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EESM · FDA · AAIM / NIC

Zero distortion is not
a tuning problem— it is a physics problem.

BitDiamond rebuilds the transducer with magnetless electro-excited drive: the permanent-magnet gap is removed and force stays strictly proportional to input current. Combined with active magnetic bearing and active acoustic impulse management, a 1.5-litre micro-enclosure behaves as an infinite cavity, holding total harmonic distortion below 0.005%.

Explore the range Book a demo
The BitDiamond 16-unit acoustic tower: a gold faceted column with transparent diamond ballistic glass panels and a silver diamond-turned diaphragm
Acoustic span
2 kHz – 100 kHz
Total harmonic distortion
< 0.005%
Flagship tower height
1200 mm
All-digital drive noise floor
0.0005%
Positioning

The zero-distortion substrate

Not making coloration sound better — preventing it from happening in the first place.

Devialet uses ADH and SAM to make the amplifier track the speaker, KEF uses MAT to absorb enclosure standing waves, and Genesis uses GLM to calibrate the room. BitDiamond goes one level deeper: make the distortion not exist where it is created.

The harmonics of a moving-coil loudspeaker do not come from the diaphragm but from the non-linearity of the gap between the permanent magnet and the voice coil. EESM removes the permanent magnet: the coil’s own current generates the field, which interacts with an external bias field to produce Lorentz force. With no second magnetic material in the circuit, there is no magnetic saturation, no gap asymmetry and no thermal drift.

AMB is layered on top, holding the voice coil in the working air gap with no physical contact. Finally AAIM’s negative impedance converter actively cancels the rear-cavity sound pressure, making the 1.5-litre physical enclosure acoustically transparent. Chained together, that is what "ultra-pure water" means.

Acoustic diaphragm physics diagram: the natural opposition between rigidity and internal damping, and the answer given by a CVD diamond / CNT airbag-foam composite metamaterial
The core tension in diaphragm physics: stiffness and internal damping are natural opposites. The resolution is not a compromise but a composite sandwich — a CVD diamond skin carrying absolute stiffness, with an ultra-light aerogel core carrying all of the damping.
Technical base

Three technologies, one chain

From electromagnetic drive, to mechanical suspension, to active control of acoustic impedance — these are not parallel features but a causal chain, each stage enabling the next.

1
EESM
Magnetless Electro-Excited Speaker

Magnetless electro-excited system

The voice coil is driven directly by the Lorentz force, removing the gap non-linearity between the permanent magnet and the coil so that only a linear electrical-to-magnetic relationship remains between force and input signal.

  • Force linearity
    Strictly proportional to input current
    No permanent-magnet gap involved
  • Magnetic saturation
    None
    Magnetic circuit sustained by the coil itself
  • Transducer topology
    Lorentz-force drive
    No ferrite, no neodymium circuit
EESM-AMB transducer product manual: cutaway of the EESM electromagnetic drive structure and its acoustic topology
2
AMB
Active Magnetic Bearing

Active magnetic bearing

The voice coil floats inside an actively controlled magnetic field, and the suspension gap is compensated in real time by a microsecond-latency feedback loop that removes mechanical friction and non-linearity from the system entirely.

  • Suspension
    Fully active closed loop
    No physical contact wear
  • Position feedback
    Microsecond-latency loop
    Real-time compensation of manufacturing tolerances
  • Damping control
    Fully adjustable
    Prerequisite for AAIM
EESM transducer, integrated system and passive thermal design: the active magnetic bearing transducer module
3
AAIM / NIC
Active Acoustic Impulse Management & Network Impedance Control

Active acoustic damping and network impedance control

A negative impedance converter inverts and re-injects the acoustic output of the transducer rear chamber in real time, equivalent to turning a 1.5 L micro-chamber into an infinitely large one.

  • Equivalent cavity
    1.5 L → infinity
    Active cancellation of rear-chamber pressure
  • Vertical field attenuation
    -3 dB/m
    Conventional point source -6 dB/m
  • Total harmonic distortion
    < 0.005%
    Micro-displacement array strategy
Dynamic neural drive and integrated digital circuit logic: the AAIM active acoustic impulse management architecture
Product line

Three products, one acoustic base

Acoustic tower, low-frequency extension system and transducer module all share the same EESM / AMB / AAIM base.

All products →
Product render of the 16-unit acoustic tower: a gold faceted column with transparent diamond ballistic glass and a silver diamond-lathed diaphragm
AT-16
01 Flagship acoustic tower

16-Unit Acoustic Tower

A hexagonal honeycomb sealed enclosure with 16 × 120 mm EESM-AMB transducers stacked vertically delivers near-omni coverage through -3 dB/m vertical field attenuation.

  • Enclosure form
    120 × 140 × 1600 mm
  • Transducers
    16 × 120 mm EESM-AMB
  • Rear chamber volume
    1.5 L micro-sealed
  • Vertical field attenuation
    -3 dB/m
View technical details
3D product render of the Sub-Zero low-frequency extension system: a faceted bass system
SZ-1
02 Flagship low-frequency extension system

Sub-Zero Low-Frequency Extension System

A 5-inch FMLA sandwich composite diaphragm paired with dual 9.5-inch ultra-long-stroke drivers uses all-digital direct drive to push low-frequency error below the audible threshold.

  • Mid-bass driver
    5" FMLA sandwich composite diaphragm
  • Ultra-low driver
    2 × 9.5" ultra-long stroke
  • Amplifier
    700 W Class-D all-digital direct drive
  • Physical noise floor
    < 0.0005%
View technical details
Principle and structure deconstruction of the industrial 5-inch EESM test unit
ET-120
03 Core transducer module

EESM Coaxial Transducer

A 120 mm coaxial transducer module combining magnetless excitation with active magnetic levitation — the shared acoustic and mechanical foundation of the entire product line.

  • Diaphragm material
    CVD diamond / CNT airbag-foam composite
  • Diamond outer-skin sound speed
    17,320 m/s
  • Core layer density
    1/5 of a conventional paper cone
  • First breakup mode
    > 35 kHz
View technical details
Materials

Breakup: the dividing line for diaphragm linearity

A diaphragm’s first breakup decides the moment it stops behaving like a piston. Push that from 2 kHz past 35 kHz and the whole midrange curve finally has a chance to be straight.

Key physical parameters compared across conventional paper cone, metal diaphragm and CVD / CNT composite metamaterial.
Material Density Young's modulus Sound speed First breakup mode
Conventional paper cone ~0.5 g/cm³ ~2–6 GPa ~1,800–2,800 m/s 2 kHz – 4 kHz
Metal diaphragm — — ~12,450 m/s 15 kHz – 20 kHz
CVD / CNT composite metamaterial 1/5 of a paper cone 1,050 GPa (diamond matrix) ~17,220 m/s > 35 kHz
Implementation guide for acoustic metamaterials and COMSOL multiphysics simulation: coupled acoustic, structural and optical fields
Simulation chain: micro/nano machining parameters imported into the finite-element model → COMSOL coupling of acoustic, structural and optical fields → micro-displacement array strategy reaching THD < 0.005%.
Acoustic lab

From one prototype to one production line

The BitDiamond acoustic lab is not a showroom. It does three things: diaphragm process validation, magnetic circuit simulation and whole-unit acoustic calibration.

  • Diaphragm process validation

    AL7075-T6 precision tooling, hot-pressed at 130°C / 0.6 MPa, femtosecond laser trimming at 355 nm to ±0.01 mm.

  • Magnetic circuit simulation

    Glass alloy plus supersaturated soft-magnetic alloy closed into a magnetic circuit, with air-gap flux density B > 2.2 T.

  • Whole-unit closed-loop calibration

    IPAL-grade control chain: DSP dynamic prediction → FPGA main controller → 10-channel GaN FDA power stage.

Enter the lab →
An integrated digital audio amplifier in the lab: whole-unit commissioning and electroacoustic measurement station
Whole-unit tuning station
EESM diaphragm and suspension topology drawing: sandwich diaphragm structure, progressive wave mode and active metal spider suspension
EESM-TS-003 diaphragm and suspension topology
Diagram of the precision tooling and hot-press forming process for the 5-inch carbon-fibre / PMI sandwich composite diaphragm
5-inch composite diaphragm: hot-press forming and femtosecond laser trimming
Book a demo

Zero distortion has to be confirmed by ear.

Submit a request and we will set up a 45-minute controlled listening session: the same material, switched live between ultra-pure-water mode and warm-valve mode.

Request a demo → Read the technical detail first