FM 214 Precision Balanced Line Driver and

FM 216 Precision Line Level Interface

Problemsolvers: the FM ACOUSTICS Line Level Interfaces remain absolutely transparent while providing the ultimate solution for balancing / unbalancing equipment.
Problemsolvers: the FM ACOUSTICS Line Level Interfaces remain absolutely transparent while providing the ultimate solution for balancing / unbalancing equipment.
  • The FM 214 and FM 216 are employed in a variety of professional and domestic applications and are welcome problem solvers that impove reproduction.

  • The FM 214 interfaces single-ended/unbalanced outputs of all audio equipment such as CD players and converters, DVD players, preamplifiers, audio mixers, tape machines, digital audio workstations, console monitoring sections etc. and converts the signal into an accurate balanced signal with ultimate CMRR (Common Mode Rejection Ratio). Interfacing between unbalanced and balanced units is optimized which results in more accurate reproduction.


  • In domestic use the applications are similar. Any source be they CD players, converters, preamplifiers or whatever will sound more accurate when the FM 214 is connected to their unbalanced outputs - this even if the source equipment has its own so-called 'balanced' outputs (most of the time these are just simple phase inverter circuits hat are pseudo-balanced, not true balanced at all).
  • The FM 216 offers the inverse function and operates as precision interface when balanced signals must be attenuated and converted to a single-ended signal, e.g. from a balanced preamp output to a subwoofer with unbalanced -10dB input.
  • The FM 214 and FM 216 are the only interface units which guarantee uncoloured reproduction. Both units:
  • provide perfect interfacing between components
  • are totally transparent
  • have no compression
  • are built with inherently distortion-free stages
  • feature extremely low hum and noise levels
  • are Ideal interface units for digital and analogue recorders, processors, mixing desks, CD and DVD players, preamplifiers, workstations etc.
  • preserve finest musical details
  • exceed the most demanding professional standards
  • provide perfect step response and superb rise time
  • have no time-based distortion or slew rate limitation
  • are totally free of overshoot and ringing
  • preserve the original dynamic range
  • yield superb results thanks to proprietary pure Class A circuitry built with selected discrete components
  • use no transformers, no op-amps, no IC's, no monolytic circuits, not even discrete op-amp circuitry
  • Internal ground-lift isolates electrical ground from chassis to avoid ground problems (e.g. when multiple interface units are installed in the same rack)
  • guarantee superb headroom reserves
  • come with a separate external power transformer for optimal hum and noise rejection and protection from ground loops
  • have precision on-board power supply regulation and stabilization
  • include delayed turn-on with automatic muting and instantaneous switch-off to protect loads
  • guarantee highest drive capability and precision signal transfer over very long distances (hundreds of meters). Units can drive any impedance (including highest inductances and capacitances - several 100nF! - with absolute stability).
  • are available with an optional 19" rack panel so up to 3 interface units can be rack mounted in a single rack space.
  • guarantee the ultimate accuracy of interfacing.

Their unique accuracy

guarantees that unbalanced signals from consumer, video, semi-pro and pro equipment remain pristine when interfaced with true balanced equipment operating at levels of +4dBv, +6dBv, at the nominal broadcast level of +8dBv or any other high level - this with absolutely unparalleled performance. With its superior headroom and the capability of delivering a maximum output of +28dBv (50Vpp), the 2-channel FM 214 and FM 216 exceed the most exacting standards of state-of-the-art recording and reproduction systems. Due to their capability of driving very difficult impedances and long cables without the headroom and drive limitation of the usual interface units and line buffers, the FM 214 and FM 216 instantly solve line drive and interface problems in critical applications.

By substituting these units for existing interface units, or by adding the FM 214 at the output of equipment with the usual mediocre output drive-circuits, an astounding performance improvement can be realized.

High quality domestic systems can be lifted to a superior balanced configuration.

The FM 216 complements the FM 214 in applications where a true precision step-down/un-balancing interface is required (for special applications its fixed attenuation of 14dB can internally be adjusted to any other level between 7dB and 60dB).

The FM 214 and FM 216 are the ultimate interface units, capable of resolving any level and/or impedance problem that arise between any kind of audio equipment.

These two units provide a breakthrough in accuracy of reproduction, being the only interface units available which guarantee no signal degradation and absolute transparency. These results have been verified under the most demanding of conditions in numerous state-of-the-art recording, mastering and broadcast facilities around the world.

One important aspect

which frequently is not given adequate attention is how the unit will perform with real world loads and real world cables connected to the output (sometimes hundreds of meters!). Within a given electronic circuit performance is quite predictable, as the input impedance of the next stage is clearly defined and the driving stage can then be optimized for this fixed and non-varying load impedance. An output line level stage, however, will in real world applications be asked to drive many different and varying loads (combinations of resistance /capacitance / inductance) - much like a power amplifier. To guarantee pristine signal transfer operation, it must therefore have a much more extended phase margin, absolute stability and high voltage and current drive capability without any limiting action of protection circuitry. Of course it must also be short-circuit proof.

FM ACOUSTICS' proprietary Class A output stages feature a dedicated circuit. They are capable of driving almost any length of cable and impedance with absolute stability and highest interference rejection. The majority of other products using line-level output stages are typical test bench designs that work well on the test bench (with correspondingly short cables and fixed resistive loads) but fail to perform adequately in real world applications. The best circuitry is of no use if the following stage and interface (cables and connectors) are not driven optimally. These are much underrated facts which critically influence the performance in actual system installations.

FM ACOUSTICS proprietary circuitry results in extremely stable, accurate and super-fast interfaces which can handle and supply levels of up to +28dBv at highest linearity, and do this also into highly capacitive and/or inductive loads. The resulting inherently distortion-free circuitry avoids any possibility of signal degradation and guarantees preservation of the finest musical details. The result is absolutely unparalleled accuracy and pristine signal transfer.
The improvement in performance over existing line drivers is astounding. Clear improvements are also experienced when adding the FM 214 to output stages of the existing equipment (it improves signal transmission between source and load) by ameliorating the output stage.

Using FM ACOUSTICS technology any possibility of signal degradation is avoided, and preservation of the finest musical detail is guaranteed. The result is absolutely unparalleled accuracy in interfacing and superior system performance. The improvement in performance compared with existing line drivers is astounding; once this difference is experienced, it becomes clear why the FM 214 and the FM 216 are such a success.


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Phone:  + 41-44-7257777

Fax:     + 41-44-7257790


Last updated : 23.04.2024