: ''This article relates to loudspeaker driving. See

Zobel network : ''For the wave filter invented by Zobel and sometimes named after him see m-derived filters.'' Zobel networks are a type of filter section based on the image-impedance design principle. They are named after Otto Zobel of Bell Labs, who pub ...

for a more general description of telecommunications usage.'' A Boucherot cell (or Zobel network) is an

electronic filter Electronic filters are a type of signal processing filter in the form of electrical circuits. This article covers those filters consisting of lumped electronic components, as opposed to distributed-element filters. That is, using component ...

, used in

audio amplifier An audio power amplifier (or power amp) is an electronic amplifier that amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspea ...

s to damp high-frequency oscillations that might occur in the absence of loads at high frequencies. Named after Paul Boucherot a Boucherot cell typically consists of a

resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias activ ...

and

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of a ...

in series, usually placed across a load for stability. It is commonly seen in analog power amplifiers at the output of the driver stage, just before the output inductor. The speaker coil inductance of a loudspeaker generates a rising impedance, which is worsened by the output inductor generally found in analog power amplifiers; the cell is used to limit this impedance.Zobel network or Zobel filter
in AES Professional Audio Reference. The documentation for some power operation amplifiers suggests the use of a "Boucherot cell between outputs and ground or across the load". Additionally, Boucherot cells are sometimes used across the bass driver (and mid-range) of a speaker system, in order to maintain a more constant

driving point impedance Driving is the controlled operation and movement of a vehicle, including cars, motorcycles, trucks, buses, and bicycles. Permission to drive on public highways is granted based on a set of conditions being met and drivers are required to f ...

as "seen" by a passive crossover. In this specific arrangement, the Boucherot cell is sometimes also known as a

. Some loudspeaker crossover designs aim to stabilize impedance at high frequencies by including Zobel networks.Bell Labs Journal: Zobel, O. J., "Theory and Design of Uniform and Composite Electric Wave Filters", Bell Sys. Tech. J., Vol. 2, pp. 1–46, Jan 1923.

References

{{Reflist Electronic circuits Filter theory de:Boucherot-Glied

See also

References