: ''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 publish ...

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 components ...

, 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 Paul Boucherot (1869–1943) was an engineer with the Chemins de Fer du Nord (Northern Railway of France). He studied at the elite École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI) where he later also taught e ...

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 active el ...

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 ...

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 fol ...

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