A1.5 Two-channel Power Amplifier

Like its bigger brother, the M1.1 Reference power amplifier, there’s a lot more to the A1.5 than meets the eye – just in a more compact and more affordable form

“Importantly, the improvements result in a more musically engaging delivery. The A1.5 is nothing short of a giant killer amp. Yup: miracles do exist! Even at 3 minutes into the listening session, I already knew that there was no way back!”

CHRISTIAN PUNTER, HIFI-ADVICE.COM

Product Description

Faced with exactly the same challenges as the M1.1, the A1.5 embodies the same sophisticated, modular and scalable approach. It might be (slightly) smaller than the M1.1 and around two-thirds of its weight, but it’s still four amplifiers in one. It still offers the same adaptable, software controlled topology, adjustable input configuration and gain, user selectable global feedback ratio and cost-effective upgrade path. It offers exactly the same, incredibly short signal path, fully discrete, fully balanced and fully complementary circuit, built with the same carefully selected components to the same exacting standards. Even the casework, although shorter, has the same footprint, uses the same construction and includes the same mechanical grounding/stacking system. In fact, in every important way, the A1.5 is, quite literally, an M1.1 writ small – or, in Hollywood terms, “Honey, I shrank the amp…”.

Read more (PDF)

Physical And Conceptual Modularity

  • Modular input boards to match system topology (one or two inputs as required)
  • Output stage can deliver 2x 150W RMS into 8 Ohms stereo, 150W into 8 Ohms mono (high-current), 550W mono (bridged) or 2x 150W bi-amped (single input, differential channel gain and global feedback settings)

Analog Input Stage

  • Pure class A, fully symmetrical circuit topology
  • Fully discrete, ultra low noise, high slew rate design
  • DC coupled with no series capacitors in the audio signal path
  • Gain adjustable through 24dB in 0.5dB steps

Analog Output Stage

  • Pure class A ultra low noise driver and class AB pure follower power stage
  • ExactBias circuitry ensures constant bias, independent of room temperature and amplifier loading
  • Constant monitoring of output power and temperature
  • User configurable display will show amplifier status, power output etc
  • Customized Argento loudspeaker binding posts, accept spades and banana connectors

Power Supply

  • 1700VA power transformer mounted on separate, mechanically isolated chassis bed to eliminate mechanical vibration
  • Magnetically and electrostatically shielded transformers to reduce noise and EM interference
  • Hyper fast, soft recovery diode bridge rectifiers meet dynamic demands without strain
  • Twin 82,000uF custom-built, ultra low ESR reservoir and filtering capacitors

User Adjustable Global Feedback

  • Ratio of Global to Local Feedback can be adjusted from 0% to 100%, in six steps (0, 10, 20, 40, 70, 100%) via the user interface or control app
  • Allows user optimization of amplifier/speaker interface, especially lowfrequency damping relative to speaker/room interaction
  • Each channel can be adjusted individually to control specific drivers/ranges in bi-amplification modes

Light Touch Protection

  • No output relay in signal path; full short circuit protection
  • Non-invasive output stage voltage, current and temperature monitoring protects your amplifier – and your speakers

Optional Hardware Monaural Analog Input Board

  • Option board needed for stereo and active applications (only buy the inputs you need)
  • XLR, RCA and 75 Ohm BNC inputs
  • Balanced pass-through for daisy-chaining amplifiers in multi-amp systems
  • Existing A1 amplifiers factory upgradable to full A1.5 specification

Technical Specifications

Nominal input voltage
2.2V RMS balanced
1.1V RMS single-ended

Input impedance
94kΩ balanced
47kΩ or 300Ω single-ended

Output power
2x 150W / 8Ω, 2x 275W / 4Ω, 2x 450W / 2Ω in stereo and bi-amp modes
1x 275W / 4Ω, 1x 450W / 2Ω, 1x 700W / 1Ω in monaural mode
1x 550W / 8Ω, 1x 800W / 4Ω, 1x 1200W / 2Ω in bridge mode

Bandwidth
DC to 450kHz (-3dB) at 1W into an 8Ω resistive load

Signal to Noise Ratio
> 115dB in stereo and bi-amp modes
> 118dB in bridge mode

Total Harmonic Distortion + Noise
< 0.1% (0% global feedback) < 0.01% (100% global feedback) Max power consumption
1800W

Dimensions/Weight
440 x 440 x 198mm (W x D x H), 47kg

A1.5 Specific Downloads

Some of our awards

View all of our awards