with Amplifer


Passive 10″ long-throw woofer with passive 10″ aluminum radiator, birch plywood cabinet, and Neutrik Speakon connector, plus 500W BaseAmp500 power amplifer

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SKU: AMPBASEONE25 Categories: , Brand:

The Amphion BaseOne25 is an all-in-one bass-extension system with passive radiator subwoofer, two extension towers that serve as stands for Amphion monitors, and 500-watt crossover/amplifier with foot-switchable bypass

The Amphion BaseOne25 bass extension system is just about adding a subwoofer to your existing monitor array. It’s an extremely well-thought-out all-in-one system that gives you a true, full-range monitoring experience with a breathtaking three-dimensional soundscape that puts you in the room with the musicians. With bass extension down to an impressive 20Hz, the BaseOne25 doesn’t just give you bass management, it improves dynamic range while minimizing overall distortion, since all the low-end energy is handled separately from the rest of the audible spectrum.

Amphion BaseOne25 bass extension system in one take:

  • Complete, all-in-one bass extension system
  • BaseAmp500 crossover/power amp; 2x500W
  • Full-range/monitor only button and latching foot-switch input
  • Integrated monitor stands
  • Passive-radiator subwoofer
  • Handmade to exacting specifications
  • BaseAmp500 crossover/power amp

The Amphion BaseOne25 also includes the 500-watt BaseAmp500 crossover/amplifier module, matched to the BaseOne25 passive subwoofer. It features Marten’s patented adaptive modulation servo amplifier technology, which provides wide bandwidth, ultra low distortion, and high power output. Meticulously hand-wired and assembled with only the finest components, the BaseAmp500 front panel has bypass switch and indicator, power switch and indicator, and a bass-level rotary control below 100Hz, for matching the system to your main monitors. The rear panel has stereo XLR inputs and stereo XLR outputs for the main monitor amp, speaker outputs for the BaseOne25 subwoofer, an auto-voltage switching power connector for global use.

Full-range/monitor only button and latching foot-switch input

The front panel full-range/ monitor only switch is a true hard-wired bypass that also functions when the unit is off. The bypass enables you to make instantaneous A/B comparisons between full range and just monitors. There is also a rear-panel latching bypass footswitch input (1/4″) in case the BaseAmp500 is racked away from easy reach.

Integrated extension towers

The BaseOne25 also includes extension towers that serve as stands for existing studio monitors, thus achieving greater phase coherence and time alignment by physically integrating the subwoofer with your monitors. The BaseOne25 has a 10″ long-throw, aluminum woofer and 10″ aluminum passive radiator, with a Neutrik Speakon connector. The extension cabinets are made from 1″ (35 mm) birch plywood with high-tensile, machined steel reinforcement pins, and 3/16″ (5 mm) steel support plate/energy dispersion ring.

Passive radiator for deep controlled bass

The passive radiator is a diaphragm or speaker that doubly serves to cover inconveniently large ports and increase bass response. The radiator vibrates in sympathy with the low-frequency driver. Passive radiators maintain the same low-frequency response regardless of volume—hence the BaseOne25 providing exceptional tonal balance and sound stage at lower and more comfortable listening levels.

Handmade in Finland to exacting specifications

Amphion comprises a small, dedicated team of highly skilled craftsmen and technicians who are passionate about music and sound. All Amphion monitors and amplifiers are meticulously hand-built to impeccable standards, with high specs and tolerances. The result is a range of high-end monitors that enable audio professionals to focus on the mix, not the sound of the speaker.

Who’s using Amphion?

Among the growing list of mixers, engineers, sound editors, and composers taken with the Amphion sound, are pro audio luminaries such as Dave Pensado, Jacquire King, multiple Grammy winner Dave Reitzas, BAFTA award-winning composer, Jasper Kyd, and the legendary Bruce Swedien, engineer and mixer of the world’s best-selling album, Michael Jackson’s Thriller (which, by the way, was recorded right here at our very own Westlake Studios).

The Amphion BaseOne25 provides a complete solution to seamlessly transform Amphion studio monitors to a true stereo system with an astoundingly three-dimensional sound stage. For more information, call or chat online with your Westlake Pro sales consultant today.


BaseOne25 speaker specifications:

  •  Speaker: 10″ aluminum, long-throw
  • Operating principle: One-way Passive Radiator: 10″ aluminum
  • Frequency response: 20Hz – 100Hz; ±3dB
  • Crossover: 100Hz
  • Connector: 1x Neutrik Speakon
  • Dimensions (H x W x D): 37-5/8″ x 7-17/32″ x 15-3/16″ (956 x 191 x 386 mm)
  • Weight: 90.3 lb. (41 kg)

 Amphion BaseAmp500 specifications:

  • Power: 2x500W into 2 ohm @ 1% THD; 2x330W @ 4 ohm; 900W Bridge tied load (BTL) into 4 ohm @ 1% THD
  • Amp technology: Patented AMS (adaptive modulation servo) amplifier technology
  • Load-independent frequency range: 100kHz (-3dB)
  • THD vs. frequency: Almost flat
  • Dynamic range: 115dB
  • Output impedance: <10M ohm 20Hz – 20kHz
  • Mains: Automatic voltage doubler for universal use (115/230V)
  • Certification: CE, EuP, and Energy Star
  • 2U High-quality aluminum rackmount chassis with front-panel power switch
  • Connectors: 2 x Neutrik XLR inputs; stereo outputs for main monitor amp and for BaseOne25 speakers
  • Power Switch: Front; bypass switch (front) and bypass latching input footswitch (rear)
  • Dimensions (W x H x D): 19″ x 3-5/8” x 10-1/4″ (483 x 88 x 260 mm)
  • Weight: 12 lb. (5 kg)

Additional information


2x Speakon, XLR

Frequency Response

20Hz – 100Hz




2x 10"


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