Passive radiator (speaker)

Passive radiator (speaker)

A speaker enclosure using a passive radiator usually contains an "active driver" (or main driver), and a "passive cone" (or drone or passive radiator). The active driver is a regular driver, and the passive is typically the same or similar, but without a voice coil and magnet assembly. It is only a suspended cone, not attached to a voice coil or electrical circuit. The passive radiator usually has some means to adjust its mass, thereby allowing the speaker designer to change the box tuning. Internal air pressure produced by movements of the active driver cone moves the passive radiator cone as well.

Passive radiators are used instead of a reflex port for much the same reasons—to tune the small volume and driver for better low frequency performance. Especially in situations in which a port would be inconveniently sized (usually too long for practical box configurations). They are also used to eliminate port turbulence and reduce motion compression caused by high velocity airflow in small ports (especially small diameter ones). Passive radiators are tuned by mass variations (Mmp), changing the way their compliance interacts with motion of the air in the box. The weight of the cone of the passive radiator should be approximately equivalent to the mass of the air that would have filled the port which might have been used for that design. Passive radiators do not behave exactly as do (more or less) equivalent bass-reflex designs in that they cause a notch in system frequency response at the PR's free air resonant frequency; this causes a steeper roll-off below the system's tuned frequency Fb, and poorer transient response. Due to the lack of vent turbulence and vent pipe resonances, many prefer the sound of PRs to reflex ports. PR speakers, however, are more complex to design and likely to be more expensive as compared to standard reflex enclosures.

The frequency response of a passive radiator will be similar to that of a ported cabinet, with two exceptions. The system low frequency rolloff in a passive radiator design will be slightly steeper, and will have a notch (dip) in frequency response due to the Vas (compliance, or stiffness of the speaker cone) of the passive radiator. The goal in designing a passive radiator is to adjust the tuning so that this notch is below audible levels.

Misconceptions

In technical support circles, it has long been known that some owners of speaker cabinets featuring a passive radiator have taken the cabinet apart, and have come to the conclusion that someone (the manufacturer or salesperson) has taken advantage of them, by leaving out much of one of the drivers. They misconstrue the technology, and sometimes think the manufacturer put a fake speaker in the cabinet (since there is no magnet or wire) just to give the appearance of a larger more powerful speaker.


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • WOOx Technology — (rendered wOOx) is a brand created by Royal Philips Electronics to identify loudspeaker systems that employ passive radiator technology and active equalization to maximize the output of the passive diaphragm. wOOx technology is primarily… …   Wikipedia

  • Loudspeaker enclosure — A loudspeaker enclosure is a cabinet designed to transmit sound to the listener via mounted loudspeaker drive units. The major role of the enclosure is to prevent the out of phase sound waves from the rear of the speaker from combining with the… …   Wikipedia

  • Loudspeaker — For other uses, see Loudspeaker (disambiguation). An inexpensive, low fidelity 3½ inch speaker, typically found in small radios …   Wikipedia

  • Bass instrument amplification — for the bass guitar, double bass and similar instruments is distinct from other types of amplification systems due to the particular challenges associated with low frequency sound reproduction. This distinction affects the design of the… …   Wikipedia

  • Thiele/Small — commonly refers to a set of electromechanical parameters that define the specified low frequency performance of a loudspeaker driver. These parameters are published in specification sheets by driver manufacturers so that designers have a guide in …   Wikipedia

  • Bowers & Wilkins — Type Private Industry Consumer electronics Founded 1966 Headquarters …   Wikipedia

  • Digital Sound System 80 — The Digital Sound System 80, short DSS80, was a three piece PC audio system co developed by Microsoft and Philips. It debuted on the 1998 Electronic Entertainment Expo (E³) and is most likely the only speaker system ever released by the Microsoft …   Wikipedia

  • Air Motion Transformer — The Air Motion Transformer (AMT) is a loudspeaker mechanism, or audio transducer, invented by Dr. Oskar Heil. It operates on a different principle than both electrodynamic and electrostatic speaker drivers. The AMT moves air in an augmented, semi …   Wikipedia

  • ESS speakers — ESS (ElectroStatic Sound) was a company that was based in Sacramento California. They were one of the only manufacturers of Heil Air Motion Transformer. Consumer Products The AMT was first used in 1970 by ESS (ElectroStatic Sound) a Californian… …   Wikipedia

  • Audio crossover — A passive 2 way crossover designed to operate at loudspeaker voltages Audio crossovers are a class of electronic filter used in audio applications. Most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”