Description
BaseTwo25 is a bass extension system, which transforms a 2-way monitor into a 3-way full range system. The system consists of a 2U crossover/amplifier unit and two identical, double-sided extenders. Each side of the extender has a long-throw 10” woofer at the top and a matching passive radiator below. For the best possible integration, extenders also act as a monitor stand. Due to the benefits of force cancellation, the extenders remain stable even during the most demanding bass tracks.
BaseTwo25 has four possible crossover settings: 40 Hz, 60 Hz, 80 Hz, and 100 Hz.
For optimal integration BaseTwo25 creates an additional crossover point and transforms your 2-way monitor into a cohesive 3-way full range system. BaseTwo25 improves power-handling and reduces the intermodulation distortion of the mid-woofers. The best crossover-setting depends on the monitor and listening level.
The system has a by-pass option for those moments when you want to use your monitors for a narrower midrange view. The by-pass is selectable via foot-switch or a push button on the front plate of the BaseAmp. BaseTwo25 works with all Amphion products, as well as with monitors that have sufficient speed and resolution in the critical upper-bass/lower-mid frequencies.
Stereo to the lowest octave
Amphion’s introduced their first Base Extension system in 2015. The concept of keeping stereo information all the way down has become widely adopted since.
Seamless integration
Designed to work seamlessly with all monitor sizes. System can even be paired with a smaller model for an ultra-fast, easy to adjust small room full-range system.
Elevate your monitors
As the bass frequencies are transferred to the Base system, the midrange clarity and power-handling of the paired monitors are greatly enhanced.
Industry-defining clarity
Force-cancelling driver configuration and highest quality components lead into industry-defining clarity, control, and low frequency detail.
Simple setup
Always placed under the monitors. Fixed placement and physical proximity between the monitor and bass extender ensure perfect integration.
2-way, 3-way or Amphion way?
Simplicity of a 2-way monitor or the power handling of a 3-way design? The system can easily switch between both with a push of a button or foot switch.
BaseTwo25 Technical Specifications:
Operating Principle | One way with passive radiator, stereo |
Drivers | 4 x 25cm aluminium driver, 4 x 25cm aluminium radiator |
Crossover | Active 4th-order selectable @ 40, 60, 80, 100 Hz |
Max SPL | 127dB |
Frequency Response | 20 Hz – 100 Hz +/-3dB (low pass) |
100 Hz – 200 kHz +/-3dB (high pass) | |
Connection | 3.5m long, terminated with 4-pole Neutrik |
Speakon connectors | |
Measurements (H x W x D) | 360 x 958 x 386 mm |
Weight | 2 x 32 kg |

1. Power Button
2. Active Button
3. Crossover Frequency
4. Level

BaseAmp1200 Technical Specifications:
Output Power | 2 x 700 W (4 Ω) |
THD+ noise | @ 10W: 0,0025% |
@ 100W: 0,0015% | |
Dynamic Range | 127 dB (A) |
Efficiency | 230 V / 50 Hz – 700 W |
Standby Mode | ErP (1275/2008/EC), Energy Star® v3.0 compliant |
Mains | Universal mains including Power Factor Correction (100 – 240V) |
Casing | 19” rack mountable (2U) high quality aluminium |
Weight | 6 kg |
Assembled in Finland